Search

The diverse biomolecular landscape of tissue-specific decellularized extracellular matrix (dECM) biomaterials provides a multiplicity of bioinstructive cues to target cells, rendering them highly valuable for various biomedical applications. However, the isolation of dECM biomaterials entails cumbersome xenogeneic enzymatic digestions and also additional inactivation procedures. Such, increases processing time, increments costs and introduces residues of non-naturally present proteins in dECM formulations that remain present even after inactivation. To overcome these limitations, herein we report an innovative conjugation of light and ultrasound-mediated dECM biomaterial processing for fabricating dECM biomaterials. Such approach gathers on ultrasound waves to facilitate dECM-in-liquid processing and visible light photocrosslinking of tyrosine residues naturally present in dECM biomaterials. This dual step methodology unlocked the in-air production of cell laden dECM hydrogels or programmable dECM hydrogel spherical-like beads by using superhydrophobic surfaces. These in-air produced units do not require any additional solvents and successfully supported both fibroblasts and breast cancer cells viability upon encapsulation or surface seeding. In addition, the optimized photoacoustic methodology also enabled a rapid formulation of dECM biomaterial inks with suitable features for biofabricating volumetrically defined living constructs through embedded 3D bioprinting. The biofabricated dECM hydrogel constructs supported cell adhesion, spreading and viability for 7 days. Overall, the implemented photoacoustic processing methodology of dECM biomaterials offers a rapid and universal strategy for upgrading their processing from virtually any tissue. Leveraging decellularized extracellular matrix (dECM) as cell instructive biomaterials has potential to open new avenues for tissue engineering and in vitro disease modelling. The processing of dECM remains however, lengthy, costly and introduces non-naturally present proteins in the final biomaterials formulations. In this regard, here we report an innovative light and ultrasound two-step methodology that enables rapid dECM-in-liquid processing and downstream photocrosslinking of dECM hydrogel beads and 3D bioprinted constructs. Such photoacoustic based processing constitutes a universally applicable method for processing any type of tissue-derived dECM biomaterials. [Display omitted] [ABSTRACT FROM AUTHOR]

Although several technologies have been developed to isolate cells of interest from a heterogenous sample, clogging and impaired cell viability limit such isolation. We have developed the Enrich TROVO system as a novel, nonfluidic technology to sort live cells. The TROVO system combines imaging-based cell selection and photo-crosslinking of (gelatin methacrylate) gelMA-hydrogel to capture cells. After capture, cells are released by enzymatic digestion of the hydrogel and then retrieved for downstream analysis or further cell culturing. The system can capture cells with a recovery rate of 48% while maintaining 90% viability. Moreover, TROVO can enrich rare cells 506-fold with 93% efficiency using single step isolation from a 1:104 cell mixture, and can also capture one target cell from 1 million cells, reaching an enrichment ratio of 9128. In addition, 100% purity and 49% recovery rate can be achieved by a following negative isolation process. Compared to existing technologies, the TROVO system is clog-resistant, highly biocompatible, and can process a wide range of sample sizes. • A fluidics free platform to isolate rare cells from complicated samples. • Touchless, high throughput capture via parallel micro light beams. • Image based phenotypes used as sorting criteria. • Flexible isolation strategies such as positive and negative capture. • CTCs, cell pools, cell-cell interaction events can be visualized and isolated. [ABSTRACT FROM AUTHOR]

In tissue engineering, crosslinking with carbodiimides such as EDC is omnipresent to improve the mechanical properties of biomaterials. However, in collagen biomaterials, EDC reacts with glutamate or aspartate residues, inactivating the binding sites for cellular receptors and rendering collagen inert to many cell types. In this work, we have developed a crosslinking method that ameliorates the rigidity, stability, and degradation rate of collagen biomaterials, whilst retaining key interactions between cells and the native collagen sequence. Our approach relies on the UV-triggered reaction of diazirine groups grafted on lysines, leaving critical amino acid residues intact. Notably, GxxGER recognition motifs for collagen-binding integrins, ablated by EDC crosslinking, were left unreacted, enabling cell attachment, spreading, and colonization on films and porous scaffolds. In addition, our procedure conserves the architecture of biomaterials, improves their resistance to collagenase and cellular contraction, and yields material stiffness akin to that obtained with EDC. Importantly, diazirine-crosslinked collagen can host mesenchymal stem cells, highlighting its strong potential as a substrate for tissue repair. We have therefore established a new crosslinking strategy to modulate the mechanical features of collagen porous scaffolds without altering its biological properties, thereby offering an advantageous alternative to carbodiimide treatment. This article describes an approach to improve the mechanical properties of collagen porous scaffolds, without impacting collagen's natural interactions with cells. This is significant because collagen crosslinking is overwhelmingly performed using carbodiimides, which results in a critical loss of cellular affinity. By contrast, our method leaves key cellular binding sites in the collagen sequence intact, enabling cell-biomaterial interactions. It relies on the fast, UV-triggered reaction of diazirine with collagen, and does not produce toxic by-products. It also supports the culture of mesenchymal stem cells, a pivotal cell type in a wide range of tissue repair applications. Overall, our approach offers an attractive option for the crosslinking of collagen, a prominent material in the growing field of tissue engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

Visible light-induced photocrosslinking techniques have attracted significant attention for their flexibility, controllability, safety, and energy conservation, especially in tissue engineering and biofabrication, compared to UV photocrosslinking. Despite these advantages, current photoinitiators are constrained by various challenges, including inadequate photoinitiation efficiency, low biocompatibility, poor water solubility, and limited compatibility with diverse crosslinking systems. Here, a water-soluble derivative of riboflavin, flavin mononucleotide (FMN−), was used to assess its potential as an initiator in multiple-photocrosslinking systems, including radical photopolymerization, dityrosine, and ditryptophan coupling crosslinking, under blue light irradiation. Blue light irradiation facilitated an efficient electron transfer reaction between FMN− and persulfate, owing to their suitable spectral compatibility and photoactivity. The resulting oxidizing free radicals and excited triplet state of FMN− served as initiating active species for the multiple-photocrosslinking reactions. The combination of FMN− and potassium persulfate (KPS) exhibited exceptional photoinitiation efficiency for various biomaterials, including silk fibroin, gelatin, poly(ethylene glycol) diacrylate, and carboxymethyl cellulose modified with amino acids. Furthermore, the cytocompatibility of the FMN−/KPS photoinitiator was demonstrated by the survival rates of 3T3-LI fibroblasts encapsulated in it, which exceeded 95 % when compared to a commercial initiator. By introducing persulfate, the photoinitiation efficiency of flavin mononucleotide was significantly improved. The application scenarios of flavin mononucleotide and persulfate combinations were also greatly extended, including radical photopolymerization, dityrosine, diphenylalanine, and ditryptophan coupling crosslinking. Among them, the coupling crosslinking of amino acids (di-phenylalanine, and di-tryptophan) modified carboxymethyl cellulose, to our knowledge, was first reported. The excellent cytocompatibility of cell encapsulation further proved that the combinations of flavin mononucleotide and persulfate have great potential in tissue engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

The two-signal model of T cell activation has helped shape our understanding of the adaptive immune response for over four decades. According to the model, activation of T cells requires a stimulus through the T cell receptor/CD3 complex (signal 1) and a costimulatory signal 2. Stimulation of activatory signals via T cell agonists has thus emerged. However, for a robust T cell activation, it necessitates not only the presence of both signal 1 and signal 2, but also a high signaling strength. Herein, we report a photo-activable nano-agonist for the two-signal model of T cell in vivo activation. A UV-crosslinkable polymer is coated onto upconversion nanoparticles with satisfactory NIR-to-UV light conversion efficiency. Then dual signal molecules, i.e. , signal 1 and signal 2, are conjugated to the polymer end to yield the photo-activable T cell nano-agonist. In melanoma and breast cancer models, photo-activable nano-agonist could bind onto corresponding activatory receptors on the surface of T cells, but has limited activity without the application of NIR light (absence of photo-crosslinking of receptors and consequently a poor signaling strength). While when the NIR light is switched on locally, T cells in tumor are remarkably activated and kill tumor cells effectively. Moreover, we do not observe any detectable toxicities related to the photo-activable nano-agonist. We believe with two activatory signals being simultaneously strengthened by local photo-switched crosslinking, T cells realize a robust and selective activation in tumor and, consequently contribute to an enhanced and safe tumor immunotherapy. [Display omitted] • A photo-activable nano-agonist for T cell in vivo activation to achieve tumor suppression with safety. • Photo-clustering of activatory receptors on the cell surface improves the activation and expansion of T cells. • A chemical tool to manipulate cell behavior in situ which can be easily tailored for other therapies. [ABSTRACT FROM AUTHOR]

Photocrosslinkable gelatin has attracted increasing interest in the field of biofabrication, with the most studied and widely used photocrosslinkable gelatin being gelatin methacrylate (GelMa). However, the 3D fabrication of GelMa has presented several limitations and challenges, primarily due to its slow crosslinking speed. It is generally known that acryl-based functional groups have faster reaction kinetics than methacryl-base groups. However, gelatin acrylamide (GelAc) has not been widely investigated, largely due to its increased complexity of synthesis relative to GelMA. In this study, we developed a novel synthesis method for GelAc. By varying the reaction ratio of reagents, GelAc with a degree of substitution from 20% to 95% was produced. The UV crosslinking properties of GelAc was studied, demonstrating significantly faster crosslinking kinetics than GelMa, especially at lower concentrations and low photoinitiator concentrations. The swelling ratio and mechanical properties of the crosslinked GelAc hydrogel were also characterized, and biocompatibility experiments conducted via both surface seeding and hydrogel encapsulation of cells, with good cell viability observed. The application of GelAc for 3D biofabrication was demonstrated by 3D printing. GelAc can be a useful material for the fabrication of 3D conduits for tissue engineering applications. [ABSTRACT FROM AUTHOR]

A novel mussel-inspired adhesive hydrogel with enhanced adhesion based on methacrylated catechol-chitosan (MCCS) and dopamine methacrylate (DMA) was prepared via photopolymerization. The structure and morphology of the MCCS/DMA adhesive hydrogel were investigated by using FTIR, NMR, XRD, TG, and SEM. The rheological and texture properties, swelling and degradation characteristics, as well as the adhesion mechanism of the hydrogels were also examined. These results revealed that the MCCS/DMA hydrogels have a dense double cross-linking network structure with porous internal microstructures, and exhibited controllable swelling and degradation properties, good thermostability, and stable rheological characteristics. Furthermore, the adhesive mechanism of MCCS/DMA hydrogel has been confirmed by the FTIR and 2D correlation FTIR spectroscopy. Additionally, the results of in vitro cytotoxicity assessment indicated that the resulting hydrogels have good cytocompatibility. Overall, the MCCS/DMA adhesive hydrogel may have potential applications in medical bioadhesives. [ABSTRACT FROM AUTHOR]

In recent years, ionic conductive hydrogels have attracted significant attention in the wearable sensors field due to their simplified preparation process, cost- effectiveness, and high conductivity. However, a large amount of water in traditional hydrogels inevitably condense into ice at low temperatures and make them lose various properties in their practical applications. Hence, this study proposes a method to rapidly synthesized a water/glycerol binary anti-freezing hydrogel only in 10 s through photo-initiated free-radical polymerization. The introduction of LiCl into the crosslinked network composed of acrylamide (AAm) and poly (ethylene glycol) diacrylate (PEGDA) regulated the ionic conductivity of the hydrogel. The hydrogel exhibits a fracture strain of 1062.1 %, a tensile strength of 31 kPa, and an adhesive strength of 6.49 kPa. The synergistic effects of glycerol and LiCl imparted excellent anti-freezing properties (−60 °C). The three-dimensional network structure of the hydrogel facilitates ion transport, exhibiting superior conductivity (30.25 S/m), maintaining high conductivity capability of 1.46 S/m even at a low temperature of −55 °C. Notably, the hydrogel demonstrates prolonged durability and stability in real-time human motion monitoring applications while concurrently exhibiting remarkable sensitivity as an ECG sensor. Hence, this as-prepared hydrogel can adapt to extreme environments and deliver comprehensive performance as an ECG sensor. [Display omitted] [ABSTRACT FROM AUTHOR]

Urinary catheters necessitate a surface with antifouling and lubricating properties in order to mitigate bacterial infection, calculus formation, and tissue trauma. Hydrophilic coating is a promising strategy but suffers from the complications of the manufacturing method as well as the lack of longevity. Herein, we report an antifouling and lubricating hydrophilic coating based on zwitterionic copolymer poly(2-Methacryloyloxyethyl phosphatidylcholine- co -hydroxyethyl methacrylate-co-(Benzoyl)phenyl methacrylate (poly(MPC- co -HEMA- co -BP)) through pre-gel solution spin-coating followed by UV-curing. The poly(MPC- co -HEMA- co -BP (PMHB) coatings possess hygroscopic properties that facilitate the formation of a hydrated layer, thereby leading to friction reduction. Moreover, both antibacterial and protein resistance tests substantiate the exceptional antifouling characteristics exhibited by the PMHB coating. Furthermore, after 7 days of coincubation, the antibacterial rates of PMHB coatings against Escherichia coli (E. coli) , Staphylococcus aureus (S. aureus) , and Proteus mirabilis (P. mirabilis) are 72.98 %, 75.11 %, and 88.23 %, respectively. Subsequently, PMHB coating reduced the attachment of encrustation in a 7 days artificial urine cycling experiment. This study brings new perspective on designing urinary catheter surfaces with lubricating and antifouling properties. [Display omitted] • Development of a hydrogel coating based on zwitterionic polymers for urinary catheters using photo-crosslinking. • This coating exhibits superior antifouling and anti-encrustation properties. • Design concept provides new avenue for developing antibacterial and lubricant medical coatings. [ABSTRACT FROM AUTHOR]

Thermo-responsive hydrogels (thermogels), known for their sol-gel transition capabilities, have garnered significant interest for biomedical applications over recent decades. However, conventional thermogels are hindered by intrinsic physicochemical and functional limitations that impede their broader utility. This study introduces methacryl glycol chitosan (MGC) as a novel thermogel, offering enhanced functionality and addressing these limitations. MGCs, synthesized through N -methacrylation of glycol chitosan, exhibit tunable thermogelling and photo-crosslinking behaviors. The thermo-reversible sol-gel transition of MGCs occurs within a 21–54 °C range, adjustable by polymer concentration and methacryl substitution degree. Photo-crosslinking using UV light further enhances the mechanical properties of MGC thermogels, creating thermo-irreversible, chemically crosslinked hydrogels. MGCs show no cytotoxic effects and effectively support cell encapsulation. In vivo studies demonstrate stable crosslinking with minimal UV-induced skin damage. Due to their unique thermo-sensitivity, multi-functionality, and customizable properties, MGC thermogels are promising novel biomaterials for various biomedical applications, particularly injectable tissue engineering and cell encapsulation, thus overcoming the limitations of conventional thermogels. [ABSTRACT FROM AUTHOR]

Hydrogels are widely used due to their exceptional biocompatibility and adaptability, but their weak mechanical properties limit their application in biomedical engineering. Herein, we rapidly attained a comprehensive enhancement of silk fibroin hydrogels in mechanical properties by employing a physical-chemical double crosslinking strategy. The SF was ultrasonicated and simultaneously photo-crosslinked to form a di-tyrosine network interspersed with β -sheet blocks, resulting in a SF hydrogel network structure with both rigid and flexible domains. The SF hydrogels exhibited a maximum breaking strength of 59.7 kPa and a Young's modulus of 82.2 MPa, demonstrating significant rigidity and flexibility. Subsequently, the silk screws prepared by this double crosslinking strategy showed extraordinary compressive strength and Young's modulus of 41.8 MPa and 10.9 MPa, respectively. The silk screws cocultured with osteoblasts showed optimal biocompatibility, and the rate of biodegradation could be matched to the rate of osteogenesis. The screw also exhibited high adaptability in the requirements of bone screws. In this study, the SF hydrogels prepared by physical-chemical double crosslinking have extraordinary mechanical properties and biocompatibility, which provides a new avenue for the preparation of high-performance hydrogels and has great potential in bone tissue engineering. • The efficient photo-crosslinking system for SF, enables a faster and eco-friendly dual crosslinking process. • These two SF crosslinking methods complement each other, providing the hydrogels with both rigidity and flexibility. • The double-crosslinked SF bone screws offer rapid molding, simplified processing, and optimal mechanical properties. • Physical and chemical double crosslinking of SF can be performed simultaneously. • Adjusting crosslinking ways of SF can achieve the desired mechanical strength, expanding its application range. [ABSTRACT FROM AUTHOR]

Nonalcoholic steatohepatitis (NASH) is the severe subtype of nonalcoholic fatty diseases (NAFLD) with few options for treatment. Patients with NASH exhibit partial responses to the current therapeutics and adverse effects. Identification of the binding proteins for the drugs is essential to understanding the mechanism and adverse effects of the drugs and fuels the discovery of potent and safe drugs. This paper aims to critically discuss recent advances in covalent and noncovalent approaches for identifying binding proteins that mediate NASH progression, along with an in-depth analysis of the mechanisms by which these targets regulate NASH. A literature search was conducted to identify the relevant studies in the database of PubMed and the American Chemical Society. The search covered articles published from January 1990 to July 2024, using the search terms with keywords such as NASH, benzophenone, diazirine, photo-affinity labeling, thermal protein profiling, CETSA, target identification. The covalent approaches utilize drugs modified with diazirine and benzophenone to covalently crosslink with the target proteins, which facilitates the purification and identification of target proteins. In addition, they map the binding sites in the target proteins. By contrast, noncovalent approaches identify the binding targets of unmodified drugs in the intact cell proteome. The advantages and limitations of both approaches have been compared, along with a comprehensive analysis of recent innovations that further enhance the efficiency and specificity. The analyses of the applicability of these approaches provide novel tools to delineate NASH pathogenesis and promote drug discovery. [Display omitted] • Photoaffinity labeling approaches identify the drug targets that regulate NASH. • Target identification delineates the adverse effects and toxicity of anti-NASH drugs. • Noncovalent approaches identify the in situ binding targets for small molecules. • Multidisciplinary advances greatly facilitate target identification to treat NASH. [ABSTRACT FROM AUTHOR]

In this work, self-healing cellulose nanocrystals/fluorinated polyacrylate with dual dynamic networks of photoreversible crosslinking network and high-density hydrogen bonds was prepared by Pickering emulsion polymerization. The main work was to study the effects of 7-(2-methacryloyloxy)-4-methylcoumarin (CMA) and 2-ureido-4[1H]-pyrimidinone methyl methacrylate (UPyMA) monomer dosage on emulsion polymerization and latex film properties. The monomer conversion increased first and then decreased as the CMA and UPyMA monomer dosage increased, while a reverse trend was noted for the particle size and particle size distribution. Incorporating UPyMA allowed the rapid formation of hydrogen bonds at the crosslinking sites, which increased the interaction force between the healing surfaces. Besides, reversible photocrosslinking reaction of coumarin groups provided another support for self-healing performance. Moreover, the influence of self-healing temperature, self-healing time and UV irradiation on the self-healing ability was also systematically investigated The tensile strength of the prepared cellulose nanocrystals/fluorinated polyacrylate latex film exhibited a self-healing efficiency of 91.4 % under 365 nm UV irradiation and 80 °C for 12 h. The latex film had excellent thermal stability as was shown by TG and DTG analyses. The outstanding self-healing capability of latex film was attributed to the reversible photodimerization of coumarin groups and multiple hydrogen bonds. In addition, the water-oil repellent and mechanical properties of the latex films were improved as the CMA and UPyMA monomer dosage increased. • Polyacrylate polymers with dual self-healing functions prepared by Pickering emulsion polymerization. • Construction of dual dynamic networks of photoreversible crosslinking network and high-density hydrogen bonds. • The effects of different monomer contents on emulsion polymerization and latex films properties were investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel MOH containing –CHO and −C=C- was successfully prepared by NaIO 4 oxidation and MA modification. • The injectable NGF-loaded CMHN hydrogel was established by Schiff base and photocrosslinking for irregular bone defect. • CMHN hydrogel with excellent performance promoted DRG neuron growth and BMSCs osteogenesis mediated by NGF- CGRP axis. • CMHN hydrogel possessed a better bone repair effect with a long-lasting NGF-promoting neuro-osteogenic action. The structural and functional repair of critical-sized irregular bone defect is still considered a serious challenge. Most bone implant materials used in current clinic are not able to induce reconstruction of functional neural network, which is the key in bone regeneration via neural-osteogenic pathway. In this study, we aimed to manufacture a novel injectable double-crosslinked collagen/hyaluronic acid hydrogel loaded with nerve growth factor (NGF), which was capable of well filling irregularly shaped bone defects and inducing reconstruction of neural network. Hyaluronic acid (HA) was sequentially oxidized by sodium periodate and modified by methacrylic anhydride to prepare methacrylated oxidized HA (MOH) as a crosslinker. Subsequently, the Collagen-MOH@NGF (CMHN) hydrogel was established by Schiff base reaction and double-bond photocrosslinking. Our results demonstrated the excellent microporous structure, injectable, self-healing, in-situ rapid crosslinking properties of CMHN hydrogel along with suitable mechanics, rheology, swelling, degradation and biocompatibility. Significantly, the introduction of NGF endowed CMHN hydrogel with better biological properties than that without NGF. In vitro , CMHN hydrogel promoted DRG neuron growth and osteogenic differentiation of BMSCs mediated by NGF-calcitonin gene-related peptide (CGRP) axis. In vivo , CMHN hydrogel possessed a better bone repair effect than free NGF and blank hydrogel, with a long-lasting NGF-promoting neuro-osteogenic action within 8 w in a rat cranial critical defect model. Overall, the prepared injectable NGF-loaded collagen/HA dual network hydrogel is a promising material to facilitate functional and structural repair of complex bone defects. [ABSTRACT FROM AUTHOR]

Bone defects are one of the main causes of disability worldwide. Due to the disadvantages associated with autografts, the latest advances have been focused on tissue regeneration approaches that use injectable hydrogels or 3D printed hydrogel-based structures that could refill appropriately the bone gap area without the need for external fixatives, leading to bone formation in the long term. Injectable hydrogels could be applied in extrusion-based 3D printing as inks; in this sense, double-crosslinking hydrogels appear as ideal candidates. In this work, injectable and printable double crosslinkable hydrogels based on oxidized xanthan gum (XGox) and methacrylate polyaspartylhydrazide (PAHy-MA) were produced. The formation of dynamic hydrazone bonds, occurring between aldehyde groups on the polysaccharide backbone and hydrazine moieties of PAHy-MA, induced an instant gelation, conferring, also, injectability and self-healing properties to the hydrogels. The presence of methacrylic moieties on the synthetic polymer allowed further crosslinking upon UV irradiation that stabilized the hydrogel shape and mitigated its susceptibility to hydrolytic degradation. Obtained hydrogels showed pseudoplastic behaviour and good recovery of viscoelastic properties over time. The physicochemical and rheological characterization highlighted increased stability and higher viscoelastic moduli after photo-crosslinking. The hydrogels also showed good printability, cytocompatibility and the early formation of a bone-like matrix when osteosarcoma-derived cells (MG-63) were cultured in the scaffolds for 21 days, with an increased collagen I deposition, mineralization and the expression of characteristic osteogenic markers. [Display omitted] • Xanthan gum and methacrylate polyaspartylhydrazide to produce injectable and printable double crosslinkable hydrogels. • Good viscoelastic properties, injectability and printability. • Potential application in bone regenerative medicine. [ABSTRACT FROM AUTHOR]

Herein, we report for the first time the incorporation of riboflavin as a bioactive additive in soy protein isolate films, along with investigating the impact of UV light treatment, thereby creating functional packaging material. Our investigation involves a comprehensive characterization of the films, including morphological, physicochemical, and mechanical properties, as well as their effectiveness as light barriers, antimicrobial potential, and biodegradation properties. The UV treatment of riboflavin/soy protein dispersions leads to the formation of films exhibiting minor water swelling and total soluble matter compared to those untreated with UV light, suggesting the development of a cross-linked network. Moreover, increased riboflavin content enhances the cross-linked network's robustness. The mechanical properties of the films exhibit a notable improvement with UV treatment and with increasing riboflavin content until a limit value, showcasing increased tensile strength and Young's modulus. Films showed homogeneous surfaces with an absence of pores and cracks and the ability to act as a barrier for oil passage. Films were assayed as a coating material for chia oil samples exposed to high-intensity UV light, showing great protection capacity. It has been demonstrated that an increase in riboflavin concentration enhances the UV light-blocking properties, making these films promising candidates for storing light-sensitive food products while preserving their nutritional quality. In addition, antibacterial action against S. aureus was determined by disk diffusion assay. Furthermore, the films exhibited relatively short disintegration times under soil burial conditions, even after chemical modification. This research contributes valuable insights to the innovative field of sustainable food packaging materials. [Display omitted] • UV treatment and riboflavin incorporation lead to improved mechanical properties. • Films exhibiting superior water resistance compared to those untreated with UV light. • Increasing riboflavin proportion enhances UV light-blocking properties of the films. • Films exhibited relatively short biodegradation times under soil burial conditions. • The prepared films are promising candidates for storing light-sensitive food products. [ABSTRACT FROM AUTHOR]

Tissue engineering (TE) of adipose tissue (AT) is a promising strategy that can provide 3D constructs to be used for in vitro modelling, overcoming the limitations of 2D cell cultures by closely replicating the complex breast tissue extracellular matrix (ECM), cell-cell, and cell-ECM interactions. However, the challenge in developing 3D constructs of AT resides in designing artificial matrices that can mimic the structural properties of native AT and support adipocytes biological functions. Herein, we developed photocrosslinkable hydrogels by employing gelatin methacrylate (GelMA) and hyaluronic acid methacrylate (HAMA) to mimic the collagenous and glycosaminoglycan components of AT microenvironment, respectively. The physico-mechanical properties of the hydrogels were tuned to target AT biomimetic properties by varying the hydrogel formulation (with or without hyaluronic acid), and the amount of photoinitiator (ruthenium/sodium persulfate) used to crosslink the hydrogels via visible light. The physical and mechanical properties of the developed hydrogels were tuned by varying the material formulation and the photoinitiator concentration. Preadipocytes were encapsulated inside the hydrogels and differentiated into mature adipocytes. Findings enlightened that HAMA addition in hybrid hydrogels boosted an increased lipid accumulation. The engineered biomimetic adipocyte-based constructs resulted promising as scaffolds or 3D in vitro models of AT. [Display omitted] • GelMA and GelMA/HAMA hydrogels were photocrosslinked with visible light. • Long term in vitro stability was assessed for obtained hydrogels. • GelMA hydrogels mimicked healthy adipose tissue mechanical properties. • GelMA/HAMA hydrogels resembled breast cancer tissue mechanical properties. • Encapsulated preadipocytes proliferated and differentiated in obtained hydrogels. [ABSTRACT FROM AUTHOR]

PpiD and YfgM are inner membrane proteins that are both composed of an N-terminal transmembrane segment and a C-terminal periplasmic domain. Escherichia coli YfgM and PpiD form a stable complex that interacts with the SecY/E/G (Sec) translocon, a channel that allows protein translocation across the cytoplasmic membrane. Although PpiD is known to function in protein translocation, the functional significance of PpiD-YfgM complex formation as well as the molecular mechanisms of PpiD-YfgM and PpiD/YfgM-Sec translocon interactions remain unclear. Here, we conducted genetic and biochemical studies using yfgM and ppiD mutants and demonstrated that a lack of YfgM caused partial PpiD degradation at its C-terminal region and hindered the membrane translocation of Vibrio protein export monitoring polypeptide (VemP), a Vibrio secretory protein, in both E. coli and Vibrio alginolyticus. While ppiD disruption also impaired VemP translocation, we found that the yfgM and ppiD double deletion exhibited no additive or synergistic effects. Together, these results strongly suggest that both PpiD and YfgM are required for efficient VemP translocation. Furthermore, our sitedirected in vivo photocrosslinking analysis revealed that the tetratricopeptide repeat domain of YfgM and a conserved structural domain (NC domain) in PpiD interact with each other and that YfgM, like PpiD, directly interacts with the SecG translocon subunit. Crosslinking analysis also suggested that PpiD-YfgM complex formation is required for these proteins to interact with SecG. In summary, we propose that PpiD and YfgM form a functional unit that stimulates protein translocation by facilitating their proper interactions with the Sec translocon. [ABSTRACT FROM AUTHOR]

Chitosan-based nanogels are effective carriers for drug delivery due to their biocompatibility and biodegradability. However, the chemically cross-linked nanogels usually require complicated procedures or tough conditions. Herein, we report a simple approach to generate chitosan-based nanogels by photo-crosslinking of poor solvent-induced nanoaggregates without requiring any emulsifying agent, catalyst, or external crosslinker. O-nitrobenzyl alcohol-modified carboxymethyl chitosan was synthesized and self-crosslinked into the nanogels in a mixed solution of ethanol and water under 365 nm light irradiation due to UV-induced primary amine and o-nitrobenzyl alcohol cyclization. The nanogels (CMC-NBA NPs) and lactobionic acid-decorated nanogels (LACMC-NBA NPs) displayed a uniform diameter (~200 nm) and excellent stability under physiological conditions. Notably, the nanogels exhibited a high loading content (~28 %) due to π-π stacking and electrostatic interactions between doxorubicin (DOX) and the carriers. These DOX-loaded nanogels showed rapid drug release under slightly acidic conditions. The cell and animal experiments confirmed that LACMC-NBA NPs increased cellular uptake, improved cytotoxicity in tumor cells, and enhanced growth inhibition in vivo than CMC-NBA NPs. Thus, these photo-crosslinked nanogels possess great potential for DOX delivery. [ABSTRACT FROM AUTHOR]

Biocompatible and biodegradable hydrogels with biomimetic properties, such as self-repairing, are increasingly interesting for biomedical applications, particularly when they can be printed or in situ formed to mimic extracellular matrix or as personalized implantable devices in tissue regeneration or drug delivery. Photocrosslinkable hydrogels based on methacrylated chitosan (CHIMe) and hyaluronic acid that exhibit according with their composition, tuneable physico-chemical properties are here presented. The study of the conversion, gelation time, mechanical and rheological properties of photopolymerized CHIMe showed an optimal phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) initiator feed (0.1 % w). These photocrosslinkable hydrogels demonstrated being able to promote doubly crosslinked hydrogels with similar Young Moduli regardless the cycles of self-healing processes, and tailored swelling (25–70 swelling factor), mechanical (1 × 10−4-2 × 10−2 MPa) and rheological properties, as a function of polysaccharides relative content. Clear evidences have been found that fast photopolymerization of CHIMe/HA solutions leads to biocompatible (>80 % cell viability), biodegradable (20–24 days in hydrolytic medium) and robust self-healable hydrogels suitable for advanced biomedical and tissue engineering applications. [ABSTRACT FROM AUTHOR]

Misfolded proteins in the lumen of the endoplasmic reticulum (ER) are retrotranslocated into the cytosol and degraded by the ubiquitin-proteasome system, a pathway termed luminal ER-associated protein degradation. Retrotranslocation is mediated by a conserved protein complex, consisting of the ubiquitin ligase Hrd1 and four associated proteins (Der1, Usa1, Hrd3, and Yos9). Photocrosslinking experiments provided preliminary evidence for the polypeptide path through the membrane but did not reveal specific interactions between amino acids in the substrate and Hrd1 complex. Here, we have used site-specific disulfide crosslinking to map the interactions of a glycosylated model substrate with the Hrd1 complex in live S. cerevisiae cells. Together with available electron cryo-microscopy structures, the results show that the substrate interacts on the luminal side with both a groove in Hrd3 and the lectin domain of Yos9 and inserts a loop into the membrane, with one side of the loop interacting with the lateral gate of Der1 and the other with the lateral gate of Hrd1. Our disulfide crosslinking experiments also show that two Hrd1 molecules can interact through their lateral gates and that Hrd1 autoubiquitination is required for the disassembly of these Hrd1 dimers. Taken together, these data define the path of a polypeptide through the ER membrane and suggest that autoubiquitination of inactive Hrd1 dimers is required to generate active Hrd1 monomers. [ABSTRACT FROM AUTHOR]

The construction of suitable biomaterials for pulp regeneration has always been a major challenge in the field of stomatology. Considering the complex and irregular anatomy of the root canal system, injectable hydrogels have received extensive attention as cell carriers in dental pulp regeneration. Here, we developed an injectable photocrosslinked methacrylylated silk fibroin (RSFMA)/methacrylylated hyaluronic acid (MeHA) composite hydrogel and characterized its physicochemical properties. The biocompatibility of encapsulated human dental pulp stem cells (hDPSCs) was subsequently investigated. With the addition of RSFMA, the pore size of the scaffolds became more regular with negligible change in porosity and exhibited excellent mechanical properties. Furthermore, the low concentration of RSFMA hydrogel in the composite hydrogel had higher cross-linking efficiency. In contrast to MeHA hydrogels, hDPSCs were encapsulated in hydrogels either in the absence or presence of high concentrations of RSFMA. The results indicated that cells in low-concentration RSFMA composite gel presented better growth ability, proliferation ability and osteogenic differentiation ability. This injectable photocrosslinked silk fibroin/hyaluronic acid hydrogel show s great potential in the field of dental pulp tissue engineering. [Display omitted] • Hydrogels with proteins and glycosaminoglycans mimic the chemical structure and tissue structure of human soft tissue. • Methacrylylated silk fibroin and methacrylylated hyaluronic acid have the ability to photocrosslink. • The physicochemical properties and biological activities of hydrogels with different concentrations are different. • The UV covalent cross-linking method can well fill the complex root canal system. [ABSTRACT FROM AUTHOR]

Scleral photocrosslinking is increasingly investigated for treatment of myopia and glaucoma. In this study a computational model was developed to predict crosslinking efficiency of visible/near infrared photosensitizers in the sclera. Photocrosslinking was validated against riboflavin corneal crosslinking experimental studies and subsequently modeled for the sensitizer, methylene blue, administered by retrobulbar injection to the posterior sclera and irradiated with a transpupillary light beam. Optimal ranges were determined for treatment parameters including light intensity, methylene blue concentration, injection volume, and inspired oxygen concentration. Additionally, sensitivity of crosslinking to various parameters was quantified. The most sensitive parameters were oxygen concentration in the injection solution, scleral thickness, and injection reservoir thickness (i.e., injection volume). [Display omitted] • Scleral stiffening by photocrosslinking was modeled for glaucoma/myopia treatments. • The model was validated against published riboflavin corneal photocrosslinking data. • Scleral crosslinks and treatment parameters were modeled over space and time. • Optimal ranges for treatment parameters for photocrosslinking were predicted. • Sensitivity analysis suggests tissue parameters were most impactful to crosslinking. [ABSTRACT FROM AUTHOR]

A carboxyl-containing polyimide (PI) was synthesized with a flexible main chain. Then, a polymer reaction was conducted to introduce a chalcone side chain. The polymer reaction occurred stoichiometrically, and a high yield of the resulting photocrosslinkable polyimide (PI-Ch) polymer was obtained (91 %) along with a high molecular weight of 9.4 × 104 g/mol. The PI-Ch had a density of 1.15 g/cm3, a fractional free volume of 0.20, and a solubility parameter of 18.8 MPa1/2. Due to its low polarity, the PI-Ch was very soluble in a moderately polar, low-boiling-point solvent of THF. Moreover, the temperature required to promote 5 % weight loss was quite high at 383 °C, while the glass transition temperature was relatively low at 146 °C. The THF solution was considered to be optimal for the dip-coating method and was applied to PE separator coating. The ATR-mode FTIR analysis of the separator coated with a 1 wt% PI-Ch solution showed that the PI-Ch was coated extensively on the surface of the PE separator. Further, the photodimerization reaction of the chalcone side chain via UV irradiation was successful. The PE separator had a thermal shrinkage of 46 % before coating, which decreased to 29 % after coating and UV treatment. When coated with a 3 wt% PI-Ch solution, some of the pores in the separator were blocked, while the air permeability and average pore size also decreased. All the pores appeared blocked after coating with the 5 wt% PI-Ch solution. [Display omitted] • A photocrosslinkable polyimide (PI-Ch) with a chalcone side chain is synthesized. • PI-Ch is nonpolar and dissolves well in tetrahydrofuran (THF). • PI-Ch has a quite high T d5% of 383 °C and a relatively low T g of 146 °C. • Thermal shrinkage of the separator is reduced after coating with the THF solution. • Air permeability and average pore size of the separator are reduced after the coating. [ABSTRACT FROM AUTHOR]

The skin is the immune system's first line of defense. Extensive skin burns can lead to tissue necrosis, sepsis, and even death. Anti-infectious care of burn wounds is a major challenge in clinical medicine. However, the extensive use of antibiotics led to the emergence of multi-drug-resistant bacteria and silver dressings with antibacterial effects are also cytotoxic. We used the natural cationic antibacterial agent ε-polylysine (EPL) to graft Epigallocatechin-3-gallate (EGCG) to synthesize EPL-EGCG. Then, we used methacrylated gelatin (GelMA) with arginine-glycine-aspartate-rich acid (RGD) sequence and EPL-EGCG form interpenetrating polymer network hydrogels with excellent swelling properties. The hydrogel's inherent antibacterial properties and photo-cross-linking properties can cover irregular burn wounds and isolate bacteria to prevent infection. In addition, we used polydopamine (PDA) to coat GelMA microspheres with excellent hemostatic efficacy and load platelet-rich plasma (PRP) to enhance the hemostatic efficacy of the microspheres and impart inflammation-regulating functions. The hydrogel showed excellent hemostatic efficacy in rat liver injury and tail vein injury models. In the rat infected burn model, the hydrogel exhibited favorable antimicrobial, pro-angiogenic, and anti-inflammatory phenotype polarization of macrophages. Our study shows that GelMA/EPL-EGCG/GM-PDA@PRP hydrogel application has excellent antibacterial, hemostatic and anti-inflammatory effects, providing a new treatment strategy for wound care before burn skin grafting. • The interpenetrating polymer network of GelMA/EPL-EGCG hydrogels presented excellent swelling properties. • GelMA/EPL-EGCG hydrogels had inherent antibacterial properties due to the cationic properties of EPL. • GM-PDAmicrospheres loaded with platelet-rich plasma (PRP) have hemostatic and inflammatory properties. • GelMA/EPL-EGCG/GM-PDA@PRP hydrogels exhibited excellent antibacterial and anti-inflammatory effects in burn wounds. [ABSTRACT FROM AUTHOR]

Collagen has been extensively investigated as a bioactive material in cartilage tissue engineering. Recombinant humanized collagen type III (rhCol III) possessed excellent biocompatibility and imperative interactions with various cells shows a significant advantage as the starting material of medical devices. To investigate the bioactivation effect of rhCol III in cartilage tissue engineering, methacrylated hyaluronic acid (HA-MA) was prepared and rhCol III was further compounded to establish a photo-crosslinked composite hydrogel (HA-rhCol Ⅲ) platform to study the cartilage regeneration with chondrocytes encapsulated. The results verified that the HA-rhCol III hydrogels could be rapidly formed with stable mechanical properties using the blue light curing system. Meanwhile, the rhCol III could be effectively retained inside the composite hydrogel, which was conducive to maintain its bioactive function for a longer period. In vitro cell experiments confirmed that rhCol III improved the local microenvironment for chondrocytes, which provided abundant adhesion sites and further promoted cell migration, proliferation and differentiation. In vivo results indicated that the composite hydrogels could be conveniently applied to fulfill the cartilage defect in rabbit, and the histological and immunohistological results suggested that cartilage regeneration could be achieved with the application of HA-rhCol Ⅲ composite hydrogels. It could be concluded that the addition of rhCol III could bioactivate the hydrogel and promote the tissue regeneration, showing potential for application in tissue engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • GelMA-SilMA hydrogels with good mechanical properties modified the tissue suitability of polypropylene mesh. • GelMA-SilMA hydrogel demonstrated biocompatibility, biodegradability, and bioactivity in vitro. • GelMA-SilMA hydrogel enhanced the efficiency of open abdominal wound repair in vivo. • GelMA-SilMA hydrogel accelerated wound repair by activating specific signaling pathways. Open abdomen (OA), a major advance in modern trauma surgery, enables the treatment of severe abdominal trauma, infections, and hypertension by temporarily closing the abdominal cavity without suturing. Although OA can reduce mortality rates, it also presents challenges such as disruption of the abdominal environment, intestinal exposure, and impaired wound healing. Current temporary abdominal closure (TAC) techniques using polypropylene (PP) mesh are susceptible to abrasion and rupture of the intestine, leading to adhesions and serious complications such as intestinal fistulas and chronic wounds. These complications seriously impact outcomes due to mesh rigidity and its incompatibility with surrounding tissues. In this study, we designed a multifunctional hydrogel composed of GelMA (Gelatin Methacryloyl) and SilMA (Silk Fibroin Methacryloyl) as a promising solution for open abdominal wound repair. In vitro experiments confirmed the biocompatibility, self-healing properties, pro-angiogenic effects, and promotion of macrophage polarization. In vivo studies revealed that the GelMA-SilMA hydrogel could enhance abdominal wall tissue thickness and integrity via isolating the peritoneal cavity, protecting the intestinal tract, polarizing macrophages, promoting collagen formation, inducing neovascularization, inhibiting oxidative stress, and suppressing inflammation. Furthermore, immunofluorescence, immunohistochemistry, and RNA sequencing were employed to evaluate the wound healing mechanisms of GelMA-SilMA hydrogels. The results demonstrated that the hydrogels can promote angiogenesis, inhibit inflammation and immune responses, and enhance wound healing by activating the HIF-a-VEGF signaling pathway, RAP1 signaling pathway, and PI3K-AKT signaling pathway. Hence, the multifunctional GelMA-SilMA hydrogel has tremendous potential for clinical use in open abdominal wound repair. [ABSTRACT FROM AUTHOR]

Covalent and oriented immobilization of antibodies (Abs) can substantially improve the sensitivity and stability of solid-phase immunoassays. By modifying the natural Abs with functional groups that provide unique handles for further conjugation, Abs could be immobilized onto the solid matrices with uniform orientation. Herein, an effective approach for Fc-specific modification of Abs was developed for the oriented and covalent immobilization of Abs. Twelve photoreactive Z -domain variants, incorporated with a photoactivable probe (p -benzoyl- L -phenylalanine, Bpa) at different positions and carrying a C-terminal Cys-tag (i.e. Z Bpa -Cys variants), were individually constructed and produced in Escherichia coli and tested for photo-cross-linking to various IgGs. The different Z Bpa -Cys variants demonstrated large differences in photo-conjugation efficiency for the tested IgGs. The conjugation efficiencies of 17thZ Bpa -Cys ranged from 90 % to nearly 100 % for rabbit IgG and mouse IgG 2a , IgG 2b and IgG 3. Other variants, including 5thZ Bpa -Cys, 18thZ Bpa -Cys, 32thZ Bpa -Cys, and 35thZ Bpa -Cys, also displayed conjugation efficiencies of 61 %–83 % for mouse IgG 1 , IgG 2a and IgG 3. Subsequently, the photo-modified Abs, namely IgG–Cys conjugates, were covalently immobilized onto a maleimide group-functionalized solid-phase carrier on the basis of the reaction of sulfhydryl and maleimide. Thus, a generic platform for the controlled and oriented immobilization of Abs was developed, and the efficacy and potential of the proposed approach for sensitive immunoassays was demonstrated by detecting human α-fetoprotein. [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) is a common lethal injury to the central nervous system (CNS), which severely affects the quality of life of SCI patients. Attempts to enhance the treatment of SCI typically tend to develop functional bioactive hydrogel scaffolds with drug encapsulation. In this work, we proposed novel RGD-functionalized bioactive hydrogel loaded with bone marrow stromal cells-derived exosomes (BMSC-EXOs) and glial cell line-derived neurotrophic factor (GDNF) to synergistically promote SCI repair. The functional hydrogel consisted of methacrylic anhydride-grafted sodium alginate and acrylated RGD, and then combined with BMSC-EXOs and GDNF by photocrosslinking to form a composite bioactive hydrogel. The hydrogel showed good drug-release properties and biocompatibility. When the bioactive hydrogel was implanted into the SCI area of the SD rats, it effectively modulated the adverse inflammatory response in the SCI area. Furthermore, the bioactive hydrogel promoted the regeneration of spinal cord neurons and axons, leading to the improvement in motor function recovery. These results indicate that the bioactive hydrogel loaded with BMSC-EXOs and GDNF has great potential as a therapeutic approach for the repair of spinal cord injuries. • Bioactive hydrogels loaded with BMSC-EXOs and GDNF promotes neural and motor function recovery after spinal cord injury. • RGD-functionalized bioactive hydrogels encapsulated therapeutic bioactive factors. • BMSC-EXOs regulates the inflammatory microenvironment in the injured area. • GDNF enhances neuronal survival and promotes axon regeneration. [ABSTRACT FROM AUTHOR]

The root bark of Ulmus davidiana var. japonica (Rehder) Nakai (Japanese elm) has been used for inflammatory disease treatments. In this work, we isolated pectic polysaccharides from the root bark of U. davidiana (UDP) and explored the immune activities of intact and ultrasonicated UDP on human macrophages. The UDP-treated macrophages showed a proinflammatory response, indicating classical activation via Toll-like receptor-mediated recognition. For hydrogel formation, the ultrasonicated UDP was modified with methacrylate groups, then subjected to photocrosslinking. The formed bulk hydrogel was pulverized into microgels by homogenization, and the microgel size was modulated for macrophage phagocytosis. The UDP microgel-treated macrophages displayed microgel internalization and classical activation that involved upregulation of M1 polarization markers (IL6, TNF-α, and CCR7), indicating that the microgel can be used as a carrier for macrophage-targeted drug delivery. [Display omitted] • Evaluation immune-activity of pectin isolated from Ulmus davidiana var. japonica. • Fabrication of UDP microgels via photo-crosslinking and mechanical pulverization. • UDP microgel-treated macrophage activation, inducing M1 polarization. [ABSTRACT FROM AUTHOR]

Cells are known to constantly interact with their local extracellular matrix (ECM) and respond to a variety of biochemical and mechanical cues received from the ECM. Nonetheless, comprehensive understanding of cell-ECM interactions has been elusive. Many studies rely on analysis of cell behavior on 2D substrates, which do not reflect a natural cell environment. Further, lack of dynamic control over local stiffness anisotropies and fiber alignment hinders progress in studies in naturally derived fibrous 3D cultures. Here, we present a cell-safe method of patterned photocrosslinking, which can aid in studying biological hypotheses related to mechanotransduction in 3D hydrogels. As previously described by our group, ruthenium-catalyzed photocrosslinking (RCP) of selected ECM regions promotes localized increase in stiffness mediated by focused blue laser light in a confocal microscope. In this study, we further demonstrate that RCP can induce localized strain stiffening and fiber alignment outside of the selected crosslinked region and induce stiffness anisotropy biased towards the direction of fiber alignment. MDA-MB-231 cells are shown to respond to RCP-induced changes in local ECM architecture and display directional bias towards the direction of fiber alignment, as compared to control cells. Further, the effect of patterned crosslinking on a stiffness landscape is measured using multi-axes optical tweezers active microrheology (AMR) with backscattered laser beam illumination. AMR validates RCP as a suitable tool for creating distinct stiffness anisotropies which promote directed migration of cells, further underscoring the usefulness of RCP in cell-ECM studies. Studies on cell-ECM interactions in 3D cultures have often been hindered by the lack of available tools to dynamically alter local ECM stiffness and fiber alignment. Here, we present a non-invasive, cell-safe and easily applicable method of patterned photocrosslinking, which can aid in studying biological hypotheses in fibrous 3D hydrogels. Ruthenium-catalyzed crosslinking (RCP) of selected fibrin ECM regions promotes localized increase in stiffness and creates distinct stiffness anisotropies in the presence of the focused blue laser light. Outside of the crosslinked region, RCP causes fiber alignment and strain stiffening in the ECM, verified using multi-axes optical tweezers active microrheology (AMR). Following RCP, human breast cancer MDA-MB-231 exhibit directed cell migration, validating usefulness of this method in cell-ECM studies. [Display omitted] [ABSTRACT FROM AUTHOR]

RNA structure in the influenza A virus (IAV) has been the focus of several studies that have shown connections between conserved secondary structure motifs and their biological function in the virus replication cycle. Questions have arisen on how to best recognize and understand the pandemic properties of IAV strains from an RNA perspective, but determination of the RNA secondary structure has been challenging. Herein, we used chemical mapping to determine the secondary structure of segment 8 viral RNA (vRNA) of the pandemic A/California/04/ 2009 (H1N1) strain of IAV. Additionally, this long, naturally occurring RNA served as a model to evaluate RNA mapping with 4-thiouridine (4sU) crosslinking. We explored 4-thiouridine as a probe of nucleotides in close proximity, through its incorporation into newly transcribed RNA and subsequent photo-activation. RNA secondary structural features both universal to type A strains and unique to the A/California/04/2009 (H1N1) strain were recognized. 4sU mapping confirmed and facilitated RNA structure prediction, according to several rules: 4sU photocross-linking forms efficiently in the double-stranded region of RNA with some flexibility, in the ends of helices, and across bulges and loops when their structural mobility is permitted. This method highlighted three-dimensional properties of segment 8 vRNA secondary structure motifs and allowed to propose several long-range three-dimensional interactions. 4sU mapping combined with chemical mapping and bio-informatic analysis could be used to enhance the RNA structure determination as well as recognition of target regions for anti-sense strategies or viral RNA detection. [ABSTRACT FROM AUTHOR]

Biomaterials for effective hemorrhage control are urgently needed in clinics as uncontrolled bleeding is associated with high mortality. Herein, we developed an injectable and in situ photo-crosslinkable hybrid hemostatic hydrogel by combining pectin methacrylate (PECMA) and gelatin methacryloyl (GelMA). This modular material system combines ionic- and photo-crosslinking chemistries to design interpenetrating networks (IPN) exhibiting tunable rheology, highly porous structure, and controllable swelling and mechanical properties. By simply changing the calcium (0–15 mM) and polymer (1.5–7%) content used for the sequential crosslinking of hydrogels via calcium gelation and UV-photopolymerization, it was possible to precisely modulate the injectability, degradation, and swelling ratio. Moreover, it is demonstrated that PECMA/GelMA hydrogels present good cytocompatibility and uniquely synergize the hemostatic properties of calcium ions on PECMA, the amine residues on GelMA, and the highly porous network toward rapid blood absorption and fast coagulation effect. An in vitro porcine skin bleeding model confirmed that the hydrogel could be directly injected into the wound and rapidly photo-crosslinked, circumventing the bleeding and decreasing the coagulation time by 39%. Importantly, the crosslinked hydrogel could be easily removed to prevent secondary wound injury. Overall, this injectable hybrid PECMA/GelMA hydrogel stands as a promising hemostatic material. • Dual-crosslinked PECMA/GelMA networks as hemostatic hydrogels • Hydrogels exhibit tunable swelling, porosity and mechanical properties. • Hybrid hydrogels significantly decreased the in vitro coagulation time. • Hydrogel injection and in situ photocrosslinking onto the wound bed • Easily removed from the wound, preventing secondary injury. [ABSTRACT FROM AUTHOR]

In this study, multifunctional polyurethane nanoparticles (MPUNs) were embedded into the methacrylated gellan gum (MGG) to prepare stimuli-responsive hydrogels with improved mechanical properties including remarkable fatigue resistance and excellent self-recoverability. The photocurable MPUNs/MGG nanocomposite hydrogels with different formulations were synthesized through a facile and green solution mixing method. The result obtained from mechanical analysis displayed an excellent improvement in compression strength (120 6 ± 83.7 kPa) and ultimate strain (94.2 ± 2.7%) in the optimized formulation. Furthermore, the optimized formulation could restore approximately its original shape after continuous loading-unloading compression tests over 100 cycles which might result from its favorable crosslinked structure. These reinforced hydrogels exhibited a dual physical and chemical crosslinking mechanism based on the hydrogen bonding formation and photocrosslinking of methacrylate functional groups, respectively. Interestingly, the nanocomposite hydrogels exhibited no significant cytotoxicity to human dermal fibroblast cells which made them suitable as the appropriate biomaterials for the engineering of soft tissues. • Polyurethane nanoparticles were embedded in modified gellan gum hydrogel through a one-pot and green solution mixing method. • The effect of MPUNs incorporation on mechanical, rheological and stimuli-responsive properties was investigated. • The incorporation of polyurethane nanoparticles caused an improvement in both mechanical and rheological properties. • Prepared Hydrogel had good cell viability. [ABSTRACT FROM AUTHOR]

Novel hydrogel-based multifunctional systems prepared utilizing photocrosslinking and freeze-drying processes (PhotoCross/Freeze-dried) dedicated for bone tissue regeneration are presented. Fabricated materials, composed of methacrylated gelatin, chitosan, and chondroitin sulfate, possess interesting features including bioactivity, biocompatibility, as well as antibacterial activity. Importantly, their degradation and swellability might be easily tuned by playing with the biopolymeric content in the photocrosllinked systems. To broaden the potential application and deliver the therapeutic features, mesoporous silica particles functionalized with methacrylate moieties decorated with hydroxyapatite and loaded with the antiosteoporotic drug, alendronate, (MSP-MA-HAp-ALN) were dispersed within the biopolymeric sol and photocrosslinked. It was demonstrated that the obtained composites are characterized by a significantly extended degradation time, ensuring optimal conditions for balancing hybrids removal with the deposition of fresh bone. We have shown that attachment of MSP-MA-HAp-ALN to the polymeric matrix minimizes the initial burst effect and provides a prolonged release of ALN (up to 22 days). Moreover, the biological evaluation in vitro suggested the capability of the resulted systems to promote bone remodeling. Developed materials might potentially serve as scaffolds that after implantation will fill up bone defects of various origin (osteoporosis, tumour resection, accidents) providing the favourable conditions for bone regeneration and supporting the infections' treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

A new photo-crosslinkable donor polymer, PM6-Br50 facilitates the fabrication of p- PHJ OPDs through LbL deposition of D and A materials overcoming solvent-imposed constraints. The integration of a p- PHJ architecture with a conjugated polyelectrolyte as a hole-transport layer resulted in a significantly reduced dark current, leading to a remarkably high specific detectivity. [Display omitted] • A new polymer donor is synthesized by introduction of photo-crosslinkable side chains. • Layer-by-layer OPDs are fabricated utilizing a photo-crosslinkable polymer donor. • A conjugated polyelectrolyte-based HTL is employed to inhibit electron injection. • A significantly high detectivity is achieved with a suppressed dark current. The effective reduction of dark (or noise) current presents a significant hurdle in enhancing the detectivity of organic photodetectors (OPDs). To address this challenge, a photo-crosslinkable donor polymer, PM6-Br50, is synthesized by introducing bromoalkyl side-chains onto the PM6 structure. This modification enables the formation of a pseudo planar heterojunction (p- PHJ) structure of crosslinked donor/acceptor through a layer-by-layer (LbL) sequential process without the necessity for an semi-orthogonal solvent. This innovation effectively overcomes solvent-related limitations in the LbL process. Additionally, we replace the semi-metallic hole-transport layer (HTL), PEDOT:PSS, with a semiconducting conjugated polyelectrolyte (TPAFS-TMA) with a high conduction band. The p- PHJ configuration, featuring pure donor/anode and pure acceptor/cathode contacts, enhances the charge injection barrier for electrons (holes) from the anode (cathode) in the dark under reverse bias, effectively minimizing dark current. Furthermore, the TPAFS-TMA HTL serves to impede electron injection from the anode. Through the synergistic combination of these two strategies, a significantly reduced dark current density (4.03 × 10−10 A cm−2) is measured by four orders of magnitude, compared to the bulk heterojunction OPDs with PEDOT:PSS. Furthermore, we measure remarkably high shot noise-based and total noise current-based specific detectivities of 4.27 × 1013 and 6.97 × 1012 cm Hz1/2 W−1 (with linear dynamic range of 73.7 dB), respectively. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) and other drug-resistant bacteria have become more common in recent years, which has made it extremely difficult to treat and heal many different kinds of wounds and caused enormous financial losses. Because of its unique "Trojan horse" function, Ga3+ has been recognized as a new possible candidate for inhibiting and eradicating drug-resistant bacteria. Furthermore, natural polysaccharide materials with outstanding biological characteristics, such as insect chitosan (CS) and pullulan (PUL), have attracted significant interest. In this study, we used quaternized-catechol chitosan (QDCS-PA), methacrylate-dialdehyde pullulan (DPUL-GMA), and gallium ion (Ga) to create a multi-crosslinked photo-enhanced hydrogel (Q-D/Ga/UV) with antimicrobial, hemostatic, self-healing, and injectable properties for promoting MRSA-infected wound healing. In vitro, the Q-D/Ga/UV hydrogels demonstrated good mechanical properties, antioxidant capabilities, biocompatibility, hemostatic properties, and antibacterial activity. The addition of gallium ions enhanced the hydrogels' mechanical properties, hemostatic capabilities, antibacterial activity, and ability to induce wound healing. Q-D/Ga/UV hydrogel significantly promoted wound contraction, collagen deposition, and angiogenesis while also suppressing inflammation in a whole-skin wound model of MRSA-infected rats. In conclusion, Q-D/Ga/UV hydrogels demonstrate significant promise for healing wounds infected with drug-resistant bacteria. [Display omitted] [ABSTRACT FROM AUTHOR]

Glycans decorate all cells and are critical mediators of cellular processes through recognition by glycan-binding proteins (GBPs). While targeting glycan–protein interactions has great therapeutic potential, these interactions are challenging to study as they are generally transient and exhibit low binding affinities. Glycan-based photo-crosslinkable probes have enabled covalent capture and identification of unknown GBP receptors and glycoconjugate ligands. Here, we review recent progress in photo-crosslinking approaches targeting glycan-mediated interactions. We discuss two prominent emerging strategies: 1) development of photo-crosslinkable oligosaccharide ligands to identify GBP receptors; and 2) cell-surface glyco-engineering to identify glycoconjugate ligands of GBPs. Overall, photoaffinity labeling affords valuable insights into complex glycan–protein networks and is poised to help elucidate the glycan–protein interactome, providing novel targets for therapeutic intervention. [Display omitted] [ABSTRACT FROM AUTHOR]

Recurrent inflammation, intense bacterial infections, and inadequate blood vessel growth make diabetic wounds non-healing. Under pathological environment, cellular functions are also inhibited. In this paper, we developed a novel in situ injectable photo-crosslinking hydrogel embedded with heterojunction Ag@ZnO nanoparticles (NPs) which exhibit dual-channel synergistic ion release and reactive oxygen species (ROS) production for anti-bacteria and cutaneous regeneration. This novel hydrogel platform can be introduced onto any irregular wound and form gelation with 395 nm UV light irradiation in only 5 s. After being affixed to the wound, Ag+ and Zn2+ can be released as the first interaction for wound healing. Foremost, the heterojunction formed on interface of Ag and ZnO has the ability to capture oxygen and water to instigate the generation of a "ROS storm", which can disrupt the structural integrity of bacteria, trigger the leakage of bacterial cytoplasmic content, enhance angiogenesis by activating VEGF and CD31 expression, and stimulate the steps of wound healing. The continuous release of Ag+, Zn2+ and "ROS storm" collaboratively drive bacterial deactivation, suppress inflammation, promote cellular proliferation, collagen deposition and angiogenesis. These effects significantly accelerate diabetic chronic wounds healing. Therefore, such dual-channel synergistic hydrogel platform might provide a promising new insight to diabetic chronic wound treatment. [Display omitted] • In situ injectable hydrogel embedded with nanoparticles can be adapted to wound and crosslinked by light for few seconds. • Zinc and silver ions releasing and "ROS storm" generation enhance the antibacterial effect as dual-channel synergistic interaction. • The hydrogel reduce inflammation, promote cell proliferation and angiogenesis for the therapy of diabetic chronic wounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful modification of poly(2-ethyl-2-oxazoline) with cinnamoyl groups. • Nanofibrous membranes of cinnamoyl modified poly(2-ethyl-2-oxazline) are easily electrospun from eco-friendly solvents. • Treatment of the nanofibrous membranes with UVB induces cinnamoyl dimerization, and hence photo-crosslinking of the polymeric chains, resulting in water-stable nanofibers. • UVC treatment causes full disintegration in water of the crosslinked membranes, due to a combination of photo-degradation and cleavage of the cinnamoyl dimers. • Prolonged UVB and UVC exposure induces extended photo-degradation in poly(2-ethyl-2-oxazoline) nanofibrous membranes. Poly(2-ethyl-2-oxazoline) (PEtOx) is a potent member of the versatile poly(2-oxazoline) polymer platform with its high hydrophilicity that could be beneficial in numerous biomedical applications, especially in the form of a nanofibrous membrane. However, its water-solubility limits its application in situations where a stable, nanofibrous morphology is required in aqueous environments. The present work offers a straightforward route towards water-stable PEtOx-based nanofibrous membranes, via post-polymerization functionalization with cinnamoyl moieties (PEtOx-Cin) and photo-crosslinking of the electrospun membranes. It is shown that a UVB treatment does not significantly affect the nanofibrous morphology, while successfully inducing the cinnamoyl dimerization process and hence the formation of a polymeric network, as evidenced by spectral analysis. The hereby crosslinked PEtOx-based nanofibers exhibit a prolonged water-stability (at least 45 days), while, interestingly, intermediate irradiation times yield the best results. Full disintegration of the photo-crosslinked nanofibers in aqueous media could be achieved by subsequent UVC exposure. This is not only due to decrosslinking of the cinnamoyl dimers, but was also found to be due to partial degradation of the polymeric backbone. The investigation of UVB/UVC exposure on pure PEtOx nanofibrous membranes confirmed the photo-degradation of the polymeric backbone by a significant decrease in molar mass as observed by size exclusion chromatography and supported by spectral analysis. The hereby proposed, straightforward route for reversible crosslinking of PEtOx-based nanofibrous membranes and their accessible disintegration will contribute to the promotion of these materials in biomedical applications where a water-stable, nanofibrous morphology combined with high hydrophilicity and easy removal is required. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanical performance is linked to network architecture in tough PEG-based hydrogels. • Entanglements dominate the hydrogel mechanics below a certain crosslinking density threshold. • Modeling of stretching experiments highlights the role of crosslinks and entanglements on mechanical performance. • Photocrosslinking using thiol-ene chemistry lends itself to digital light processing (3D printing). Hydrogels have been widely investigated for applications in the human body due to their tunability and biocompatibility. Nevertheless, their application is still limited by their relatively low mechanical strength relative to load-bearing tissue scaffolds like articular cartilage. In this work, we synthesized hydrogels by combining linear poly(ethylene glycol) dimethacrylate (PEGDMA) with a 3-arm-PEG end-functionalized with thiol. We demonstrate that the combination of thiol-ene click chemistry with a multifunctional crosslinker reduces the crosslink and entanglement density in comparison with the otherwise statistically crosslinked/polymerized PEGDMA, whereby the only viable mode of gelation is through radical propagation or termination at the double bond. The corresponding minimization of topological heterogeneities that arises during thiol-ene crosslinking results in hydrogels with compressive strength in the range of tens of MPa. The molar mass of the linear PEGDMA precursor is readily tunable, unlocking access to a wider range of mechanical properties. We employed photo-mediated crosslinking protocol, which is amenable to advanced processing technologies such as light-based 3D printing techniques. Such advanced fabrication processes offer high precision and control during the generation of customizable macroscopic objects. Simple prototypes were generated using digital light processing (DLP) equipment. We demonstrate that integrating a simple co-macromonomer into a widely employed hydrogel platform can unlock new mechanical regimes and mitigate the inherent brittleness associated with these materials. The simplicity of this approach, coupled with its easy tunability and adaptability to light-based techniques, holds promise for broadening hydrogel applications in tissue engineering. Our findings contribute to advancing materials and methodologies, facilitating enhanced design and fabrication of functional constructs. [ABSTRACT FROM AUTHOR]

A continuously stable moist healing environment is immensely beneficial for wound healing, which can be availably achieved by providing an in situ hydrogel with enough strength resembling skin tissue and self-healing ability. Herein, through a dual-crosslinking strategy, hyaluronic acid-based hydrogels with excellent self-healing capacity and enhanced mechanical properties are fabricated via the acylhydrazone linkages and subsequent photocrosslinking based on hydrazide-modified sodium hyaluronate and aldehyde-modified maleic sodium hyaluronate. The hydrogels demonstrate the fast gelation process (< 1 min), the controlled swelling behaviors, and the good biocompatibility. Notably, they possess enhanced mechanical strength similar to the human dermis (∼ 2.2 kPa). Also, they can self-heal rapidly with a self-healing efficiency of ∼90 % at 6 h. Based on this, the hyaluronic acid-based hydrogels, without any biological factors involved, can facilitate the full-thickness skin wound reconstruction process by accelerating the three phases of the wound repair, including reducing wound inflammation in the inflammatory phase, promoting angiogenesis in the proliferative phase, and promoting the deposition and reconstruction of collagen in the remodeling phase. The produced hyaluronic acid hydrogel can serve as an ideal candidate for wound healing. [Display omitted] [ABSTRACT FROM AUTHOR]

Open globe injuries (OGIs) demand immediate attention to prevent further complications and improve vision prognosis. Herein, we developed a thermo/photo dual-crosslinking injectable hydrogel, HBC_m_Arg, for rapidly sealing OGIs in emergency ophthalmic cases. HBC_m_Arg was prepared with arginine and methacrylic anhydride modified hydroxybutyl chitosan (HBC). HBC_m_Arg was initially in liquid form at 25 °C, enabling easy injection at the injury site. After reaching the ocular surface temperature, it underwent reversible heat-induced gelation to achieve in situ transformation. Further, HBC_m_Arg was capable of rapid photocrosslinking under UV light, forming a dual network structure to bolster mechanical strength, thereby facilitating effective OGI closure. Biocompatibility assessments, including in vitro studies with three ocular cell types and in vivo experiments on rabbit eyes, confirmed the safety profile of HBC_m_Arg. Ex vivo and in vivo burst pressure tests demonstrated the hydrogel's ability to promptly restore intraocular pressure and withstand elevated pressures, underscoring its potential for OGI stabilization. Additionally, the suitable degradation of HBC_m_Arg within ocular tissues, coupled with its stability in ex vivo assessments, presented a delicate balance between stability and biodegradability. In conclusion, HBC_m_Arg holds promise for improving emergency ophthalmic care by providing a rapid, effective, and safe way to seal OGIs in critical situations. [Display omitted] [ABSTRACT FROM AUTHOR]

Gelatin-based hydrogels are extensively used for 3D cell culture, bioprinting, and tissue engineering due to their cell-adhesive nature and tunable physio-chemical properties. Gelatin hydrogels for 3D cell culture are often developed using high-gelatin content (frequently 10–15 % w / v) to ensure fast gelation and improved stability. While highly stable, such matrices restrict the growth of encapsulated cells due to creating a dense, restrictive environment around the encapsulated cells. Hydrogels with lower polymer content are known to improve 3D cell growth, yet fabrication of ultra-low concentration gelatin hydrogels is challenging while ensuring fast gelation and stability. Here, we demonstrate that physical gelation and photo-crosslinking in gelatin results in a fast-gelling hydrogel at a remarkably low gelatin concentration of 1 % w / v (Gel Phy/Photo ). The Gel Phy/Photo hydrogel was highly stable, allowed uniform 3D distribution of cells, and significantly improved the spreading of encapsulated 3T3 fibroblast cells. Moreover, human cholangiocarcinoma (HuCCT-1) cells encapsulated in 1 % Gel Phy/Photo matrix grew and self-assembled into epithelial cysts with lumen, which could not be achieved in a traditional high-concentration gelatin hydrogel. These findings pave the way to significantly improve existing gelatin hydrogels for 3D cell culture applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • GSH-responsive nanogel was innovatively constructed by photocrosslinking. • AVM@PFTA realized the comprehensive improvement of pesticide efficiency. • AVM@PFTA improved deposition, retention, photostability of pesticide. • AVM@PFTA achieves better pest control efficiency than commercial formulations. • A multifunctional emulsify-crosslinking agent (PFTA) was designed and synthesized. The extremely low utilization efficiency of pesticides has driven the development of various smart, green pesticide-delivery systems. However, the existing strategies for controlling pesticide losses are step-specific or complicated preparation processes. Here, by precisely designing a multifunctional emulsify-crosslinking agent (PFTA) and innovating drug loading means, we constructed a simple and compatible nanogel delivery system by photocrosslinking, realizing the comprehensive improvement of pesticide efficiency in terms of encapsulation, deposition, retention, photodegradation resistance and release of pesticides. The nanosized networks can effectively and firmly encapsulate pesticides and protect pesticides from photodegradation, 82.42 % of the loaded AVM remained in the nanogel after UV irradiation for 28 h. Meanwhile, the chain structure of PTFA and nanosize network ensure nanogel complete deposition on superhydrophobic plant surfaces and inhibition of rainwater erosion. More importantly, glutathione-induced disruption of the nanosized networks determines the precise pesticide release. Our findings provide new insight into and new directions for the study of novel agrochemical-delivery systems. [ABSTRACT FROM AUTHOR]

The interest in environmentally friendly coatings is rising to substitute for the oil-derived materials in the coating industry. In the present study, natural tannic acid (TA) is investigated as an additive to an epoxidized soybean oil-based (ESO) coating. TA solutions in propylene carbonate at two different concentrations were prepared and added to an ESO matrix with different weight ratios. The UV-curing process of the coatings was deeply assessed through real-time Fourier Transform Infrared (FTIR) spectroscopy and Differential Scanning photo Calorimetry (photo-DCS). A significant increase in high epoxy group conversion, around 90 %, was achieved thanks to the activated monomer mechanism, which involves the TA polyphenols. This mechanism accelerated the photocrosslinking process, but reduced the coatings' crosslinking density, as demonstrated by the dynamic thermal mechanical analysis. The hardness of coatings containing the TA additive decreased, while the hydrophobicity of the surface coatings remained unchanged after the TA incorporation. Lastly, the adhesion of the UV-cured coating was evaluated on low-carbon steel substrates. An outstanding enhancement in adhesion property was provided by the TA additive, whose phenols not only participate in the photocrosslinking reaction but also coordinate iron on the steel surface. Moreover, the influence of two different steel surface pre-treatments, the pickling and plasma processes, on the coatings' adhesion strength was studied. [ABSTRACT FROM AUTHOR]

Flexographic printing has received tremendous attention in the printing field due to the advantages of short preparation processes and high printing efficiency. Its printing quality heavily depends on the preparation of the printing plate. However, plate clarity and plate softness are contradictory. This paper reports the development of a clear and soft self-plasticizing modified polyvinyl alcohol (m-PVA) coating that can be UV-cured at room temperature. Glycidyl methacrylate (GMA) was used to prepare unsaturated m-PVA (m-PVA-GMA) in an aqueous system. Meanwhile, the effects of acidic and alkaline environments on the grafted products have been further investigated, suggesting that they differ from those obtained via the dimethyl sulfoxide system. The structural comparison has demonstrated that the reactivity of GMA and m-PVA is higher in alkaline aqueous than in acidic conditions. When the unsaturation degree increases, the crystallization of PVA chain segments will be effectively destroyed. The photographic film, which can be directly photo-crosslinked, was prepared by m-PVA-GMA and washed away the uncrosslinked portion with water. The glass transition temperature (31.4 °C) of the photographic m-PVA-GMA film prepared under alkaline conditions is close to room temperature, and the crosslink density is as high as 3.01 × 103 mol m−3. More importantly, the elongation at break after water washing and the elastic recovery are 110.8 ± 5.3 % and 99 %, respectively. In addition, irradiating selected areas and then removing the non-irradiated portions with water could produce patterns. The m-PVA-GMA film prepared under alkaline conditions has outstanding development accuracy, much higher than the commercially available product nyloprint®. This direct UV-curable film with water-soluble and water-developable properties enables it to be a promising candidate in the fine flexographic printing industry, such as photoresists, electronic devices, and sensors. • Glycidyl methacrylate was grafted onto self-plasticized polyvinyl alcohol molecular chain. • After washing, the elastic recovery rate of the photosensitive film can be up to 99 %. • The modified UV curing film has clearer images than the commercial product. [ABSTRACT FROM AUTHOR]

The human amniotic membrane (HAM) collagen matrix derived from human placenta can be decellularized (dHAM) to form a natural biocompatible material. dHAM has different bioactive substances and has been used widely in human tissue engineering research. However, dHAM has some disadvantages, e.g., poor mechanical properties, easy degradation and inconvenient operation and use, so it is not conducive to large-area or full-thickness skin defect healing. To overcome these limitations, for the first time, dHAM was grafted with methacrylic anhydride (MA) to form photocrosslinked dHAM methacrylate (dHAMMA); dHAMMA was then blended with methacrylated gelatin (GelMA), followed by the addition of a photosensitizer for photocrosslinking to obtain the fast-forming GelMA-dHAMMA composite hydrogel. Further, GelMA-dHAMMA was found to have the porous structure of a bicomponent polymer network and good physical and chemical properties. In vitro experiments, GelMA-dHAMMA was found to promote fibroblast proliferation and α-smooth muscle actin (α-SMA) expression. In vivo investigations also demonstrated that GelMA-dHAMMA promotes wound collagen deposition and angiogenesis, and accelerates tissue healing. GelMA-dHAMMA inherits the good mechanical properties of GelMA and maintains the biological activity of the amniotic membrane, promoting the reconstruction and regeneration of skin wounds. Thus, GelMA-dHAMMA can serve as a promising biomaterial in skin tissue engineering. Since the early 20th century, the human amniotic membrane (HAM) has been successfully used for trauma treatment and reconstruction purposes. dHAM has different bioactive substances and has been used widely in human tissue-engineering research. In this work, the dHAM and gelatin were grafted and modified by using methacrylic anhydride (MA) to form photocrosslinked dHAMMA and methacrylated gelatin (GelMA). Then, the dHAMMA and GelMA were blended with a photosensitizer to form the GelMA-dHAMMA composite hydrogel derived from gelatin-dHAM. GelMA-dHAMMA exhibits a bicomponent-network (BCN) interpenetrating structure. dHAM dydrogel has advantages, e.g., good mechanical properties, slow degradation and convenient operation, so it is conducive to large-area or full-thickness skin defect healing. [Display omitted] [ABSTRACT FROM AUTHOR]

Towards the repair of damaged tissues, numerous scaffolds have been fabricated to recreate the complex extracellular matrix (ECM) environment to support desired cell behaviors; however, it is often challenging to design scaffolds with the requisite cell-anchorage sites, mechanical stability, and tailorable physicochemical properties necessary for many applications. To address this and to improve on the properties of hyaluronic acid (HA) hydrogels, we combined photocrosslinkable norbornene-modified HA (NorHA) with human platelet lysate (PL). These PL-NorHA hybrid hydrogels supported the adhesion of cells when compared to NorHA hydrogels without PL, exhibited tailorable physicochemical properties based on the concentration of individual components, and released proteins over time. Using microfluidic techniques with on-chip mixing of NorHA and PL and subsequent photocrosslinking, spherical PL-NorHA microgels with a hierarchical fibrillar network were fabricated that exhibited the sustained delivery of PL proteins. Microgels could be jammed into granular hydrogels that exhibited shear-thinning and self-healing properties, enabling ejection from syringes and the fabrication of stable 3D constructs with 3D printing. Again, the inclusion of PL enhanced cellular interactions with the microgel structures. Overall, the combination of biomolecules and fibrin self-assembly arising from the enriched milieu of PL-derived proteins improved the bioactivity of HA-based hydrogels, enabling the formation of dynamic systems with modular design. The granular systems can be engineered to meet the complex demands of functional tissue repair using versatile processing techniques, such as with 3D printing. Image, graphical abstract [ABSTRACT FROM AUTHOR]