Bioinspired Injectable Self-Healing Hydrogel Sealant with Fault-Tolerant and Repeated Thermo-Responsive Adhesion for Sutureless Post-Wound-Closure and Wound Healing

A novel multi-functional PVA- alginate hydrogel with dynamic bond crosslinking for infected wound repair

The development of multifunctional antibacterial hydrogel dressings with enhanced mechanical properties and biological activity is essential for advancing wound healing strategies. In this study, we report the design and synthesis of a novel multifunctional hydrogel (PVA-Alg/FP), developed by integrating Fe3+, protocatechualdehyde (PA), polyvinyl alcohol (PVA), and sodium alginate (Alg). The hydrogel was crosslinked via multiple dynamic bonds and hydrogen bonds, avoiding the use of toxic crosslinking agents and eliminating the need for additional modification or purification steps. This approach enables the straightforward and efficient preparation of the hydrogel. The resulting hydrogel exhibits outstanding mechanical properties, with a tensile strength of 88.2 kPa. More importantly, compared with conventional PVA-Alg hydrogels crosslinked by glutaraldehyde or epichlorohydrin, our PVA-Alg/FP hydrogel demonstrates a diverse range of functional characteristics, including a high self-healing efficiency of 87.4 % within 10 min, as well as plasticity, ductility, adhesion, Deferoxamine mesylate (DFO)-responsive removal, and near-infrared (NIR) photothermal properties. Additionally, it demonstrates outstanding biocompatibility and a broad spectrum of biological activities, including antioxidant, anti-inflammatory, and antibacterial effects, as well as promoting cell migration. Furthermore, the hydrogel accelerates full-thickness skin wound healing in a Staphylococcus aureus(S.aureus)-infected rat model, providing compelling evidence of its potential as a therapeutic material for infection-induced wounds.

Recent advances in smart hydrogels derived from polysaccharides and their applications for wound dressing and healing

Owing to their inherent biocompatibility and biodegradability, hydrogels derived from polysaccharides have emerged as promising candidates for wound management. However, the complex nature of wound healing often requires the development of smart hydrogels---intelligent materials capable of responding dynamically to specific physical or chemical stimuli. Over the past decade, an increasing number of stimuli-responsive polysaccharide-based hydrogels have been developed to treat various types of wounds. While a range of hydrogel types and their versatile functions for wound management have been discussed in the literature, there is still a need for a review of the crosslinking strategies used to create smart hydrogels from polysaccharides. This review provides a comprehensive overview of how stimuli-responsive hydrogels can be designed and made using five key polysaccharides: chitosan, hyaluronic acid, alginate, dextran, and cellulose. Various methods, such as chemical crosslinking, dynamic crosslinking, and physical crosslinking, which are used to form networks within these hydrogels, ultimately determine their ability to respond to stimuli, have been explored. This article further looks at different polysaccharide-based hydrogel wound dressings that can respond to factors such as reactive oxygen species, temperature, pH, glucose, light, and ultrasound in the wound environment and discusses how these responses can enhance wound healing. Finally, this review provides insights into how stimuli-responsive polysaccharide-based hydrogels can be developed further as advanced wound dressings in the future.

"Monitor-and-treat" that integrates bacterio-therapeutics and bio-optics for infected wound management

Wound infections are one of the major threats to human health, accounting for millions of deaths annually. Real-time monitoring, accurate diagnosis, and on-demand therapy are crucial to minimizing complications and saving lives. Herein, we propose a "monitor-and-treat" strategy for infected wound management by integrating the emerging development of bacterio-therapeutics and bio-optics. The upper layer consists of gelatin methacryloyl (GelMA)-collagen III methacryloyl (Col3MA) (GC), Reuterin (Reu) isolated from the probiotic Lactobacillus reuteri (L. reuteri) and microfluidic safflower polysaccharide (SPS)@GelMA microspheres using 3D printing technology. The lower layer is made of acryloylated glycine (ACG) hydrogel with tissue adhesion capability, which enables the hydrogel to adapt to the movement and stretching of the skin. By integrating temperature-sensitive polydimethylsiloxane (PDMS) optical fibers, the ACG-GC/Reu/SPS-PDMS hydrogel could accurately and steadily sense and send wound temperature information to intelligent devices for real-time monitoring of the healing status ("monitor"). The double-layered hydrogel not only inhibited bacterial survival and colonization (97.4 % against E. coli and 99 % against S. aureus), but also exhibited remarkable hemostatic properties. Furthermore, it was conducive to L929 cell proliferation and pro-angiogenesis, and promoted the polarization of pro-inflammatory M1 macrophages to the anti-inflammatory M2-phenotype, therefore creating a favorable immune microenvironment at the wound site. Animal experiments using SD rats and Bama minipigs demonstrated that this hydrogel promoted wound closure, directed polarization to M2 macrophages, alleviated inflammation, enhanced neovascularization, therefore accelerating infected wound healing ("treat"). In addition, RNA-Seq analysis revealed the mechanism of action of ACG-GC/Reu/SPS-PDMS hydrogel in modulating key signaling pathways, including down-regulation of AMPK, IL-17, and NF-κB signaling pathways, activation of NLRP3 inflammatory vesicles, and enrichment of MAPK, TGF-β, PI3K-Akt, TNF, and VEGF signaling pathways. The modulation of these signaling pathways suggests that hydrogels play an important role in the molecular mechanisms that promote wound healing and tissue regeneration. Therefore, the design of this study provides an innovative and multifunctional bandage strategy that can significantly improve pathologic diagnosis and wound treatment.

Injectable Hydrogels Based on Hyperbranched Polymers for Biomedical Applications

Injectable hydrogels (IHs) have garnered significant attention in biomedical applications due to their minimally invasive nature, adaptability, and high degree of customization. However, traditional design methods of IHs have limitations in addressing complex clinical needs, such as precise regulation of the gelation time and mechanical strength within a wide window. Hyperbranched polymers (HBPs), due to their unique highly branched structures and abundant functional sites, can be easily prepared and functionalized to enable decoupled modulation of mechanical properties of IHs and address the clinical challenges of IHs. Our research group developed a library of HBPs via a dynamically controllable polymerization method and built a series of adjustable, controllable, and responsive IHs based on the resulting HBPs. The prepared IHs fed by HBPs demonstrate an adjustable gelation process, a wide-range tuning of mechanical properties, and responsiveness on demand, which show the capabilities in the various biomedical applications. In this review, we summarize the role of HBPs in the gelation process, mechanical properties, self-healing ability, and responsiveness of IHs. However, achieving IHs through HBPs and extending them to a broad range of biomedical applications are still in its infancy. This review provides an overview of IHs fabricated by a variety of multifunctional HBPs, and their biomedical applications in diverse fields are also presented. Meanwhile, we point out the future development of IHs based on HBPs and their potential challenges.

Nanocellulose Wound Dressings with Integrated Protease Sensors for Detection of Wound Pathogens

Wound infections result in delayed healing, morbidity, and increased risks of sepsis. Early detection of wound infections can facilitate treatment and reduce the need for the excessive use of antibiotics. Proteases are normally active during the healing process but are overexpressed during infection as part of the inflammatory response. Proteases are also produced by the bacteria infecting the wounds, making proteases a highly relevant biomarker for infection monitoring. Here, we show a fluorescence turn-on sensor for real-time monitoring of protease activity in advanced nanocellulose wound dressings for rapid detection of wound pathogens. Colloidal gold nanoparticles (AuNPs) were adsorbed on bacterial cellulose (BC) nanofibrils by using a carefully optimized self-assembly process. The AuNPs could either be homogeneously incorporated in BC dressings or 3D printed in wood-derived cellulose nanofiber (CNF) dressings using a BC-AuNP ink. The BC-adsorbed AuNPs were subsequently functionalized with fluorophore-labeled protease substrates. Cleavage of the substrates by proteases produced by the wound pathogens Staphylococcus aureus and Pseudomonas aeruginosa resulted in a significant increase in fluorescence that correlated with the growth phase of the bacteria. Wound dressing with integrated sensors for the detection of proteolytic activity can enable the sensitive and rapid detection of infections, allowing for optimization of treatment and reducing the risks of complications.

A facilely prepared dual-crosslinking adhesive with enhanced adhesive strength for hemostasis and infected wound healing

Although biological adhesives have shown advantages in replacing traditional wound suturing techniques, there are still limitations in wound closure, hemostasis, and healing, including insufficient tissue adhesion, potential biological toxicity, and complex preparation processes. In this study, a facile route for preparing injectable dual-crosslinking multifunctional hydrogel adhesive (Gel/EN/FBTA) was developed. The Gel/EN/FBTA adhesive is a dynamic cross-linked network composed of tannic acid (TA), 3-formylphenylboronic acid (3-FPBA) and gelatin, which can provide a large number of bonding sites and strengthen the adhesive cohesion through energy dissipation. The amidation reaction inside gelatin can form stable rigid crosslinks and maintain the structure of the adhesive stably. The balance between adhesion and cohesion can be regulated by adjusting the chemical composition and crosslinking density of the dual-crosslinking network. Under this equilibrium condition, the adhesion strength of Gel/EN/FBTA2 hydrogel is 3 times that of commercial fibrin glue, which shows good hemostatic effects in rat liver injury, rat tail injury, and rabbit liver cross incision models. Furthermore, Gel/EN/FBTA2 hydrogel adhesive can effectively treat wound infection, reduce inflammation level, promote re-epithelialization, accelerate collagen deposition, and achieve the healing of infectious full-thickness wounds. This dual-network design paradigm provides a versatile strategy for developing next-generation bioadhesives with tailored mechanical and bioactive properties, demonstrating significant potential for non-compressible hemorrhage and infected wound management.

Preparation and characterization of thermosensitive phase-transition hydrogel based on decanoic acid-modified chitosan and methyl cellulose for wound healing

Hydrogels with good biocompatibility, suitable physicochemical properties, and effective wound healing promotion are currently recognized as ideal candidates for wound dressings. This study introduced an innovative thermosensitive phase-transition hydrogel (CSDA-MC-HG) for skin wound repair, prepared using decanoic acid-modified chitosan (CSDA) and methyl cellulose (MC). The enhanced hydrophobic interaction with increasing temperature was the primary mechanism behind the thermosensitive phase-transition property of CSDA-MC-HG. Rheological measurement confirmed that CSDA-MC-HG possessed adequate spreadability and adaptability, allowing it to conform well to irregular shaped wounds and be easily applied and replaced. The other characterization findings indicated that CSDA-MC-HG possessed ideal interconnected porous structure, along with superior swelling capacity, water retention ability, and water vapor permeability necessary for an optimal wound dressing. Biocompatibility experiments indicated that CSDA-MC-HG exhibited satisfactory blood compatibility and cell compatibility, supporting the proliferation and migration of L929 cells. Furthermore, the hydrogel's potential as a wound dressing was tested on SD rats with full-thickness skin wounds. The results indicated that CSDA-MC-HG effectively promoted wound healing by enhancing fibroblast proliferation, accelerating the formation of new blood vessels and skin appendages, and facilitating collagen deposition. The findings presented suggested that CSDA-MC-HG held significant potential for application as a wound healing dressing.

Recent advances in tannic acid-based gels: Design, properties, and applications

With the flourishing of mussel-inspired chemistry, the fast-growing development for environmentally friendly materials, and the need for inexpensive and biocompatible analogues to PDA in gel design, TA has led to its gradual emergence as a research focus due to its remarkable biocompatible, renewable, sustainable and particular physicochemical properties. As a natural building block, TA can be used as a substrate or crosslinker, ensuring versatile functional polymeric networks for various applications. In this review, the design of TA-based gels is summarized in detail (i.e., different interactions such as: metal coordination, electrostatic, hydrophobic, host-guest, cation-π and π-π stacking interactions, hydrogen bonding and various reactions including: phenol-amine Michael and Schiff base, phenol-thiol Michael addition, phenol-epoxy ring opening reaction, etc.). Subsequently, TA-based gels with a variety of functionalities, including mechanical, adhesion, conductive, self-healing, UV-shielding, anti-swelling, anti-freezing, shape memory, antioxidant, antibacterial, anti-inflammatory and responsive properties are introduced in detail. Then, a summary of recent developments in the use of TA-based gels is provided, including bioelectronics, biomedicine, energy, packaging, water treatment and other fields. Finally, the difficulties that TA-based gels are currently facing are outlined, and an original yet realistic viewpoint is provided in an effort to spur future development.

Endoscopic Delivery of a Double-Umbrella-Shaped Hydrogel Occluder with Instant Mechanical Interlock and Robust Wet Adhesion for Gastric Perforation Repair

Achieving robust adhesion of bioadhesives on wet tissues to block gastric perforation remains a challenge due to the gradually deteriorated adhesive-tissue interactions by interfacial acidity and multienzyme gastric fluids, thus accompanying failure shedding and life-threatening risks. Here, we report a biocompatible double-umbrella-shaped endoscopy-deliverable hydrogel occluder (EHO) made of caffeic acid (CA)-grafted chitosan (CS) and polyacrylamide (PAM) by molding technique, which is capable of the customizable, rapid, robust, and long-term sealing of large gastric perforations. In addition to interfacial physiochemical interactions (e.g., H-bonding, chelation) between the tissues and polymers, efficient sealing also integrates the advantages of fast mechanical interlocking in space and gradual self-expansion over time to tolerant acidic and mechanically dynamic environments. The EHO exhibits favorable biodegradability due to the reducible disulfide cross-linkers and remarkable protective barrier functions to impede the infiltration of gastric acid and digestive pepsin into the wound. To validate EHO's therapeutic efficacy, we further demonstrate the robust in vivo sealing to large gastric tissues via endoscopic delivery to the porcine stomach and monitor of healing process with improved retention of endogenous growth factors. Besides, in views of simple hydrogel fabrication using molding technique, the biodegradable EHO can be facilely tailored with various topologies according to application scenarios in surgical and minimally invasive endoscopic delivery, thus offering a promising alternative for clinical repair of gastrointestinal perforations and other organs.

Dual-action MOF-on-MOF hydrogel: A chemo-photodynamic strategy for enhanced antibacterial activity and infected wound healing

Open skin wounds are susceptible to bacterial infections, which can delay healing and even trigger life-threatening complications. The improper and prolonged use of antibiotics can accelerate bacterial resistance, complicating the treatment of clinical infections. Therefore, there is an urgent need for effective antibiotic-free therapeutic strategies to treat bacterial infections in wounds. In this study, we loaded the growth factor Dimethyloxalylglycine (DMOG) into the pores of PCN-224 and subsequently deposited 2-Methylimidazole zinc salt (ZIF-8) on its surface, creating an injectable hydrogel based on a MOF-on-MOF design. This approach leverages metal ion release in conjunction with photodynamic therapy (PDT) to achieve effective antibacterial activity. Additionally, the injectable hydrogel can adapt to various wound morphologies and enable hemostasis for acute tissue injuries due to its fast gelation speed and adhesiveness. Meanwhile, the sustained release of DMOG promotes angiogenesis. Results demonstrated that the GelMA/HA/DMOG@PCN-224/ZIF-8 (GelMA/HA/D@PZ) hydrogel achieves a 99.9 % bactericidal rate against Staphylococcus aureus, Escherichia coli, and MRSA, while also significantly promoting the healing of infected wounds. Therefore, the GelMA/HA/D@PZ composite material facilitates initial hemostasis, mid-term antibacterial activity, and long-term angiogenesis, providing a novel, efficient, and safe approach to promote the healing of infected wounds.

Antimicrobial chitosan-based hydrogels: A novel approach to obtain sanitizers

The study presents novel hydrogels obtained by crosslinking chitosan with both furfural and glutaraldehyde via dynamic imine bonds. Scanning electron microscopy confirmed the formation of porous networks with a mean diameter of the pores between 15 and 35 μm, while the supramolecular characterization by polarized optical microscopy and wide-angle X-ray diffraction proved the gelation mechanism. The hydrogels presented great rheological properties, along with an anti-creep behavior. The resulting materials were highly adhesive and had great antioxidant activity, leading to an inhibition of 78 % of DPPH free radicals, and exhibiting antimicrobial activity against Gram-positive and Gram-negative bacteria and fungi, reaching a maximum of the diameter of the inhibition zone of 31 mm against Candida albicans. The MTS assay, performed on NHDF cells confirmed the non-toxicity of the hydrogels, the viability of the cells remaining at values higher than 90 % for all samples, revealing their potential for bioapplications. In vitro release studies of the furfural monoaldehyde showed distinct release kinetics for each hydrogel, emphasizing their versatility. Fitting the data on different mathematical models indicated a diffusion-controlled release mechanism during the entire release process. All these findings highlighted the potential of these hydrogels to be used as biocidal agents for topical applications.

A biomimetic nanofiber composite hydrogel with tissue adhesion, self-healing and antibacterial ability for infected wound healing

Skin injuries represent a significant clinical challenge, as conventional dressings frequently induce secondary trauma and microbial infiltration due to suboptimal barrier properties, ultimately delaying tissue repair. Ideal wound dressings should not only replicate the structure of native skin tissue but also create an environment conducive to cell viability. In this study, an injectable nanofiber composite self-healing hydrogel was developed for treating infected wounds. The antimicrobial properties of the hydrogel were achieved through the adsorption of branched polyethyleneimine (PEI) on gelatin fibers, while its self-healing capabilities were enhanced via Schiff base reactions and its tissue adhesion was strengthened by the incorporation of dopamine. Results demonstrated that the hydrogel exhibited strong biocompatibility and antimicrobial activity, promoted macrophage polarization towards the M2 phenotype, effectively suppressed inflammation, and facilitated wound healing in an infected wound model. STATEMENT OF SIGNIFICANCE: Wound infections pose a significant clinical challenge, often impeding healing and, in severe cases, leading to ulceration or life-threatening complications. In this study, a gelatin nanofiber composite hydrogel (PGF@ALG/PLGA hydrogel) functionalized with branched polyethyleneimine (PEI) was developed to address infected wounds through a biomimetic structure and enhanced pro-healing properties. The gelatin nanofibers within the hydrogel matrix facilitated electrostatic immobilization of PEI, effectively mitigating its inherent cytotoxicity by restricting free cationic charge exposure while ensuring localized surface enrichment. The resulting hydrogel exhibited robust tissue adhesion and autonomous self-healing capability. In infected wound models, the PEI-modified nanofibers within PGF@ALG/PLGA hydrogels demonstrated obvious antibacterial efficacy and promoted macrophage polarization to the M2 phenotype, synergistically accelerating the transition from the inflammatory phase to tissue regeneration. These findings underscore the therapeutic potential of PGF@ALG/PLGA hydrogel as a multifunctional platform for managing chronic infected wounds.

Smart self-healing hydrogel wound dressings for diabetic wound treatment

Diabetic wounds are difficult to treat clinically because they heal poorly, often leading to severe complications such as infections and amputations. Hydrogels with smart self-healing properties show great promise for treating diabetic wounds. These hydrogels are capable of continuously and dynamically responding to changes in the wound environment, feature improved mechanical qualities and the capacity to self-heal damage. We explore the latest developments in smart self-healing hydrogels for diabetic wound healing in this review. First, we systematically summarize the obstacles in treating diabetic wounds. We then highlighted the significance of smart self-healing hydrogels, explaining their stimulus-responsive mechanisms and self-healing design approaches, along with their applications in addressing these challenges. Finally, we discussed the unresolved obstacles and potential avenues for future research. We anticipate that this review will facilitate the continued refinement of smart self-healing hydrogels for diabetic wound dressings, aiming for broader clinical adoption.

Supramolecular cyclodextrin deep eutectic solvent-strengthened chitosan eutectogel as a novel percutaneous delivery system of resveratrol for anti-psoriasis

Psoriasis is a chronic and incurable inflammatory skin disease usually requiring long-term disease management. Natural phytochemical resveratrol (RES) has been known for high efficiency and low toxicity, exhibiting good anti-psoriasis potential. However, its biological activity is limited by poor solubility, chemical instability, and insufficient skin retention. Herein, we developed an adhesive eutectogel loaded with RES constructed through electrostatic and hydrogen bonding cross-linking between cyclodextrin-levulinic acid supramolecular deep eutectic solvent (DES) and chitosan (CS). A series of characterizations combined with molecular dynamics simulations demonstrated that such DES not only significantly increased the solubility and stability of RES, but also acted as the cross-linker and plasticizer in eutectogel preparation. When applied to the skin surface, the eutectogel formed a soft film in situ that established tight contact with the skin, thereby enhancing RES sustained penetration into the skin. In an imiquimod-induced psoriasis-like mice model, the eutectogel effectively alleviated psoriasis symptoms, inhibited the excessive proliferation of keratinocytes, and regulated the expression of IL-23/IL-17 axis-related factors, whose therapeutic effect was better than that of commercially available calcipotriol ointment. Overall, The DES-strengthened eutectogel offers a promising topical drug delivery platform for psoriasis treatment and expands the applications of green polysaccharide medical materials.

Procoagulant, antibacterial and antioxidant high-strength porous hydrogel adhesives in situ formed via self-gelling hemostatic microsheets for emergency hemostasis and wound repair

Procoagulant, antibacterial and analgesic hemostatic hydrogel dressing with high wet tissue adhesion, ultra-high burst pressure, and easy preparation shows huge promising for rapid hemostasis in emergencies, yet it remains a challenge. Herein, we propose hemostatic microsheets based on quaternized chitosan-g-gallic acid (QCS-GA) and oxidized hyaluronic acid (OHA), which merge the benefits of sponges, hydrogels, and powders for rapid hemostasis and efficient wound healing. Specifically, they exhibit a large specific surface area and excellent hydrophilicity, rapidly absorbing blood and self-gelling through electrostatic interaction and Schiff base crosslinking. And this results in dense, porous hydrogel adhesives with superior mechanical properties, adhesion strength, and ultra-high burst pressure. Furthermore, the microsheets are biocompatible, biodegradable, and possess procoagulant, antibacterial, and antioxidant properties. In mouse and rat liver hemorrhage models, the optimized formulation (QCS-GA + OHA4) demonstrated superior hemostatic effects compared to Celox. In particular, QCS-GA + OHA4 microsheets could stop bleeding quickly from rat femoral artery transection and deliver lidocaine to provide analgesia during emergency treatment. Additionally, they promoted wound healing in mouse full-thickness skin defect wound. These easy-to-manufacture hemostatic microsheets are adaptable to irregular wounds, providing a novel solution for rapid hemostasis and wound healing.

Bioactive hemostatic materials: a new strategy for promoting wound healing and tissue regeneration

Wound healing remains a critical global healthcare challenge, with an annual treatment cost exceeding $50 billion worldwide. Over the past decade, significant advances in wound care have focused on developing sophisticated biomaterials that promote tissue regeneration and prevent complications. Despite these developments, there remains a crucial need for multifunctional wound healing materials that can effectively address the complex, multiphase nature of wound repair while being cost effective and easily applicable in various clinical settings. This review systematically analyzes the latest developments in wound healing materials, examining their chemical composition, structural design, and therapeutic mechanisms. We comprehensively evaluate various bioactive components, including natural polymers, synthetic matrices, and hybrid composites, along with their different forms, such as hydrogels, powders, and smart dressings. Special attention is given to emerging strategies in material design that integrate multiple therapeutic functions, including sustained drug delivery, infection prevention, and tissue regeneration promotion. The insights provided in this review illuminate the path toward next-generation wound healing materials, highlighting opportunities for developing more effective therapeutic solutions that can significantly improve patient outcomes and reduce healthcare burden.

A Constant Filgotinib Delivery Adhesive Platform Based on Polyethylene Glycol (PEG) Hydrogel for Accelerating Wound Healing via Restoring Macrophage Mitochondrial Homeostasis

Skin wound healing is often hindered by disrupted mitochondrial homeostasis and imbalanced macrophage glucose metabolism, posing a critical challenge to improve patient outcomes. Developing new wound healing dressings capable of effectively regulating macrophage immune-metabolic functions remains a pressing issue. Herein, a highly adhesive polyethylene glycol (PEG) hydrogel loaded with the Janus kinase 1 (JAK1) inhibitor Filgotinib (Fil@GEL) is prepared to modulate macrophage metabolic reprogramming and restore normal mitochondrial function. Fil@GEL exhibits superior shear adhesion strength compared to commercially available tissue binder products, providing adequate adhesion for skin wound closure. Additionally, Fil@GEL exhibits the capacity to inhibit M1-type macrophage polarization by suppressing the JAK-STAT signaling pathway, and induces a metabolic shift in macrophages from aerobic glycolysis to oxidative phosphorylation, which results in decreased lactate production, reduced reactive oxygen species (ROS) levels, and the restoration of mitochondrial homeostasis. The Fil@GEL hydrogel significantly accelerates skin wound healing compared to the control group, reduces intra-wound inflammation, and promotes collagen regeneration. In summary, this highly adhesive hydrogel demonstrates exceptional performance as a drug carrier, exerting immunometabolic modulation through firm wound adhesion and sustained filgotinib release, underscoring its substantial potential as an effective wound dressing.

In Vitro Evaluation of a Semi-Autologous Fibrin Sealant for Surgical Applications

Surgical success relies on precise tissue approximation using sutures, clips, or staples. Fibrin sealant provides a user-friendly alternative, saving time and maintaining tissue integrity. Yet, its cost and potential bioburden risk are notable drawbacks. To address these concerns, a semi-autologous fibrin sealant is produced from human cryoprecipitate and compared it to a commercial fibrin sealant. The microstructure of the semi-autologous sealant closely resembles the commercial one. Initially, the commercial sealant has superior bonding strength, however, over time, both demonstrate strong adhesive properties. Moreover, when the two sealants contain equivalent fibrinogen concentrations, they show similar bonding strength and rheological properties, including thixotropic behavior, which is essential for their application as bioadhesives. Notably, it is discovered that the mechanical properties of the adhesive are mainly governed by the fibrinogen concentration, with minimal impact of other blood components. This understanding paves the way for the development of an efficient method to boost fibrinogen in blood without extensive separation. This study indicates semi-autologous fibrin glue matches commercial sealant in adhesive properties. This may offer several advantages, such as reduced bioburden, costs, improved immunomodulation, and reduced hypersensitivity and virus transmission risks. These findings hold promising prospects for enhancing the wound healing process in various medical conditions.

Facile preparation of carboxymethyl chitosan/dextran/poly(ionic liquid)-based hydrogel with intrinsic antibacterial and antioxidant properties for accelerating skin wound healing

Bleeding, bacterial infections and inflammation of skin open wounds are still threat to the public. Traditional wound dressings lost their adaptability to wound shape and lack of therapeutic effects. Herein, the composite POCP hydrogel was prepared by introducing poly(ionic liquids)-poly(1-butyl-3-vinylimidazolium gluconate) with gluconate as the counter ion into a phenylboronic acid group-grafted carboxymethyl chitosan and oxidized dextran-based hydrogel for promoting skin wound healing. The dynamic Schiff base and borate ester crosslinks constructed the gel networks, which gives POCP excellent self-healing ability and thus being beneficial for adapting to wound shape. The poly(ionic liquids) matrix not only effectively enhanced the mechanical properties and antibacterial abilities of the hydrogel, but also endowed the hydrogel with good radical scavenging capacity. POCP also exhibited good adhesiveness towards different tissues and could effectively stop tissue bleeding. Through an in vivo skin defect model, this biocompatible POCP could accelerate wound closure and promote tissue regeneration by relieving inflammatory responses and facilitating angiogenesis. This work provides an effective drug-free strategy to prepare hydrogel dressings with multi-intrinsic properties for clinical wound management.

Nanoconfinement-guided in situ co-deposition of single-atom cascade nanozymes combined with injectable sodium alginate hydrogels for enhanced diabetic wound healing

Treating diabetic wounds remains a major clinical challenge due to high glucose levels, bacterial infection, insufficient oxygen supply, and oxidative stress. Herein, guided by the nanoconfinement effect, single-atom Au/Pt nanoparticles (NPs) are in situ co-deposited in mesoporous metal-organic frameworks (MOF), while synergizing with DNA aptamer (DNA-Apt) with bacterial targeting functionality and an excellent biocompatible sodium alginate hydrogel (Gel), to prepare a multifunctional bimetallic cascade nanozyme combine hydrogels (Au-Pt@ZIF-8/Apt@gel). ZIF-8 degrades in the acidic environment of a wound infection, releasing Zn2+ and Au/Pt nanoparticles, which produce reactive oxygen species (ROS) under the catalysis of glucose to inactivate bacteria. Notably, Au-Pt@ZIF-8 nanozymes depositing Au/Pt nanoparticles exhibit a nanoconfinement effect that enhances the cascade nanozymes activity, which is about 2-3 times higher than that of monoconfined or nonconfined nanozyme. In addition, in vitro bacteriostatic tests show the nanozymes have broad-spectrum antimicrobial effects, with better inhibition of Gram-positive than negative bacteria. In vivo experiments indicate that Au-Pt@ZIF-8/Apt@gel has satisfactory antibacterial efficacy in both normal and diabetic mice, as well as optimal skin wound healing ability and significant reduction of inflammation in infected wounds. Consequently, the proposed system holds great potential for developing integrated nanoplatforms for on-demand treatment of bacterial-infected diabetic wounds.

Material Design, Fabrication Strategies, and the Development of Multifunctional Hydrogel Composites Dressings for Skin Wound Management

The skin is fragile, making it very vulnerable to damage and injury. Untreated skin wounds can pose a serious threat to human health. Three-dimensional polymer network hydrogels have broad application prospects in skin wound dressings due to their unique properties and structure. The therapeutic effect of traditional hydrogels is limited, while multifunctional composite hydrogels show greater potential. Multifunctional hydrogels can regulate wound moisture through formula adjustment. Moreover, hydrogels can be combined with bioactive ingredients to improve their performance in wound healing applications. Stimulus-responsive hydrogels can respond specifically to the wound environment and meet the needs of different wound healing stages. This review summarizes the material types, structure, properties, design considerations, and formulation strategies for multifunctional hydrogel composite dressings used in wound healing. We discuss various types of recently developed hydrogel dressings, highlights the importance of tailoring their physicochemical properties, and addresses potential challenges in preparing multifunctional hydrogel wound dressings.

The formation and performance tuning mechanism of starch-based hydrogels

Starch-based hydrogels, characterized by their three-dimensional network structures, are increasingly explored for their biodegradability, low cost, and abundance of modifiable hydroxyl groups. However, a comprehensive understanding of the mechanisms behind the formation and property modulation of these hydrogels has not been systematically described. Drawing from literature of the past decade, this review provides insights into designing multifunctional starch-based hydrogels through various gelation mechanism, crosslinking strategies, and second-network structure. This comprehensive review aims to establish a theoretical framework for controlling the properties of starch-based hydrogels. A crucial aspect of starch hydrogel formation is the dense, cellular structure produced by swollen particles; when these particles fully disrupt, amylose recrystallization creates "junction zones" essential for network stability. In double-network hydrogels, materials such as polyvinyl alcohol (PVA), sodium alginate (SA), and polyacrylamide (PAM) form an effective secondary network, enhancing the mechanical strength and versatility of the hydrogel. The functionalization of starch-based hydrogels is primarily achieved through the introduction of functional group, secondary networks, and ionic liquids.

Recent Advances in Self-Powered Sensors Based on Ionic Hydrogels

After years of research and development, flexible sensors are gradually evolving from the traditional "electronic" paradigm to the "ionic" dimension. Smart flexible sensors derived from the concept of ion transport are gradually emerging in the flexible electronics. In particular, ionic hydrogels have increasingly become the focus of research on flexible sensors as a result of their tunable conductivity, flexibility, biocompatibility, and self-healable capabilities. Nevertheless, the majority of existing sensors based on ionic hydrogels still mainly rely on external power sources, which greatly restrict the dexterity and convenience of their applications. Advances in energy harvesting technologies offer substantial potential toward engineering self-powered sensors. This article reviews in detail the self-powered mechanisms of ionic hydrogel self-powered sensors (IHSSs), including piezoelectric, triboelectric, ionic diode, moist-electric, thermoelectric, potentiometric transduction, and hybrid modes. At the same time, structural engineering related to device and material characteristics is discussed. Additionally, the relevant applications of IHSS toward wearable electronics, human-machine interaction, environmental monitoring, and medical diagnostics are further reviewed. Lastly, the challenges and prospective advancement of IHSS are outlined.

Self-healing adhesive hydrogels for sustained ozone release: Enhanced antibacterial properties and improved wound healing

Antibacterial hydrogels have generated significant interest for their potential therapeutic applications. Ozone (O₃) is recognized for its antibacterial, anti-inflammatory, immunomodulatory, and anti-hypoxic properties, along with its minimal residual impact. However, the development of sustained O₃-release antibacterial hydrogels has been challenging due to the low solubility and short lifespan of ozone. We present an ozone-loaded emulsion hydrogel (ozonegel), which encapsulates ozonized oil within a nanoclay-poly(methacryloxyethyl sulfobetaine) supramolecular network. This adhesive, self-healing ozonegel achieves high ozone loading (91.3 mmol/kg) and releases O₃ and reactive oxygen species (ROS) over 36 h. It demonstrates broad antibacterial and anti-inflammatory effects, promoting wound healing. The remarkable properties of ozonegels suggest significant potential for advanced biomedical applications.

Multifunctional Adhesive Hydrogels: From Design to Biomedical Applications

Adhesive hydrogels characterized by structural properties similar to the extracellular matrix, excellent biocompatibility, controlled degradation, and tunable mechanical properties have demonstrated significant potential in biomedical applications, including tissue engineering, biosensors, and drug delivery systems. These hydrogels exhibit remarkable adhesion to target substrates and can be rationally engineered to meet specific requirements. In recent decades, adhesive hydrogels have experienced significant advancements driven by the introduction of numerous multifunctional design strategies. This review initially summarizes the chemical bond-based design strategies for tissue adhesion, encompassing static covalent bonds, dynamic covalent bonds, and non-covalent interactions. Subsequently, the multiple functionalities imparted by these diverse design strategies, including highly stretchable and tough performances, responsiveness to microenvironments, anti-freezing/heating properties, conductivity, antibacterial activity, and hemostatic properties are discussed. In addition, recent advances in the biomedical applications of adhesive hydrogels, focusing on tissue repair, drug delivery, medical devices, and wearable sensors are reviewed. Finally, the current challenges are highlighted and future trends in this rapidly evolving field are discussed.

Regulating the Atomic Active Center by Covalent Organic Framework-Derived Photothermal Nanozyme to Arm Self-Gelling Powder for Bacterial Wound Healing

Creating simple methods to produce antioxidant nanozymes with clear structure-activity relationships, particularly aiming to improve disinfection and create practical drug formulations for bacterial wound healing, remains a crucial challenge. Herein, we synthesized iron-loaded covalent organic framework nanospheres, which were then controllably transformed into a carbon-based nanozyme with both iron single atoms and iron clusters through simple pyrolysis. We discovered that the gradual growth of iron clusters significantly boosted the nanozyme's adsorption onto the substrate and electron transfer, greatly influencing its activity. The nanozyme, optimized by the coexistence of single iron atoms and Fe4 clusters, exhibited the strongest catalase and superoxide dismutase enzyme activities as well as high photothermal efficiency. Under physiological conditions, its peroxidase and oxidase enzymatic activities, which stimulate oxidative stress, remained low. Furthermore, we created an antibacterial self-gelling powder capable of dispersing the nanozyme using polyacrylamide and poly(acrylic acid). The powder can rapidly gel and adhere to wet wound areas, synergistically sterilizing the wound through the combined actions of the gel's amino groups and the nanozyme's photothermal effect, while leveraging the antioxidant enzymatic effects to mitigate wound inflammation. These properties contribute to the fast healing of infectious wounds, thus promising a clear formulation and treatment.

Design Strategy, On-Demand Control, and Biomedical Engineering Applications of Wet Adhesion

The adhesion of tissues to external devices is fundamental to numerous critical applications in biomedical engineering, including tissue and organ repair, bioelectronic interfaces, adhesive robotics, wearable electronics, biomedical sensing and actuation, as well as medical monitoring, treatment, and healthcare. A key challenge in this context is that tissues are typically situated in aqueous and dynamic environments, which poses a bottleneck to further advancements in these fields. Wet adhesion technology (WAT) presents an effective solution to this issue. In this review, we summarize the three major design strategies and control methods of wet adhesion, comprehensively and systematically introducing the latest applications and advancements of WAT in the field of biomedical engineering. First, single adhesion mechanism under the frameworks of the three design strategies is systematically introduced. Second, control methods for adhesion are comprehensively summarized, including spatiotemporal control, detachment control, and reversible adhesion control. Third, a systematic summary and discussion of the latest applications of WAT in biomedical engineering research and education were presented, with a particular focus on innovative applications such as tissue-electronic interface devices, ingestible devices, end-effector components, in vivo medical microrobots, and medical instruments and equipment. Finally, opportunities and challenges encountered in the design and development of wet adhesives with advanced adhesive performance and application prospects are discussed.

A multifunctional hydrogel dressing loaded with antibiotics for healing of infected wound

Wound bacterial infections can significantly delay the healing process and even lead to fetal sepsis. There is a need for multifunctional dressings that possess antibacterial property, tissue adhesive property, self-healing capability, and biocompatibility to effectively treat bacteria-infected wound. In this study, we report a dual dynamically crosslinked hydrogel, OHA-PBA/PVA/Gen, which incorporates the antibiotic gentamicin (Gen) as a dynamic crosslinker. The hydrogel is formed through the formation of Schiff base bonds between phenylboronic acid-grafted oxidized hyaluronic acid (OHA-PBA) and Gen, as well as boronic acid ester bonds between OHA-PBA and polyvinyl alcohol (PVA). This unique composition imparts tissue adhesiveness, injectability and self-healing property to the hydrogel. The hydrogel also exhibits pH-responsive antibiotic release behavior due to the acid-responsive dissociation of Schiff base bonds. As a result, it demonstrates strong antibacterial activity against both Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli through contact killing and diffusion killing mechanisms. Importantly, the OHA-PBA/PVA/Gen hydrogel avoids incorporation of toxic small molecular crosslinking agents, and all the components of the hydrogel are biocompatible, ensuring its biosafety. In a S. aureus-infected wound mouse model, this hydrogel effectively eradicated bacteria and promoted angiogenesis, leading to significantly accelerated wound healing. These results highlight the potential of the dual dynamically crosslinking hydrogel OHA-PBA/PVA/Gen as a multifunctional wound dressing for the treatment of bacteria-infected wound.

Multi-functional Gleditsia sinensis galactomannan-based hydrogel with highly stretchable, adhesive, and antibacterial properties as wound dressing for accelerating wound healing

Design and development of a multifunctional wound dressing with self-healing, adhesive, and antibacterial properties to attain optimal wound closure efficiency are highly desirable in clinical applications. Nevertheless, conventional hydrogels face significant barriers in their mechanical strength, adhesive performance, and antibacterial properties. Herein, a tough hydrogel based on aldehyde-grafted galactomannan was synthesized through radical copolymerization and Schiff base reaction, incorporating hyaluronic acid, acrylamide, and the zwitterionic monomer to create a multi-crosslinked structure. The multiple crosslink structure pattern consisting of multiple hydrogen bonding, ionic interactions, reversible Schiff bases bonds, and molecular chain entanglement endowed this hydrogel with multiple functionalities, including high tensile strength (25 kPa), tensile strain (2200 %), toughness (391.59 kJ/m3), and Young's modulus (9.77 kPa). The presence of catechol groups and zwitterionic groups endow hydrogels with outstanding adhesion strength (42.21 kPa), which satisfied the adhesive demand for the ample motion of specific areas. The zwitterionic monomer provided long-lasting antibacterial properties and promoted migration and growth of negatively charged cells, capable of establishing efficient antibacterial barriers and serving as wound dressing. The in vivo and vitro experiments manifested that the optimized hydrogel demonstrated an inconspicuous inflammatory response, facilitating rapid healing of full-thickness skin wound in rat models. Therefore, this work provides a promising strategy and an ideal candidate for wound healing dressings in treating infected skin wounds.

Bio-inspired designs: leveraging biological brilliance in mechanical engineering-an overview

Nature's evolutionary mastery has perfected design over the years, yielding organisms superbly adapted to their surroundings. This research delves into the promising domain of bio-inspired designs, poised to revolutionize mechanical engineering. Leveraging insights drawn from prior conversations, we categorize innovations influenced by life on land, in water, and through the air, emphasizing their pivotal contributions to mechanical properties. Our comprehensive review reveals a wealth of bio-inspired designs that have already made substantial inroads in mechanical engineering. From avian-inspired lightweight yet robust materials to hydrodynamically optimized forms borrowed from marine creatures, these innovations hold immense potential for enhancing mechanical systems. In conclusion, this study underscores the transformative potential of bio-inspired designs, offering improved mechanical characteristics and the promise of sustainability and efficiency across a broad spectrum of applications. This research envisions a future where bio-inspired designs shape the mechanical landscape, fostering a more harmonious coexistence between human technology and the natural world.

Reconfiguring the endogenous electric field of a wound through a conductive hydrogel for effective exudate management to enhance skin wound healing

The ionic environment has a strong influence on the bioelectricity of skin, which is also present in the wound healing process. Inspired by this, we proposed a mechanism for hydrogel-based dressings to respond to endogenous electric fields through exudate absorption and conducted a verification study using a typical hydrogel, namely, polyacrylamide and sodium alginate (PAM-SA) hydrogels, as an example. Theoretical calculations showed that the PAM-SA hydrogels could absorb and orient the various electrolytes of exudate in the hydrogel at the wound site, contributing to the reconstruction of the electric field at the wound site. During the treatment process, this effect significantly accelerated the healing process of the rat epidermis, which exceeded the conventional dressing in terms of healing speed and efficacy, and the wounds on the complete layer of rat skin (wound area: 1.13 cm2) could be rapidly repaired within 10 days. Revealing the electrophysiological behavior of PAM-SA dressings during wound healing can help further improve the design model, the optimization concept, and development paths for the bioelectrical structures of modern dressings and bioelectrical stimulation in wound healing.

External Bleeding and Advanced Biomacromolecules for Hemostasis

Hemorrhage is a significant medical problem that has been an active area of research over the past few decades. The human body has a complex response to bleeding that leads to blood clot formation and hemostasis. Many biomaterials based on various biomacromolecules have been developed to either accelerate or improve the body's natural response to bleeding. This review examines the mechanisms of hemostasis, types of bleeding, and the in vitro or in vivo models and techniques used to study bleeding and hemostatic materials. It provides a detailed overview of the diverse hemostatic materials, including those that are highly absorbent, wet adhesives, and those that accelerate the biochemical cascade of blood clotting. These materials are currently marketed, under preclinical testing, or being researched. In exploring the latest advancements in hemostatic technologies, this paper highlights the potential of these materials to significantly improve bleeding control in clinical and emergency situations.

Amino acid-crosslinked 4arm-PLGA Janus patch with anti-adhesive and anti-bacterial properties for hernia repair

Presently, the non-biodegradable polypropylene (PP) patches frequently used for hernia repair can cause fibrous tissue growth and adhesions. This study created a Janus Patch with anti-adhesion and antimicrobial properties to improve hernia repair while promoting tissue repair. The biologically active 4arm-PLGA-BLPD was initially synthesized through the modification of 4arm-PLGA with lysine, followed by the fabrication of a Janus patch using a layer-by-layer electrostatic spinning technique. This patch consisted of three layers: a repair layer composed of 4arm-PLGA-BLPD/PCL fiber membrane, a mechanical layer of 4arm-PLGA/PCL fiber membrane, and an antimicrobial layer of EMO-4arm-PLGA/PCL fiber membrane loaded with Emodin (EMO). The results showed that Janus patch exhibited notable tensile strength and elongation at break, enabling it to offer enhanced mechanical reinforcement for abdominal wall defects. In addition, it slowly releases lysine for repair and inhibits bacterial growth with EMO. In vivo experiments demonstrated that the patch effectively induced neovascularization, reduced collagen ac-cumulation, and stabilized the expression of relevant proteins through the up-regulation of MMP1 and MMP9. This facilitated successful repair of the abdominal wall defect model and prevented adhesions. In summary, the Janus patch offers both practical application and theoretical insight for hernia repair.

Biopolymer hydrogels and synergistic blends for tailored wound healing

Biopolymers have a transformative role in wound repair due to their biocompatibility, ability to stimulate collagen production, and controlled drug and growth factor delivery. This article delves into the biological parameters critical to wound healing emphasizing how combinations of hydrogels with reparative properties can be strategically designed to create matrices that stimulate targeted cellular responses at the wound site to facilitate tissue repair and recovery. Beyond a detailed examination of various biopolymer types and their functionalities in wound dressings acknowledging that the optimal choice depends on the specific wound type and application, this evaluation provides concepts for developing synergistic biopolymer blends to create next-generation dressings with enhanced efficiencies. Furthermore, the incorporation of therapeutic agents such as medications and wound healing accelerators into dressings to enhance their efficacy is examined. These agents often possess desirable properties such as antibacterial activity, antioxidant effects, and the ability to promote collagen synthesis and tissue regeneration. Finally, recent advancements in conductive hydrogels are explored, highlighting their capabilities in treatment and real-time wound monitoring. This comprehensive resource emphasizes the importance of optimizing ingredient efficiency besides assisting researchers in selecting suitable materials for personalized wound dressings, ultimately leading to more sophisticated and effective wound management strategies.

Polyphenol-mediated hyaluronic acid/tannic acid hydrogel with short gelation time and high adhesion strength for accelerating wound healing

Wound healing is a complex process involving a complicated interplay between numerous cell types and vascular systems. Hyaluronic acid (HA)-based hydrogel facilitates wound healing, and is involved in all processes. However, slow gelation speed and weak adhesion strength limit its ability to form a stable physical barrier quickly. Herein, we propose a HA-based composite hydrogel as the wound dressing based on oxidative coupling reaction. Tannic acid and dopamine-coated carbon particles (DCPs) containing abundant phenolic hydroxyl groups are incorporated into the HA-based hydrogel for increasing the number of crosslinking sites of oxidative coupling of the hydrogel and enhancing adhesion through the formation of covalent bonds and hydrogen bonds between hydrogel and wound sites. The composite hydrogel exhibits short gelation time (<6 s) and high adhesion strength (>8.1 kPa), which are superior to the references and commercial products of its kind. The in vitro experiments demonstrate that the hydrogel has low hemolytic reaction, negligible cytotoxicity, and the ability to promote fibroblast proliferation and migration. The in vivo full-thickness skin defect model experiments demonstrate that the hydrogel can accelerate wound healing under mild photothermal stimulation of DCPs by reducing inflammation, relieving tissue hypoxia, and promoting angiogenesis and epithelialization.

Polyphenol-Mediated Adhesive and Anti-Inflammatory Double-Network Hydrogels for Repairing Postoperative Intervertebral Disc Defects

Hydrogels have garnered tremendous attention for their applications in the repair of intervertebral disk (IVD) degeneration and postoperative IVD defects. However, it is still challenging to develop a hydrogel fulfilling the requirements for high mechanical properties, adhesive capability, biocompatibility, antibacterial properties, and anti-inflammatory performance. Herein, we report a multifunctional double-network (DN) hydrogel composed of physically cross-linked carboxymethyl chitosan (CMCS) and tannic acid (TA) networks as well as chemically cross-linked acrylamide (AM) networks, which integrates the properties of high strength, adhesion, biocompatibility, antimicrobial activity, and anti-inflammation for the repair of postoperative IVD defects. The treatment with CMCS/TA/PAM DN hydrogels can significantly decrease the levels of inflammatory cytokines and degeneration-related factors and upregulated collagen type II alpha 1. In addition, the hydrogels can effectively seal the annulus fibrosus defect, prevent nucleus pulposus degeneration, retain IVD height, and restore the biomechanical properties of the disc to some extent. This polyphenol-mediated DN hydrogel is promising for sealing IVD defects and preventing herniation after lumbar discectomy.

Assembly of polysaccharide-based polymer brush for supramolecular hydrogel dressing

Extracted from Platycodon grandiflorum, platycodon grandiflorum polysaccharides (PGPs) with diverse biological functions have been extensively employed for modification and fabrication of hydrogels for biomedical applications, such as wound dressings. However, since the lack of effective structural design, the reported polysaccharide-based hydrogel dressings are still suffered from structural failures and limited bio-functionality. Herein, we demonstrate a facile and general strategy to fabricate a supramolecular hydrogel composed of PGP-based polymer brush as building blocks combined with a Ca2+-mediated self-assembly process. The specific polymer brush with high branch functionality was achieved with polyacrylamide arms evenly grown on the PGP (grafting efficiency as high as 80 %) with series of chemical modifications. With above structural merits, the resulting hydrogel with densely crosslinked polymer brush featured enhanced mechanical strength as well as self-healing, and shear-thinning behaviors. Further biocompatible investigation indicated the as-prepared hydrogels with admirable performances in self-adhesion (adhesive strength of 16.7-79.5 kPa), a pH-responsive swelling ratio as high as 44 at pH 5.4, and pH-responsive degradation. They also showed antioxidant capacity by scavenging DPPH activity of nearly 80 % in 20 min, hemocompatibility, cell viability and cell migration. Impressively, the PGP-based polymer brush hydrogel served as a wound dressing revealed significant acceleration on wound closure.

An Intelligent Hydrogel Platform with Triple-Triggered On-Demand Release for Accelerating Diabetic Wound Healing

The hydrogel platform with intelligent drug delivery system possesses great potential in the treatment of diabetic wounds. Nevertheless, the intelligent elimination of reactive oxygen species (ROS) remains a formidable challenge in facilitating diabetic wound healing. Herein, a hydrogel platform with triple-triggered on-demand release is constructed to intelligently scavenge ROS and modulate the wound microenvironment to accelerate diabetic wound healing through the release of antioxidative factors. Specifically, the gelatin (Gel) is modified with phenylboronic acid (PBA) to obtain a glucose-sensitive Gel derivative (Gel-BA), which is mixed with oxidized dextran (ODex) and the strong antioxidant myricetin (MY) to swiftly generate a hydrogel platform (OGM). Significantly, the smart release of MY from the hybrid hydrogel under inflammatory conditions intelligently eliminates ROS, effectively alleviating oxidative stress and promoting angiogenic reprogramming of the wound immune microenvironments by activating the Nrf2 pathway. In summary, in vitro and in vivo studies reveal that the OGM hydrogel platform significantly promotes cell proliferation, migration, and tube formation and greatly accelerates diabetic wound healing, offering a local-specific triple-response drug release strategy for the treatment of diabetic wound management.

Mussel-Inspired Injectable Adhesive Hydrogels for Biomedical Applications

The impressive adhesive capacity of marine mussels has inspired various fascinating designs in biomedical fields. Mussel-inspired injectable adhesive hydrogels, as a type of promising mussel-inspired material, have attracted much attention due to their minimally invasive property and desirable functions provided by mussel-inspired components. In recent decades, various mussel-inspired injectable adhesive hydrogels have been designed and widely applied in numerous biomedical fields. The rational incorporation of mussel-inspired catechol groups endows the injectable hydrogels with the potential to exhibit many properties, including tissue adhesiveness and self-healing, antimicrobial, and antioxidant capabilities, broadening the applications of injectable hydrogels in biomedical fields. In this review, we first give a brief introduction to the adhesion mechanism of mussels and the characteristics of injectable hydrogels. Further, the typical design strategies of mussel-inspired injectable adhesive hydrogels are summarized. The methodologies for integrating catechol groups into polymers and the crosslinking methods of mussel-inspired hydrogels are discussed in this section. In addition, we systematically overview recent mussel-inspired injectable adhesive hydrogels for biomedical applications, with a focus on how the unique properties of these hydrogels benefit their applications in these fields. The challenges and perspectives of mussel-inspired injectable hydrogels are discussed in the last section. This review may provide new inspiration for the design of novel bioinspired injectable hydrogels and facilitate their application in various biomedical fields.

Thermoresponsive On-Demand Adhesion and Detachment of a Polyurethane-Urea Bioadhesive

The development of bioadhesives with strong adhesion and on-demand adhesion-detachment behavior is still critically important and challenging for facilitating painless and damage-free removal in clinical applications. In this work, for the first time, we report the easy fabrication of novel polyurethane-urea (PUU)-based bioadhesives with thermoresponsive on-demand adhesion and detachment behavior. The PUU copolymer was synthesized by a simple copolymerization of low-molecular-weight, hydrophilic, and biocompatible poly(ethylene glycol), glyceryl monolaurate (GML, a special chain extender with a long side hydrophobic alkyl group), and isophorone diisocyanate (IPDI). Here, GML was expected to not only adjust the temperature-dependent adhesion behavior but also act as an internal plasticizer. By simple adjustment of the water content, the adhesion strength of the 15 wt % water-containing PUU film toward porcine skin is as high as 55 kPa with an adhesion energy of 128 J/m2 at 37 °C. The adhesion strength dramatically decreases to only 3 kPa at 10 °C, exhibiting switching efficiency as high as 0.95. Furthermore, the present PUU-based adhesive also shows good on-demand underwater adhesion and detachment with a cell viability close to 100%. We propose that biomaterial research fields, especially novel PUU/polyurethane (PU)-based functional materials and bioadhesives, could benefit from such a novel thermoresponsive copolymer with outstanding mechanical and functional performances and an easy synthesis and scaled-up process as described in this article.

An injectable hydrogel based on sodium alginate and gelatin treats bacterial keratitis through multimodal antibacterial strategy

Bacterial keratitis is among the most prevalent causes of blindness. Currently, the abuse of antibiotics in clinical settings not only lacks bactericidal effects but also readily induces bacterial resistance, making the clinical treatment of bacterial keratitis a significant challenge. In this study, we present an injectable hydrogel (GS-PNH-FF@CuS/MnS) containing self-assembled diphenylalanine dipeptide (FF) and CuS/MnS nanocomposites (CuS/MnS NCs) that destroy bacterial cell walls through a synergistic combination of mild photothermal therapy (PTT), chemodynamic therapy (CDT), ion release chemotherapy, and self-assembled dipeptide contact, thereby eliminating Pseudomonas aeruginosa. Under 808 nm laser irradiation, the bactericidal efficiency of GS-PNH-FF@CuS/MnS hydrogel against P. aeruginosa in vitro reach up to 96.97 %. Furthermore, GS-PNH-FF@CuS/MnS hydrogel is applied topically to kill bacteria, reduce inflammation, and promote wound healing. Hematoxylin-eosin (H&E) staining, Masson staining, immunohistochemistry and immunofluorescence staining are used to evaluate the therapeutic effect on infected rabbit cornea models in vivo. The GS-PNH-FF@CuS/MnS demonstrate good biocompatibility with human corneal epithelial cells and exhibit no obvious eyes side effects. In conclusion, the GS-PNH-FF@CuS/MnS hydrogel in this study provides an effective and safe treatment strategy for bacterial keratitis through a multimodal approach.

Epidermal growth factor-loaded, dehydrated physical microgel-formed adhesive hydrogel enables integrated care of wet wounds

Integrated wound care, a sequential process of promoting wound hemostasis, sealing, and healing, is of great clinical significance. However, the wet environment of wounds poses formidable challenges for integrated care. Herein, we developed an epidermal growth factor (EGF)-loaded, dehydrated physical microgel (DPM)-formed adhesive hydrogel for the integrated care of wet wounds. The DPMs were designed using the rational combination of hygroscopicity and reversible crosslinking of physical hydrogels. Unlike regular bioadhesives, which consider interfacial water as a barrier to adhesion, DPMs utilize water to form desirable adhesive structures. The hygroscopicity allowed the DPMs to absorb interfacial water and subsequently, the interfacial adhesion was realized by the interactions between tissue and DPMs. The reversible crosslinks further enabled DPMs to integrate into hydrogels (DPM-Gels), thus achieving wet adhesion. Importantly, the water-absorbing gelation mode of DPMs enabled facile loading of biologically active EGF to promote wound healing. We demonstrated that the DPM-Gels possessed wet tissue adhesive performance, with about 40 times the wet adhesive strength of fibrin glue and about 4 times the burst pressure of human blood pressure. Upon application at the injury site, the EGF-loaded DPM-Gels sequentially promoted efficient wound hemostasis, stable sealing, and quick healing, achieving integrated care of wet wounds.

Preparation of antimicrobial peptides and their combination with hydrogels for wound healing applications

The problem of drug resistance caused by long-term use of antibiotics has been a concern for many years. As this problem worsens, there are various bacterial-induced infections that have a serious impact on human health. Currently, antimicrobial peptides are good alternatives to antibiotics, which have powerful antimicrobial activity and unique antimicrobial mechanisms. Developing bacterial resistance is not easy. In addition, how to reduce the production cost of antimicrobial peptides and improve the screening efficiency are the problems that must be solved for antimicrobial peptide application. In this study, we employed cell membrane chromatography linked with the one-bead-one-substance approach to screen and prepare the antimicrobial peptide (SALSP), which offers the benefits of fast synthetic screening and easy operation. Meanwhile, the antimicrobial peptide showed great antimicrobial activity and biocompatibility. We prepared a conjugated sodium alginate/gelatin hydrogel wound dressing incorporating antimicrobial peptides to promote wound healing. In conclusion, this research provides solutions for the development and application of antimicrobial peptides.

Smart theranostics for wound monitoring and therapy

To overcome the challenges of poor wound diagnosis and limited clinical efficacy of current wound management, wound dressing materials with the aim of monitoring various biomarkers vital to the wound healing process such as temperature, pH, glucose concentration, and reactive oxygen species (ROS) and improving the therapeutic outcomes have been developed. These innovative theranostic dressings are smartly engineered using stimuli-responsive biomaterials to monitor and regulate local microenvironments and deliver cargos to the wound sites in a timely and effective manner. This review provides an overview of recent advances in novel theranostics for wound monitoring and therapy as well as giving insights into the future treatment of wounds via smart design of theranostic materials.

Novel Biomaterials for Wound Healing and Tissue Regeneration

Skin is the first defense barrier of the human body, which can resist the invasion of external dust, microorganisms and other pollutants, and ensure that the human body maintains the homeostasis of the internal environment. Once the skin is damaged, the health threat to the human body will increase. Wound repair and the human internal environment are a dynamic process. How to effectively accelerate the healing of wounds without affecting the internal environment of the human body and guarantee that the repaired tissue retains its original function as much as possible has become a research hotspot. With the advancement of technology, researchers have combined new technologies to develop and prepare various types of materials for wound healing. This article will introduce the wound repair materials developed and prepared in recent years from three types: nanofibers, composite hydrogels, and other new materials. The paper aims to provide reference for researchers in related fields to develop and prepare multifunctional materials. This may be helpful to design more ideal materials for clinical application, and then achieve better wound healing and regeneration effects.

Bio-gel nanoarchitectonics in tissue engineering

Given the creation of materials based on nanoscale science, nanotechnology must be combined with other disciplines. This role is played by the new concept of nanoarchitectonics, the process of constructing functional materials from nanocomponents. Nanoarchitectonics may be highly compatible with applications in biological systems. Conversely, it would be meaningful to consider nanoarchitectonics research oriented toward biological applications with a focus on materials systems. Perhaps, hydrogels are promising as a model medium to realize nanoarchitectonics in biofunctional materials science. In this review, we will provide an overview of some of the defined targets, especially for tissue engineering. Specifically, we will discuss (i) hydrogel bio-inks for 3D bioprinting, (ii) dynamic hydrogels as an artificial extracellular matrix (ECM), and (iii) topographical hydrogels for tissue organization. Based on these backgrounds and conceptual evolution, the construction strategies and functions of bio-gel nanoarchitectonics in medical applications and tissue engineering will be discussed.

Injectable Biomimetic Gels for Biomedical Applications

Biomimetic gels are synthetic materials designed to mimic the properties and functions of natural biological systems, such as tissues and cellular environments. This manuscript explores the advancements and future directions of injectable biomimetic gels in biomedical applications and highlights the significant potential of hydrogels in wound healing, tissue regeneration, and controlled drug delivery due to their enhanced biocompatibility, multifunctionality, and mechanical properties. Despite these advancements, challenges such as mechanical resilience, controlled degradation rates, and scalable manufacturing remain. This manuscript discusses ongoing research to optimize these properties, develop cost-effective production techniques, and integrate emerging technologies like 3D bioprinting and nanotechnology. Addressing these challenges through collaborative efforts is essential for unlocking the full potential of injectable biomimetic gels in tissue engineering and regenerative medicine.

Self-Healing Dynamic Hydrogel Microparticles with Structural Color for Wound Management

Chronic diabetic wounds confront a significant medical challenge because of increasing prevalence and difficult-healing circumstances. It is vital to develop multifunctional hydrogel dressings, with well-designed morphology and structure to enhance flexibility and effectiveness in wound management. To achieve these, we propose a self-healing hydrogel dressing based on structural color microspheres for wound management. The microsphere comprised a photothermal-responsive inverse opal framework, which was constructed by hyaluronic acid methacryloyl, silk fibroin methacryloyl and black phosphorus quantum dots (BPQDs), and was further re-filled with a dynamic hydrogel. The dynamic hydrogel filler was formed by Knoevenagel condensation reaction between cyanoacetate and benzaldehyde-functionalized dextran (DEX-CA and DEX-BA). Notably, the composite microspheres can be applied arbitrarily, and they can adhere together upon near-infrared irradiation by leveraging the BPQDs-mediated photothermal effect and the thermoreversible stiffness change of dynamic hydrogel. Additionally, eumenitin and vascular endothelial growth factor were co-loaded in the microspheres and their release behavior can be regulated by the same mechanism. Moreover, effective monitoring of the drug release process can be achieved through visual color variations. The microsphere system has demonstrated desired capabilities of controllable drug release and efficient wound management. These characteristics suggest broad prospects for the proposed composite microspheres in clinical applications.

Nature-Inspired Gelatin-Based Adhesive Hydrogel: A Rapid and User-Friendly Solution for Hemostatic Applications

Conventional hemostatic agents face challenges in achieving rapid hemostasis and effective tissue repair due to limited hemostatic scenarios, suboptimal efficacy, and inadequate adhesion to wet tissues. Drawing inspiration from nature-sourced materials, a gelatin-based adhesive hydrogel (AOT)  is designed, easily prepared and quick to form, driven by Schiff base and multiple hydrogen bonds for applications in arterial and liver bleeding models. AOT exhibits exceptional adhesion to wet tissues (48.67 ± 0.16 kPa) and displays superior hemostatic properties with reduced blood loss and hemostatic time compared to other hydrogels and conventional hemostatic materials. Moreover, AOT exhibits good biocompatibility and biodegradability. In summary, this easily prepared adhesive hydrogel has the potential to supplant traditional hemostatic agents, offering a novel approach to achieve swift sealing of hemostasis and facilitate wound healing and repair in broader application scenarios, owing to its unique advantages.