Search

The mechanical interactions among integrated cellular structures in soft tissues dictate the mechanical behaviors and morphogenetic deformations observed in living organisms. However, replicating these multifaceted attributes in synthetic soft materials remains a challenge. In this work, we develop a smart hydrogel system featuring engineered stiff cellular patterns that induce strain-driven heterogeneous subdomains within the hydrogel film. These subdomains arise from the distinct mechanical responses of the pattern and film domains under applied mechanical forces. Unlike previous studies that incorporate reinforced inclusions into soft matrices to tailor material properties, our method manipulates the localization, integration, and interaction of these subdomain building blocks within the soft film. This enables extensive tuning of both local and global behaviors. Notably, we introduce a subdomain-interface mechanism that allows for the concurrent customization and decoupling of mechanical properties and shape transformations within a single material system-an achievement rarely accomplished with current synthetic soft materials. Additionally, our use of in-situ imaging characterizations, including full-field strain mapping via digital imaging correlation and reciprocal-space patterns through fast Fourier transform analysis of real-space pattern domains, provides rapid real-time monitoring tools to uncover the underlying principles governing tailored multiscale heterogeneities and intricate behaviors.

Timely and effective interventions after tracheal mucosal injury are lack in clinical practices, which elevate the risks of airway infection, tracheal cartilage deterioration, and even asphyxiated death. Herein, we proposed a biomaterial-based strategy for the repair of injured tracheal mucosal based on a copper hydrogen phosphate nanosheets (CuHP NSs) functionalized commercial hydrogel (polyethylene glycol disuccinimidyl succinate-human serum albumin, PH). Such CuHP/PH hydrogel achieved favorable injectability, stable gelation, and excellent adhesiveness within the tracheal lumen. Moreover, CuHP NSs within the CuHP/PH hydrogel effectively stimulate the proliferation and migration of endothelial/epithelial cells, enhancing angiogenesis and demonstrating excellent tissue regenerative potential. Additionally, it exhibited significant inhibitory effects on both bacteria and bacterial biofilms. More importantly, when injected injured site of tracheal mucosa under fiberoptic bronchoscopy guidance, our results demonstrated CuHP/PH hydrogel adhered tightly to the tracheal mucosa. The therapeutic effects of the CuHP/PH hydrogel were further confirmed, which significantly improved survival rates, vascular and mucosal regeneration, reduced occurrences of intraluminal infections, tracheal stenosis, and cartilage damage complications. This research presents an initial proposition outlining a strategy employing biomaterials to mitigate tracheal mucosal injury, offering novel perspectives on the treatment of mucosal injuries and other tracheal diseases.

Bacterial nanocellulose (BNC) is a durable, flexible, and dynamic biomaterial capable of serving a wide variety of fields, sectors, and applications within biotechnology, healthcare, electronics, agriculture, fashion, and others. BNC is produced spontaneously in carbohydrate-rich bacterial culture media, forming a cellulosic pellicle via a nanonetwork of fibrils extruded from certain genera. Herein, we demonstrate engineering BNC-based scaffolds with tunable physical and mechanical properties through postprocessing. Human skeletal muscle myoblasts (HSMMs) were cultured on these scaffolds, and in vitro electrical stimulation was applied to promote cellular function for tissue engineering applications. We compared physiologic maturation markers of human skeletal muscle myoblast development using a 2.5-dimensional culture paradigm in fabricated BNC scaffolds, compared to two-dimensional (2D) controls. We demonstrate that the culture of human skeletal muscle myoblasts on BNC scaffolds developed under electrical stimulation produced highly aligned, physiologic morphology of human skeletal muscle myofibers compared to unstimulated BNC and standard 2D culture. Furthermore, we compared an array of metrics to assess the BNC scaffold in a rigorous head-to-head study with commercially available, clinically approved matrices, Kerecis Omega3 Wound Matrix (Marigen) and Phoenix as well as a gelatin methacryloyl (GelMA) hydrogel. The BNC scaffold outcompeted industry standard matrices as well as a 20% GelMA hydrogel in durability and sustained the support of human skeletal muscle myoblasts in vitro. This work offers a robust demonstration of BNC scaffold cytocompatibility with human skeletal muscle cells and sets the basis for future work in healthcare, bioengineering, and medical implant technological development.

Dehydration has been a key limiting factor for the operation of conductive hydrogels in practical application. Here, we report self-healable ionic skins that can self-regulate their internal moisture level by capturing extenral moistures via hygroscopic ion-coordinated polymer backbones through antipolyelectrolyte effect. Results show the ionic skin can maintain its mechanical and electrical functions over 16 months in the ambient environment with high stretchability (fracture stretch ∼2216 %) and conductivity (23.5 mS/cm). The moisture self-regulating capability is further demonstrated by repeated exposures to harsh environments such as 200°C heating, freezing, and vacuum drying with recovered conductivity and stretchability. Their reversible ionic and hydrogen bonds also enable self-healing feature as a sample with the fully cut-through damage can restore its conductivity after 24 h at 40 % relative humidity. Utilizing the ionic skin as a building block, self-healing flexible piezoelecret sensors have been constructed to monitor physiological signals. Together with a facile transfer-printing process, a self-powered sensing system with a self-healable supercapacitor and humidity sensor has been successfully demonstrated. These results illustrate broad-ranging possibilities for the ionic skins in applications such as energy storage, wearable sensors, and human-machine interfaces.

Focused ultrasound has experimentally been found to enhance the diffusion of nanoparticles; our aim with this work is to study this effect closer using both experiments and non-equilibrium molecular dynamics. Measurements from single particle tracking of 40 nm polystyrene nanoparticles in an agarose hydrogel with and without focused ultrasound are presented and compared with a previous experimental study using 100 nm polystyrene nanoparticles. In both cases, we observed an increase in the mean square displacement during focused ultrasound treatment. We developed a coarse-grained non-equilibrium molecular dynamics model with an implicit solvent to investigate the increase in the mean square displacement and its frequency and amplitude dependencies. This model consists of polymer fibers and two sizes of nanoparticles, and the effect of the focused ultrasound was modeled as an external oscillating force field. A comparison between the simulation and experimental results shows similar mean square displacement trends, suggesting that the particle velocity is a significant contributor to the observed ultrasound-enhanced mean square displacement. The resulting diffusion coefficients from the model are compared to the diffusion equation for a two-time continuous time random walk. The model is found to have the same frequency dependency. At lower particle velocity amplitude values, the model has a quadratic relation with the particle velocity amplitude as described by the two-time continuous time random walk derived diffusion equation, but at higher amplitudes, the model deviates, and its diffusion coefficient reaches the non-hindered diffusion coefficient. This observation suggests that at higher ultrasound intensities in hydrogels, the non-hindered diffusion coefficient can be used. [ABSTRACT FROM AUTHOR]

Tracer diffusion in polymer networks and hydrogels is relevant in biology and technology, while it also constitutes an interesting model process for the dynamics of molecules in fluctuating, heterogeneous soft matter. Here, we systematically study the time-dependent dynamics and (non-Markovian) memory effects of tracers in polymer networks based on (Markovian) implicit-solvent Langevin simulations. In particular, we consider spherical tracer solutes at high dilution in regular, tetrafunctional bead-spring polymer networks and control the tracer–network Lennard-Jones (LJ) interactions and the polymer density. Based on the analysis of the memory (friction) kernels, we recover the expected long-time transport coefficients and demonstrate how the short-time tracer dynamics, polymer fluctuations, and the viscoelastic response are interlinked. Furthermore, we fit the characteristic memory modes of the tracers with damped harmonic oscillations and identify LJ contributions, bond vibrations, and slow network relaxations. Tuned by the LJ interaction parameter, these modes enter the kernel with an approximately linear to quadratic scaling, which we incorporate into a reduced functional form for convenient tracer memory interpolation and extrapolation. This eventually leads to highly efficient simulations utilizing the generalized Langevin equation, in which the polymer network acts as an additional thermal bath with a tunable intensity. [ABSTRACT FROM AUTHOR]

The objective of this preclinical study was to evaluate the feasibility and safety of transcatheter endocardial alginate hydrogel injection (TEAi) in a large animal model, utilizing the high-stiffness XDROP® alginate hydrogel in combination with the dedicated EndoWings® catheter-based system. All swine (n = 9) successfully underwent TEAi without complications. Acute results from a subset of animals (n = 5) demonstrated the ability of the catheter to access a wide range of endomyocardial areas and achieve consecutive circumferential hydrogel distribution patterns within the mid-left ventricular wall. Histological examinations at 6 months (n = 4) demonstrated that the XDROP® remained localized within the cardiac tissue. In addition, serial echocardiographic imaging showed that XDROP® had no adverse impacts on LV systolic and diastolic functions. In conclusion, this innovative combination technology has the potential to overcome the translational barriers related to alginate hydrogel delivery to the myocardium.

Neutrophils are the first line of defense of the innate immune system. In response to methicillin-resistant Staphylococcus aureus infection in the skin, hematopoietic stem, and progenitor cells (HSPCs) traffic to wounds and undergo extramedullary granulopoiesis, producing neutrophils necessary to resolve the infection. This prompted the engineering of a gelatin methacrylate (GelMA) hydrogel that encapsulates HSPCs within a matrix amenable to subcutaneous delivery. The authors study the influence of hydrogel mechanical properties to produce an artificial niche for granulocyte-monocyte progenitors (GMPs) to efficiently expand into functional neutrophils that can populate infected tissue. Lin-cKIT+ HSPCs, harvested from fluorescent neutrophil reporter mice, are encapsulated in GelMA hydrogels of varying polymer concentration and UV-crosslinked to produce HSPC-laden gels of specific stiffness and mesh sizes. Softer 5% GelMA gels yield the most viable progenitors and effective cell-matrix interactions. Compared to suspension culture, 5% GelMA results in a twofold expansion of mature neutrophils that retain antimicrobial functions including degranulation, phagocytosis, and ROS production. When implanted dermally in C57BL/6J mice, luciferase-expressing neutrophils expanded in GelMA hydrogels are visualized at the site of implantation for over 5 days. They demonstrate the potential of GelMA hydrogels for delivering HSPCs directly to the site of skin infection to promote local granulopoiesis.

The work demonstrates, for the first time, thermo-responsive, water-insoluble, hydrogel-based, nano-fibrous filter media comprised of copolymers of N-isopropylacrylamide (NIPAM) and methyl methacrylate formed by electrospinning. Moreover, a comprehensive novel physical explanation of all aspects responsible for the physical mechanisms resulting in the thermo-responsive regulation of the water flow rate and an enhanced interception of nanoparticles by such filter membranes is given. They are the wettable-non-wettable transition, pore, and fiber-size changes, as well as a diminishing filter thickness at the lower critical solution temperature (LCST) of the copolymers developed here, which interplay with a significant reduction in the water viscosity with temperature. Poly(N-isopropylacrylamide) (PNIPAM) hydrogel is an attractive material because of its thermo-responsive properties. Its wettability changes with water temperature. This characteristic holds great promise for the development of advanced filter media and related responsive materials. In this study, PNIPAM hydrogels were designed and transformed into filter membranes for applications in water filtration in biomedical and other related systems. These thermo-responsive filter membranes offer the potential for enhanced filtration efficiency, selectivity, and the overall system performance. Here, two different procedures were adopted to form water-insoluble thermo-responsive filter media based on PNIPAM hydrogels. The PNIPAM-based hydrogels were electrospun, resulting in the formation of thermo-responsive water-insoluble nanofiber membranes. These membranes underwent a series of comprehensive experiments to assess their performance and characteristics, including mass loss, water droplets for the wettability assessment, filtration tests, shrinkage measurements, and microscopic observations. These diverse experiments yield a full understanding of the PNIPAM-based nanofiber membranes' properties and their potential applications. [ABSTRACT FROM AUTHOR]

The network structure within polymers significantly influences their mechanical properties, including their strength, toughness, and fatigue resistance. All-atom molecular dynamics (AAMD) simulations offer a method to investigate the energy dissipation mechanism within polymers during deformation and fracture; Such an approach is, however, computationally inefficient when used to analyze polymers with complex network structures, such as the common chemically double-networked hydrogels. Alternatively, coarse-grained molecular dynamics (CGMD) models, which reduce the computational degrees of freedom by concentrating a set of adjacent atoms into a coarse-grained bead, can be employed. In CGMD simulations, a coarse-grained force field (CGFF) is a critical factor affecting the simulation accuracy. In this paper, we proposed a data-based method for predicting the CGFF parameters to improve the simulation efficiency of complex cross-linked network in polymers. Here, we utilized a typical chemically double-networked hydrogel as an example. An artificial neural network was selected, and it was trained with the tensile stress–strain data from the CGMD simulations using different CGFF parameters. The CGMD simulations using the predicted CGFF parameters show good agreement with the AAMD simulations and are almost fifty times faster. The data-inspired CGMD model presented here broadens the applicability of molecular dynamics simulations to cross-linked polymers and has the potential to provide insights that will aid the design of polymers with desirable mechanical properties. [ABSTRACT FROM AUTHOR]

Osteoarthritis is characterized by enzymatic breakdown of the articular cartilage via the disruption of chondrocyte homeostasis, ultimately resulting in the destruction of the articular surface. Decades of research have highlighted the importance of inflammation in osteoarthritis progression, with inflammatory cytokines shifting resident chondrocytes into a pro-catabolic state. Inflammation can result in poor outcomes for cells implanted for cartilage regeneration. Therefore, a method to promote the growth of new cartilage and protect the implanted cells from the pro-inflammatory cytokines found in the joint space is required. In this study, we fabricate two gel types: polymer network hydrogels composed of chondroitin sulfate and hyaluronic acid, glycosaminoglycans (GAGs) known for their anti-inflammatory and prochondrogenic activity, and interpenetrating networks of GAGs and collagen I. Compared to a collagen-only hydrogel, which does not provide an anti-inflammatory stimulus, chondrocytes in GAG hydrogels result in reduced production of pro-inflammatory cytokines and enzymes as well as preservation of collagen II and aggrecan expression. Overall, GAG-based hydrogels have the potential to promote cartilage regeneration under pro-inflammatory conditions. Further, the data have implications for the use of GAGs to generally support tissue engineering in pro-inflammatory environments.

Pancreatic ductal adenocarcinoma (PDAC) accounts for about 90% of all pancreatic cancer cases. Five-year survival rates have remained below 12% since the 1970s, in part due to the difficulty in detection prior to metastasis (migration and invasion into neighboring organs and glands). Mechanical memory is a concept that has emerged over the past decade that may provide a path toward understanding how invading PDAC cells "remember" the mechanical properties of their diseased ("stiff", elastic modulus, E ≈ 10 kPa) microenvironment even while invading a healthy ("soft", E ≈ 1 kPa) microenvironment. Here, we investigated the role of mechanical priming by culturing a dilute suspension of PDAC (FG) cells within a 3D, rheologically tunable microgel platform from hydrogels with tunable mechanical properties. We conducted a suite of acute (short-term) priming studies where we cultured PDAC cells in either a soft (E ≈ 1 kPa) or stiff (E ≈ 10 kPa) environment for 6 h, then removed and placed them into a new soft or stiff 3D environment for another 18 h. Following these steps, we conducted RNA-seq analyses to quantify gene expression. Initial priming in the 3D culture showed persistent gene expression for the duration of the study, regardless of the subsequent environments (stiff or soft). Stiff 3D culture was associated with the downregulation of tumor suppressors (LATS1, BCAR3, CDKN2C), as well as the upregulation of cancer-associated genes (RAC3). Immunofluorescence staining (BCAR3, RAC3) further supported the persistence of this cellular response, with BCAR3 upregulated in soft culture and RAC3 upregulated in stiff-primed culture. Stiff-primed genes were stratified against patient data found in The Cancer Genome Atlas (TCGA). Upregulated genes in stiff-primed 3D culture were associated with decreased survival in patient data, suggesting a link between patient survival and mechanical priming.

Macrophages are innate immune cells that interact with complex extracellular matrix environments, which have varied stiffness, composition, and structure, and such interactions can lead to the modulation of cellular activity. Collagen is often used in the culture of immune cells, but the effects of substrate functionalization conditions are not typically considered. Here, we show that the solvent system used to attach collagen onto a hydrogel surface affects its surface distribution and organization, and this can modulate the responses of macrophages subsequently cultured on these surfaces in terms of their inflammatory activation and expression of adhesion and mechanosensitive molecules. Collagen was solubilized in either acetic acid (Col-AA) or N-(2-hydroxyethyl)piperazine-N'-ethanesulfonic acid (HEPES) (Col-HEP) solutions and conjugated onto soft and stiff polyacrylamide (PA) hydrogel surfaces. Bone marrow-derived macrophages cultured under standard conditions (pH 7.4) on the Col-HEP-derived surfaces exhibited stiffness-dependent inflammatory activation; in contrast, the macrophages cultured on Col-AA-derived surfaces expressed high levels of inflammatory cytokines and genes, irrespective of the hydrogel stiffness. Among the collagen receptors that were examined, leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) was the most highly expressed, and knockdown of the Lair-1 gene enhanced the secretion of inflammatory cytokines. We found that the collagen distribution was more homogeneous on Col-AA surfaces but formed aggregates on Col-HEP surfaces. The macrophages cultured on Col-AA PA hydrogels were more evenly spread, expressed higher levels of vinculin, and exerted higher traction forces compared to those of cells on Col-HEP. These macrophages on Col-AA also had higher nuclear-to-cytoplasmic ratios of yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), key molecules that control inflammation and sense substrate stiffness. Our results highlight that seemingly slight variations in substrate deposition for immunobiology studies can alter critical immune responses, and this is important to elucidate in the broader context of immunomodulatory biomaterial design.

PURPOSE: Radiation therapy (RT) plays an important role in the treatment of glioblastoma multiforme (GBM). However, inherent intrinsic resistance of tumors to radiation, coupled with the need to consider the tolerance of normal tissues and the potential effects on neurocognitive function, impose constraints on the amount of RT that can be safely delivered. A strategy for augmenting the effectiveness of RT involves the utilization of radiation sensitizers (RS). Directly implanting RS-loaded fibrin glue (FG) into the tumor resection cavity would by-pass the blood brain barrier, potentially enhancing the impact of RT on tumor recurrence. This study investigated the ability of FG to incorporate and release, in non-degraded form, the radiation sensitizers 5-Fluorouracil (5FU) and Motexafin gadolinium (MGd). METHODS: FG layers were created in a 24-well plate by combining thrombin, fibrinogen, and 5FU or MGd. Supernatants from these layers were collected at various intervals and added to F98 glioma spheroid cultures in 96-well plates. Radiation was applied either before or after RS application as single or fractionated dosages. Spheroid growth was monitored for 14 days. RESULTS: Combined treatment of FG-released 5FU and RT significantly inhibited spheroid growth compared to RS or RT as a single treatment. As a free drug, MGd demonstrated its efficacy in reducing spheroid volume, but had diminished potency as a released RS. Fractionated radiation was more effective than single dose radiation. CONCLUSION: Non-degraded RS was released from the FG for up to 72 h. FG-released 5FU greatly increased the efficacy of radiation therapy.

The presence of gradient softer outer layers, commonly observed in biological systems (such as cartilage and ocular tissues), as well as synthetic crosslinked hydrogels, profoundly influences their interactions with opposing surfaces. Our prior research demonstrated that gradient-stiffness hydrogel layers, characterized by increasing elasticity with depth, control contact mechanics, particularly in proximity to the layer thickness. We postulate that the distribution of polymers within these gradient layers imparts extraordinary stretch and adhesion characteristics due to network adaptability and stress-induced reorganization. To investigate this phenomenon, we utilized Atomic Force Microscopy nanoindentation to assess the depth-dependent adhesion behavior of polyacrylamide hydrogels with varying gradient layer thicknesses. Two gradient layer thicknesses were achieved by employing different molding materials: glass and polyoxymethylene (POM). Glass-molded hydrogels exhibited a thinner gradient layer alongside a stiffer bulk layer compared to their POM-molded counterparts. In indentation experiments, the POM-molded hydrogel had larger adhesion compared to glass-molded hydrogel. We find that indenting within the gradient layer engenders increased load-unload hysteresis due to heightened fluid transport in the sparse outer polymer network. Consequently, this led to augmented adhesion and work of separation at shallow depths. We suggest that the prominent stretching capability of the sparse outer polymer network during probe retraction contributes to enhanced adhesion. The Maugis–Dugdale adhesive model only fits well to indentations on the thin layer or indentations which engage significantly with the bulk. These results facilitate a comprehensive characterization of adhesion mechanics in gradient-stiffness hydrogels, which could foster their application across emerging contexts in health science and environmental domains. [ABSTRACT FROM AUTHOR]

ObjectiveTo characterize adverse events related to use of the perirectal spacing agent SpaceOAR, we examined the Manufacturer and User Facility Device Experience (MAUDE) database.MethodsThe MAUDE database was queried for "SpaceOAR" and "Augmenix" from June 2015 (when SpaceOAR was approved by the Food and Drug Administration) to October 2022. Reports were reviewed for adverse events (AEs), operative procedures performed because of the AE, and changes to the radiation plan. AEs were categorized using Common Terminology Criteria for Adverse Events (CTCAE), version 5.0.ResultsSix hundred fifty-four reports were reviewed. Eighty-four were excluded and 4 reports reviewed 2 separate cases of SpaceOAR administration. Five hundred seventy-four cases were ultimately included. Three deaths were reported (0.5% of all AEs). One point six percent of cases represented CTCAE grade 4 injuries (life-threatening consequences; urgent intervention indicated), 15.9% grade 3 (severe but not immediately life-threatening; hospitalization), 24.2% grade 2 (moderate; local/noninvasive intervention), and 57% of events were CTCAE grade 1 (mild; asymptomatic or mild symptoms). Bowel diversion occurred in 29 cases (9%).ConclusionBoth asymptomatic (n = 311) and debilitating (n = 12) complications of SpaceOAR hydrogel use were identified. Death, gel embolization, anaphylaxis, rectal ulcerations, and infections requiring bowel or urinary diversions were among the complications reviewed. Providers should consider these potential complications before perirectal spacer administration and during patient counseling.

Biomaterial wound dressings, such as hydrogels, interact with host cells to regulate tissue repair. This study investigates how crosslinking of gelatin-based hydrogels influences immune and stromal cell behavior and wound healing in female mice. We observe that softer, lightly crosslinked hydrogels promote greater cellular infiltration and result in smaller scars compared to stiffer, heavily crosslinked hydrogels. Using single-cell RNA sequencing, we further show that heavily crosslinked hydrogels increase inflammation and lead to the formation of a distinct macrophage subpopulation exhibiting signs of oxidative activity and cell fusion. Conversely, lightly crosslinked hydrogels are more readily taken up by macrophages and integrated within the tissue. The physical properties differentially affect macrophage and fibroblast interactions, with heavily crosslinked hydrogels promoting pro-fibrotic fibroblast activity that drives macrophage fusion through RANKL signaling. These findings suggest that tuning the physical properties of hydrogels can guide cellular responses and improve healing, offering insights for designing better biomaterials for wound treatment.

The development of new type of hydrogels featuring enhanced properties is a recent topic and of particular interest for a wide range of industrial applications, especially in biomedical sector. The present contribution focuses on the mutliscale modeling of hydrogels that are treated by the enzymatic mineralization and thus enriched with calcium phosphate. More specifically, the calcium phosphate forms spherical or honeycomb structures in the hydrogel matrix, which significantly improves effective material properties such as stiffness and strength. The chosen multiscale finite element method (FEM) homogenization strategy uses the Hill–Mandel macrohomogeneity condition for bridging two scales: the macroscopic boundary value problem (BVP) simulates the specimen behavior, whereas the microscopic BVP investigates the representative volume element (RVE) depicting the heterogeneous multiphase microstructure. The approach proposed uses the Ogden model to simulate the hydrogel and the neo‐Hooke model for the calcium phosphate phase. It varies the RVE type and the macroscopic tests in order to study the influence of the microstructure on the effective behavior and uses experimental data to determine missing microscopic material parameters. Chosen numerical examples demonstrate the applicability of the numerical tool for the estimation of the optimal microscopic arrangement of phases. [ABSTRACT FROM AUTHOR]

Excessive ultraviolet (UV) radiation can cause human skin erythema, tanning, inflammation and other adverse reactions. Human skin can spontaneously synthesize endogenous melanin under UV radiation to defend against the damage of UV, but skin problems such as light damage and light aging cannot be avoided due to its low UV shielding efficiency. Therefore, we design a natural and biocompatible PGDA (poly-γ-glutamic acid/melanin-like hydrogel) sunscreen hydrogel by crosslinking melanin-like L -lysine-doped polydopamine (PDA- L) and amino acid biopolymer poly-γ-glutamic acid, which displays good biosafety, efficient UVA shielding performance and excellent anti-inflammatory performance in the applications of skin protection from the sun and repair after sunburn. The introduction of PDA- L to the hydrogel can improve the absorption intensity in the UV region and the antioxidative performance of the hydrogel. Meanwhile, the usage of biocompatible PGDA sunscreen hydrogel can avoid the skin oxidative damage and penetrative toxicity of conventional sunscreens. [ABSTRACT FROM AUTHOR]

Photochromic inks have been employed as a certification measure to increase the efficiency of document anti-counterfeiting. However, they have shown several critical drawbacks, such as weak photostability and poor durability. Herein, a self-healable photochromic hydrogel was developed for advanced anti-counterfeiting applications. Carboxymethyl cellulose (CMC) was used to immobilize nanoparticles (2–4 nm) of lanthanide-activated strontium aluminate (LaSA) as a photochromic agent, and electrospun glass nanofibers (80–140 nm) as a reinforcement agent. Photostability and durability can be guaranteed by efficiently immobilizing a hosting hydrogel with an inorganic photochromic agent. As a result, the LaSA-encapsulated carboxymethyl cellulose (LaSA@CMC) nanocomposite showed excellent reversibility and photostability in response to ultraviolet light. When various ratios of LaSA nanoparticles were applied, a wide variety of carboxymethyl cellulose hydrogels with distinct emission properties were produced. Under visible daylight, the LaSA@CMC nanocomposite showed transparency; however, a green emission was observed under UV irradiation. The excitation intensity was recorded at 365 nm to specify transparency, whereas the released emission was detected at wavelength 517 nm to indicate a green color. Numerous techniques were employed to determine the morphologies and chemical components of the glass nanofiber-reinforced carboxymethyl cellulose nanocomposite hydrogel films. We investigated the mechanical performance of sheets stamped with the LaSA@CMC nanocomposite hydrogel. [ABSTRACT FROM AUTHOR]

Hydrogels, known for their 3D polymer networks and high water content, are widely used in applications ranging from agriculture to tissue engineering and soft electronics. However, balancing toughness and stiffness in hydrogels remains a significant challenge due to the inverse relationship between these properties. In this study, a dual‐network hydrogel is developed composed of lignin/poly(N,N‐dimethylacrylamide) (PDMA) and sodium alginate/Ca2⁺ (SA/Ca2⁺) using a solvent exchange method. This hydrogel incorporates multi‐level energy dissipative structures, resulting in both high stiffness and toughness. Specifically, the DL/S0.1Ca0.5 hydrogel exhibited impressive mechanical performance, including a tensile stress of 3.7 MPa, a tensile strain of 1100%, and a tensile modulus of 8.7 MPa, along with remarkably high toughness of 97,000 J m−2 and work of extension of 25 MJ m−3. Additionally, it demonstrates exceptional rupture and collision resistance, outstanding conductivity of 19.7 S m−1, and high strain sensitivity with a gauge factor up to 7.78. These features highlight its potential for use in extreme sports protection and wearable sensors, representing a significant advancement in the development of multifunctional hydrogels. [ABSTRACT FROM AUTHOR]

Alginates, hydrophilic anionic polysaccharides with notable bioactivity and biocompatibility, have drawn significant attention, particularly due to their extensive use in the pharmaceutical industry and associated health benefits. Brown seaweeds serve as the primary source of alginates. However, extraction methods, especially traditional ones, face efficiency challenges, impacting the yield. Green extraction methods promise an eco-friendly alternative, but their industrial-scale implementation is still unproven. Importantly, these extraction methods could yield alginates of different molecular weights and consequent varied biological effects. Alginates possess antibacterial, antioxidant, anti-diabetic, and immunomodulatory properties, forming the cornerstone of their health benefits and pharmaceutical applications. The hydrogel formation characteristic of alginates is crucial for pharmaceutical applications, including drug delivery, wound dressing, and tissue regeneration. Despite the existence of numerous articles exploring the extraction methods, properties, and applications of alginates, a gap exists in the literature that connects these aspects with health benefits. This review aims to bridge this gap by providing a comprehensive discussion of the extraction methods, properties, health benefits, and pharmaceutical applications of alginates. [ABSTRACT FROM AUTHOR]

Carbodiimides and pyridines form reversible adducts that slowly deliver carbodiimide "fuels" to out-of-equilibrium reaction networks, slowing activation kinetics and elongating transient state lifetimes. More-nucleophilic pyridines give more adduct under typical conditions. This approach can be used to extend the lifetimes of transient polymer hydrogels. [ABSTRACT FROM AUTHOR]

Heparosan (Hep), an unsulfated glycosaminoglycan (GAG), has a chemical structure closely resembling that of hyaluronic acid (HA). However, Hep has not been utilized in injectable dermal fillers as HA has been. In this article, injectable Hep crosslinked hydrogels were fabricated using 1,4-butanediol diglycidyl ether (BDDE) as the crosslinking agent. The physicochemical properties of the Hep crosslinked hydrogel, including pH and osmolality, were verified to be compatible with human physiology. The Hep crosslinked hydrogels exhibit higher viscoelasticity and a longer in vitro lifespan compared to HA crosslinked hydrogels. Furthermore, biocompatibility and safety assessments supported their potential use as injectable dermal fillers. [ABSTRACT FROM AUTHOR]

Hydrogels are insoluble three-dimensional polymer networks that are water insoluble but can absorb large amounts of water or biological fluid. They can be prepared using a variety of polymers, including both synthetic and natural ones. Either physical crosslinking, chemical crosslinking, or both are used for the preparation of polymeric hydrogels. Hydrogels made from natural polymers like chitosan, gelatin, alginate, cellulose, and hyaluronic acid are promising biomaterials for applications in tissue engineering, cosmetics, agriculture, wound healing, etc. because of their high biocompatibility and biodegradability. The present work reviews the classification of natural polymer-based hydrogels, properties, cross-linking methods, characterization, and their biomedical applications. [ABSTRACT FROM AUTHOR]

Psoriasis is chronic autoimmune inflammatory skin disorder affecting millions of people worldwide (2–3% of world population). Treatment of psoriasis ranges from use of topicals to biologicals. Although topical treatments are preferred for mild to moderate cases of psoriasis, the thickened, inflamed skin, and the absence of moisturizing properties make conventional topical treatment challenging, hindering the effective management of the condition. The hydrogel-based systems are reported to be excellent vehicles and carriers for overcoming the barriers in topical delivery of drugs by hydrating the thick plaques and providing controlled release of medicament into the tough scaly skin. Recently, many nanocarrier loaded hydrogels-based system has gained popularity for effective delivery of drugs across psoriatic skin. The present review focuses on psoriasis, the deviation from normal skin in psoriatic condition which renders the effective delivery of drugs through topical route a greater challenge and how hydrogels-based system can effectively help alleviate psoriasis through effective drug delivery across the hyperkeratinized skin. In summary, hydrogels have emerged as effective carriers in psoriasis treatment as they provide a soothing effect, better patient acceptance, good penetration, controlled, sustained, and even smart drug release thus providing relief along with treatment. [ABSTRACT FROM AUTHOR]

Self‐hygroscopic hydrogels, characterized by high evaporation enthalpy, cooling efficiency, and self‐regulating properties, have garnered significant attention. However, most current research focuses on enhancing the hygroscopic and desorption performance, often overlooking the importance of monitoring the self‐regulation process, which limits its further application. Advanced visualization technologies, such as in situ electrical impedance tomography, low‐field nuclear magnetic resonance, and hyperspectral imaging, offer potential insights into this behavior, yet they often require additional devices, incur high costs, and involve complex sample preparation processes. Therefore, drawing inspiration from nature, humidity‐color‐sensitive hydrogels (HCSHs) strategy is proposed for visualized cooling. Benefiting from the strong polar responsiveness of the aggregation‐induced emission (AIE) molecules, the hydrogel's fluorescence significantly changes with varying interior water content, thereby its self‐regulation process is monitored easily. Further, the obtained hydrogel could be applied in the electronic device cooling owing to the polymer skeletons’ high swelling ratio, strong adhesion, and excellent self‐hygroscopic properties. This strategy overcomes current limitations in the visual technology of self‐hygroscopic materials and provides new insights into intelligent thermal management for electronic devices. [ABSTRACT FROM AUTHOR]

Electrically conductive hydrogels are highly hydrated 3D networks consisting of a hydrophilic polymer skeleton and electrically conductive materials. Conductive hydrogels have excellent mechanical and electrical properties and have further extensive application prospects in biomedical treatment and other fields. Whereas numerous electrically conductive hydrogels have been fabricated, a set of general principles, that can rationally guide the synthesis of conductive hydrogels using different substances and fabrication methods for various application scenarios, remain a central demand of electrically conductive hydrogels. This paper systematically summarizes the processing, performances, and applications of conductive hydrogels, and discusses the challenges and opportunities in this field. In view of the shortcomings of conductive hydrogels in high electrical conductivity, matchable mechanical properties, as well as integrated devices and machines, it is proposed to synergistically design and process conductive hydrogels with applications in complex surroundings. It is believed that this will present a fresh perspective for the research and development of conductive hydrogels, and further expand the application of conductive hydrogels. [ABSTRACT FROM AUTHOR]

In recent years, the prevalence of bone diseases is showing an increasing trend, which is mainly attributed to the aging of the global population. However, bone repair and regeneration are still an unsolved problem in the treatment of bone diseases, which include a series of biological events. Photocrosslinked natural hydrogel‐based microspheres (PNHMs) are spherical particles composed of photocrosslinked natural hydrogel components. Due to their morphology, injectability, and biocompatibility, PNHMs are widely used in tissue regeneration, particularly for bone defects. In this article, we review the available photocrosslinked natural materials for PNHMs, and then introduce their preparation methods. After that, we summarize the important advanced functionalities of PNHMs. For example, PNHMs can be loaded with different active ingredients to exert anti‐inflammatory, antibacterial, and antioxidant effects, while also realizing lubrication due to their specific shape and size distribution. In addition, the function of capturing ions can be realized via coordination. When applied in bone tissue engineering, PNHMs can promote angiogenesis and osteogenesis, with great potential in the treatment of bone diseases. Finally, the challenges and prospects of PNHMs for bone repair are discussed. [ABSTRACT FROM AUTHOR]

The use of biocide-loaded hydrogels has recently been exploited for cleaning the biological attacks of cultural heritage and architectural stone materials. However, considering the drawbacks of traditional biocides, and the high costs of synthetic polymers, growing research for innovative and sustainable solutions are taking place. The aim of this work is to explore a bacterial cellulose (BC) hydrogel functionalized with ozone as a renewable, biodegradable, and easy-to-use antimicrobial remedy for stone biodeterioration. The BC microstructure was characterized by Field Emission-Scanning Electron Microscopy observation and high crystallinity was detected by X-ray diffraction analysis. Ozonated BC (OBC) hydrogels were tested against selected biodeteriogenic microorganisms in water suspension abolishing their viability, with its complete suppression after a 10-min and a 24-h treatment with OBC, for bacterial and fungal spores, respectively. Furthermore, the OBC was assessed on contaminated marble, brick, and biocalcarenitic stone specimens for simulating in situ conditions. A 100% reduction of microbial viability after a 24-h treatment was obtained. Successively, the shelf-life of the hydrogel and the antimicrobial activity were also evaluated after 30 days, demonstrating a subsequent cleaning efficiency along time. This research highlights the potential of the new ozonated BC hydrogel as a green and highly effective antimicrobial treatment, with advantages in sustainability. [ABSTRACT FROM AUTHOR]

Objective: Biomaterials loaded with ingredients derived from traditional Chinese medicine (TCM) are viewed as a promising strategy for treating spinal cord injury (SCI). However, a comprehensive analysis of the existing literature on this topic has not yet been conducted. Therefore, this paper systematically reviews researches related to this approach, aiming to identify gaps and shortcomings in the field. Methods: PubMed, EMBASE, Web of Science, Chinese Biomedical Literature, Wanfang, and China National Knowledge Infrastructure (CNKI) were searched for retrieving studies on biomaterials loaded with TCM ingredients published from their inception to October 2024. Two reviewers performed screening of search results, information extraction, and literature quality assessment independently. Results: For this systematic review, 41 publications were included. Six TCM ingredients-paclitaxel, curcumin, tetramethylpyrazine, resveratrol, berberine, and tanshinone IIA were combined with biomaterials for treatment of SCI. Biomaterials were categorized into hydrogels, biodegradable scaffolds, nanoparticles, and microspheres according to the type of scaffold. These drug delivery systems exhibit commendable biocompatibility, drug-loading capacity, and drug-release capabilities, and in combination with TCM ingredients, synergistically contribute to anti-oxidative stress, anti-inflammatory, neuroprotective, and anti-apoptotic effects. Conclusion: These studies demonstrated the efficacy of biomaterials loaded with TCM ingredients in facilitating motor function recovery and neuroprotection in SCI rats, providing evidence for future research. However, in the complex microenvironment of SCI, achieving the maximum drug loading capacity of TCM ingredients within biomaterials, along with sustained and controlled release to fully exert their pharmacological effects, remains a major challenge for future research. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/ identifier CRD42024505000. [ABSTRACT FROM AUTHOR]

The use of materials from renewable sources instead of fossil fuels is a crucial step forward in the industrial transition toward sustainability. Among polysaccharides, alginate stands out as a versatile and eco‐friendly candidate due to its ability to form functional complexes with cations. This review provides an up‐to‐date and comprehensive description of alginate complexation with specific cations, focusing on how interaction forces can be harnessed to tailor the physicochemical properties of cation‐alginate‐based functional materials. Methodologies and approaches for the development and multiscale characterization of these materials are introduced and discussed. Alginate complexes with mono‐, di‐, tri‐, and tetravalent cations (namely Ag+, Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Cr3+, Fe3+, Al3+, Ga3+, Y3+, La3+, Ce3+, Nd3+, Eu3+, Tb3+, Gd3+, Zr4+, Th4+) are reviewed. Each cation is discussed individually, highlighting how it can uniquely influence the material properties thereby unlocking new potentials for the design of advanced functional materials. Key challenges and opportunities in applying these complexes across diverse fields, such as biomedicine, environmental remediation, food additives and supplements, flame retardants, sensors, supercapacitors, catalysis, and mechanical isolators are assessed, providing evidence of the transformative potential of cation‐alginate complexes for tackling global challenges and advancing cutting‐edge technologies. [ABSTRACT FROM AUTHOR]

Recently, solar‐driven interfacial evaporation (SDIE) has been developed quickly for low‐cost and sustainable seawater desalination, but addressing the conflict between a high evaporation rate and salt rejection during SDIE is still challenging. Here, a spatial confinement strategy is proposed to prepare the gel composite solar evaporator (SCE) by loading one thin hydrogel layer onto the skeleton of a carbon aerogel. The SCE retains the hierarchically porous structure of carbon aerogels with an optimized water supply induced by dual‐driven forces (capillary effects and osmotic pressure) and takes advantage of both aerogels and hydrogels, which can gain energy from air and reduce water enthalpy. The SCE has a high evaporation rate (up to 4.23 kg m−2 h−1 under one sun) and excellent salt rejection performance and can maintain structural integrity after long‐term evaporation even at high salinities. The SDIE behavior, including heat distribution, water transport, and salt ion distribution, is investigated by combining theoretical simulations and experimental results. This work provides new inspiration and a theoretical basis for the development of high‐performance interfacial evaporators. [ABSTRACT FROM AUTHOR]

ABSTRACT Cold atmospheric plasma‐activated hydrogel (PAH) exhibits excellent loading and slow‐release capacity for plasma‐generated reactive species. In this study, plasma‐activated pluronic F127 hydrogel (PAH‐PF127) was obtained using surface dielectric barrier discharge (SDBD), and the anticancer effects of PAH‐F127 synergies with the clinical drug paclitaxel (PTX) were investigated. The results indicated that PAH‐PF127 could load plasma‐generated long‐lived reactive species efficiently, and in vitro research revealed that PAH‐PF127 exerts significant anticancer effects by inducing intracellular oxidative stress, and synergies with 50 μg/mL (low‐dose) PTX could easily replace 200 μg/mL (high‐dose) PTX alone. These results suggested that PAH‐PF127 has the potential to address the toxic side effects of high‐dose drugs and expand the application of plasma technology in anticancer treatment. [ABSTRACT FROM AUTHOR]

3D printing of bio‐hydrogel scaffolds are widely used in tissue regeneration. However, due to the ultra‐soft properties of bio‐hydrogels, it is hard to print them precisely. Here, crystal transduction 3D printing with high fidelity is proposed to address this challenge. A phase‐transition bio‐inks system with beeswax is developed for crystal transduction, which can accelerate energy consumption and induce soft bio‐inks to quickly harden during printing. Interestingly, an interconnected porous hydrogel scaffold can be obtained after washing the crystal beeswax. The porous hydrogel scaffold demonstrated excellent biocompatibility and cell proliferation effect in vitro and is free from defense responses and immunogenicity in vivo. Muscle analog porous scaffolds constructed by high‐fidelity 3D printing significantly improve the tissue function recovery of rats with muscle defects, compared with the conventional printed hydrogel with a non‐matched shape. These structure‐performance design rules create exciting opportunities to customize 3D‐printed porous hydrogel scaffolds with high fidelity. [ABSTRACT FROM AUTHOR]

MicroRNA (miRNA) is a type of short, non-coding nucleic acid molecule that plays essential roles in diagnosing and prognosing various types of cancer. MiRNA is abundantly present in skin interstitial fluid (ISF), providing real-time and localized physiological information. Hydrogel microneedle (HMN) patches enable miRNA collection in a fast, pain-free, minimally invasive, and user-friendly manner. In this study, we introduced a fluorescence-based HMN assay, namely the HMN-miR sensor, composed of methacrylated hyaluronic acid (MeHA) and a graphene oxide–probe DNA (GO.pDNA) conjugate for miR21 and miR210 detection. The HMN-miR sensor demonstrates excellent skin penetration efficiency, rapid ISF collection capability, and sufficient miRNA detection and sequence identification specificity. The HMN-miR sensor facilitates a new assay that, with further optimization, could be applied in future clinical settings. Its simple fabrication process and excellent biocompatibility give it significant potential for various clinical uses, such as personalized cancer treatment and monitoring the healing progress of burn wounds. [ABSTRACT FROM AUTHOR]

Articular cartilage has limited self-healing ability, resulting in injuries often evolving into osteoarthritis (OA), which poses a significant challenge in the medical field. Although some treatments exist to reduce pain and damage, there is a lack of effective means to promote cartilage regeneration. Reactive Oxygen Species (ROS) have been found to increase significantly in the OA micro-environment. They play a key role in biological systems by participating in cell signaling and maintaining cellular homeostasis. Abnormal ROS expression, caused by internal and external stimuli and tissue damage, leads to elevated levels of oxidative stress, inflammatory responses, cell damage, and impaired tissue repair. To prevent excessive ROS accumulation at injury sites, biological materials can be engineered to respond to the damaged microenvironment, release active components in an orderly manner, regulate ROS levels, reduce oxidative stress, and promote tissue regeneration. Hydrogels have garnered significant attention due to their excellent biocompatibility, tunable physicochemical properties, and drug delivery capabilities. Numerous antioxidant hydrogels have been developed and proven effective in alleviating oxidative stress. This paper discusses a comprehensive treatment strategy that combines antioxidant hydrogels with existing treatments for OA and explores the potential applications of antioxidant hydrogels in cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

Hydrogel electrolytes have been widely explored in aqueous zinc‐iodine batteries (AZIBs), in light of their intrinsic strong water‐retention capability and superior flexibility of hydrogel network. However, hydrogel‐based AZIBs are still facing challenges due to the inferior ionic conductivity, dendrite formation, and corresponding fatigue‐induced damage. Herein, a hydrogel electrolyte is designed and engineered with preferentially aligned porous structures, where Zn2+ can promptly transport along the pores. AZIBs fabricated from the hydrogel electrolyte exhibited distinct cycling stability over 1,000 h (500 cycles) at 0.5 mA cm−2. Moreover, in light of the substantially improved mechanical robustness, the hydrogel electrolyte network remained intact over a 27,000‐cycle charging/discharging test at 5 A g−1, with a slight change in capacity, surpassing most previously reported AZIBs. Such kind of hydrogel electrolyte‐based AZIBs can be further explored as the flexible power system for wearable devices, enabling significantly accelerated wound healing through electrical stimulation over the epidermal wounds. This work sheds light on hydrogel electrolytes design for long‐life aqueous zinc‐based batteries, with great potential as power systems for wearable and implantable devices. [ABSTRACT FROM AUTHOR]

Polymeric supramolecular hydrogels (PSHs) leverage the thermodynamic and kinetic properties of non‐covalent interactions between polymer chains to govern their structural characteristics. As these materials are formed via endothermic or exothermic equilibria, their thermal response is challenging to control without drastically changing the nature of the chemistry used to join them. In this study, we introduce a novel class of PSHs utilizing the intercalation of double‐stranded DNA (dsDNA) as the primary dynamic non‐covalent interaction. The resulting dsDNA intercalating supramolecular hydrogels (DISHs) can be tuned to exhibit both endothermically or exothermically driven binding through strategic selection of intercalators. Bifunctional polyethylene glycol (MW~2000 Da) capped with intercalators of varying hydrophobicity, charge, and size (acridine, psoralen, thiazole orange, and phenanthridine) produced DISHs with comparable moduli (500–1000 Pa), but unique thermal viscoelastic responses. Notably, acridine‐based cross‐linkers displayed invariant and even increasing relaxation times with temperature, suggesting an endothermic binding mechanism. This methodology expands the set of structure‐properties available to biomass‐derived DNA biomaterials and promises a new material system where a broad set of thermal and viscoelastic responses can be obtained due to the sheer number and variety of intercalating molecules. [ABSTRACT FROM AUTHOR]

Spatiotemporally controlled two‐photon photodegradation of hydrogels has gained increasing attention for high‐precision subtractive tissue engineering. However, conventional photolabile hydrogels often have poor efficiency upon two‐photon excitation in the near‐infrared (NIR) region and thus require high laser dosage that may compromise cell activity. As a result, high‐speed two‐photon hydrogel erosion in the presence of cells remains challenging. Here we introduce the design and synthesis of efficient coumarin‐based photodegradable hydrogels to overcome these limitations. A set of photolabile coumarin‐functionalized polyethylene glycol linkers are synthesized through a Passerini multicomponent reaction. After mixing these linkers with thiolated hyaluronic acid, semi‐synthetic photodegradable hydrogels are formed in situ via Michael addition crosslinking. The efficiency of photodegradation in these hydrogels is significantly higher than that in nitrobenzyl counterparts upon two‐photon irradiation at 780 nm. A complex microfluidic network mimicking the bone microarchitecture is successfully fabricated in preformed coumarin hydrogels at high speeds of up to 300 mm s−1 and low laser dosage down to 10 mW. Further, we demonstrate fast two‐photon printing of hollow microchannels inside a hydrogel to spatiotemporally direct cell migration in 3D. Collectively, these hydrogels may open new avenues for fast laser‐guided tissue fabrication at high spatial resolution. [ABSTRACT FROM AUTHOR]

Hydrogel foams are widely used in many applications such as biomaterials, cosmetics, foods, or agriculture. However, controlling precisely foam morphology (bubble size or shape, connectivity, wall and strut thicknesses, homogeneity) is required to optimize their properties. Therefore, a method is proposed here for generating, controlling, and characterizing the morphology of hydrogel foams from liquid foam templates: Using the example of Alginate‐CaHPO4‐based hydrogel foams, a highly controllable foaming process is provided by bubbling nitrogen through nozzles into the solution, which produces hydrogel foams with millimeter‐sized bubbles. A rheological characterization protocol of the foam's constituent material is first implemented and highlights the impact of the initial liquid foam properties and of the competition between the solidification kinetics and the foam aging mechanisms on the resulting morphology. X‐ray tomographic characterization performed on solidifying and solidified samples then demonstrates that by controlling the temporal evolution of the foam via its formulation, it is possible to tune the final morphology of the alginate foams. This method can be adapted to other hydrogel or polymer formulations, foam characteristics and length scales, as soon as solidification processes happen on timescales shorter than foam destabilization mechanisms. [ABSTRACT FROM AUTHOR]

Evaporative cooling is being re‐evaluated in the context of eco‐systems and environmental friendliness to improve the efficiency of thermoelectric and photovoltaic power generation. One of the essential tasks to improve evaporative cooling performance is the development of materials that can maintain the evaporation path and supply the lost water. Here, we synthesized a macroporous hydrogel by freeze casting at a slow cooling rate. A series of open spaces was designed between the aligned columns of the hydrogel, and water is stably supplied by extensive capillary channels. In a cooling test, it was shown to be effective in reducing the target's equilibrium temperature. As the heat input increased, the cooling effect (that is, the temperature reduction by the hydrogels) tended to increase. In addition, under airflow, the effect was stable, and further enhanced. These results extend design strategies for hydrogel‐based evaporative cooling and offer opportunities to maximize cooling performance by searching for optimal surface shape and exploiting airflow conditions. [ABSTRACT FROM AUTHOR]

Spatiotemporally controlled two‐photon photodegradation of hydrogels has gained increasing attention for high‐precision subtractive tissue engineering. However, conventional photolabile hydrogels often have poor efficiency upon two‐photon excitation in the near‐infrared (NIR) region and thus require high laser dosage that may compromise cell activity. As a result, high‐speed two‐photon hydrogel erosion in the presence of cells remains challenging. Here we introduce the design and synthesis of efficient coumarin‐based photodegradable hydrogels to overcome these limitations. A set of photolabile coumarin‐functionalized polyethylene glycol linkers are synthesized through a Passerini multicomponent reaction. After mixing these linkers with thiolated hyaluronic acid, semi‐synthetic photodegradable hydrogels are formed in situ via Michael addition crosslinking. The efficiency of photodegradation in these hydrogels is significantly higher than that in nitrobenzyl counterparts upon two‐photon irradiation at 780 nm. A complex microfluidic network mimicking the bone microarchitecture is successfully fabricated in preformed coumarin hydrogels at high speeds of up to 300 mm s−1 and low laser dosage down to 10 mW. Further, we demonstrate fast two‐photon printing of hollow microchannels inside a hydrogel to spatiotemporally direct cell migration in 3D. Collectively, these hydrogels may open new avenues for fast laser‐guided tissue fabrication at high spatial resolution. [ABSTRACT FROM AUTHOR]

In this paper, poly (acrylamide-co-N-vinylcaprolactam) [poly(AM-co-NVCL)] hydrogels were modified by aqueous solution polymerization using sodium carboxymethyl cellulose (CMC-Na) and Laponite. Their properties were characterized by infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), rheological testing, and scanning electron microscopy (SEM). The swelling kinetics showed that the equilibrium swelling ratio of the xerogel was influenced by the monomer ratio, crosslinking agent, and modifier content. As the Laponite and CMC-Na content increased, the compressive strength of the composite hydrogel increased, while the elongation at break decreased. The modified composite hydrogel exhibited dual sensitivity to pH and temperature. DSC and rheological tests indicated that CMC-Na functioned as a physical crosslinking agent in the system, and with the increase in CMC-Na content, the crosslinking effect was enhanced. SEM demonstrated that the addition of Laponite and CMC-Na increased the number of pores in the hydrogel and decreased the pore size. [ABSTRACT FROM AUTHOR]

To realize single-stimulus-induced simultaneous multi-behaviors in hydrogels is still quite challenging nowadays. Herein, an intelligent pH-responsive hydrogel (BP4VA/PAS) with rapid and high contrast changes in color, fluorescence, and shape simultaneously is reported. The BP4VA/PAS hydrogel is fabricated by incorporating styryl anthracene derivative (BP4VA) into copolymer networks (PAS) of acrylamide and sodium 4-styrene sulfonate. Under acid conditions, the protonation of BP4VA generates a rapid change with high color contrast from yellow to red and a fluorescence switch between bright green and weak red emission. At the same time, the electrostatic interactions between 2H-BP4VA2+ and sulfonate anions suspended on PAS trigger BP4VA/PAS hydrogels to shrink. Upon alkaline treatment, the 2H-BP4VA2+/PAS hydrogel deprotonates and recovers to its original color, fluorescence, and shape. Furthermore, utilizing rapid and remarkable pH-responsive properties of BP4VA/PAS hydrogels, we successfully demonstrated its applications in biomimicry, camouflage, and multistage information encryption. Collectively, this work provided an elegant strategy to develop intelligent hydrogels in applications of biomimetic smart materials and information encryption. [ABSTRACT FROM AUTHOR]

Controlling the hierarchical self-assembly of surfactants in aqueous solutions has drawn much attention due to their broad range of applications, from targeted drug release, preparation of smart material, to biocatalysis. However, the synthetic procedures for surfactants with stimuli-responsive hydrophobic chains are complicated, which restricts the development of surfactants. Herein, a novel single-tailed responsive surfactant, 1-methyl-3-(2-(4-((tetradecylimino) methyl) phenoxy) ethyl)-3-imidazolium bromides (C14PMimBr), was facilely fabricated in situ by simply mixing an aldehyde-functionalized imidazolium cation (3-(2-(4-formylphenoxy) ethyl)-1-methyl imidazolium bromide, BAMimBr) and aliphatic amine (tetradecylamine, TDA) through dynamic imine bonding. With increasing concentration, micelles, vesicles, and hydrogels were spontaneously formed by the hierarchical self-assembly of C14PMimBr in aqueous solutions without any additives. The morphologies of vesicles and hydrogels were characterized by cryogenic transmission electron microscopy and scanning electron microscopy. The mechanical properties and microstructure information of hydrogels were demonstrated by rheological measurement, X-ray diffraction, and density functional theory calculation. In addition, the vesicles could be disassembled and reassembled with the breakage and reformation of imine bonds by adding acid/bubbling CO2 and adding alkali. This work provides a simple method for constructing stimuli-responsive surfactant systems and shows great potential application in targeted drug release, drug delivery, and intelligent materials. [ABSTRACT FROM AUTHOR]

Background/Objectives: To assess the cytocompatibility, antibacterial and anti-biofilm efficacy of grape seed extract (GSE) and quercetin hydrogels versus calcium hydroxide (CH) as intracanal medications (ICMs) against an endodontic ex vivo biofilm model. Methods: Single-rooted teeth (n = 50) were prepared and sterilized before being infected with E. faecalis to develop a mature biofilm. They were divided into five equal groups according to the ICM used: G1: medicated with CH paste, G2: medicated with GSE hydrogel, G3: medicated with quercetin hydrogel, G4: positive control group that was infected and not medicated, and G5: negative control group that was neither infected nor medicated. After 1 week, the ICM was removed, and the root canals were cultured to assess the antibacterial efficacy by counting the colony-forming units and the anti-biofilm efficacy by the crystal violet assay. Dead/live bacterial viability was assessed by CFLSM examination, while the cytocompatibility was assessed using the MTT assay. Results: CH had the best antibacterial efficacy, followed by GSE and quercetin hydrogels (p < 0.001). Regarding the anti-biofilm efficacy, GSE was superior, followed by quercetin and CH (p < 0.001). CFLSM examination showed CH and GSE hydrogel to be highly effective in comparison to the positive control (p < 0.0001), with no statistical difference between them (p > 0.05). CH showed significantly higher cell viability percentages using a 500 μg/mL, while quercetin and GSE started to show cell viability > 70% at concentrations of 125 μg/mL and 62.5 μg/mL. Conclusions: CH fulfilled the ideal requirements of ICM as being both antibacterial and non-cytotoxic compared to the other materials tested. [ABSTRACT FROM AUTHOR]

Photochromic inks have shown disadvantages, such as poor durability and high cost. Self-healable hydrogels have shown photostability and durability. Herein, a viologen-based covalent polymer was printed onto a paper surface toward the development of a multi-stimuli responsive chromogenic sheet with thermochromic, photochromic, and vapochromic properties. Viologen polymer was created by polymerizing a dialdehyde-based viologen with a hydroxyl-bearing dihydrazide in an acidic aqueous medium. The viologen polymer was well immobilized as a colorimetric agent into a polyvinyl alcohol (PVA)/tricarboxy cellulose (TCC)-based self-healable hydrogel. The viologen/hydrogel nanocomposite films were applied onto a paper surface. The coloration measurements showed that when exposed to ultraviolet light, the orange layer printed on the paper surface switched to green. The photochromic film was used to develop anti-counterfeiting prints using the organic hydrogel composed of a PVA/TCC composite and a viologen polymer. Reversible photochromism with strong photostability was observed when the printed papers were exposed to UV irradiation. A detection limit was monitored in the range of 0.5–300 ppm for NH3(aq). The exposure to heat (70 °C) was found to reversibly initiate a colorimetric change. [ABSTRACT FROM AUTHOR]

Conductive hydrogels, characterized by their unique features of flexibility, biocompatibility, electrical conductivity, and responsiveness to environmental stimuli, have emerged as promising materials for sensitive strain sensors. In this study, a facile strategy to prepare highly conductive hydrogels is reported. Through rational structural and synthetic design, silver nanowires (AgNWs) are incorporated into poly(N‐acryloyl glycinamide) (PNAGA) hydrogels, achieving high electrical conductivity (up to 0.88 S m−1), significantly enhanced mechanical properties, and elevated deformative sensitivity. Furthermore, surface modification with polyhexafluoropropylene oxide (PHFPO) has substantially improved the water retention capacity and dressing comfort of this hydrogel material. Based on the above merits, these hydrogels are employed to fabricate highly sensitive wearable strain sensors which can detect and interpret subtle hand and finger movements and enable precise control of machine interfaces. The AgNWs/PNAGA based strain sensors can effectively sense finger motion, enabling the control of robotic fingers to replicate the human hand's gestures. In addition, the high deformative sensitivity and elevated water retention performance of the hydrogels makes them suitable for flow sensing. These conceptual applications demonstrate the potential of this conductive hydrogel in high‐performance strain sensors in the future. [ABSTRACT FROM AUTHOR]