pH/Glucose Dual Responsive Metformin Release Hydrogel Dressings with Adhesion and Self-Healing via Dual-Dynamic Bonding for Athletic Diabetic Foot Wound Healing

Elastic sac-shaped hydrogel dressing with responsive antibacterial and pro-healing in movable wounds via MOF activated ink spraying

In daily life, sports frequently cause skin injuries, particularly in movable parts such as joints. However, the frequent movement of joints can impede the proper fitting of dressings, resulting in re-tearing of the wound, an increased infection risk, and prolonged healing. Moreover, demand for skin wound dressings in movable parts has risen, as around 2.4 million joint surgeries are performed annually. Therefore, it is crucial to design an elastic wound dressing that can accommodate repeated joint movements and control wound infection responsively. In this study, a biomimetic hydrogel dressing was designed based on the inkjet behaviour of the elastic ink sac of cuttlefish through repeated extrusion. This dressing comprises a highly elastic polyether F127 diacrylate-based ink sac with micro-nozzles, along with antibacterial and pro-healing ink, metal-organic framework modified gelatin, possessing responsive release properties. With the movement rhythm, the super-elastic dressing perfectly conforms to the wounds in joints or other movable parts to absorb exudation and release therapeutic ink in response to the microenvironment to prevent infection. In conclusion, the biomimetic dressing demonstrates excellent mechanical properties with a deformation of approximately 400 %, and attains an antibacterial rate exceeding 95 %. Compared with the control group, collagen production increases by 2.6 times, and the wound healing speed is enhanced by over 20 %. Therefore, the application of the biomimetic dressing is anticipated to offer a novel approach for managing skin infection wounds in movable parts.

All-in-one extracellular matrix-based powders with instant self-assembly and multiple bioactivities integrate hemostasis and in-situ tissue functional repair

Non-compressible hemorrhage poses a severe threat to life globally, yet achieving effective hemostasis and facilitating tissue repair remain a significant challenge and desired requirement. Herein, the all-in-one extracellular matrix (ECM)-based powder, composed of modified small intestinal submucosa (SIS) and sodium alginate, was ingeniously designed to realize one-stop management for non-compressible hemorrhage. Specifically, upon contact bleeding site, the powder's extreme liquid absorption allows for the rapid removal of interfacial blood. Simultaneously, based on the instant self-assembly strategy of covalent/non-covalent interaction, the powder can transform to wet bio-adhesive hydrogel within 5 s, effectively sealing the wound. Using the inherent bioactivities, the ECM-based powder exhibits satisfactory biocompatibility, enhanced cell recruitment, angiogenesis and endothelial cell functions. Ulteriorly, excellent hemostasis performance have verified in rabbit liver non-compressible hemorrhage and heart/artery massive hemorrhage models, significantly reducing the blood loss. More importantly, after hemostasis, the impaired liver demonstrates functional restoration that the more vessels and bile ducts formation, facilitated by the biodegradation of ECM-derived powders in vivo and the multi-biological cues response. Collectively, leveraging the merits of powder and hydrogel, this novel powder fulfills the all-in-one need for both non-compressible hemorrhage control and subsequent tissue repair, signifying it a valuable material in first aid.

A multifunctional hydrogel loaded with magnesium-doped bioactive glass-induced vesicle clusters enhances diabetic wound healing by promoting intracellular delivery of extracellular vesicles

The treatment of diabetic wounds (DWs) poses a significant medical challenge. Mesenchymal stem cell-derived small extracellular vesicles (sEVs) have demonstrated potential in accelerating healing by delivering growth factors and microRNAs. However, the rapid clearance by the circulatory system limits their concentration and bioavailability within cells. This study employed magnesium-doped bioactive glass (MgBG) to autonomously program sEVs into a vesicle cluster (EPPM), which was subsequently incorporated into a hydrogel to create a comprehensive repair system that enhanced the delivery of both sEVs and MgBG, thereby promoting rapid healing of diabetic wounds. This hydrogel exhibited excellent injectable, self-healing and bioadhesive properties, making it an ideal physical barrier for DWs. In addition, the hydrogels also possessed photoresponsive properties that facilitated their bactericidal activity. The released EPPM significantly increased the intracellular uptake and accumulation of sEVs, with approximately 8.2-fold enhancement in macrophages and 16.7-fold in endothelial cells. The EPPM clusters efficiently induce macrophage M2 polarization, reduce inflammatory responses at the wound site, and recruit cells, thereby promoting angiogenesis and collagen deposition. This integrated repair system provided a new platform for the comprehensive treatment of diabetic 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.

Hydrogel adhesives for tissue recovery

Hydrogel adhesives (HAs) are promising and rewarding tools for improving tissue therapy management. Such HAs had excellent properties and potential applications in biological tissues, such as suture replacement, long-term administration, and hemostatic sealing. In this review, the common designs and the latest progress of HAs based on various methodologies are systematically concluded. Thereafter, how to deal with interfacial water to form a robust wet adhesion and how to balance the adhesion and non-adhesion are underlined. This review also provides a brief description of gelation strategies and raw materials. Finally, the potentials of wound healing, hemostatic sealing, controlled drug delivery, and the current applications in dermal, dental, ocular, cardiac, stomach, and bone tissues are discussed. The comprehensive insight in this review will inspire more novel and practical HAs in the future.

A dual-dynamic crosslinking network enabled strong, flexible, self-healing, and biodegradable chitosan fiber paper/vitrimer composites for plastic substitution

The development of high-performance biomass-based vitrimers has emerged as a crucial research topic to reduce reliance on petroleum-based plastics. Achieving both high strength and toughness is essential for most biomass-based vitrimers, yet these properties typically tend to be mutually exclusive. Here we show a multifunctional composite, CFP/TAV-PI, prepared by integrating an all-natural polyimine vitrimer (TAV-PI) into chitosan fiber paper (CFP) through in-situ polymerization and heat-pressing treatments. The CFP/TAV-PI films, featuring a dual-dynamic crosslinking network of hydrogen bonds and dynamic imine bonds, achieve a tensile strength of 57.93 MPa, elongation at break of 44.66 %, and toughness of 18.00 MJ m-3. Additionally, CFP/TAV-PI possess high transparency, self-healing ability, and thermal/chemical stability. Importantly, they are also readily degradable under both chemical and natural conditions. Our findings highlight a novel approach to prepare degradable composites with remarkable strength and flexibility, offering the potential to replace conventional plastic products.

A multifunctional metformin loaded carboxymethyl chitosan/tannic acid/manganese composite hydrogel with promising capabilities for age-related bone defect repair

As the global population ages, age-related bone defects have become a major public health challenge. The decline in bone tissue repair capacity among the elderly is primarily attributed to the senescence of bone marrow mesenchymal stem cells (BMSCs), which leads to reduced proliferation and differentiation capabilities, thereby impeding the bone healing process. Additionally, the deterioration of the bone microenvironment, characterized by chronic inflammation and oxidative stress, further complicates bone repair. To address these issues, a multifunctional hydrogel drug delivery system, the metformin-loaded carboxymethyl chitosan/tannic acid/manganese (MCTM) hydrogel was developed. This system integrates the synergistic effects of CMCS, TA, Mn2+, and metformin to effectively alleviate BMSCs senescence, optimize the local chronic inflammatory microenvironment, eliminate oxidative stress, and reduce post-implantation infection risks. Detailed material characterization revealed that the introduction of Mn2+ significantly enhances the mechanical properties and optimizes the degradation characteristics of the CMCS/TA hydrogel, ensuring continuous and stable drug release at tissue repair sites. In vitro and in vivo experiments demonstrated MCTM's excellent biocompatibility and its ability to combine stem cell senescence alleviation with bone repair microenvironment improvement, thereby effectively overcoming various adverse factors affecting bone defect repair in the elderly. This study presents a promising strategy for enhancing bone regeneration under senescent conditions.

A dual-action strategy: Wound microenvironment responsive hydrogel and exosome-mediated glucose regulation enhance inside-out diabetic wound repair

Sustained hyperglycemia induces complex pathological microenvironment in diabetic wounds, significantly hindering wound healing. Most current therapeutic approaches (e.g., hydrogel dressings) have paid little attention to the effect of blood glucose levels on diabetic wound healing. In this study, a synergetic therapeutic strategy including a wound microenvironment responsive, multifunctional hydrogel and the exosome-mediated glucose regulation is developed for diabetic wound treatment. First, a gelatin-dopamine (Gel-DA) crosslinked hyaluronic acid-phenylboronic acid (HA-PBA) hydrogel (GDHP) is constructed with good injectable, self-healing, and adhesive abilities. Such GDHP hydrogel not only can effectively relieve oxidative stress and reduce inflammation, but also promote keratinocyte migration. Then, ciprofloxacin hydrochloride (CIP·H) is loaded to prepare the GDHPC hydrogel that may respond to diabetic wound microenvironment (e.g., low pH, high glucose and reactive oxygen species) and degrade for controlled release of CIP·H, showing on-demand antibacterial properties. Exosomes derived from human umbilical cord mesenchymal stem cells (hucMSC-exos) are administered via tail vein injection in diabetic mice, which may repair injured pancreatic islets by modulating the pancreatic immune microenvironment, thus promoting insulin secretion and further reducing blood glucose levels. By applying this synergetic therapeutic strategy, the full-thickness cutaneous wounds in type 1 diabetic mice heal well and quickly compared to that treated with the GDHPC hydrogel and the hucMSC-exos alone. This promotion effect on wound healing may associate with reducing inflammation and promoting angiogenesis. This study sheds new light on the development of a dual-action strategy that can effectively maintain glucose homeostasis, improve the wound microenvironment, and consequently promote inside-out repair of diabetic wounds, offering a promising therapeutic avenue for future diabetic wound treatment.

Stimuli-responsive hydrogel with spatiotemporal co-delivery of FGF21 and H₂S for synergistic diabetic wound repair

Chronic diabetic wounds pose significant clinical challenges due to persistent inflammation, impaired angiogenesis, and disrupted cellular homeostasis. To address these multifactorial barriers, we engineered an injectable, biodegradable, and biocompatible methylated silk fibroin (SilMA) hydrogel system co-loaded with cobalt sulfide (CoS) and fibroblast growth factor 21 (FGF21), designed for on-demand therapeutic release. In the acidic microenvironment characteristic of the inflammatory phase of diabetic wounds, the hydrogel rapidly releases hydrogen sulfide (H₂S) and Co2+ ions, mitigating inflammation and exerting antibacterial effects. Subsequently, during the proliferative and remodeling phases, sustained release of FGF21 promotes cellular proliferation, angiogenesis, and enzymatic homeostasis, thereby accelerating wound healing. Mechanistic studies reveal that the hydrogel facilitates M2 macrophage polarization and activates the JAK/STAT signaling pathway, leading to upregulation of vascular endothelial growth factor (VEGF). Additionally, it enhances antioxidant enzyme activities (superoxide dismutase, catalase, glutathione) while suppressing pro-oxidant enzymes (NADPH oxidase, lipoxygenase, cyclooxygenase). In vivo studies using a diabetic mouse model demonstrate that this dual-functional hydrogel significantly improves wound closure rates and tissue regeneration. These findings suggest that the SilMA-FGF21/CoS hydrogel represents a promising therapeutic strategy for the management of diabetic wounds.

Application of a novel thermal/pH-responsive antibacterial paeoniflorin hydrogel crosslinked with amino acids for accelerated diabetic foot ulcers healing

Diabetic foot ulcers (DFUs), a severe and common complication of diabetes, present significant treatment challenges due to the limitations of conventional dressings, such as poor mechanical properties, bioactivity, and limited functionality, which hinder fast and effective wound healing. To address these issues, we developed a novel natural amino acid-based hydrogel loaded with paeoniflorin (PF@PNMA1) and comprehensively evaluated its properties and functions. The nanogel particles (NGs) were synthesized via emulsion polymerization using N-isopropylacrylamide (NIPAM), methacrylic acid (MAA), and chemically modified arginine (MArg). The poly(NIPAM-co-MAA) (PNM) and poly(NIPAM-co-MAA-co-MArg) (PNMA) gels were prepared by functionalizing the NGs with glycidyl methacrylate (GMA). The different concentrations of amino acids were added to explore the optimal mechanical properties of the gel. Through the rheological measurement, we found that PNMA1 gel has good ductile properties with a critical strain up to about 63 %. At the same time, we also verified its antibacterial activity and found that the viability of bacteria decreased to 47.46 % after 3 h. Preliminary tests using network pharmacology and molecular docking confirmed the therapeutic potential of PF for DFUs. The PF@PNMA1 gel demonstrated excellent biocompatibility, and in vivo experiments revealed its effectiveness in promoting angiogenesis and wound healing. After 10 days, the wound healing rate was 25.6 % higher than that of the control group. The PF@PNMA1 shows great potential as an effective therapy for DFUs treatment.

Herbal micelles-loaded ROS-responsive hydrogel with immunomodulation and microenvironment reconstruction for diabetic wound healing

Persistent inflammation is a major cause of diabetic wounds that are difficult to heal. This is manifested in diabetic wounds with excessive reactive oxygen clusters (ROS), advanced glycation end products (AGE) and other inflammatory factors, and difficulty in polarizing macrophages toward inhibiting inflammation. Berberine is a natural plant molecule that inhibits inflammation; however, its low solubility limits its biological function through cytosis. In this study, we designed F127 micelles to encapsulate berberine with the aim of improving its solubility and bioavailability. Meanwhile, in order to achieve effective drug delivery at the wound site, we designed an injectable ferrocene-cyclodextrin self-assembled oxidation-reactive supramolecular hydrogel drug delivery system. Cellular experiments have shown that the hydrogel can reduce intracellular ROS and AGE production, attenuate cellular damage, promote macrophage polarization toward inhibition of inflammation, and reduce the secretion of inflammatory factors. In an animal model of diabetic mice, this hydrogel dressing reduces the level of inflammation in diabetic wounds, optimizes collagen deposition in diabetic wounds, and ultimately achieves high-quality diabetic wound healing. The work offers a straightforward and effective solution to the challenge of administering hydrophobic anti-inflammatory agents in the context of diabetic wound therapy.

Microenvironment-sensitive hydrogels as promising drug delivery systems for co-encapsulating microbial homeostasis probiotics and anti-inflammatory drugs to treat periodontitis

Developing and utilizing effective local antimicrobial agents can help treat periodontitis while minimizing the risks associated with systemic antibiotic use. Recent studies have shown that the mucosal adhesion properties of hydrogels can play a potential role in the treatment of periodontitis. The hydrogel can improve the contact and retention time of drugs in the periodontal pocket. Through the adhesion of mucosa, it interacts with the mucin coating surface of epithelium and teeth to form a specific interface force. The hydrogel exhibits strong mucosal adhesion (adhesion strength: 5-6 N/cm2) and prolonged retention in periodontal pockets (≥6 h), enabling sustained drug release through dynamic sol-gel transitions triggered by pH and reactive oxygen species (ROS). This design overcomes the limitations of poor mechanical stability in conventional formulations. The dynamic balance of oral microbiota plays an important role in maintaining oral health. Probiotics, by colonizing the oral cavity, transform the infected site from an environment rich in inflammatory cytokines to a more benign environment, inhibit harmful pathogenic microorganisms, and contribute to overall health. Microenvironment sensitive hydrogels can perform dynamic sol gel transformation in situ, and can accurately control drug release when exposed to various stimuli (such as temperature change, light, pH change, reactive oxygen species, etc.). Oral probiotics and anti-inflammatory drugs are encapsulated in hydrogels to inhibit the proliferation and adhesion of oral pathogens by planting in the mouth and producing metabolites, effectively preventing and treating oral diseases.

Magnesium Ion/Gallic Acid MOF-Laden Multifunctional Acellular Matrix Hydrogels for Diabetic Wound Healing

The main objective for diabetic wound treatment is the design of a functional dressing that scavenges free radicals, alleviates inflammation, and is antibacterial while promoting neovascularization. Herein, a multifunctional acellular matrix hydrogel was prepared with the antimicrobial peptide jelleine-1 and a magnesium ion/gallic acid metal framework to exhibit antioxidant, anti-inflammatory, and proangiogenesis effects in diabetic wounds. The prepared hydrogel termed Gel-J-MOF efficiently released gallic acid in the acidic microenvironment of the diabetic wound, scavenged excess free radicals in vitro, and effectively reduced the levels of inflammation by regulating M2 macrophage polarization in vivo. The antimicrobial peptide jelleine-1 in the composite hydrogel effectively inhibited S. aureus and E. coli in vitro, promoting a suitable microenvironment for wound healing. In the later stage of wound healing, the composite hydrogel stimulated angiogenesis, accelerating the re-epithelialization and collagen deposition in the wound. In conclusion, this multifunctional composite hydrogel provides a regulated microenvironment for treating diabetic wounds and, therefore, has significant potential application promise in the treatment of chronic diabetic wounds.

Topical metformin in wound healing: a comprehensive systematic review of therapeutic outcomes

Metformin's topical application has proven to be a therapeutic wound healing dressing via pro-angiogenic, anti-inflammatory, autophagy-promoting, and antibacterial effects. The systematic review article aimed to evaluate the available evidence (from both preclinical and clinical studies), in order to better understand its therapeutic potential in wound care. We performed a systematic literature search in PubMed, Scopus, Web of Science, Embase, and Cochrane databases till January 2025. A total of 26 studies included in final analysis according to inclusion criteria. The majority of preclinical investigations demonstrated accelerated wound healing with characterized of increased wound closure and collagen deposition, elevated pro-angiogenic markers (e.g., VEGF, CD31, and α-SMA), suppression of pro-inflammatory cytokines, and induction of autophagy signaling. Notably, biomaterial-based delivery platform applications such as hydrogels and nanofibers greatly magnified these therapeutic effects. While encouraging results in in-vitro, in-vivo and animal models have been documented, clinical studies remain limited in scope. In fact, this large disparity between preclinical results and limited clinical evidences obviously highlights the urgent need for properly designed human trials to determine safety, efficacy, and best delivery modalities of topical metformin. Collectively, topical metformin is a novel and potentially valuable addition to wound treatment cares, which could be subjected to further clinical study.

Immune-Vascular Synergy: A Photodynamic Hydrogel Activating ALDH2 to Combat Inflammation and Enhance Angiogenesis in Diabetic Wound Healing

Infected diabetic wounds present serious therapeutic challenges, primarily due to persistent infections, impaired immune responses, and insufficient vascularization. Excessive secretion of neutrophil extracellular traps (NETs) is increasingly recognized as a key driver of inflammation in diabetic wounds. Single-cell sequencing analysis of clinical specimens reveals a deficiency in aldehyde dehydrogenase 2 (ALDH2) within wound tissues, which plays a critical role in sustaining inflammation and hindering vascular regeneration. Unlike conventional treatments that focus on either infection control or vascular repair, a photodynamic hydrogel with a dual-function strategy is developed, uniquely integrating ALDH2 activation with immune-vascular modulation to address these multifaceted challenges. The hydrogel-mediated activation of ALDH2 effectively reduces NET formation and mitigates chronic inflammation, while promoting macrophage polarization from the pro-inflammatory M1 phenotype to the reparative M2 phenotype. This transition fosters an anti-inflammatory microenvironment that not only facilitates tissue repair but also enhances angiogenesis by stimulating endothelial cell activity, improving vascularization at the wound site. In contrast to existing therapeutics, the approach directly targets the interplay between immune regulation and vascular regeneration, offering a synergistic mechanism to enhance wound healing outcomes. The findings introduce an immune-vascular synergy-based therapeutic strategy, emphasizing the translational potential of this hydrogel technology for chronic wound management.

Advances in the application of hydrogel adhesives for wound closure and repair in abdominal digestive organs

The abdominal cavity houses the majority of the digestive system organs, which frequently suffer from diseases with limited responsiveness to pharmacological treatments, such as bleeding, perforation, cancer, and mechanical obstruction. Invasive procedures, including endoscopy and surgery, are typically employed to manage these conditions. Currently, sutures and staplers remain the gold standard for internal wound closure. However, these methods inevitably cause secondary tissue damage. Unlike superficial organs such as the skin, the abdominal cavity presents a relatively confined environment where postoperative complications tend to be more severe. To achieve wound closure and repair, hydrogel adhesives have garnered attention due to their minimal invasiveness, robust sealing, and ease of application. Nonetheless, the application of hydrogel adhesives within the abdominal cavity faces several challenges, including adhesion in moist environments, selective adhesion, and resistance to acids and digestive enzymes. To date, there has been no comprehensive review focused on the use of hydrogel adhesives for wound closure in abdominal digestive organs. This review introduces the design principles of hydrogel adhesives tailored for abdominal organs and provides a detailed overview of recent advances in their applications for esophageal endoscopic submucosal dissection, gastric perforation, hepatic bleeding, pancreatic leakage, and intestinal anastomotic leakage. Additionally, the current challenges and future directions of hydrogel adhesives are discussed. This review aims to provide valuable insights for the development of next-generation hydrogel adhesives for wound closure and repair in abdominal digestive organs.

Review of self-healing polysaccharide-based hydrogels in tissue regeneration: Characterization methods and applications

The design of hydrogels with self-healing properties represents a significant advancement in the biomedical field. Polysaccharide-based self-healing hydrogels have garnered attention because of their unique attributes, including biocompatibility and biodegradability, as well as their ability to autonomously repair damage. Polysaccharide-based self-healing hydrogels consist mainly of crosslinked hydrophilic polymer networks that mimic the self-repair mechanisms of biological tissues. This review examines the self-healing mechanisms of polysaccharide-based hydrogels, evaluates their healing ability, and discusses characterization techniques to quantify their healing efficiency. In addition, the review highlights the advantages of self-healing hydrogels and discusses potential applications, particularly in the areas, such as medical dressings, drug delivery, and tissue regeneration. By addressing the challenges of self-healing hydrogels, these materials represent a promising frontier in the field of advanced biomaterials.

Stimulus-responsive hydrogels for diabetic wound management via microenvironment modulation

Diabetic wounds, a major complication of diabetes mellitus, pose a significant clinical challenge. The treatment of diabetic wounds requires comprehensive interventions tailored to their pathophysiological characteristics, such as recurring bacterial infection, persistent inflammation, excessive oxidative stress, and impaired angiogenesis. The development of stimulus-responsive hydrogel dressings offers new strategies for diabetic wound treatment. By responding to various physical and biochemical signals, these smart hydrogels enable real-time monitoring and precise modulation of the wound microenvironment to accelerate diabetic wound healing. In this review, we provide an overview of the disease characteristics of chronic diabetic wounds and introduce the current clinical treatment approaches. We summarize the cutting-edge applications of physical and biochemical signal-responsive hydrogels for diabetic wound treatment by modulating the wound microenvironment.

Multifunctional nanocomposite hydrogels: an effective approach to promote diabetic wound healing

Diabetes, a metabolic disease that is becoming increasingly severe globally, presents a significant challenge in the medical field. Diabetic wounds are characterized by their chronicity, difficulty healing, and complex microenvironment that harbors multiple adverse factors, including elevated hyperglycemia, persistent inflammation, susceptibility to infections, and oxidative stress, all of which contribute to the impaired healing process. Nanocomposite hydrogels, as materials with unique physicochemical properties and biocompatibility, have gained growing attention in recent years for their potential applications in diabetic wound healing. These hydrogels provide a moist healing environment for wounds and regulate cellular behavior and signaling pathways, promoting wound repair and healing. By introducing specific functional groups and nanoparticles, nanocomposite hydrogels can respond to pathological features of wounds, enabling adaptive drug release. Owing to their diverse bioactive functions, nanocomposite hydrogels are powerful tools for the treatment of diabetic wounds. Thus, this article provides an overview of recent progress in the use of nanocomposite hydrogels for diabetic wound healing.

Review: Advances in multifunctional hydrogels based on carbohydrate polymer and protein in the treatment of diabetic wounds

Diabetic wounds healing is often severely slowed by hyperglycemia, elevated oxidative stress, bacterial infections, and persistent inflammation. This review focuses on the development of hydrogels derived from carbohydrate polymer and protein to facilitate diabetic wound healing. We discuss the primary sources of cellulose, chitosan, hyaluronic acid, sodium alginate, collagen, and gelatin along with their advantages in the preparation of hydrogels. Based on the microenvironment of diabetic wounds, i.e., hyperglycemia, increased oxidative stress, and persistent inflammation, the application of multifunctional hydrogels in promoting diabetic wounds, including stimulus responsiveness, injection self-healing, antibacterial, antioxidant, anti-inflammatory, and synergistic effects, is discussed. We address the main challenges and future perspectives of multifunctional hydrogels based on carbohydrate polymer and protein in the treatment of diabetic wounds.

An adhesive, antibacterial hydrogel wound dressing fabricated by dopamine-grafted oxidized sodium alginate and methacrylated carboxymethyl chitosan incorporated with Cu(II) complex

Effective wound dressings play an important role in preventing infections and promoting wound healing. Most polysaccharide-based hydrogel dressings have the drawbacks of weak tissue adhesion and poor antibacterial properties. Herein, a multifunctional dopamine-grafted oxidized sodium alginate-methacrylated carboxymethyl chitosan/gallic acid‑copper(II) complex (OD-CM/GA-CuIIUV) hydrogel was fabricated through Schiff base bonds and photo-crosslinked polymerization between dopamine-grafted oxidized sodium alginate (OSA-DA) and methacrylated carboxymethyl chitosan (CMC-MA), with the integration of gallic acid‑copper(II) complexes (GA-CuII). The double cross-linked network and mussel-inspired adhesion mechanism endowed the hydrogel with attractive physicochemical properties, including excellent self-healing properties, pH-responsive biodegradability, robust toughness, and a maximum adhesion strength of 15.06 kPa. Moreover, the composite hydrogel exhibited an antibacterial ratio of > 99 % against Escherichia coli and Staphylococcus aureus, as well as good antioxidant activity. The MTT assay showed that the cell viability of the composite hydrogel reached > 85 %. The in vivo full-thickness skin defect healing assays in rats demonstrated that the composite hydrogel remarkably accelerated wound repair by attenuating the inflammatory response and promoting epithelial tissue remodeling. Therefore, this novel multifunctional hydrogel has potential applications in biomedical wound dressing.

Hemostatic and antimicrobial properties of chitosan-based wound healing dressings: A review

Uncontrolled bleeding and microbial infections pose significant hurdles in wound healing, and the use of specialized functional dressings is pivotal in overcoming these obstacles. Among the various wound dressings currently under investigation, those based on chitosan and its derivatives have garnered significant attention due to their superior biocompatibility, antimicrobial properties, hemostatic capabilities, and healing promoting ability. In this comprehensive review, we initially delve into the hemostatic capabilities of chitosan, elucidating its interactions with blood cells and plasma proteins. We also dissect the intricate antimicrobial mechanisms of chitosan, which operate through both intracellular and extracellular pathways. The centerpiece of this review is the systematic classification of dressings based on chitosan and its derivatives, across various forms, such as hydrogels, sponges, membranes, fibers, and powders. This is followed by an exhaustive analysis of their hemostatic and antibacterial efficacy in wound healing, providing a robust foundation for further research and the advancement of clinical applications in the field.

Enhanced dual-drug loaded κ-carrageenan/agar hydrogel films for wound dressing: Optimizing swelling and drug release

This study presents the development of antibacterial hydrogel films based on natural biopolymers, κ-carrageenan and agar, crosslinked with KCl for wound healing applications. The hydrogels were loaded with tetracycline (TC) and clove extract to enhance antimicrobial properties, while the addition of Triton X-100 (TX-100) improved drug solubility and bioavailability, leading to higher drug release rates. Swelling behavior was evaluated in distilled water (DW), simulated wound fluid (SWF), and phosphate-buffered saline (PBS), with maximum swelling observed at 399 %, 222 %, and 124 %, respectively. Swelling kinetics followed pseudo-second-order and Korsmeyer-Peppas models, suggesting a Fickian diffusion mechanism. Drug release profiles were influenced by medium type and clove concentration, with the highest release observed in SWF at a clove concentration of 8 mg L-1. Antimicrobial tests demonstrated significant inhibition of E. coli and S. aureus, supporting the hydrogel's potential for infection control in wounds. Mechanical analysis showed that the hydrogels could withstand a peak force of 438.364 g, while water vapor permeability tests suggested an optimal moisture environment conducive to healing. The developed hydrogel films have a high potential for wound care, combining enhanced drug release, effective antimicrobial activity, and mechanical durability.

Thiolated chitosan hydrogel combining nitric oxide and silver nanoparticles for the effective treatment of diabetic wound healing

Nitric oxide (NO) has shown significant potential in chronic wound healing due to its ability of promoting blood circulation. However, excessive NO can trigger local inflammatory response, potentially hindering wound healing. Therefore, controlled and sustained NO release to minimize pro-inflammation effects during treatment is in great demand for diabetic wounds. Herein, an injectable thiolated chitosan hydrogel loaded with NO donors (GNO) and silver nanoparticles (AgNPs) is presented for effective diabetic wound treatment, from which NO was released stably and sustainably responsive to reactive oxygen species (ROS) at the wound site. The combination of NO and AgNPs demonstrated robust antibacterial activity and biofilm dissipation. During diabetic wound treatments, the sustained release of NO promoted blood vessel regeneration while inhibiting inflammatory factors, thereby accelerating wound healing. This combined approach achieves efficient antibacterial action, biofilm prevention, inflammation suppression, vascular repair, improved local blood circulation, ultimately facilitating the reconstruction of epithelial structures at the wound site, thereby providing a promising solution for the diabetic chronic wound healing.

Mechanisms and therapeutic opportunities in metabolic aberrations of diabetic wounds: a narrative review

Metabolic aberrations are fundamental to the complex pathophysiology and challenges associated with diabetic wound healing. These alterations, induced by the diabetic environment, trigger a cascade of events that disrupt the normal wound-healing process. Key factors in this metabolic alternation include chronic hyperglycemia, insulin resistance, and dysregulated lipid and amino acid metabolism. In this review, we summarize the underlying mechanisms driving these metabolic changes in diabetic wounds, while emphasizing the broad implications of these disturbances. Additionally, we discuss therapeutic approaches that target these metabolic anomalies and how their integration with existing wound-healing treatments may yield synergistic effects, offering promising avenues for innovative therapies.

Bone Morphogenetic Protein-2-Derived Peptide-Conjugated Nanozyme-Integrated Photoenhanced Hybrid Hydrogel for Cascade-Regulated Bone Regeneration

Critical-sized bone defects present a clinical challenge due to their limited self-repair capacity. Application of bone tissue-engineering scaffolds often overlooks the dynamic modulation of the microenvironment, resulting in unsatisfactory bone-regeneration outcomes. In this study, a bone morphogenetic protein-2-derived peptide-loaded honeycomb manganese dioxide (BHM) nanozyme was incorporated into a composite hydrogel (BHM@CG) composed of l-arginine-modified methacrylated carboxymethyl chitosan and gallic acid-grafted methacrylated gelatin. This hydrogel demonstrated a cascade-regulated enhancement of hemostasis, antibacterial activity, anti-inflammatory effects, and osteogenesis. Initially, the BHM@CG hydrogel achieved rapid hemostasis by quickly adhering to irregular defects upon injury. Subsequently, it displayed robust antibacterial activity through synergistic hydrogen bonding, hydrophobic interactions, and cationic interactions. Meanwhile, the BHM nanozyme and polyphenol groups from gallic acid effectively eliminated reactive oxygen species, enabling long-term inflammation regulation. Finally, sustained release of bioactive components promoted cell migration, angiogenesis, and osteogenesis, achieving a bone-formation rate of nearly 40% in a critical-sized calvarial defect model by week 8. More interestingly, the hydrogel also demonstrated efficient antibacterial and bone-regeneration capabilities in an infected critical-sized calvarial defect model. Overall, this hydrogel dynamically modulated the bone-defect microenvironment and effectively enhanced bone regeneration, offering a promising strategy for critical-sized bone-defect repair.

Advancements and Prospects of pH-Responsive Hydrogels in Biomedicine

As an intelligent polymer material, pH-sensitive hydrogels exhibit the capability to dynamically sense alterations in ambient pH levels and subsequently initiate corresponding physical or chemical responses, including swelling, contraction, degradation, or ion exchange. Given the significant pH variations inherent in human pathophysiological microenvironments, particularly in tumor tissues, inflammatory lesions, and the gastrointestinal system, these smart materials demonstrate remarkable application potential across diverse domains such as targeted drug delivery systems, regenerative medicine engineering, biosensing, and disease diagnostics. Recent breakthroughs in nanotechnology and precision medicine have substantially propelled advancements in the design and application of pH-responsive hydrogels. This review systematically elaborates on the current research progress and future challenges regarding pH-responsive hydrogels in biomedical applications, with particular emphasis on their stimulus-response mechanisms, fabrication methodologies, multifunctional integration strategies, and application scenarios.

Oncolytic polymer-mediated combretastatin A4 phosphate delivery for enhancing vascular disrupting therapy

Although vascular disrupting agents (VDAs) can induce shutdown of blood flow and necrosis in the tumor core, eradicating tumor rim cells remains a significant challenge. Recently, researchers have developed various combination treatment strategies to improve the efficacy of VDAs. However, the aggravated hypoxic tumor microenvironment following vascular disruption limits the effectiveness of conventional therapeutic approaches. Here, we developed an ε-polylysine-derived oncolytic polymer (named OPAA) with membrane lytic activity. Its cytotoxic effect on tumor cells is largely unaffected by hypoxic conditions, as evidenced by the ratio of its IC50 value for 4 T1 cells under normoxic conditions to that under hypoxic conditions, which is 0.98. Subsequently, a pH-responsive combretastatin A4 phosphate disodium salt (CA4P)-loaded nanoparticle (OPAA@CA4P NPs) has been designed to efficiently deliver OPAA and CA4P to solid tumors. OPAA@CA4P NPs exhibited a prolonged serum half-life (t1/2 = 3.15 h) compared to CA4P (t1/2 = 0.31 h) and an enhanced tumor accumulation. In addition, CA4P can be responsively released within the tumor microenvironment, leading to necrosis in the tumor center. Concurrently, OPAA released from the nanoparticles eradicated the surviving cancer cells at the tumor periphery, thereby improving the overall therapeutic effect. Notably, compared to the CA4P + doxorubicin group (tumor suppression rates, TSR = 36.17 %), the OPAA@CA4P NPs group demonstrated superior therapeutic outcomes (TSR = 60.30 %). Overall, the introduction of oncolytic polymers provides new insights into the potential future applications of VDAs.

Polymer Applied in Hydrogel Wound Dressing for Wound Healing: Modification/Functionalization Method and Design Strategies

Hydrogel wound dressings have emerged as a promising solution for wound healing due to their excellent mechanical and biochemical properties. Over recent years, there has been significant progress in expanding the variety of raw materials used for hydrogel formulation along with the development of advanced modification techniques and design approaches that enhance their performance. However, a comprehensive review encompassing diverse polymer modification strategies and design innovations for hydrogel dressings is still lacking in the literature. This review summarizes the use of natural polymers (e.g., chitosan, gelatin, sodium alginate, hyaluronic acid, and dextran) and synthetic polymers (e.g., poly(vinyl alcohol), polyethylene glycol, Pluronic F-127, poly(N-isopropylacrylamide), polyacrylamide, and polypeptides) in hydrogel wound dressings. We further explore the advantages and limitations of these polymers and discuss various modification strategies, including cationic modification, oxidative modification, double-bond modification, catechol modification, etc. The review also addresses design principles and synthesis methods, aligning polymer modifications with specific requirements in wound healing. Finally, we discuss future challenges and opportunities in the development of advanced hydrogel-based wound dressings.

Biobased Physicochemical Reversible Dual-Cross-Linked Hydrogel: Self-Healing, Antibacterial, Antioxidant, and Hemostatic Properties for Diabetic Wound Healing

Skin wound healing remains challenging due to a lack of ideal wound dressings suitable for acute and chronic wounds. This study introduced a biocompatible hydrogel wound dressing, synthesized through a green chemistry approach, specifically designed to meet the dual needs of acute and chronic wound care. The innovative strategy utilized sustainable biomaterials, soy protein, and vanillin, to construct a physical-reversible chemical dual-cross-linked hydrogel exhibiting high mechanical strength, excellent adhesion, and toughness. Schiff base reversible covalent bonds enabled rapid self-healing within 10 s, significantly improving durability. In a rat liver hemorrhage model, the hydrogel rapidly sealed wounds, achieving effective hemostasis, indicating great potential for acute wound care. Furthermore, vanillin imparted the hydrogel with antimicrobial and antioxidant properties, effectively accelerating diabetic chronic wound healing. This safe and efficient advanced biobased hydrogel offers a novel perspective for wound treatment and holds significant promise for clinical applications.

Ultrasound-induced piezoionic hydrogels with antibacterial and antioxidant properties for promoting infected diabetic wound healing

The effective treatment of infected diabetic wounds remains a major challenge due to bacterial infection and severe oxidative stress. Herein, an antibacterial and antioxidant piezoionic hydrogel (ANDT) is synthesized via a one-pot photocuring process of a precursor solution containing acrylic acid, N-isopropyl acrylamide, quaternary ammonium salt (DPAB), and tannic acid (TA). The ANDT hydrogel exhibits reliable adhesion and appropriate mechanical properties, which can provide a favorable physical barrier. Owing to the introduction of antibacterial DPAB and antioxidant TA, the ANDT hydrogel can reduce inflammation and create an optimal microenvironment for cellular growth. Furthermore, due to the piezoionic effects, the ANDT hydrogel under ultrasound stimulation can generate a biomimetic endogenous electric field to modulate cellular behaviors, thereby achieving an active pro-healing effect. The infected diabetic wound model demonstrates that the ANDT hydrogel combined with ultrasound therapy can effectively reduce inflammation, increase collagen deposition, and promote angiogenesis, thus accelerating the healing process of infected diabetic wounds. This work may provide a promising strategy for developing advanced wound dressing to promote infected diabetic wound healing.

Electric-Field Regulation of Adhesion/De-Adhesion/Release Capacity of Transparent and Electrochromic Adhesive

Removing adhesive nondestructively and intact from the adhered surface is a difficult challenge for advanced adhesive materials. Compared with the commonly used thermal or chemical release, the controlled adhesive release via electric-field offers practical application advantages. However, a noninvasive release mode such as this has not been available for the de-bonding of supramolecular adhesives that originate from small organic molecules. Herein, a conductive hydrogel with surface adhesion and electric field-triggered de-adhesion and release is fabricated from thioctic acid (TA) and L-arginine (LA). The non-covalent intermolecular attractions of poly[TA-LA], especially its electrostatic interactions, not only endow it with useful bulk-state properties and strong adhesion (up to 363.3 kPa) but also generate electric responsiveness for on-demand de-adhesion and release. The poly[TA-LA] adhesive layer can be easily released within a short time (<60 s) under a mild voltage (5≈10 V). After a combined experimental and theoretical investigation, It is concluded that the adhesive-layer morphological and mechanical changes, activated by a weak current (1.1≈3.2 mA), are responsible for the adhesion failure, which takes place primarily at the anode. Importantly, rapid electric release of poly[TA-LA] is applicable at low temperatures (5 V, 60 s, -40 °C) or underwater (5 V, 60 s, 25 °C).

Self-Healing Hydrogel Dressing with Solubilized Flavonoids for Whole Layer Regeneration of Diabetic Wound

Hydrogels are soft, tissue-like materials that have great potential as wound dressings. However, most hydrogels are unsatisfactory in achieving whole-layer regeneration of diabetic wounds due to the complex pathological microenvironment and irregular wound shapes. Here, a glucose-responsive and self-adaptive phenylboronic acid (PBA) hydrogel solubilized strong antioxidant flavonoids (Gel-Flavonoids) is developed via dynamic borate bonds. The Gel-Flavonoids system can spontaneously confirm to the irregular wound shape and release flavonoids in a high-glucose microenvironment to effectively eliminate reactive oxygen species (ROS). The optimized Gel-Flavonoids demonstrate remarkable efficacy in inhibiting inflammation and activating fibroblasts and endothelial cells through CD36-activated lipid metabolism in macrophages and is significantly superior to commercial dressings (3M) in healing rate (> 93%, 14 days) and whole-layer regeneration effect. This study obtained a multidimensional Gel-Flavonoids system to effectively repair diabetic wounds, and reveal the underlying therapeutic mechanisms, offering a promising insight to guide the development of medical materials to treat diabetic wounds.

Double-network hydrogel dressing regulated by cationic polymer-grafted bacterial cellulose for promote rapid healing of infected wounds

Chronic infected wounds present a prolonged and challenging healing process due to physiological imbalances, making them susceptible to secondary injuries from external mechanical contact. Conventional wound dressings lack antibacterial, strong adhesive, and on-demand detachable properties, resulting in suboptimal outcomes in treating such wounds. Here, we introduce a dual-network hydrogel consisting of SBMA (sulfobetaine methacrylate) and polyacrylamide, synthesized through a two-step thermal/light polymerization process. This hydrogel incorporates cationic modified bacterial cellulose (QBC) and quercetin to promote antibacterial and cell migration properties, designed specifically for treating full-thickness wounds infected with Staphylococcus aureus. On the 15th day of the infected wound healing experiment, the wound healing rate reached 98.9 %. SBMA within the system can enhance adhesion and provide bacterial resistance. QBC intercalated within the system ensures the stability of the gel structure and strengthens bacterial resistance. Quercetin can modulate inflammatory responses and promote fibroblast proliferation. Thus, this study introduces a multifunctional biomaterial for managing chronic infected wounds, holding promise as a next-generation dressing in wound care.

Polysaccharides, proteins and DNA based stimulus responsive hydrogels promoting wound healing and repair: A review

The healing of various wounds remains a serious challenge in the medical field, hydrogel has high hydrophilicity and biocompatibility due to its unique network structure, which shows a strong advantage in the field of wound healing. Stimulus responsive hydrogels are particularly effective，which can control the material properties according to the external stimulus source, and provide more targeted treatment for different wounds. Here, we review physiological mechanisms of wound healing and the relationship between polysaccharides, proteins and DNA based stimulus responsive hydrogels and wound healing, materials commonly used of polysaccharides, proteins and DNA based stimulus responsive hydrogels, mechanisms of stimulus responsive hydrogels formation and network structure types, common properties of polysaccharides, proteins and DNA based stimulus responsive hydrogels for promoting wound healing and discuss their applications in medicine. Finally, the limitations and application prospects of polysaccharides, proteins and DNA based stimulus responsive hydrogels were discussed and evaluated. The review focuses on the biomedical use of polysaccharides, proteins and DNA based stimulus responsive hydrogels in wound healing and repair, and provides insights for the development of clinical related materials.

pH- and glucose-responsive antioxidant hydrogel promotes diabetic wound healing

Excessive oxidative stress and persistent inflammation are key factors contributing to the formation of diabetic chronic wounds. Delivering antioxidants through a microenvironment-responsive hydrogel system can effectively enhance wound healing and tissue regeneration. In this study, we developed a novel pH- and glucose-responsive hydrogel using Schiff base reaction and phenyl borate group for intelligent antioxidant release. Hyaluronic acid (HA) modified with phenylboronic acid (PBA) (HA-PBA) was oxidized to form OHA-PBA, which was then crosslinked with carboxymethyl chitosan (CMCS) and incorporated Proanthocyanidins (PA) to create an OHA-PBA/CMCS/PA (OPCP) hydrogel. The reversible nature of imine and borate groups enabled the responsive release of PA from OPCP hydrogels under acidic and high glucose conditions. The OPCP hydrogel exhibited excellent biocompatibility, suitable mechanical properties, and biodegradability. Both in vitro and in vivo results demonstrated that the OPCP hydrogel effectively reduced reactive oxygen species (ROS), suppressed inflammation, promoted vascularization, accelerated collagen deposition, and facilitated diabetic wound healing. This strategy offers novel insights into microenvironment-responsive scaffolds, highlighting the potential application of this responsive antioxidant hydrogel scaffold for chronic diabetic wound treatment.

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.

Fabrication of amino-capped Pluronic F127 with aldehyde dextran chains: A strategy improving extensibility, compressibility and self-healing hydrogel for wound healing

It is meaningful to develop polysaccharide hydrogel dressing with good mechanical and sustained-release properties, which can adapt to irregular wounds healing. To overcome defects of some polymers with amino groups, such as chitosan (more brittle), Poly(ethylenimine) (more toxic), and gelatin (less strength), a novel hydrogel (ODEX/APF) based on amino-capped Pluronic F127 (APF) as flexible crosslinking graft between aldehyde dextran (ODEX) chains was prepared in this study. The prepared ODEX/APF hydrogel exhibited rapid gelation under physiological conditions, endurable ductility and compressibility, excellent self-repairing ability based on Schiff base, and satisfied biocompatibility. Furthermore, amphiphilic APF can self-assemble into micelles that can be loaded with curcumin (Cur) and form drug-loaded composite hydrogels (ODEX/APF@Cur) with ODEX. The hydrogel has antimicrobial and anti-inflammatory properties and allows for long-term controlled release. In a full-thickness skin wound model, ODEX/APF@Cur hydrogel presented faster healing, less scaring, milder inflammation, better collagen distribution, downregulation of TNF-α, and upregulation of VEGF, promising applications in promoting wound healing.

Antioxidant and antibacterial PU/ZnS@Keratin mats with H2S and Zn2+ release for infected diabetic wound healing

Diabetic wound healing is often hampered by persistent oxidative stress, poor angiogenesis, and bacterial infections. Herein, ZnS/keratin nanoclusters(ZnS@Ker) were first synthesized using the ion diffusion method based on chelation between keratin and metal ions, achieving the controlled release of hydrogen sulfide (H2S) and Zn2+ ions. These nanoclusters were then co-electrospun with polyurethane (PU) to afford PU/ZnS@Ker mats. These mats demonstrated acidic responsive release of Zn2+ and H2S under an infected wound microenvironment, fostering cell adhesion, migration, and angiogenesis while effectively combating bacterial infection and scavenging reactive oxygen species. Notably, in vivo wound healing studies in diabetic rats revealed that PU/ZnS@Ker mats promoted collagen deposition and tissue regeneration, thereby accelerating wound healing. Taken together, PU/ZnS@Ker biocomposite mats emerge as an up-and-coming solution for managing diabetic wound healing.

Dual physiological responsive structural color hydrogel particles for wound repair

Hydrogel-based patches have demonstrated their values in diabetic wounds repair, particularly those intelligent dressings with continuous repair promoting and monitoring capabilities. Here, we propose a type of dual physiological responsive structural color particles for wound repair. The particles are composed of a hyaluronic acid methacryloyl (HAMA)-sodium alginate (Alg) inverse opal scaffold, filled with oxidized dextran (ODex)/quaternized chitosan (QCS) hydrogel. The photo-polymerized HAMA and ionically cross-linked Ca-Alg constitute to the dual-network hydrogel with stable structural color. Furthermore, the ODex/QCS hydrogel, combined with glucose oxidase (GOX), exhibits pH/glucose dual responsiveness. Moreover, antimmicrobial peptide (AMP) plus vascular endothelial growth factor (VEGF) are comprised within the GOX-doped ODex/QCS hydrogel. In the high-glucose wound environment, GOX catalyzes glucose to generate acidic products, triggering rapid release of AMP and VEGF. Importantly, this process also leads to structural color changes of the particles, offering significant potential for wound monitoring. It has been demonstrated that such particles greatly promote the healing progress of diabetic wound in vivo. These results indicate that the present dual responsive particles would find valuable applications in diabetic wounds repair and the associated areas.

Advances in Electrically Conductive Hydrogels: Performance and Applications

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

A Single H2S-Releasing Nanozyme for Comprehensive Diabetic Wound Healing through Multistep Intervention

Diabetic wound healing presents a significant medical challenge and requires multistep interventions due to comprehensive wound environments, such as hyperglycemia, bacterial infection, and impaired angiogenesis. However, current multistep interventions are complicated and need on-demand sequential release and synergy of multicomponents. Herein, a H2S-releasing cascade nanozyme (FeS@Au), which is composed of ultrasmall gold nanocluster (AuNC) loaded on ferrous sulfide nanoparticle (FeSNP), is developed as a single component to regulate glucose level, eliminate infection, and promote angiogenesis, achieving multistep interventions for comprehensive diabetic wound treatment. The glucose oxidase-like activity of AuNC catalyzes glucose into gluconic acid and H2O2, which not only lowers the local glucose level but also decreases the local pH and increases H2O2 level to boost the peroxidase-like activity of FeSNP to generate abundant hydroxyl radical (reactive oxygen species, ROS), inducing ferroptosis-like death in drug-resistant bacteria. Additionally, FeSNP release H2S in the acidified environment to upregulate hypoxia-inducible factor-1 to enhance vascularization through upregulating the expression of vascular endothelial growth factor (VEGF) and other angiogenesis-related genes, reducing the damage to endothelial cells caused by excessive ROS produced by the nanozyme. In a full-thickness MRSA-infected diabetic rat model, FeS@Au significantly eliminates bacteria, enhances angiogenesis, promotes collagen deposition, and accelerates wound healing. This work presents a single nanozyme with H2S-release for multistep interventions, providing a versatile strategy for healing extensive tissue damage caused by diabetes.

Recent advances in the development of hydrogel dressings for the treatment of pressure ulcers/injuries

Pressure ulcers, also known as pressure injuries, are common conditions that result from chronic bedrest. These ulcers significantly affect quality of life and substantially burden individuals and society with health costs. The prevention and treatment of pressure ulcers is a primary concern for health care professionals. Dressings play a crucial role in the treatment of pressure ulcers. Hydrogels are innovative safe materials that show great promise for clinical applications. Recent research has demonstrated the potential of hydrogel dressings to promote the healing of pressure ulcers and chronic wounds. This review aims to summarize the mechanisms and effects of hydrogel dressings and to discuss considerations for their use in patients with pressure injuries under different circumstances. Hydrogel dressings, especially loaded with unique cargo, may represent promising new options for the treatment of pressure ulcers. However, additional clinical studies are urgently needed to validate the efficacy and accessibility of hydrogels in clinical practice.

Responsive hydrogel modulator with self-regulated polyphenol release for accelerating diabetic wound healing via precise immunoregulation

Nonhealing chronic wounds are intractable clinical complications of diabetes and are characterized by high protease activity, severe oxidative stress and sustained inflammatory response. In this case, the development of functional hydrogel dressings to modulate the immune microenvironment is a well-known strategy, where the precise stimuli-responsive and spatiotemporally controlled release of bioactive molecules remains a huge challenge. Herein, we developed responsive hydrogels with self-regulated bioactive molecule release based on the protease activity in diabetic wound sites, to serve as a smart immune microenvironment modulator for accelerating wound healing. The hydrogels were fabricated by grafting oxidized hyaluronic acid with epigallocatechin-3-gallate (EGCG) and gelatin methacryloyl (GelMA) under UV irradiation. Resveratrol nanoparticles were further loaded into the hydrogels before gelation to construct a polyphenol delivery system. The prepared hydrogels could achieve the on-demand release of polyphenol upon degradation by protease, as confirmed via degradation and polyphenol release experiments. The released polyphenol was demonstrated to have the capacity to effectively scavenge excessive free radicals, promote macrophage polarization, reduce proinflammatory factor (TNF-α) expression and augment anti-inflammatory factor (IL-10) expression in vitro. Additionally, in vivo rat wound healing model experiment results confirmed that these hydrogels promoted collagen deposition and granulation tissue regeneration, accelerating diabetic wound healing. Based on the protease-responsive degradation characteristic of the hydrogels and high protease activity in the diabetic wound microenvironment, hydrogels with exquisite polyphenol release controllability are promising candidates as dressings for diabetic wound management.

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.

Exos-Loaded Gox-Modified Smart-Response Self-Healing Hydrogel Improves the Microenvironment and Promotes Wound Healing in Diabetic Wounds

Wound management has always been a challenge in the clinical treatment of diabetes. In this study, glucose oxidase (GOx) is grafted onto natural pullulan polysaccharides, and oxidization is carried out to form a self-healing hydrogel using carboxymethyl chitosan by means of reversible Schiff base covalent bonding. The smart-response drug release properties of this natural self-healing hydrogel are demonstrated in diabetic wounds by taking advantage of two key factors, namely the pH-responsive nature of Schiff base bonding and the fact that GOx reduces the pH in diabetic wounds. To further enhance the biological functions of the hydrogel dressing, exosomes (Exos) are introduced into the hydrogel system. The GOx present in the hydrogel system improves the high-glucose microenvironment of diabetic wounds, releasing H2O2 to impart antimicrobial effects, and ensuring that the hydrogel realizes a smart-response function. The carboxymethyl chitosan component used to construct the hydrogel plays an effective antibacterial role. Moreover, the Exos loaded into the hydrogel effectively promotes neovascularization of the wound. The Exos also regulates macrophage polarization and reduces the levels of persistent inflammation in diabetic wounds. These results suggest that this smart responsive, multifunctional, and self-healing hydrogel dressing is ideal for the management of diabetic wounds.

A Modified Polydopamine Nanoparticle Loaded with Melatonin for Synergistic ROS Scavenging and Anti-Inflammatory Effects in the Treatment of Dry Eye Disease

Dry eye disease (DED) is a multifaceted ocular surface disorder that significantly impacts patients' daily lives and imposes a substantial economic burden on society. Oxidative stress, induced by the overproduction of reactive oxygen species (ROS), is a critical factor perpetuating the inflammatory cycle in DED. Effectively scavenging ROS is essential to impede the progression of DED. In this study, boronophenylalanine- containing polydopamine (PDA-PBA) nanoparticles are developed loaded with melatonin (MT), which are blended with poly(vinyl alcohol) (PVA) to create eye drops PVA/ PDA-PBA@MT (PPP@MT). In vitro and in vivo studies demonstrate that PPP@MT exhibits dual functionalities in reducing ROS production and downregulating inflammatory pathways, thereby preserving mitochondrial integrity and further inhibiting programmed cell death. Following PPP@MT treatment, tear secretion, corneal structure, and the number of goblet cells are markedly restored in a mouse model of dry eye, indicating the therapeutic efficacy of this agent. Collectively, PPP@MT, characterized by minimal side effects and favorable bioavailability, offers promising therapeutic insights for the management of DED and other ROS-mediated disorders.

Design and advances in antioxidant hydrogels for ROS-induced oxidative disease

Reactive oxygen species (ROS) play a crucial role in human physiological processes, but oxidative stress caused by excessive ROS may lead to a variety of acute and chronic diseases. Despite the development of various strategies and biomaterials, an efficiently and broadly applied method for treatment of ROS-induced oxidative disease remains a bottleneck. Aiming to improve the local oxidative stress environment, numerous bioactive hydrogels with antioxidant properties have emerged and are proven to quickly and continuously eliminate excessive ROS. To deeply understand the design principles and applications of antioxidant hydrogels is highly beneficial for designing antioxidant hydrogels for treatment of oxidative disease. This review provides a detailed summary of recent advances in design and applications of antioxidant hydrogels for various ROS-induced oxidative diseases. In this review, the kinds of antioxidant components in antioxidant hydrogels are outlined in detail. Additionally, the crosslinking methods and the biomedical applications of antioxidant hydrogels are widely summarized and discussed, especially focusing on their usage in different types of diseases and the attention given to the treatment of diseases such as skin wounds, myocardial infarction, and osteoarthritis. Finally, the future development direction of antioxidant hydrogel is further proposed. STATEMENT OF SIGNIFICANCE: Oxidative stress is a pivotal biochemical process that plays a critical role in cellular homeostasis. Excessive cellular oxidative stress triggers an inflammatory response, which is implicated in a spectrum of associated diseases. Given the critical need for managing oxidative stress, antioxidant therapies have become a vital focus in medical research. Hydrogels have garnered substantial interest among biomaterial scientists due to their hydrophilic nature and biocompatibility. The review delves into the realm of antioxidant hydrogels, encompassing the classification of antioxidant components, the synthesis and fabrication of hydrogels, and a comprehensive overview of the biological applications and challenges of these antioxidant hydrogels. Aiming to provide new perspectives for researchers in developing cutting-edge therapeutic approaches that leverage antioxidant hydrogels.

Versatile conductive hydrogel orchestrating neuro-immune microenvironment for rapid diabetic wound healing through peripheral nerve regeneration

Diabetic wound (DW), notorious for prolonged healing processes due to the unregulated immune response, neuropathy, and persistent infection, poses a significant challenge to clinical management. Current strategies for treating DW primarily focus on alleviating the inflammatory milieu or promoting angiogenesis, while limited attention has been given to modulating the neuro-immune microenvironment. Thus, we present an electrically conductive hydrogel dressing and identify its neurogenesis influence in a nerve injury animal model initially by encouraging the proliferation and migration of Schwann cells. Further, endowed with the synergizing effect of near-infrared responsive release of curcumin and nature-inspired artificial heterogeneous melanin nanoparticles, it can harmonize the immune microenvironment by restoring the macrophage phenotype and scavenging excessive reactive oxygen species. This in-situ formed hydrogel also exhibits mild photothermal therapy antibacterial efficacy. In the infected DW model, this hydrogel effectively supports nerve regeneration and mitigates the immune microenvironment, thereby expediting the healing progress. The versatile hydrogel exhibits significant therapeutic potential for application in DW healing through fine-tuning the neuro-immune microenvironment.

Glucose-Activated Programmed Hydrogel with Self-Switchable Enzyme-Like Activity for Infected Diabetic Wound Self-Adaptive Treatment

The defective blood glucose regulation ability of diabetic patients leading to bacterial infection, cellular oxidative stress, and vascular damage results in delayed healing of chronic diabetic wounds. Here, a glucose-activated self-switching enzyme-like activity programmed hydrogel is proposed to provide self-regulated timely intelligent insulin release affected by blood glucose fluctuations, thereby forming feedback blood glucose management and exerting a full-stage wound healing. The hydrogel is composed of Au─MoS2─phenylboronic acid nanozyme and insulin-loaded nitroimidazole-modified sodium alginate hypoxia-sensitive microcapsules and penylboronic-acid-modified chitosan. It utilizes glucose as a sacrificial agent to generate antibacterial reactive oxygen species by recognizing the hyperglycemia environment, and releasing insulin for blood glucose regulation for up to 12 h with the help of the enzyme-like catalysis-generated hypoxia environment. In a normoglycemia environment, the hydrogel switches the enzyme-like activity to supply oxygen, inhibiting further insulin release. The hydrogel achieves ≈3 times the wound recovery rate of commercial dressings through blood glucose regulation and improved wound microenvironment. The hydrogel has been proven to significantly improve the healing of chronic diabetic wounds by regulating the body's blood glucose homeostasis and implementing a staged healing treatment plan, providing a powerful solution for diabetic wound care.