Hydrogel Components Research Articles

Ion-Mediated Cross-Linking of Hyaluronic Acid into Hydrogels without Chemical Modification.

Hyaluronic acid (HA) is a biomedically relevant polymer widely explored as a component of hydrogels. The prevailing approaches for cross-linking HA into hydrogels require chemically modifying the polymer, which can increase processing steps and complicate biocompatibility. Herein, we demonstrate an alternative approach to cross-link HA that eliminates the need for chemical modifications by leveraging the interactions between metal cations and the negatively charged, ionizable functional groups on HA. We demonstrate that HA can be cross-linked with the bivalent metal cations Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), and notably Mg(II). Using Mg(II) as a model, we show that ion-HA hydrogel rheological properties can be tuned by altering the HA molecular weight and concentrations of ions, NaOH, and HA. Mg(II)-HA hydrogels showed the potential for self-healing and stimulus response. Our findings lay the groundwork for developing a new class of HA-based hydrogels for use in biomedical applications and beyond.

Carbon Dots Infused 3D Printed Cephalopod Mimetic Bactericidal and Antioxidant Hydrogel for Uniaxial Mechano-Fluorescent Tactile Sensor.

Cephalopods use stretchy skin and dynamic color-tuning organs for visual communication and camouflage. Inspired by these natural mechanisms, a fluorescent biomaterial for deformation-induced illumination and optical communication is proposed. This is the first report of 3D printed soft biomaterials infused with carbon dots hydrothermally derived from chitosan and benzalkonium chloride. These biomaterials exhibit a comprehensive array of properties, including significant uniaxial stretching, near-instantaneous response to tactile stimuli and pH, UV resistance, antibacterial, antioxidant, noncytotoxicity, and highlighting their potential as mechano-optical materials for biomedical applications. The hydrogel's durability is evaluated by cyclic stretching, folding, rolling, and twisting tests to ensure its integrity and good signal-to-noise ratio. The diffusion mechanism is determined by water imbibition kinetics, network parameters, and time-dependent breathing. Overcoming the common limitations of short lifespans and complex manufacturing processes in existing soft hybrids, this work demonstrates a straightforward method to produce durable, energy-independent, mechano-optical hydrogel. Combined with investigations, molecular dynamic modeling is used to understand the interactions of hydrogel components.

Strategic Approaches in Generation of Robust Microphysiological 3D Musculoskeletal Tissue System

AbstractSkeletal muscle plays a vital role in maintaining the body's shape and regulating various physiological processes. Its function is influenced by a multitude of factors. Given the lack of uniformity in prior research regarding the size and placement of structural pillars within the chip, as well as the choice of cell‐laden hydrogel components with various densities of extracellular matrix, in different gelation times, and cell densities, a meticulous investigation is conducted to enhance the robustness of 3D in vitro musculoskeletal tissues. This study provides guidance on how to optimize the design parameters of skeletal muscle‐on‐a‐chip and hydrogel recipe by evaluating the impact of design elements and hydrogel fabrication conditions on tissue formation and musculoskeletal differentiation. This research reports the direct evidence of mechanical properties of hydrogels are critical in influencing cellular differentiation and tissue functionality through the process of mechanotransduction. The study highlights the importance of standardizing experimental conditions in 3D in vitro musculoskeletal research, and presents a validated framework as a foundation to aid in the development of functional musculoskeletal tissue for clinical and research applications, including disease modeling and regenerative therapies.

RhBMP-2-loaded hydroxyapatite/beta-tricalcium phosphate microsphere/hydrogel composite promotes bone regeneration in a novel rat femoral nonunion model.

Nonunion following fracture treatment remains a significant clinical challenge, adversely affecting the patient's quality of life and imposing a substantial economic burden. The emergence of bone morphogenetic protein 2 (BMP-2) for bone regeneration represents a promising avenue, albeit limited by side effects such as inflammatory reactions primarily due to suboptimal drug delivery systems. This study focuses on NOVOSIS putty (NP), a novel biomaterial designed for the sustained release of BMP-2, aiming to mitigate these limitations and enhance bone healing. This research aimed to evaluate the effectiveness of NP, a hydroxyapatite granules/β-tricalcium phosphate hydrogel composite (HA/β-TCP/hydrogel), as a BMP-2 carrier for promoting bone regeneration in a new rat nonunion model of long bone. Using Sprague Dawley rats, a 2-mm silicone disk was interposed at the femoral fracture site, and intramedullary fixation with K-wire was performed to create a nonunion with a 2-mm bone defect. After 3weeks, internal fixation with a plate, removal of the silicon disk, and refreshing the nonunion site were performed by implanting three different materials into the nonunion sites: allogenic iliac bone (IB), collagen sponge (CS) containing 10μg of BMP-2, or NP containing 10μg of BMP-2. Bone healing was evaluated weekly using micro-computed tomography (CT); ex vivo micro-Ct and histological evaluation were conducted at 6weeks. At 6weeks, NP demonstrated a significantly higher bone union rate (76.5%) compared with the CS group (35.3%, p = 0.037), and the IB group (6.3%, p < 0.0001). Bone mineral density (BMD) and bone volume/tissue volume (BV/TV) were also significantly higher in the NP group compared with the CS group (BMD, p < 0.0001; BV/TV, p = 0.031). Histological analysis showed the fracture gap in the NP group was filled with more trabecular bone and less fibrous tissue compared with the CS group. The study confirms NP is a highly effective BMP-2 carrier, significantly improving bone union rates and new bone formation in nonunion fractures. The sustained release of BMP-2 from the hydrogel component reduced inflammatory responses and enhanced bone regeneration. NP can be a promising alternative to collagen-based BMP-2 delivery systems.

Dynamic polysaccharide/platelet-rich plasma hydrogels with synergistic antibacterial activities for accelerating infected wound healing

Platelet-rich plasma (PRP) has been recognized as an effective therapy in regenerative medicine and surgery, which can reduce the risk of antibiotic abuse and promote the healing of infected wounds. Recent advances in PRP-based treatments have focused on the controlled release of growth factors in PRP with biocompatible hydrogels and antimicrobial promotion by introducing hydrogel components or antibiotics, while the inherent antimicrobial activity of PRP is mostly neglected or sacrificed. Here, we demonstrate the combination of an antimicrobial polysaccharide, carboxymethyl chitosan, and PRP to construct an antimicrobial hydrogel via dynamic bonding with oxidized chondroitin sulfate. Significant inhibitory effects against Staphylococcus aureus and Escherichia coli (95 % of inhibition rate) are achieved through the synergistic contributions of the polysaccharide and PRP. Additionally, the resulting hydrogel promotes the migration of NIH-3T3 fibroblasts and collagen deposition by approximately 1.7 and 1.8 times, respectively, thereby accelerating the healing process of infected wounds. This work may bring new perspectives for potent applications of PRP-based hydrogel dressings for antibiotic-free management of infected wounds.

Silk-enriched hydrogels with ROS-scavenging dendrimers for advanced wound care

This study explores the development of novel hydrogel composites for wound care, incorporating silk fibroin and reactive oxygen species (ROS)-scavenging dendrimers into a polyvinyl alcohol (PVA) matrix. Utilizing ionizing gamma radiation, we fabricated pristine PVA, silk-PVA (SPVA) binary, and dendrimer-silk-PVA (DSPVA) ternary hydrogel composites, with their composition confirmed via UV–visible absorption spectroscopy. Fourier-transform infrared (FTIR) and Raman spectroscopy analyses indicated complex interactions between the hydrogel components, enhancing their structural and biocompatible properties. Scanning electron microscopy (SEM) analysis revealed that dendrimer integration in DSPVA hydrogels significantly increased surface porosity, vital for tissue regeneration. The DSPVA hydrogels demonstrated effective ROS scavenging, reducing hydrogen peroxide (H2O2) concentrations by approximately 70 % within 24 h. In vivo wound healing studies in a diabetic mouse model showed enhanced wound closure in the DSPVA group, with a relative wound area reduction to 30 ± 4.3 % on day 10, compared to 56.5 ± 2.7 % in the control group. By the 16th day, the treated group exhibited near-complete wound contraction, markedly outperforming the control group. These findings underscore the potential of DSPVA hydrogels in diabetic wound management, combining silk fibroin's mechanical support, dendrimers' antioxidative properties, and PVA's structural benefits. Thus, DSPVA hydrogels are promising candidates for advanced wound care applications.

Regulating natural galactomannan into composite hydrogels for improved adhesion, anti-swelling capability and efficient dye pollution removal

Constructing bio-based composite hydrogel materials are receiving much interest, while regulating the interactions of the hydrogel components and integrating functions for multi-application meet various challenges. Herein, composite hydrogels were prepared by cross-linking of poly-acrylamide (PAM) and poly-N-[3-(Dimethylamino) propyl] acrylamide (PDMAPAA), assisted by natural galactomannan (GM) regulation. Even distribution and compatibility of GM in the three-dimensional materials were proved by a series of chemical and morphological characterizations, which favored the improvement of mechanical properties (~80 kPa) and flexibility. Besides, the hydrogels were well-connected with double networks of noncovalent intermolecular hydrogen bonding interactions and hydrophobic interactions, in addition to covalent-linked polymers. Due to great amount of inner hydrogen bond linkages, the hydrogels present satisfying anti-swelling capabilities (<15 %), exhibiting high potential for application in water treatment. Meanwhile, abundant surface functional groups provided possibilities to form interactive layer with the various substrates surface, exhibiting highly adhesive properties. Significant dyes adsorption capabilities were revealed on the hydrogels according to the electrostatic attraction with Congo red and hydrogen bond interactions with Brilliant green respectively. Thus, the proposed composite hydrogels integrated multi-functions due to the tuning the surface groups and cross-linking interactions, which provided deeper understanding on bio-based materials on fields of water treatment and environmental protection.

Architectural engineering of Cyborg Bacteria with intracellular hydrogel

Synthetic biology primarily uses genetic engineering to control living cells. In contrast, recent work has ushered in the architectural engineering of living cells through intracellular materials. Specifically, Cyborg Bacteria are created by incorporating synthetic PEG-based hydrogel inside cells. Cyborg Bacteria do not replicate but maintain essential cellular functions, including metabolism and protein synthesis. Thus far, Cyborg Bacteria have been engineered using one primary composition of intracellular hydrogel components. Here, we demonstrate the versatility of controlling the physical and biochemical aspects of Cyborg Bacteria using different structures of hydrogels. The intracellular cell-gel architecture is modulated using a different photoinitiator, PEG-diacrylate (PEG-DA) of different molecular weights, 4arm PEG-DA, and dsDNA-PEG. We show that the molecular weight of the PEG-DA affects the generation and metabolism of Cyborg Bacteria. In addition, we show that the hybrid dsDNA-PEG intracellular hydrogel controls protein expression levels of the Cyborg Bacteria through post-transcriptional regulation and polymerase sequestration. Our work creates a new frontier of modulating intracellular gel components to control Cyborg Bacteria function and architecture.

Light‐Encoding of a Supramolecular Hydrogel for Assembly‐Free Soft Machines Capable of Sequential and Multistage Shape‐Morphing

AbstractShape‐morphing hydrogels can mimic the dynamism of living creatures and are popular for designing soft machines, such as actuators and robots. However, most existing shape‐morphing hydrogels present a single morphing pathway between two shapes, sequential and multistage shape‐morphing in real scenarios has rarely been captured. Although a strategy that assembles functional hydrogel components has been reported, it is likely to simultaneously increase the complexity and weaken the versatility of hydrogel machines. Here, a light‐encoding strategy based on the dynamic coordination between the ferric iron and carboxyl group (Fe3+─COO−) to integrate the frame and actuating units into a single hydrogel without assembly is proposed. The spatiotemporal control of light irradiation is expected to make the light‐encoding process sequential and reprogrammable. Results demonstrate that the light‐encoded patterns determine the morphing route and further activate shape‐morphing owing to swelling mismatch. The actuating units can be successively created by localized irradiation or elaborately turned by re‐coordinating and light‐encoding. This endows the encoded hydrogel with sequential and multistage shape‐morphing behavior, similar to the living creatures. This strategy allows the design of assembly‐free soft machines with sequential and multistage shape‐morphing performance, which will benefit the design of more types of hydrogel machines.

Synergistic antibacterial and wound healing effects of chitosan nanofibers with ZnO nanoparticles and dual antibiotics.

One concern that has been considered potentially fatal is bacterial infection. In addition to the development of biocompatible antibacterial dressings, the screening and combination of new antibiotics effective against antibiotic resistance are crucial. In this study, designing hemostasis electrospun composite nanofibers containing chitosan (CS), polyvinyl pyrrolidone (PVP) and Gelatin (G) as the major components of hydrogel and natural nanofibrillated sodium alginate (SA)/polyvinyl alcohol (PVA) and ZnO nanoparticles (ZnONPs) combination as the nanofiller ingredient, has been investigated which demonstrated significant potential for accelerating wound healing. The hydrogels were developed for the delivery of the amikacin and cefepime antibiotics, along with zinc oxide nanoparticles that were applied to an electrospun layer. Amikacin is a highly effective aminoglycoside antibiotic, particularly for hospital-acquired infections, but its use is limited due to its toxicity. By utilizing it in low concentrations in the form of nanofibers and combining it with cefepime, which exhibits synergistic effects, enhanced efficacy against bacterial pathogens is achieved while potentially minimizing cytotoxicity compared to individual antibiotics. This dressing demonstrated efficient drug release, flexibility, and good swelling properties, indicating its suitable mechanical properties for therapeutic applications. After applying the biocompatible hydrogel to wounds, a significant acceleration in wound closure was observed within 14 days compared to the control group. Furthermore, the notable antibiotic and anti-inflammatory properties underscore its effectiveness in wound healing, making it a promising candidate for medical applications.

Nanozyme microspheres with structural color-coding labels for synergistic therapy of psoriasis

Psoriasis is an immune system-mediated skin disease identified by the appearance of erythematous as a central symptom. As a recurrent and chronic inflammatory disease, psoriasis is influenced by both genetic and environmental factors and is known to be with no effective cure. Considering a multifaceted etiology of psoriasis, synergistic therapy exhibits great benefits over monotherapy, which becomes common for the treatment of various diseases. Herein, we present the nanozyme microspheres with structural color-coding labels for synergistic therapy of psoriasis. In particular, microsphere hydrogel is fabricated by the edible hydroxypropyl cellulose (HPC), which can generate a photonic liquid crystalline mesophase under lyotropic conditions in solution. Through adjustment of hydrogel components, microspheres endow with different functions, including moisturizing (paraffin), cfDNA scavenging (chitosan), and anti-inflammation (cerium oxide nanozyme). To improve patient convenience, hydrogel drops with different properties are tailored with different vivid structural colors by exploiting the lyotropic behavior of HPC. Of particular note, both in vitro and in vivo experiments have demonstrated the significant therapeutic effects of the encoded structural color microspheres. Green moisturizing microspheres facilitate to relieve dry, flaky skin patches; blue cfDNA scavenging and red anti-inflammatory microspheres significantly reduce skin inflammation. More importantly, combination therapy with encoded microspheres exerted the synergistic effects, including the increased body weight, thicker epidermal layer, and reduced immune activation. Overall, this synergistic treatment offers a promising platform for personalized management of psoriasis and various inflammatory skin diseases.

Nanolignin-Facilitated Robust Hydrogels.

Recently, certain challenges and accompanying drawbacks have emerged in the preparation of high-strength and tough polymer hydrogels. Insights from wood science highlight the role of the intertwined molecular structure of lignin and crystalline cellulose in contributing to wood's strength. Herein, we immersed prestretched poly(vinyl alcohol) (PVA) polymer hydrogels into a solution of nanosized lignosulfonate sodium (LS), a water-soluble anionic polyelectrolyte, to creatively reconstruct this similar structure at the molecular scale in hydrogels. The nanosized LS effectively fixed and bundled the prestretched PVA polymers while inducing the formation of dense crystalline domains within the polymer matrix. Consequently, the interwoven structure of crystalline PVA and LS conferred good strength to the composite hydrogels, exhibiting a tensile strength of up to ∼23 MPa, a fracture strain of ∼350%, Young's modulus of ∼17 MPa, toughness of ∼47 MJ/m3, and fracture energy of ∼42 kJ/m2. This hydrogel far outperformed previous hydrogels composed directly of lignin and PVA (tensile strength <1.5 MPa). Additionally, the composite hydrogels demonstrated excellent antifreezing properties (<-80 °C). Notably, the LS-assisted reconstruction technology offers opportunities for the secondary fixation of PVA hydrogel shapes and high-strength welding of hydrogel components. This work introduces an approach for the high-value utilization of LS, a green byproduct of pulp production. LS's profound biomimetic strategy will be applied in multifunctional hydrogel fields.

Hydrogel-based hybrid membrane enhances in vitro ophthalmic drug evaluation in the OphthalMimic device

Envisaging to improve the evaluation of ophthalmic drug products while minimizing the need for animal testing, our group developed the OphthalMimic device, a 3D-printed device that incorporates an artificial lacrimal flow, a cul-de-sac area, a moving eyelid, and a surface that interacts effectively with ophthalmic formulations, thereby providing a close representation of human ocular conditions. An important application of such a device would be its use as a platform for dissolution/release tests that closely mimic in vivo conditions. However, the surface that artificially simulates the cornea should have a higher resistance (10 min) than the previously described polymeric films (5 min). For this key assay upgrade, we describe the process of obtaining and thoroughly characterizing a hydrogel-based hybrid membrane to be used as a platform base to simulate the cornea artificially. Also, the OphthalMimic device suffered design improvements to fit the new membrane and incorporate the moving eyelid. The results confirmed the successful synthesis of the hydrogel components. The membrane’s water content (86.25 ± 0.35 %) closely mirrored the human cornea (72 to 85 %). Furthermore, morphological analysis supported the membrane’s comparability to the natural cornea. Finally, the performance of different formulations was analysed, demonstrating that the device could differentiate their drainage profile through the viscosity of PLX 14 (79 ± 5 %), PLX 16 (72 ± 4 %), and PLX 20 (57 ± 14 %), and mucoadhesion of PLXCS0.5 (69 ± 1 %), PLX16CS1.0 (65 ± 3 %), PLX16CS1.25 (67 ± 3 %), and the solution (97 ± 8 %). In conclusion, using the hydrogel-based hybrid membrane in the OphthalMimic device represents a significant advancement in the field of ophthalmic drug evaluation, providing a valuable platform for dissolution/release tests. Such a platform aligns with the ethical mandate to reduce animal testing and promises to accelerate the development of safer and more effective ophthalmic drugs.

Iron protoporphyrin IX-hyaluronan hydrogel-supported luminol chemiluminescence for the detection of nitric oxide in physiological solutions

Due to its role as a free radical signal-transducing agent with a short lifespan, precise measurement of nitric oxide (●NO) levels presents significant challenges. Various analytical techniques offer distinct advantages and disadvantages for ●NO detection. This research aims to simplify the detection process by developing a hydrogel system using iron(III)-protoporphyrin IX (hemin)-loaded hyaluronan for the detection of ●NO in solution. Various hydrogel formulations were created, and the effects of their components on hydrogel-supported luminol chemiluminescence (CL) kinetics, radical scavenging, and physicochemical properties were analysed through factorial analysis. The candidate formulations were then evaluated using two ●NO donors. An increase in the degree of crosslinking in unloaded formulations enhanced interactions with the CL reaction components, hydrogen peroxide (H2O2) and luminol, thereby affecting light generation. However, hemin loading negated these effects, resulting in more prominent luminescence kinetics in formulations with lower crosslinking degrees. Similarly, ●NO influenced the kinetics differently, interacting with both the CL reaction and hydrogel components. Hemin-loaded formulations exhibited enhanced signal propagation when exposed to ●NO, followed by H2O2 and luminol, whereas reversing the order of addition inhibited this propagation. The magnitude of these luminescence changes depended on the type and concentration of the ●NO donor, demonstrating greater sensitivity to ●NO levels compared to amperometric sensing. These findings suggest that the studied hydrogel platform has potential for the facile and accurate detection of ●NO in solution, requiring minimal sample sizes.

Ionic Polymerization-Based Synthesis of Bioinspired Adhesive Hydrogel Microparticles with Tunable Morphologies from Microfluidics.

Shape-anisotropic hydrogel microparticles have attracted considerable attention for drug-delivery applications. Particularly, nonspherical hydrogel microcarriers with enhanced adhesive and circulatory abilities have demonstrated value in gastrointestinal drug administration. Herein, inspired by the structures of natural suckers, we demonstrate an ionic polymerization-based production of calcium (Ca)-alginate microparticles with tunable shapes from Janus emulsion for the first time. Monodispersed Janus droplets composed of sodium alginate and nongelable segments were generated using a coflow droplet generator. The interfacial curvatures, sizes, and production frequencies of Janus droplets can be flexibly controlled by varying the flow conditions and surfactant concentrations in the multiphase system. Janus droplets were ionically solidified on a chip, and hydrogel beads of different shapes were obtained. The in vitro and in vivo adhesion abilities of the hydrogel beads to the mouse colon were investigated. The anisotropic beads showed prominent adhesive properties compared with the spherical particles owing to their sticky hydrogel components and unique shapes. Finally, a novel computational fluid dynamics and discrete element method (CFD-DEM) coupling simulation was used to evaluate particle migration and contact forces theoretically. This review presents a simple strategy to synthesize Ca-alginate particles with tunable structures that could be ideal materials for constructing gastrointestinal drug delivery systems.

Preparation of arbutin hydrogel formulation as green skin lightener formulation: in vitro and in vivo evaluation

A hydrogel formulation containing arbutin was developed for use as a topical cosmetic product aimed at enhancing the anti-melanogenesis effect and skin delivery. To develop Arbutin-hydrogel, 1% arbutin was incorporated into a Chitosan/alginate hydrogel. The impacts of biopolymer proportion on the arbutin-hydrogel preparations were investigated. Swelling analysis, weight loss analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, toxicity study and, skin absorption test were employed to assess the arbutin-hydrogel. The swelling percentages of arbutin-hydrogel increased significantly after 4 h. In vitro, cytotoxic activity revealed that arbutin-hydrogel has no toxicity. Also, the cutaneous penetration investigation revealed that arbutin-hydrogel had a superior cutaneous accumulation (42.25 ± 0.30%) compared to plain gel (16.80 ± 0.33%). Also, physico-chemical specifications assay and solid state assessment were employed to assess of optimum formulation. Arbutin-hydrogel (60.9 ± 1.68%) inhibited melanin formation more effectively than arbutin solution. In addition, arbutin-hydrogel exhibited a more inhibitory impact on L-dopa auto-oxidation (54.90 ± 2.26%) than arbutin solution (38.62 ± 2.26%). In addition, the Wistar rat cutaneous sensitivity testing demonstrated that the hydrogel component did not affect the epidermis. These outcomes demonstrated that the arbutin-hydrogel could potentially be utilized for Arbutin topical delivery, expanding the treatment options for hyperpigmentation disorders.

Promotion and monitor wound healing by anthocyanin enhanced light curing ε-poly-l-lysine hydrogel encapsulated Cu-MOF

Drug-resistant bacterial infections and biofilm formation have long posed significant challenges to public health, particularly in the context of chronic wound healing. In this study, the CuHspMOF were derived from copper and hesperitin (Hsp). The photocurable Epsilon-poly-l-lysine (EPLMA) and blueberry anthocyanin (BA) were synthesized through free radical polymerization. The multifunctional EB@CuHsp hydrogel exhibits excellent photothermal effect. One of the key features of the EB@CuHsp hydrogel is its ability to monitor the healing environment through color changes in response to variations in pH. This property allows for real-time assessment of the wound’s pH levels, reflecting the body fluid’s pH range during the healing process (pH 5–9). The hydrogel components work synergistically to facilitate wound healing. The EPLMA, with its positively charged, could captures bacteria and enable copper ions to eradicate bacteria at lower concentrations. This dual action leads to the creation of an optimal healing environment conducive to wound healing. During the inflammatory phase, BA and Hsp could collaborate to combat inflammation, which transited from the inflammatory stage to the proliferative phase soon. Continuous release of BA and Cu2+, coupled with thermotherapy, significantly enhances epithelial and blood vessel regeneration, thereby expediting the healing of chronic wounds. Overall, this multifunctional composite hydrogel holds great promise for promoting the regeneration of infected wound tissue, making it a potential candidate for chronic wound dressings.

Delivery of dental pulp stem cells by an injectable ROS-responsive hydrogel promotes temporomandibular joint cartilage repair via enhancing anti-apoptosis and regulating microenvironment

Temporomandibular joint (TMJ) cartilage repair poses a considerable clinical challenge, and tissue engineering has emerged as a promising solution. In this study, we developed an injectable reactive oxygen species (ROS)-responsive multifunctional hydrogel (RDGel) to encapsulate dental pulp stem cells (DPSCs/RDGel in short) for the targeted repair of condylar cartilage defect. The DPSCs/RDGel composite exhibited a synergistic effect in the elimination of TMJ OA (osteoarthritis) inflammation via the interaction between the hydrogel component and the DPSCs. We first demonstrated the applicability and biocompatibility of RDGel. RDGel encapsulation could enhance the anti-apoptotic ability of DPSCs by inhibiting P38/P53 mitochondrial apoptotic signal in vitro. We also proved that the utilization of DPSCs/RDGel composite effectively enhanced the expression of TMJOA cartilage matrix and promoted subchondral bone structure in vivo. Subsequently, we observed the synergistic improvement of DPSCs/RDGel composite on the oxidative stress microenvironment of TMJOA and its regulation and promotion of M2 polarization, thereby confirmed that M2 macrophages further promoted the condylar cartilage repair of DPSCs. This is the first time application of DPSCs/RDGel composite for the targeted repair of TMJOA condylar cartilage defects, presenting a novel and promising avenue for cell-based therapy.

Synthesis of novel bioadhesive hydrogels via facile Thiol-Ene click chemistry for wound healing applications

Development of outstanding, cost-effective and elastic hydrogels as bioadhesive using Thiol-Ene click chemistry was verified. The visible light photocrosslinkable hydrogels composed of methacrylated chitosan/2,2′-(Ethylenedioxy) diethanethiol formed in presence of eosin-Y photoinitiator. Such hydrogels hold great promise for wound healing applications due to their tunable properties. Main components of hydrogels were extensively characterized using spectroscopic techniques for chemical analysis, thermal analysis, and topologic nanostructure. Various optimization conditions for best gelation time were investigated. Mechanical properties of tensile strength and elongation at break (%) were verified for best wound healing applications. Optimum hydrogel was subjected to for cytotoxicity and microbial suppression evaluation and in-vivo wound healing test for efficient wound healing evaluations. Our results demonstrate the potential use of injectable hydrogels as valuable bioadhesives in bioengineering and biomedical applications, particularly in wound closure and patches.

Mechanics of single-network hydrogels with network imperfection

Polymer network is a crucial component of hydrogels, and network imperfection is a prominent feature of polymer networks, significantly influencing the performance of hydrogels. Two essential features of network imperfection are unequal chain lengths and dangling chains, both of which have a significant impact on the mechanical properties of single-network (SN) hydrogels. However, a theoretical framework considering network imperfection in SN hydrogels is still lacking. Here, we propose a theoretical model for SN hydrogels with network imperfection to study the damage behavior during deformation, in which we adopt different chain length distributions to accurately depict the real physical characteristics of the polymer network and incorporate the normalized critical chain force for a more precise measurement of network damage. To verify our theory, we discuss the effects of model parameters on the stress-stretch responses of SN hydrogels and predict the results of uniaxial loading-unloading tests of SN hydrogels, which agree well with experimentally measured stress-stretch behaviors. Finally, we implement the constitutive model into ABAQUS as a user subroutine to study the inhomogeneous deformation of hydrogels.