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Silks are a class of proteins generated naturally by different arthropods, including silkworms, spiders, scorpions, mites, wasps, and bees. This review discusses the silk fibroin and silk sericin fabricated by Bombyx mori silkworm as versatile fibers. This silk fiber is predominantly composed of hydrophobic silk fibroin and hydrophilic silk sericin. Fibroin is defined as a structural protein that bestows silk with strength, while sericin is characterized as a gum-like protein, tying the two fibrous proteins together and endowing silk proteins with elasticity. Due to their versatile structures, biocompatibility, and biodegradability, they could be tailored into intricate structures to warrant particular demands. The intrinsic functional groups of both proteins enable their functionalization and cross-linking with various biomaterials to endow the matrix with favorable antioxidant and antibacterial properties. Depending on the target applications, they can be integrated with other materials to formulate nanofibrous, hydrogels, films, and micro-nanoparticles. Given the outstanding biological and controllable physicochemical features of fibroin and sericin, they could be exploited in pharmaceutical applications involving tissue engineering, wound repair, drug delivery, and cancer therapy. This review comprehensively discusses the advancements in the implementation of different formulations of silk fibroin and sericin in wound healing and drug delivery systems, particularly for cancer treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The use of fluorescent carbon dots (CDs) as highly precise biolabeling probes has been widespread in the fields of live cell imaging and protein labeling due to their small size and excellent photoluminescence ability to accurately target specific molecules with surface chemical properties. However, there was a lack of research on the interaction between CDs and labeled molecules. In this work, we presented a novel investigation strategy, the fluorescence microscopy-surface plasmon resonance (FM-SPR) system, which combined the use of fluorescence microscopy and wavelength modulation surface plasmon resonance to study the interaction between CDs and labeled molecules in real-time. Using this system, simultaneously recorded the SPR signals and the fluorescence images on the surface of the FM-SPR sensor chip. We observed the dynamic curve and fluorescence images of the interaction between green emissive nitrogen-doped carbon dots (N-CDs) and silk fibroin (SF) in real-time. The kinetic parameters, the quantitative analysis, and the investigation of the binding could be achieved. The results showed a strong linear relationship between the change in SPR signals and the concentration of N-CDs, with a linear coefficient of 0.99913. The linear detection range was 2.5 μg/mL-100 μg/mL, and the real lowest detection limit reached 0.5 μg/mL. Additionally, the green fluorescence points in the imaging region on the FM-SPR sensor chip increased with the concentration of N-CDs, which was consistent with the change in SPR signals. Using this system we also acquired the association rate and dissociation rate of N-CDs to SF which were 2.65 × 10 -5 /s and 1.52 × 10 -5 /s, respectively. This demonstrated the effectiveness of our method in quantitatively analyzing SF labeled with N-CDs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study aimed to detect the biocompatibility of bioactivated polycaprolactone/silk fibroin-based nanofibers in vivo using zebrafish embryos. Anti-Bisphenol A (BPA) antibody or lactase enzyme was immobilized on electrospun nanofibers, for making the nanofiber bioactive. Lactase immobilized nanofiber was developed to hydrolyze lactose and produce milk with reduced lactose. Anti-BPA antibody immobilized nanofiber was developed to remove bisphenol A from liquids. To test the biocompatibility of the bioactive nanofibers, the zebrafish embryos were divided into 4 groups; control, raw nanofiber, lactase immobilized nanofiber, and anti-BPAantibody immobilized nanofiber groups. In nanofiber-based exposure groups; nanofibers were incubated separately in the embryonic development medium. Subsequently, the embryos were kept in these development mediums for 72 h post-fertilization (72 hpf) and their developmental analyzes were performed. At the end of 72 hpf, zebrafish embryos were homogenized. Lipid peroxidation and nitrite oxide levels, and superoxide dismutase and glutathione-S-transferase activities were determined to monitor the disturbance of oxidant-antioxidant balance in zebrafish embryos. Exposure to bioactive nanofibers slightly disrupted the oxidant-antioxidant balance, but this change did not affect the mortality and hatching times of the embryos. In conclusion, zebrafish embryos have been effectively used in biocompatibility testing for bioactive nanofibers suggesting that these materials are biocompatible., Competing Interests: Declaration of competing interest The authors report no conflicts of interest., (Copyright © 2024. Published by Elsevier Ltd.)

In this study, a novel approach was employed to develop a therapeutic system for colorectal cancer treatment. Specifically, a GelMA/SilMA hydrogel loaded with curcumin-shellac nanoparticles (Cur@Lac NPs) was created. A microfluidic swirl mixer was utilized to formulate stable Cur@Lac NPs, ensuring their consistent and effective encapsulation. The pH-specific release of curcumin from the NPs demonstrated their potential for colon cancer treatment. By carefully regulating the ratio of GelMA (gelatin methacrylate) and SilMA (silk fibroin methacrylate), a GelMA/SilMA dual network hydrogel was generated, offering controlled release and degradation capabilities. The incorporation of SilMA notably enhanced the mechanical properties of the dual network matrix, improving compression resistance and mitigating deformation. This mechanical improvement is crucial for maintaining the structural integrity of the hydrogel during in vivo applications. In comparison to the direct incubation of curcumin, the strategy of encapsulating curcumin into NPs and embedding them within the GelMA/SilMA hydrogel resulted in more controlled release mechanisms. This controlled release was achieved through the disintegration of the NPs and the swelling and degradation of the hydrogel matrix. The encapsulating strategy also demonstrated enhanced cellular uptake of curcumin, leveraging the advantages of both NPs and in-situ hydrogel injection. This combination ensures a more efficient and sustained delivery of the therapeutic agent directly to the tumor site. Overall, this approach holds significant promise as a smart drug delivery system, potentially improving the efficacy of colorectal cancer treatments by providing targeted, controlled, and sustained drug release with enhanced mechanical stability and biocompatibility., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Sponge-like materials made from regenerated silk fibroin biopolymers are a tunable and advantageous platform for in vitro engineered tissue culture and in vivo tissue regeneration. Anisotropic, three-dimensional (3D) silk fibroin sponge-like scaffolds can mimic the architecture of contractile muscle. Herein, we use silk fibroin solution isolated from the cocoons of Bombyx mori silkworms to form aligned sponges via directional ice templating in a custom mold with a slurry of dry ice and ethanol. Hydrated tensile mechanical properties of these aligned sponges were evaluated as a function of silk polymer concentration (3% or 5%), freezing time (50% or 100% ethanol), and post-lyophilization method for inducing crystallinity (autoclaving, water annealing). Hydrated static tensile tests were used to determine Young's modulus and ultimate tensile strength across sponge formulations at two strain rates to evaluate rate dependence in the calculated parameters. Results aligned with previous reports in the literature for isotropic silk fibroin sponge-like scaffolds, where the method by which beta-sheets were formed and level of beta-sheet content (crystallinity) had the greatest impact on static parameters, while polymer concentration and freezing rate did not significantly impact static mechanical properties. We estimated the crystalline organization using molecular dynamics simulations to show that larger crystalline regions may be responsible for strength at low strain amplitudes and brittleness at high strain amplitudes in the autoclaved sponges. Within the parameters evaluated, extensional Young's modulus is tunable in the range of 600-2800 kPa. Dynamic tensile testing revealed the linear viscoelastic region to be between 0% and 10% strain amplitude and 0.2-2 Hz frequencies. Long-term stability was evaluated by hysteresis and fatigue tests. Fatigue tests showed minimal change in the storage and loss modulus of 5% silk fibroin sponges for more than 6000 min of continuous mechanical stimulation in the linear regime at 10% strain amplitude and 1 Hz frequency. Furthermore, we confirmed that these mechanical properties hold when decellularized extracellular matrix is added to the sponges and when the mechanical property assessments were performed in cell culture media. We also used nano-computed tomography (nano-CT) and simulations to explore pore interconnectivity and tortuosity. Overall, these results highlight the potential of anisotropic, sponge-like silk fibroin scaffolds for long-term (>6 weeks) contractile muscle culture with an in vitro bioreactor system that provides routine mechanical stimulation., (© 2024 Wiley Periodicals LLC.)

This study focused on developing electrically stimulable hyaluronic acid (HA) films incorporating lipid nanoparticles (NPs) designed for the topical administration of lipophilic drugs and macromolecules. Based on beeswax and medium-chain triglycerides, NPs were successfully integrated into silk fibroin/chitosan films containing HA (NP-HA films) at a density of approximately 10 11 NP/cm 2 , ensuring a uniform distribution. This integration resulted in a 40% increase in film roughness, a twofold decrease in Young's modulus, and enhanced film flexibility and bioadhesion work. The NP-HA films, featuring Ag/AgCl electrodes, demonstrated the capability to conduct a constant electrical current of 0.2 mA/cm 2 without inducing toxicity in keratinocytes and fibroblasts during a 15-min application. Moreover, the NPs facilitated the homogeneous distribution of lipophilic drugs within the film, effectively transporting them to the skin and uniformly distributing them in the stratum corneum upon film administration. The sustained release of HA from the films, following Higuchi kinetics, did not alter the macroscopic characteristics of the film. Although anodic iontophoresis did not noticeably affect the release of HA, it did enhance its penetration into the skin. This enhancement facilitated the permeation of HA with a molecular weight (MW) of up to 2 × 10 5 through intercellular and transcellular routes. Confocal Raman spectroscopy provided evidence of an approximate 100% increase in the presence of HA with a MW in the range of 1.5-1.8 × 10 6 in the viable epidermis of human skin after only 15 min of iontophoresis applied to the films. Combining iontophoresis with NP-HA films exhibits substantial potential for noninvasive treatments focused on skin rejuvenation and wound healing., (© 2024. Controlled Release Society.)

Peptide drug discovery for the treatment of chronic kidney disease (CKD) has attracted much attention in recent years due to the urge to find novel drugs and mechanisms to delay the progression of the disease. In this study, we identified a novel short peptide (named YR-7, primary sequence 'YEVEDYR') from the natural Fibroin protein, and demonstrated that it significantly alleviated pathological renal changes in ADR-induced nephropathy. PANX1 was identified as the most notably upregulated component by RNA-sequencing. Further analysis showed that YR-7 alleviated the accumulation of lipid droplets via regulation of the lipid metabolism-related proteins PPAR α and PANK1. Using chemical proteomics, fluorescence polarization, microscale thermophoresis, surface plasmon resonance, and molecular docking, YR-7 was proven to directly bind to β-barrel domains of TGM2 protein to inhibit lipid accumulation. TGM2 knockdown in vivo increased the protein levels of PPAR α and PANK1 while decreased the levels of fibrotic-related proteins to alleviate nephropathy. In vitro, overexpression TGM2 reversed the protective effects of YR-7. Co-immunoprecipitation indicated that TGM2 interacted with PANX1 to promote lipid deposition, and pharmacological inhibition or knockdown of PANX1 decreased the levels of PPAR α and PANK1 induced by ADR. Taken together, our findings revealed that TGM2-PANX1 interaction in promoting lipid deposition may be a new signaling in promoting ADR-induced nephropathy. And a novel natural peptide could ameliorate renal fibrosis through TGM2-PANX1-PPAR α/PANK1 pathway, which highlight the potential of it in the treatment of CKD., (Copyright © 2024. Published by Elsevier Inc.)

Liuwei Dihuang (LWDH) is a multi-component and multi-target Chinese herbal compound widely used for treating chronic conditions such as diabetes, diabetic nephropathy, hypertension, osteoporosis, and chronic kidney disease. However, traditional Chinese medicine (TCM) preparations like decoction and pill face limitations, including low active component concentration, limited bioavailability, short half-life, and the need for high dosage, which may increase the burden on liver and kidney functions and reduce clinical efficacy. In this study, LWDH was further purified using D101 macroporous adsorption resin, resulting in a soluble extract with an active component content 53.6 times higher than that of LWDH itself. The freeze-dried LWDH extract was then encapsulated within silk fibroin (SF) microspheres to significantly enhance the sustained release performance of the drug. In a human umbilical vein endothelial cell (HUVEC) model cultured under high glucose conditions, methanol vapor-treated SF/LWDH microspheres demonstrated a decrease in the 24-hour drug release rate from 61.88 % to 34.81 %, augmenting their protective effect on endothelial cells., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study presents the fabrication of an ultralight, porous, and high-performance triboelectric nanogenerator (TENG) utilizing silk fibroin (SF) aerogels and PDMS sponges as the friction layer. The transition from two-dimensional film friction layers to three-dimensional porous aerogels significantly increased the specific surface area, offering an effective strategy for designing high-performance SF aerogel-based TENGs. The TENG incorporating the porous SF aerogel exhibited optimal output performance at a 3% SF concentration, achieving a maximum open circuit voltage of 365 V, a maximum short-circuit current of 11.8 μA, and a maximum power density of 7.52 W/m 2 . In comparison to SF-film-based TENGs, the SF-aerogel based TENG demonstrated a remarkable 6.5-fold increase in voltage and a 4.5-fold increase in current. Furthermore, the power density of our SF-based TENG surpassed the previously reported optimal values for SF-based TENGs by 2.4 times. Leveraging the excellent mechanical stability and biocompatibility of TENGs, we developed an SF-based TENG self-powered sensor for the real-time monitoring of subtle biological movements. The SF-based TENG exhibits promising potential as a wearable bioelectronic device for health monitoring.

Guided bone regeneration (GBR) membranes play an important role in oral bone regeneration. However, enhancing their bone regeneration potential and antibacterial properties is crucial. Herein, silk fibroin (SF)/polycaprolactone (PCL) core-shell nanofibers loaded with epigallocatechin gallate (EGCG) were prepared using emulsion electrospinning. The nanofibrous membranes were characterized via scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, water contact angle (CA) measurement, mechanical properties testing, drug release kinetics, and 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) free radical scavenging assay. Mouse pre-osteoblast MC3T3-E1 cells were used to assess the biological characteristics, cytocompatibility, and osteogenic differentiation potential of the nanofibrous membrane. Additionally, the antibacterial properties against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were evaluated. The nanofibers prepared by emulsion electrospinning exhibited a stable core-shell structure with a smooth and continuous surface. The tensile strength of the SF/PCL membrane loaded with EGCG was 3.88 ± 0.15 Mpa, the water CA was 50°, and the DPPH clearance rate at 24 h was 81.73% ± 0.07%. The EGCG release rate of membranes prepared by emulsion electrospinning was reduced by 12% within 72 h compared to that of membranes prepared via traditional electrospinning. In vitro experiments indicate that the core-shell membranes loaded with EGCG demonstrated good cell compatibility and promoted adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. Furthermore, the EGCG-loaded membranes exhibited inhibitory effects on E. coli and S. aureus . These findings indicate that core-shell nanofibrous membranes encapsulated with EGCG prepared using emulsion electrospinning possess good antioxidant, osteogenic, and antibacterial properties, making them potential candidates for research in GBR materials., (Creative Commons Attribution license.)

Theranostic sutures are derived from innovative ideas to enhance wound healing results by adding wound diagnostics and therapeutics to typical sutures by functionalizing them with additional materials. Here, we present a new direct electrospinning method for the fast, continuous, inexpensive, and high-throughput production of versatile nanofibrous-coated suture threads, with precise control over various essential microstructural and physical characteristics. The thickness of the coating layer and the alignment of nanofibers with the thread's direction can be adjusted by the user by varying the spooling speed and the displacement between the spinneret needle and thread. To show the flexibility of our method for a range of different materials selected, gelatin, polycaprolactone, silk fibroin, and PEDOT:PSS (poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)) were the resultant nanofibers characterized by scanning electron microscopy (SEM) imaging and conductivity tests. In a series of in vitro and ex vivo tests (pig skin), sutures were successfully tested for their flexibility and mechanical properties when used as weaving and knotting sutures, and their biocompatibility with a keratinocyte cell line. For temperature-based drug-releasing tests, two fluorescent molecules as drug models with high and low molecular weight, namely fluorescein isothiocyanate-dextran (20 kDa) and rhodamine B (470 Da), were used, and their steady release with incremental increase of temperature to 37 °C over 120 min was seen, which is appropriate for bacterial treatment drugs. Given the advantages of the presented technique, it seems to have promising potential to be used in future medical applications for wound closure and bacterial infection treatment via a temperature-triggered drug release strategy.

In this study, tissue scaffolds mimicking hierarchical morphology are constructed and proposed for bone augmentation. The scaffolds are fabricated using lyophilization, before coating them with collagen (Col). Subsequently, the Col-coated scaffolds undergo a second lyophilization, followed by silk fibroin (SF) coating, and a third lyophilization. Thereafter, the scaffolds are divided into six groups with varying ratios of Col to SF: Col/SF = 7:3, 5:5, 3:7, 10:0, and 0:10, with an SF scaffold serving as the control group. The scaffold morphology is examined using a scanning electron microscope, while molecular and structural formations are characterized by Fourier transform infrared spectrometer and differential scanning calorimeter, respectively. Physical and mechanical properties including swelling and compression are tested. Biological functions are assessed through in vitro osteoblast cell culturing. Biomarkers indicative of bone formation-cell viability and proliferation, alkaline phosphatase activity, and calcium content-are analyzed. Results demonstrate that scaffolds coated with Col and SF exhibit sub-porous formations within the main pore. The molecular formation reveals interactions between the hydrophilic groups of Col and SF. The scaffold structure contains bound water and SF formation gets disrupted by Col. Physical and mechanical properties are influenced by the Col/SF ratio and morphology due to coating. The biological functions of scaffolds with Col and SF coating show enhanced potential for promoting bone tissue formation, particularly the Col/SF (7:3) ratio, which is most suitable for bone augmentation in small defect areas., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Biomedical silk protein optics has become the subject of intensive research aimed at solving the challenges associated with traditional medical devices in terms of biocompatibility and performance balance. With its significant potential for biomedical applications in the field of drug storage and wound monitoring, it is dedicated to reducing the perturbation of neighbouring tissues. The transparency and biocompatibility of silk proteins make them ideal materials in the field of optical device fabrication, effectively overcoming the challenges posed by conventional materials. In this paper, we explore in detail the complex aspects of the design, synthesis and application related to biomedical silk protein optical devices and comprehensively analyse the potential use of silk protein-centric microstructures ( e.g. , micropillars, microneedles, and photonic crystals) in the development of optical devices. This review also offers insights into the challenges of applying silk protein optical devices in healthcare and their future trends, aiming to provide a comprehensive overview of the advances, potential impacts and emerging research directions in the field of biomedical silk protein optical devices.

Nanofibers have emerged as a highly effective method for drug delivery, attributed to their remarkable porosity and ability to regulate drug release rates while minimizing toxicity and side effects. In this study, we successfully loaded the natural anticancer drugs curcumin (CUR) and hypocrellin A (HA) into pure poly(l-lactic acid) (PLLA) and PLLA-silk protein (PS) composite nanofibers through electrospinning technology. This result was confirmed through comprehensive analysis involving SEM, FTIR, XRD, DSC, TG, zeta potential, and pH stability analysis. The encapsulation efficiency of all samples exceeded 85%, demonstrating the effectiveness of the loading process. Additionally, the drug release doses were significantly higher in the composites compared to pure PLLA, owing to the enhanced crystallinity and stability of the silk proteins. Importantly, the composite nanofibers exhibited excellent pH stability in physiological and acidic environments. Furthermore, the drug-loaded composite nanofibers displayed strong inhibitory effects on cancer cells, with approximately 28% (HA) and 37% (CUR) inhibition of cell growth and differentiation within 72 h, while showing minimal impact on normal cells. This research highlights the potential for controlling drug release through the manipulation of fiber diameter and crystallinity, paving the way for wider applications of electrospun green nanomaterials in the field of medicine.

Dietary oils─rich in omega-3, -6, and -9 fatty acids─exhibit critical impacts on health parameters such as cardiovascular function, bodily inflammation, and neurological development. There has emerged a need for low-cost, accessible method to assess dietary oil consumption and its health implications. Existing methods typically require specialized, complex equipment and extensive sample preparation steps, rendering them unsuitable for home use. Addressing this gap, herein, we study passive wireless, biocompatible biosensors that can be used to monitor dietary oils directly from foods either prepared or cooked in oil. This design uses broad-coupled split ring resonators interceded with porous silk fibroin biopolymer (requiring only food-safe materials, such as aluminum foil and biopolymer). These porous biopolymer films absorb oils at rates proportional to their viscosity/fatty acid composition and whose response can be measured wirelessly without any microelectronic components touching food. The engineering and mechanism of such sensors are explored, alongside their ability to measure the oil presence and fatty acid content directly from foods. Its simplicity, portability, and inexpensiveness are ideal for emerging needs in precision nutrition─such sensors may empower individuals to make informed dietary decisions based on direct-from-food measurements.

The detection of antibiotics is crucial for safeguarding the environment, ensuring food safety, and promoting human health. However, developing a rapid, convenient, low-cost, and sensitive method for antibiotic detection presents significant challenges. Herein, an aptamer-free biosensor was successfully constructed using upconversion nanoparticles (UCNPs) coated with silk fibroin (SF), based on Förster resonance energy transfer (FRET) and the charge-transfer effect, for detecting roxithromycin (RXM). A synergistic FRET efficiency was achieved by utilizing alizarin red and RXM complexes as energy acceptors, with UCNP as the energy donor, and immobilizing an ultrathin SF protein corona within 10 nm. The biosensor detects RXM in deionized water with high sensitivity primarily through monolayer adsorption, with a detection range of 1.0 nM-141.6 nM and a detection limit as low as 0.68 nM. The performance of this biosensor was compared with the ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) method for detecting antibiotics in river water separately and a strong correlation between the two methods was observed. The biosensor exhibited long-term stability in aqueous solutions (up to 60 d) with no attenuation of fluorescence intensity. Furthermore, the biosensor's applicability extended to the highly sensitive detection of other antibiotics, such as azithromycin. This study introduces a low-cost, eco-friendly, and highly sensitive method for antibiotic detection, with broad potential for future applications in environmental, healthcare, and food-related fields., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Dynamic attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy at both solutions and coatings of a semicrystalline silk material derived from Bombyx mori was applied to monitor the β-sheet conformation, which is known to correlate with silk protein crystallinity. The secondary structure-sensitive Amide I band was analyzed. Two silk protein samples were studied: native-based silk buffer fibroin (NSF) was extracted from silk glands and regenerated silk fibroin (RSF) was extracted from degummed cocoons. Solutions of both NSF and RSF at 2 mg/mL featured low initial β-sheet contents of 5-12%, which further increased to 47-53% after 24 h. RSF and NSF solutions at 23 mg/mL also featured low initial β-sheet contents of 9-10%, which yet only slightly increased to 16-17% after 24 h. Coatings deposited from RSF solutions showed high surface integrity ( Q > 99%) after rinsing in mineralized water, enabling interfacial drug delivery applications. RSF coatings were post-treated with either formic acid (FA) or pure methanol (MeOH) vapor to showcase inducibility of crystalline domains in RSF coatings. Such coatings were loaded with the model antibiotic drugs tetracycline (TCL) and streptomycin (STRP), and the sustained release of TCL was followed in contact with (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) (HEPES) buffer. RSF/TCL coatings post-treated with formic acid (FA) vapor followed by methanol (MeOH) vapor showed a significantly lower (52%) initial burst of rather hydrophobic TCL compared to untreated RSF/TCL coatings (72%), while no such significant release difference was observed for hydrophilic STRP. This was rationalized by a specific interaction between nonpolar TCL and hydrophobic crystalline RSF domains.

A promising trend in tissue engineering is using biomaterials to improve the control of drug concentration in targeted tissue. These vehicular systems are of specific interest when the required treatment time window is higher than the stability of therapeutic molecules in the body. Herein, the capacity of silk fibroin hydrogels to release different molecules and drugs in a sustained manner was evaluated. We found that a biomaterial format, obtained by an entirely aqueous-based process, could release molecules of variable molecular weight and charge with a preferential delivery of negatively charged molecules. Although the theoretical modeling suggested that drug delivery was more likely to be driven by Fickian diffusion, the external media had a considerable influence on the release, with lipophilic organic solvents such as acetonitrile-methanol (ACN-MeOH) intensifying the release of hydrophobic molecules. Second, we found that silk fibroin could be used as a vehicular system to treat a variety of brain disorders as this biomaterial sustained the release of different factors with neurotrophic (brain-derived neurotrophic factor) (BDNF), chemoattractant (C-X-C motif chemokine 12) (CXCL12), anti-inflammatory (TGF-β-1), and angiogenic (VEGF) capacities. Finally, we demonstrated that this biomaterial hydrogel could release cholesteronitrone ISQ201, a nitrone with antioxidant capacity, showing neuroprotective activity in an in vitro model of ischemia-reoxygenation. Given the slow degradation rate shown by silk fibroin in many biological tissues, including the nervous system, our study expands the restricted list of drug delivery-based biomaterial systems with therapeutic capacity for both short- and especially long-term treatment windows and has merit for use with brain pathologies.

Within the context of seeking eco-friendly and readily available materials for energy storage, there is a pressing demand for energy storage solutions that employ environmentally sustainable, high-performance, and adaptable constituents. Specifically, such materials are essential for use in wearable technology, smart sensors, and implantable medical devices, whereas, more broadly, their use plays a pivotal role in shaping their efficiency and ecological footprint. Here, we demonstrate an entirely biopolymer-based supercapacitor with a remarkable performance, achieving a capacitance greater than 0.2 F cm -2 at a charge-discharge current of 10 mA cm -2 with 94% capacitance retention after 20,000 cycles. The supercapacitor is composed of three distinct silk fibroin (SF) composite materials, namely, photo-cross-linkable SF (Sil-MA) hydrogel, SF-polydopamine (SF-PDA), and SF bioplastic, to create a gel electrolyte, electrode binder, and encapsulation, respectively. Together, these elements form a mechanically and electrochemically robust skeleton for biofriendly energy storage devices. Moreover, these biomaterial-based supercapacitor devices show stretchability, flexibility, and compressibility while maintaining their electrochemical performance. The biomaterials and fabrication techniques presented can serve as a foundation for investigating various aqueous electrochemical energy storage systems, especially for emerging applications in wearable electronics and environmentally friendly material systems.

Background: Wound healing has always been a focal point in clinical work. Bacterial infections and immune microenvironment disorders can both hinder normal wound healing. Current wound dressings only serve a covering function. Developing wound dressings with antibacterial and immunomodulatory functions is crucial for aiding wound healing. To address this issue, we have developed a hydrogel with antibacterial and immunomodulatory functions for managing infected wounds., Methods: The present study describes a photo-crosslinked antibacterial hydrogel composed of curcumin, silver nanoparticles-loaded reduced graphene oxide, and silk fibroin methacryloyl for the treatment of infected wounds. The study assessed its antibacterial properties and its capacity to induce macrophage M2 polarization through in vitro and in vivo experiments., Results: The hydrogel demonstrates robust antibacterial properties and enhances macrophage M2 polarization in both in vitro and in vivo settings. Moreover, it accelerates the healing of infected wounds in vivo by stimulating collagen deposition and angiogenesis., Conclusion: Overall, this hydrogel shows great potential in managing wound infections., Competing Interests: The authors declare that they have no competing interests in this work., (© 2024 Han et al.)

Feeding silkworms with functional materials as additives to produce naturally modified silk is a facile, diverse, controllable, and environmentally friendly method with a low cost of time and investment. Among various additives, carbon dots (CDs) show unique advantages due to their excellent biocompatibility and fluorescence stability. Here, a new type of green fluorescent carbon dots (G-CDs) is synthesized with a high oil-water partition ratio of 147, a low isoelectric point of 5.16, an absolute quantum yield of 71%, and critically controlled surface states. After feeding with G-CDs, the silkworms weave light yellow cocoons whose green fluorescence is visible to the naked eye under UV light. The luminous silk is sewn onto the cloth to create striking patterns with beautiful fluorescence. Such G-CDs have no adverse effect on the survival rate and the life cycle of silkworms and enable their whole bodies to glow under UV light. Based on the strong fluorescence, chemical stability, and biological safety, G-CDs are found in the digestive tracts, silk glands, feces, cocoons, and even moth bodies. G-CDs accumulate in the posterior silk glands where fibroin protein is secreted, indicating its stronger combination with fibroin than sericin, which meets the requirements for practical applications.

Silk fibers' unique mechanical properties have made them desirable materials, yet their formation mechanism remains poorly understood. While ions are known to support silk fiber production, their exact role has thus far eluded discovery. Here, we use cryo-electron microscopy coupled with elemental analysis to elucidate the changes in the composition and spatial localization of metal ions during silk evolution inside the silk gland. During the initial protein secretion and storage stages, ions are homogeneously dispersed in the silk gland. Once the fibers are spun, the ions delocalize from the fibroin core to the sericin-coating layer, a process accompanied by protein chain alignment and increased feedstock viscosity. This change makes the protein more shear-sensitive and initiates the liquid-to-solid transition. Selective metal ion doping modifies silk fibers' mechanical performance. These findings enhance our understanding of the silk fiber formation mechanism, laying the foundations for developing new concepts in biomaterial design., (© 2024. The Author(s).)

Fibroin nanoparticles (FNP) have been employed in numerous biomedical applications. However, limited research has focused on the oral delivery of FNP and in-depth molecular interactions between the encapsulated drug and FNP. Therefore, this work developed the FNP, functionalized with poly(vinyl alcohol) (PVA), to orally deliver the zwitterionic ciprofloxacin, focused on the molecular interactions. The particles were formulated using both desolvation (the drug precipitated during the particles formulation) and adsorption (the drug adsorbed on the particles surfaces) methods. The optimal formula possessed a size of ~630 nm with narrow size distribution (measured by DLS method), spherical shape (determined by SEM), and moderate drug loading (confirmed by FT-IR, XRD, and DSC techniques) of ~50% for the desolvation method and ~43% for the adsorption method. More than 80% of the drug molecules resided on the particle surfaces, mainly via electrostatic forces with fibroin. The drug was physically adsorbed onto FNP, which followed Langmuir model and pseudo second-order kinetics. In the in-vitro simulated gastric condition at pH 1.2, the ciprofloxacin bound strongly with FNP via electrostatic forces, thus hindering the drug release (< 40%). Contrastingly, in the simulated intestinal condition at pH 6.8, the particles could control the drug release rates dependent on the PVA amount, with up to ~100% drug release. Lastly, the particles possessed adequate antibacterial activities on Bacillus subtilis, Escherichia coli, and Salmonella enterica, with MIC of 128, 8, and 32 μg/mL, respectively. In summary, the FNP and PVA functionalized FNP could be a potential oral delivery system for zwitterionic drugs., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Thi Phuong Thao et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Severe burn wounds face two primary challenges: dysregulated cellular impairment functions following infection and an unbalanced wound hydration microenvironment leading to excessive inflammation and collagen deposition. These results in hypertrophic scar contraction, causing significant deformity and disability in survivors., Methods: A three-dimensional (3D) printed double-layer hydrogel (DLH) was designed and fabricated to address the problem of scar formation after burn injury. DLH was developed using methacrylated silk fibroin (SFMA) and gelatin methacryloyl (GelMA) for the upper layer, and GelMA and hyaluronic acid methacryloyl (HAMA) for the lower layer. To combat infection, copper-epigallocatechin gallate (Cu-EGCG) was incorporated into the lower layer bioink, collectively referred to as DLS. To balance wound hydration levels, HaCaT cells were additionally encapsulated in the upper layer, designed as DLS/c., Findings: DLH demonstrated suitable porosity, appropriate mechanical properties, and excellent biocompatibility. DLS exhibited potent antimicrobial properties, exerted anti-inflammatory effects by regulating macrophage polarisation, and may enhance angiogenesis through the HIF-1α/VEGF pathway. In the DLS/c group, animal studies showed significant improvements in epidermal formation, barrier function, and epidermal hydration, accompanied by reduced inflammation. In addition, Masson's trichrome and Sirius red staining revealed that the structure and ratio of dermal collagen in DLS/c resembled that of normal skin, indicating considerable potential for scarless wound healing., Interpretation: This biomimetic matrix shows promise in addressing the challenges of burn wounds and aiming for scarless repair, with benefits such as anti-infection, epidermal hydration, biological induction, and optimised topological properties., Funding: Shown in Acknowledgements., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Combining a biocompatible hydrogel scaffold with the cell-supportive properties of silk fibroin (SF) and the unique functionalities of ZnFe 2 O 4 nanoparticles creates a promising platform for advanced nanobiomaterials. The research is centered on synthesizing a natural hydrogel using cellulose (Cellul) and sodium alginate (SA) combined with SF and zinc ferrite nanoparticles. A range of analytical and biological assays were conducted to determine the biological and physicochemical properties of the nanobiocomposite. The hemolysis and 2,5-diphenyl-2H-tetrazolium bromide (MTT) assays indicated that the SA-Cellul hydrogel/SF/ZnFe 2 O 4 nanobiocomposite was a biocompatible against human dermal fibroblasts (Hu02) and red blood cells (RBC). In addition, aside from demonstrating outstanding anti-biofilm activity, the nanobiocomposite also promotes the Hu02 cells adhesion, showcasing the synergistic effect of incorporating SF and ZnFe 2 O 4 nanoparticle. These promising results show that this nanobiocomposite has potential applications in various biomedical fields., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Protein materials gain new functions and applicability through redesigns in protein structure and engineering confer. However, the application and development of proteins for use in flexible devices that fit in flexible devices that fit the surface of human skin is hindered by their poor wet stability. Here, we described the design of wet-stable materials based on the reconstruction of silk fibroin (SF). The combination of polyamide-amine-epichlorohydrin (PAE) was used as a traction rope to bring SF molecular chains closer to each other, to facilitate the self-assembly of SF through branching and lengthening of molecular chains, and change its crystalline structure. SF/PAE composite films that exhibited huge improvement in ductility and wet stability were combined with flexible SF substrates via patterning and ion sputtering to prepare flexible sensors. In addition, the SF/PAE sensing system equipped with a microprocessor and Bluetooth module enabled the real-time remote acquisition of human health signals such as vocal cords, joints, pulse and meridians. This reconfiguration of the SF structure will advance the systematic exploration of protein structures and the development of protein materials for intelligent device applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The Helicobacter pylori infection in the stomach is the key reason for gastric mucosal bleeding. Eliminating gastric Helicobacter pylori by oral treatment remains difficult due to the presence of the gastric mucosal layer, which acts as a physical barrier to drugs via oral administration. In this study, a magnetic-navigable microneedle drug delivery platform (MNsD) for oral administration, featuring differential dual-mode drug release rate, was designed to fulfil rapid gastric hemostasis and overcome the gastric barriers for long-lasting Helicobacter pylori inhibition in stomach. MNs-D was created by rationally loading the carrier substrate, which was composed of silk fibroin with variable solubility, with antibiotics and hemostats. In vitro experiments showed MNs-D may sustainably eradicate Helicobacter pylori in stimulated gastric juices with long-lasting drug release (79 % in 24 h) and quickly establish hemostasis with instant drug release (92 % within 60 s). Most importantly, in vivo studies demonstrated MNs-D overcame the unsettling gastric mucosal barrier in traditional therapies of oral administration by insertion into the GML under magnetic navigation, resulting in sustained antibiotic release for long-lasting Helicobacter pylori eradiation (99 %). For differential dual-mode medication release against gastric Helicobacter pylori infections, this study may have firstly examined the effects of magnetic navigated microneedles administered orally., Competing Interests: Declaration of competing interest There are no conflicts of interest to declare., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bioactive hydrogels are currently receiving significant attention. In this study, silk fibroin tyramine-modified gelatin hydrogels (SF-TG) with varying degrees of tyramine root substitution were explored. The physicochemical property and biocompatibility of low degree of substitution tyramine-modified gelatin hydrogel (SF-LTG) and high degree of substitution tyramine-modified gelatin hydrogel (SF-HTG) were compared. The results showed that SF-LTG possessed better mechanical property and higher biocompatibility. Thus, SF-LTG was selected as a bioactive matrix and loaded with basic fibroblast growth factor (bFGF); subsequently, curcumin-coupled chitosan rods (CCCRs-EGF) enriched with epidermal growth factor (EGF) were added to obtain SF-LTG-bFGF@CCCRs-EGF hydrogels. The results showed that SF-LTG-bFGF@CCCRs-EGF retained the basic structural and mechanical properties of the SF-LTG matrix gel material and underwent multiple loading and orderly release with different activities while displaying antioxidant, anti-inflammatory, antimicrobial, and pro-cellular proliferation activities and orderly regulation of activity during wound healing. Therefore, the SF-LTG-bFGF@CCCRs-EGF hydrogel is of great value in healing complex wounds., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Biofilm formation on indwelling medical devices such as catheters and ventilators due to the adhesion of bacteria poses significant challenges in healthcare. Surface modification with micro- and nano-structures offers a promising strategy to prevent bioadhesion and is safer than surface chemical modification approaches. Here, catheters were prepared using silk fibroin (SF) hydrogels and an infusion molding method, with the inner surface featuring a micropapillae structure inspired by lotus leaves (SF-CMP). After phenylethanol (PEA) fumigation treatment, the resulting catheters (SF-CMP PEA) displayed improved swelling resistance and mechanical properties compared to methanol-treated catheters (SF-CMP MeOH). PEA was more efficient than methanol in controlling the size, distribution, and content of silk crystalline β-sheet blocks and thus the swelling and mechanical properties. Moreover, the micro-papillae structure on SF-CMP PEA remained stable over 35 days in solution, in contrast to SF-CMP MeOH, which lasted <7 days. SF-CMP PEA exhibited repellent effects against E. coli and S. aureusin vitro, and low cytotoxicity to the endothelial cells cultured on the unpatterned surface. Additionally, subcutaneous implantation studies showed reduced inflammation around the micropatterned samples compared to controls with a plain, unpatterned surface. The unique properties of SF-based materials, including tunable structures, biocompatibility, degradation, and drug-loading capability make them an attractive material for anti-bioadhesion in applications ranging from indwelling medical devices to tissue engineering scaffolds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Myocardial infarction (MI) is considered as a significant cause of death globally. Exosomes (EXOs) are essential for intercellular communication and pathophysiology of several cardiovascular diseases. Nevertheless, the short half-life and rapid clearance of EXOs leads to a lack of therapeutic doses delivered to the lesioned area. Therefore, an injectable silk fibroin and alginate (SF/Alg) composite hydrogel was developed to bind folate receptor-targeted EXOs (FA-EXOs) derived from H9C2 cells for the therapy of myocardial injury following myocardial infarction-ischemia/reperfusion (MI-I/R). The resulting composite exhibits a variety of properties, including adjustable gelation kinetics, shear-thinning injectability, soft and dynamic stability that adapts to the heartbeat, and outstanding cytocompatibility. After injected into the damaged rat heart, administration of SF/Alg + FA-EXOs significantly enhanced cardiac function as demonstrated by improved ejection fraction, fractional shortening and decreased fibrosis area. The results of real-time PCR and immunofluorescence staining show a remarkable up-regulation in the expression of proteins (CD31) and genes (VWF and Serca2a) related to the heart. Conversely, expression of fibrosis-related genes (TGF-β1) decreased significantly. Therefore, the obtained SF/Alg + FA-EXOs system remarkably enhanced the intercellular interactions, promoted cell proliferation and angiogenesis, and achieved an outstanding therapeutic effect on MI., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Mandibular defect repair has always been a clinical challenge, facing technical bottleneck. The new materials directly affect technological breakthroughs in mandibular defect repair field. Our aim is to fabricate a scaffold of advanced biomaterials for repairing of small mandibular defect. Therefore, a novel dual-channel scaffold consisting of silk fibroin/collagen type-I/hydroxyapatite (SCH) and polycaprolactone/hydroxyapatite (PCL/HA) was fabricated by cryogenic 3D printing technology with double nozzles. The mechanical properties and behaviors of the dual-channel scaffold were investigated by performing uniaxial compression, creep, stress relaxation, and ratcheting experiments respectively. The experiments indicated that the dual-channel scaffold was typical non-linear viscoelastic consistent with cancellous tissue; the Young's modulus of this scaffold was 60.1 kPa. Finite element analysis (FEA) was employed performing a numerical simulation to evaluate the implantation effect in mandible. The stress distribution of the contact area between scaffold and defect was uniform, the maximum Mises stress of cortical bone and cancellous bone in defect area were 54.520 MPa and 3.196 MPa, and the maximum displacement of cortical bone and cancellous bone in defect area were 0.1575 mm and 0.1555 mm respectively, which distributed in the incisor region. The peak maximum Mises stress experienced by the implanted scaffold was 3.128 × 10 -3  MPa, and the maximum displacement was 6.453 × 10 -2  mm distributed near incisor area. The displacement distribution of the scaffold was consistent with that of cortical and cancellous bone. The scaffold recovered well when the force applied on it disappeared. Above all, the dual-channel scaffold had excellent bio-mechanical properties in implanting mandible, which provides a new idea for the reconstruction of irregular bone defects in the mandible and has good clinical development prospects., (© 2024. International Federation for Medical and Biological Engineering.)

Bioscaffolds, which promote cell regeneration and restore tissues' functions, have emerged as significant need in clinic. The hybrid of several biomaterials in a bioscaffold renders clinically advanced and relevant properties for applications yet add challenges in cost efficiency, production, and clinical investigation. This study proposes a facile and sustainable method to formulate a triple-hybrid bioscaffold based on Vietnamese cocoon origin Silk Fibroin, Chitosan, and nano-Biphasic Calcium Phosphates (nano-BCP) that can be easily molded, has high porosity (55-80%), and swelling capacity that facilitates cell proliferation and nutrient diffusion. Notably, their mechanical properties, in particular compressive strength, can easily be tuned in a range from 50 - 200 kPa by changing the amount of nano-BCP addition, which is comparable to the successful precedents for productive cell regeneration. The latter parts investigate the biopharmaceutical properties of a representative bioscaffold, including drug loading and release studies with two kinds of active compounds, salmon calcitonin and methylprednisolone. Furthermore, the bioscaffold is highly biocompatible as the results of hemocompatibility and hemostasis tests, as well as ovo chick chorioallantoic membrane investigation. The findings of the study suggest the triple-hybrid scaffold as a promising platform for multi-functional drug delivery and bone defect repair., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 American Pharmacists Association. Published by Elsevier Inc. All rights reserved.)

Complicated peripheral nerve injuries or defects, especially at branching sites, remain a prominent clinical challenge after the application of different treatment strategies. Current nerve grafts fail to match the expected shape and size for delicate and precise branched nerve repair on a case-by-case basis, and there is a lack of geometrical and microscale regenerative navigation. In this study, we develop a sugar painting-inspired individualized multilevel epi-/peri-/endoneurium-mimetic device (SpinMed) to customize natural cues, featuring a selectively protective outer sheath and an instructive core, to support rapid vascular reconstruction and consequent efficient neurite extension along the defect area. The biomimetic perineurium dictates host-guest crosslinking in which new vessels secrete multimerin 1 binding to the fibroin filler surface as an anchor, contributing to the biological endoneurium that promotes Schwann cell homing and remyelination. SpinMed implantation into rat sciatic nerve defects yields a satisfactory outcome in terms of structural reconstruction, with sensory and locomotive function restoration. We further customize SpinMed grafts based on anatomy and digital imaging, achieving rapid repair of the nerve trunk and branches superior to that achieved by autografts and decellularized grafts in a specific beagle nerve defect model, with reliable biosafety. Overall, this intelligent art-inspired biomimetic design offers a facile way to customize sophisticated high-performance nerve grafts and holds great potential for application in translational regenerative medicine., (© 2024. The Author(s).)

Bioactive agents have demonstrated regenerative potential for cell-free bone tissue engineering. Nevertheless, certain challenges persist, including ineffective delivery methods and confined therapeutic potency. Here, we demonstrated that the biomimetic calcium phosphate coating system (BioCaP) could effectively uptake and slowly release the incorporated bioactive agents compared to the surface absorption system via osteoclast-mediated degradation of BioCaP coatings. The release kinetics were determined as a function of time. The release rate was stable without remarkable burst release during the first 1 day, followed by a sustained release from day 7 to day 19. Then, we developed the bi-functional BioCaP-coated silk fibroin scaffolds enabling the effective co-delivery of TGF-β3 and BMP-2 (SFI-T/SFI-B) and the corresponding slow release of TGF-β3 and BMP-2 exhibited superior potential in promoting chondrogenesis and osteogenesis without impairing cell vitality in vitro. The SFI-T/SFI-B scaffolds could improve cartilage and bone regeneration in 5 × 4 mm rabbit osteochondral (OC) defect. These findings indicate that the biomimetic calcium-phosphate coated silk fibroin scaffolds with slowly co-released TGF-β3 and BMP-2 effectively promote the repair of OC defects, hence facilitating the future clinical translation of controlled drug delivery in tissue engineering., (© 2024. The Author(s).)

Oral ulcers, superficial lesions on the surface of the oral mucosa, have a high incidence rate, and their main symptoms include local pain and erosion. Lipopolysaccharide (LPS)-preconditioned bone marrow mesenchymal stem cells and their secreted exosomes (LPS-pre-Exos) have been shown to promote recovery in various inflammatory conditions and wounds. However, studies documenting LPS-pre-Exos as a therapeutic intervention for oral mucosal-like diseases are lacking. In this study, we prepared a silk fibroin microneedle (MN) patch consisting of LPS-pre-Exos and zeolitic imidazolate framework-8 (ZIF-8) that localized at the tip and base, respectively, and used this MN patch for oral ulcer treatment. Upon insertion into the oral mucosa, continuous LPS-pre-Exos release was observed, which promoted macrophage polarization and tissue healing. Additionally, the ZIF-8 framework in the MN patch facilitated the controlled release of Zn 2+ , which demonstrated potent antimicrobial properties via synergistic effects. The in vitro experimental results showed that the silk fibroin MN patch can continuously release LPS-pre-Exos and Zn 2+ for more than 7 days. Thus, the LPS-pre-Exos and ZIF-8-loaded silk fibroin MN patch exhibited good anti-inflammatory and antibacterial properties, promoting oral ulcer healing, and showed good histocompatibility. Hence, it may represent a potentially valuable strategy for facilitating oral ulcer healing.

Gelation of protein condensates formed by liquid-liquid phase separation occurs in a wide range of biological contexts, from the assembly of biomaterials to the formation of fibrillar aggregates, and is therefore of interest for biomedical applications. Soluble-to-gel (sol-gel) transitions are controlled through macroscopic processes such as changes in temperature or buffer composition, resulting in bulk conversion of liquid droplets into microgels within minutes to hours. Using microscopy and mass spectrometry, we show that condensates of an engineered mini-spidroin (NT2repCT YF ) undergo a spontaneous sol-gel transition resulting in the loss of exchange of proteins between the soluble and the condensed phase. This feature enables us to specifically trap a silk-domain-tagged target protein in the spidroin microgels. Surprisingly, laser pulses trigger near-instant gelation. By loading the condensates with fluorescent dyes or drugs, we can control the wavelength at which gelation is triggered. Fluorescence microscopy reveals that laser-induced gelation significantly further increases the partitioning of the fluorescent molecules into the condensates. In summary, our findings demonstrate direct control of phase transitions in individual condensates, opening new avenues for functional and structural characterization.

Amyloid A (AA) amyloidosis is induced by administering amyloid fibrils to animals under inflammatory conditions. Silk fibroin (SF), the main component of silk threads, forms amyloid-like fibrils and has been previously reported to induce AA amyloidosis in mice. In this study, SF was cultured in ethanol solution, and after confirming fibril formation through thioflavin T assay, Congo red assay, and observation under electron microscopy, cultured SF ethanol solutions were administered to mice via various routes to investigate the induction of target organs and amyloidosis. As a result, cultured SF ethanol solutions were confirmed to reach the lungs and spleen, but no amyloid deposition was observed. While SF forms amyloid-like fibril structures through cultivation in ethanol solution, its amyloid-enhancing factor (AEF) activity is considered low in mice., (© 2024 IOP Publishing Ltd.)

Phosphate plays a vital role in spider silk spinning and has been utilized in numerous artificial silk spinning attempts to replicate the remarkable mechanical properties of natural silk fiber. Its application in artificial processes has, however, yielded varying outcomes. It is thus necessary to investigate the origins and mechanisms behind these differences. By using recombinant silk protein SC-ADF3 derived from the garden spider Araneus diadematus , here, we describe its conformational changes under various conditions, elucidating the effect of phosphate on SC-ADF3 silk protein properties and interactions. Our results demonstrate that elevated phosphate levels induce the irreversible conformational conversion of SC-ADF3 from random coils to β-sheet structures, leading to decreased protein solubility over time. Furthermore, exposure of SC-ADF3 to phosphate stiffens already formed structures and reduces the ability to form new interactions. Our findings offer insights into the underlying mechanism through which phosphate-induced β-sheet structures in ADF3-related silk proteins impede fiber formation in the subsequent phases. From a broader perspective, our studies emphasize the significance of silk protein conformation for functional material formation, highlighting that the formation of β-sheet structures at the initial stages of protein assembly will affect the outcome of material forming processes.

Encapsulation of single cells is a powerful technique used in various fields, such as regenerative medicine, drug delivery, tissue regeneration, cell-based therapies, and biotechnology. It offers a method to protect cells by providing cytocompatible coatings to strengthen cells against mechanical and environmental perturbations. Silk fibroin, derived from the silkworm Bombyx mori , is a promising protein biomaterial for cell encapsulation due to the cytocompatibility and capacity to maintain cell functionality. Here, THP-1 cells, a human leukemia monocytic cell line, were encapsulated with chemically modified silk polyelectrolytes through electrostatic layer-by-layer deposition. The effectiveness of the silk nanocoating was assessed using scanning electron microscopy (SEM) and confocal microscopy and on cell viability and proliferation by Alamar Blue assay and live/dead staining. An analysis of the mechanical properties of the encapsulated cells was conducted using atomic force microscopy nanoindentation to measure elasticity maps and cellular stiffness. After the cells were encapsulated in silk, an increase in their stiffness was observed. Based on this observation, we developed a mechanical predictive model to estimate the variations in stiffness in relation to the thickness of the coating. By tuning the cellular assembly and biomechanics, these encapsulations promote systems that protect cells during biomaterial deposition or processing in general.

Surface wrinkling provides an approach to modify the surfaces of biomedical devices to better mimic features of the extracellular matrix and guide cell attachment, proliferation, and differentiation. Biopolymer wrinkling on active materials holds promise but is poorly explored. Here we report a mechanically actuated assembly process to generate uniaxial micro-and nanosized silk fibroin (SF) wrinkles on a thermo-responsive shape-memory polymer (SMP) substrate, with wrinkling demonstrated under both dry and hydrated (cell compatible) conditions. By systematically investigating the influence of SMP programmed strain magnitude, film thickness, and aqueous media on wrinkle stability and morphology, we reveal how to control the wrinkle sizes on the micron and sub-micron length scale. Furthermore, as a parameter fundamental to SMPs, we demonstrate that the temperature during the recovery process can also affect the wrinkle characteristics and the secondary structures in the silk network. We find that with increasing SMP programmed strain magnitude, silk wrinkled topographies with increasing wavelengths and amplitudes are achieved. Furthermore, silk wrinkling is found to increase β-sheet content, with spectroscopic analysis suggesting that the effect may be due primarily to tensile ( e.g. , Poisson effect and high-curvature wrinkle) loading modes in the SF, despite the compressive bulk deformation (uniaxial contraction) used to produce wrinkles. Silk wrinkles fabricated from sufficiently thick films (roughly 250 nm) persist after 24 h in cell culture medium. Using a fibroblast cell line, analysis of cellular response to the wrinkled topographies reveals high viability and attachment. These findings demonstrate use of wrinkled SF films under physiologically relevant conditions and suggest the potential for biopolymer wrinkles on biomaterials surfaces to find application in cell mechanobiology, wound healing, and tissue engineering.

Despite recent advancements in peripheral nerve regeneration, the creation of nerve conduits with chemical and physical cues to enhance glial cell function and support axonal growth remains challenging. This study aimed to assess the impact of electrical stimulation (ES) using a conductive nerve conduit on sciatic nerve regeneration in a rat model with transection injury. The study involved the fabrication of conductive nerve conduits using silk fibroin and Au nanoparticles (AuNPs). Collagen hydrogel loaded with green fluorescent protein (GFP)-positive adipose-derived mesenchymal stem cells (ADSCs) served as the filling for the conduit. Both conductive and non-conductive conduits were applied with and without ES in rat models. Locomotor recovery was assessed using walking track analysis. Histological evaluations were performed using H&E, luxol fast blue staining and immunohistochemistry. Moreover, TEM analysis was conducted to distinguish various ultrastructural aspects of sciatic tissue. In the ES + conductive conduit group, higher S100 (p < 0.0001) and neurofilament (p < 0.001) expression was seen after 6 weeks. Ultrastructural evaluations showed that conductive scaffolds with ES minimized Wallerian degeneration. Furthermore, the conductive conduit with ES group demonstrated significantly increased myelin sheet thickness and decreased G. ratio compared to the autograft. Immunofluorescent images confirmed the presence of GFP-positive ADSCs by the 6th week. Locomotor recovery assessments revealed improved function in the conductive conduit with ES group compared to the control group and groups without ES. These results show that a Silk/AuNPs conduit filled with ADSC-seeded collagen hydrogel can function as a nerve conduit, aiding in the restoration of substantial gaps in the sciatic nerve with ES. Histological and locomotor evaluations indicated that ES had a greater impact on functional recovery compared to using a conductive conduit alone, although the use of conductive conduits did enhance the effects of ES., (© 2024. The Author(s).)

When treating orthopaedic damage or illness and accidental fracture, bone grafting remains the gold standard of treatment. In cases where this approach does not seem achievable, bone tissue engineering can offer scaffolding as a substitute. Defective and fractured bone tissue is extracted and substituted with porous scaffold structures to aid in the process of tissue regeneration. 3D bioprinting has demonstrated enormous promise in recent years for producing scaffold structures with the necessary capabilities. In order to create composite biomaterial inks for 3D bioprinting, three different materials were combined such as silk fibroin, bone particles, and synthetic biopolymer poly (ε-caprolactone) (PCL). These biomaterials were used to fabricate the two composites scaffolds such as: silk fibroin + bovine bone (SFB) and silk fibroin + bovine bone + Polycaprolactone (SFBP). The biomechanical, structural, and biological elements of the manufactured composite scaffolds were characterized in order to determine their suitability as a possible biomaterial for the production of bone tissue. The in vitro bioactivity of the two composite scaffolds was assessed in the simulated body fluids, and the swelling and degradation characteristics of the two developed scaffolds were analyzed separately over time. The results showed that the mechanical durability of the composite scaffolds was enhanced by the bovine bone particles, up to a specific concentration in the silk fibroin matrix. Furthermore, the incorporation of bone particles improved the bioactive composite scaffolds' capacity to generate hydroxyapatite in vitro. The combined findings show that the two 3D printed bio-composites scaffolds have the required mechanical strength and may be applied to regeneration of bone tissue and restoration, since they resemble the characteristics of native bone., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Developing a biodegradable sponge with rapid shape recovery and potent antibacterial and coagulation properties for traumatic hemostasis and anti-infection remains challenging. Herein, we fabricated quaternized silk fibroin (SF) sponges by freeze-drying under a constant cooling rate and modification with quaternary ammonium groups. We found the constant cooling rate enabled the sponges with a highly uniform pore structure, which provided excellent self-elasticity and shape recovery. Decoration with quaternary ammonium groups enhanced blood cells adhesion, aggregation, and activation, as well as resistance to infections from Staphylococcus aureus and Escherichia coli. The SF sponge had superior hemostatic capacity to gauze and commercial gelatin sponge in different hemorrhage models. The SF sponge exhibited favorable biodegradability and biocompatibility. Moreover, The SF sponge also promoted host cell infiltration, capillary formation, and tissue ingrowth, suggesting its potential for guiding tissue regeneration. The developed SF sponge holds great application prospects for traumatic hemostasis, anti-infection, and guiding tissue regeneration., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Silk fibroin (SF) microparticles were administered in the diet of gilthead seabream with or without experimental skin wounds to study the effects on cellular immunity and liver. A commercially available diet was enriched with varying amount of SF: 0, 50 and 100 mg kg -1 (representing the control, SF50 and SF100 diets respectively). The animals were fed for 30 days and half of them were sampled. Similar experimental wounds were then performed on the rest of fish, and they continued to be fed the same diet. At 7 days post-wounding, samples were taken from the wounded fish. Cellular immunity was studied on head kidney leucocytes (phagocytosis, respiratory and peroxidase content) and liver status (histological study and gene expression) were studied. Our results showed that experimental wounds affect both cellular immunity (by decreasing leucocyte respiratory burst and peroxidase activity) and altered liver histology (by inducing vascularisation and congestion of blood vessels). In addition, it influences the expression of genes that serve as markers of oxidative stress, endoplasmic reticulum stress and apoptosis. The highest dose of SF (SF100) increased the phagocytic capacity of leucocytes the most, as well as the expression of genes related to blood vessel formation in the liver. Furthermore, increased expression of antioxidant genes (cat and gsr) and decreased expression of genes related to reticulum endoplasmic stress (grp94 and grp170) and apoptosis (nos and jnk) were detected in these fish fed with SF100 and wounded. In conclusion, fed fish with SF100 had many beneficial effects as cellular immunostimulant and hepatoprotection in wounded fish. Its use could be of great interest for stress management in farmed fish conditions., (© 2024 The Authors. Journal of Animal Physiology and Animal Nutrition published by Wiley‐VCH GmbH.)

Critical size bone defects cannot heal without aid and current clinical approaches exhibit some limitations, underling the need for novel solutions. Silk fibroin, derived from silkworms, is widely utilized in tissue engineering and regenerative medicine due to its remarkable properties, making it a promising candidate for bone tissue regeneration in vitro and in vivo. However, the clinical translation of silk-based materials requires refinements in 3D architecture, stability, and biomechanical properties. In earlier research, improved mechanical resistance and stability of chemically crosslinked methacrylate silk fibroin (Sil-Ma) sponges over physically crosslinked counterparts were highlighted. Furthermore, the influence of photo-initiator and surfactant concentrations on silk properties was investigated. However, the characterization of sponges with Sil-Ma solution concentrations above 10 % (w/V) was hindered by production optimization challenges, with only cell viability assessed. This study focuses on the evaluation of methacrylate sponges' suitability as temporal bone tissue regeneration scaffolds. Sil-Ma sponge fabrication at a fixed concentration of 20 % (w/V) was optimized and the impact of photo-initiator (LAP) concentrations and surfactant (Tween 80) presence/absence was studied. Their effects on pore formation, silk secondary structure, mechanical properties, and osteogenic differentiation of hBM-MSCs were investigated. We demonstrated that, by tuning silk sponges' composition, the optimal combination boosted osteogenic gene expression, offering a strategy to tailor biomechanical properties for effective bone regeneration. Utilizing Design of Experiment (DoE), correlations between sponge composition, porosity, and mechanical properties are established, guiding tailored material outcomes. Additionally, correlation matrices elucidate the microstructure's influence on gene expressions, providing insights for personalized approaches in bone tissue regeneration., Competing Interests: Declaration of competing interest The authors declare no competing interest., (Copyright © 2024. Published by Elsevier B.V.)

Magnetic propulsion of nano-/micro-robots is an effective way to treat implant-associated infections by physically destroying biofilm structures to enhance antibiotic killing. However, it is hard to precisely control the propulsion in vivo . Magnetic-nanoparticle coating that can be magnetically pulled off does not need precise control, but the requirement of adhesion stability on an implant surface restricts its magnetic responsiveness. Moreover, whether the coating has been fully pulled-off or not is hard to ensure in real-time in vivo . Herein, composited silk fibroins (SFMA) are optimized to stabilize Fe 3 O 4 nanoparticles on a titanium surface in a dry environment; while in an aqueous environment, the binding force of SFMA on titanium is significantly reduced due to hydrophilic interaction, making the coating magnetically controllable by an externally-used magnet but still stable in the absence of a magnet. The maximum working distance of the magnet can be calculated using magnetomechanical simulation in which the yielding magnetic traction force is strong enough to pull Fe 3 O 4 nanoparticles off the surface. The pulling-off removes the biofilms that formed on the coating and enhances antibiotic killing both in vitro and in a rat sub-cutaneous implant model by up to 100 fold. This work contributes to the practical knowledge of magnetic propulsion for biofilm treatment.

The treatment of infected wounds remains a challenging biomedical problem. Some bioactive small-molecule hydrogelators with unique rigid structures can self-assemble into supramolecular hydrogels for wound healing. However, they are still suffered from low structural stability and bio-functionality. Herein, a supramolecular hydrogel antibacterial dressing with a dual nanofibrillar network structure is proposed. A nanofibrillar network created by a small-molecule hydrogelator, puerarin extracted from the traditional Chinese medicine Pueraria, is interconnected with a secondary macromolecular silk fibroin nanofibrillar network induced by Ga ions via charge-induced supramolecular self-assembly. The resulting hydrogel features adequate mechanical strength for sustainable retention at wounds. Good biocompatibility and efficient bacterial inhibition are obtained when the Ga ion concentration is 0.05%. Otherwise, the substantial release of Ga ions and puerarin endows the hydrogel with excellent hemostatic and antioxidative properties. In vivo, evaluation of a mouse-infected wound model demonstrates that its healing effect outperformed that of a commercially available silver-containing wound dressing. The experimental group successfully achieves a 100% wound closure rate on day 10. This study sheds new light on the design of nanofibrillar hydrogels based on supramolecular self-assembly of naturally derived bioactive molecules as well as their clinical use for treating chronic infected wounds., (© 2024 Wiley‐VCH GmbH.)

Spinal cord injury (SCI) often leads to a severe permanent disability. A poor inflammatory microenvironment and nerve electric signal conduction block are the main reasons for difficulty in spinal cord nerve regeneration. In this study, black phosphorus (BP) and glycyrrhizic acid (GA) are integrated into methacrylate-modified silk fibroin (SF) to construct a bifunctional injectable hydrogel (SF/BP/GA) with appropriate conductivity and the ability to inhibit inflammation to promote neuronal regeneration after SCI. This work discovers that the SF/BP/GA hydrogel can reduce the oxidative damage mediated by oxygen free radicals, promote the polarization of macrophages toward the anti-inflammatory M2 phenotype, reduce the expression of inflammatory factors, and improve the inflammatory microenvironment. Moreover, it induces neural stem cell (NSC) differentiation and neurosphere formation, restores signal conduction at the SCI site in vivo, and ameliorates motor function in mice with spinal cord hemisection, revealing a significant neural repair effect. An injectable, electroconductive, free-radical-scavenging hydrogel is a promising therapeutic strategy for SCI repair., (© 2024 The Authors. Advanced Healthcare Materials published by Wiley‐VCH GmbH.)

The powerful adhesion systems of marine organisms have inspired the development of artificial protein-based bioadhesives. However, achieving robust wet adhesion using artificial bioadhesives remains technically challenging because the key element of liquid-liquid phase separation (LLPS)-driven complex coacervation in natural adhesion systems is often ignored. In this study, mimicking the complex coacervation phenomenon of marine organisms, an artificial protein-based adhesive hydrogel (SFG hydrogel) was developed by adopting the LLPS-mediated coacervation of the natural protein silk fibroin (SF) and the anionic surfactant sodium dodecylbenzene sulfonate (SDBS). The assembled SF/SDBS complex coacervate enabled precise spatial positioning and easy self-adjustable deposition on irregular substrate surfaces, allowing for tight contact. Spontaneous liquid-to-solid maturation promoted the phase transition of the SF/SDBS complex coacervate to form the SFG hydrogel in situ, enhancing its bulk cohesiveness and interfacial adhesion. The formed SFG hydrogel exhibited intrinsic advantages as a new type of artificial protein-based adhesive, including good biocompatibility, robust wet adhesion, rapid blood-clotting capacity, and easy operation. In vitro and in vivo experiments demonstrated that the SFG hydrogel not only achieved instant and effective hemostatic sealing of tissue injuries but also promoted wound healing and tissue regeneration, thus advancing its clinical applications. STATEMENT OF SIGNIFICANCE: Marine mussels utilize the liquid-liquid phase separation (LLPS) strategy to induce the supramolecular assembly of mussel foot proteins, which plays a critical role in strong underwater adhesion of mussel foot proteins. Herein, an artificial protein-based adhesive hydrogel (named SFG hydrogel) was reported by adopting the LLPS-mediated coacervation of natural protein silk fibroin (SF) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS). The assembled SFG hydrogel enabled the precise spatial positioning and easy self-adjustable deposition on substrate surfaces with irregularities, allowing tight interfacial adhesion and cohesiveness. The SFG hydrogel not only achieved instant and effective hemostatic sealing of tissue injuries but also promoted wound healing and tissue regeneration, exhibiting intrinsic advantages as a new type of artificial protein-based bioadhesives., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Silk fibroin interactions with metallic surfaces can provide utility for medical materials and devices. Toward this goal, titanium alloy (Ti6Al4 V) was covalently grafted with polyacrylamide via electrochemically reducing 4-nitrobenzene diazonium salt in the presence of acrylamide. Analysis of the modified surfaces with FT-IR spectra, SEM and AFM were consistent with surface grafting. Functionalised titanium samples with a silk fibroin membrane, with and without impregnated therapeutics, were used to assess cytocompatibility and drug delivery. Initial cytocompatibility experiments using fibroblasts showed that the functionalised samples, both with and without silk fibroin coatings, supported significant increases between 72-136 % in cell metabolism, compared to the controls after 7 days. A 7-days release profiling showed consistent bacterial inhibition through gentamicin release with average inhibition zones of 239 mm 2 . Over a 5-week period, silk fibroin coated samples, both with and without growth factors, supported better human mesenchymal stem cell metabolism with increases reaching 1031 % and 388 %, respectively, compared to samples without the silk fibroin coating with., (© 2023 The Authors. ChemPlusChem published by Wiley-VCH GmbH.)