Multifunctional hydrogel with reactive oxygen species scavenging and photothermal antibacterial activity accelerates infected diabetic wound healing

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.

New insights into the cross-linking mechanism of soybean protein-based double dynamic cross-linking hydrogels for the controlled delivery of curcumin

The growing demand for functional foods requires the development of advanced delivery systems for hydrophobic bioactive ingredients. To meet this demand, a novel dual-crosslinked hydrogel was designed using a mild gelation method, incorporating Schiff base and catechol-Fe3+ chelation bonds. The effect of the content of dynamic bonds on the physical properties and delivery characteristics of the hydrogel was systematically studied. The results show that the unique dual-crosslinked structure of the hydrogel imparts superior physicochemical properties and enhanced efficacy. Enhanced physicochemical properties include faster gelation time, stronger mechanical performance, a denser network structure, and improved self-healing ability. Furthermore, these hydrogels exhibit excellent thermal stability and water retention properties, with swelling behavior gradually weakening as the content of dynamic bonds increases. The SPD8@Fe1 hydrogels have optimal thermal stability (30.69 %), best mechanical properties (26.86 kPa) and low swelling rate (45.44 g/g). In vitro gastrointestinal digestion simulations indicate that these hydrogels can withstand damage caused by gastric conditions and sustain the release of curcumin under intestinal conditions, while also demonstrating excellent bile salt adsorption capacity. The hydrogel had good pH-dependent controlled-release ability for curcumin. By adjusting the content of dynamic bonds, the sustained release behavior of the hydrogel can be regulated. This work provides important insights into the structure-function relationship of hydrogels and valuable information for the design of functional delivery carriers for hydrophobic bioactive ingredients.

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.

Hydrogel formed in situ through Schiff base reaction between gallic acid-grafted soybean protein isolate and oxidized dextran: Interactions, physicochemical properties, and digestive characteristics

Herein, we developed multifunctional hydrogels formed between soybean protein (SPI)-gallic acid conjugate and oxidized dextran (ODex) via a Schiff base reaction. The effects of ODex on the morphology, structure, and functional properties of the hydrogels were elucidated. The results showed that the crosslinking modes in the hydrogels include hydrogen bonding, Schiff bases, Michael addition, and π-π stacking. The synergistic crosslinking of gallic acid and ODex conferred the hydrogels with an appropriate equilibrium swelling ratio, dense morphology, excellent mechanical properties, high thermal stability, and water-holding properties. When the addition of ODex was 0.8 (w/w), the hydrogel had a higher crosslinking degree (76.31 %), smaller average pore diameter (0.322 μm), and higher zero shear viscosity (748.5 mPa. s). In addition, in vitro digestion tests showed that hydrogel degradation was delayed upon increasing the degree of crosslinking, which improved the hydrogel's capacity to adsorb bile salts and control the release of curcumin. This study provides a theoretical basis for the design of high-quality protein hydrogels and other multifunctional materials suitable for various applications.

Glucose-triggered NIR-responsive photothermal antibacterial gelatin/dextran hydrogel simultaneously targeting the high glucose and infection microenvironment in diabetic wound

The treatment of diabetic wounds with bacterial infection is a major challenge in the medical field. Microenvironment-responsive hydrogel dressings have shown great advantages, and photothermal antibacterial therapy is a potential antimicrobial strategy to avoid the generation of resistant bacteria. In this work, a glucose-triggered near-infrared (NIR)-responsive photothermal antibacterial hydrogel was designed and named GOGD based on a cascade reaction of glucose oxidation and polyphenol polymerization. The GOGD hydrogel was composed of gelatin and oxidized dextran (Odex), and loaded with a natural plant polyphenol gallic acid (GA) and the dual-biological enzymes (glucose oxidase GOx and horseradish peroxidase HRP). In response to the high glucose environment, GOx in the hydrogel decomposed glucose to produce hydrogen peroxide, which further catalyzed GA polymerization with HRP to produce poly-GA possessing NIR photothermal capability, thus endow GOGD hydrogel with glucose-triggered NIR responsive photothermal antibacterial property simultaneously targeting the high glucose and infection microenvironment in diabetic wounds. Furthermore, the GOGD hydrogel demonstrated good biocompatibility and a strong ability to scavenge reactive oxygen species (ROS), thereby protecting cells from oxidative damage. In a mouse model, this hydrogel not only displayed excellent hemostatic properties but also significantly enhanced the healing of Staphylococcus aureus-infected diabetic wounds by regulating inflammation and promoting angiogenesis. Therefore, the proposed GOGD hydrogel provides a novel approach to diabetic wound treatment by utilizing its unique glucose-responsive mechanism combined with integrated NIR-photothermal bacterial inhibition. This well-designed material holds great promise for significantly improving the healing of infected diabetic wounds and offers new prospects for future advancements in wound therapy.

Xanthium strumarium/gelatin methacryloyl based hydrogels with anti-inflammatory and antioxidant properties for diabetic wound healing via akt/mtor pathway

Chronic wound healing is often hindered by long-term inflammation and redox imbalance. Herbal medicine, with its rich medicinal components such as polysaccharides, flavonoids, phenolic acids, and small-molecule nutrients, has gained attention for its anti-inflammatory and antioxidant properties. Xanthium strumarium (XS) is a potent anti-inflammatory herb that has shown promise in treating conditions like rhinitis and may have specific benefits for chronic skin wounds. However, traditional XS preparations taken orally can have harmful effects on the liver and kidneys, limiting its clinical use. To date, there has been no documented method for the localized and sustained delivery of XS. This study introduces a timely development of a multifunctional hybrid hydrogel, incorporating bioactive XS extract and Gelatin Methacryloyl (GelMA), for the purpose of diabetic wound healing. In vitro experiments showed that XS/GelMA had strong anti-inflammatory and antioxidant effects through the Akt/mTOR pathway. The XS extract itself also significantly enhanced cell migration and angiogenesis. In vivo studies confirmed the superior wound healing properties of XS/GelMA. These findings suggest that XS-derived hydrogels have great potential for skin regeneration and tissue engineering applications.

Effect of different crosslinking agents on carboxymethyl chitosan-glycyrrhizic acid hydrogel: Characterization and biological activities comparison

Hydrogels were widely utilized in biomedical applications, with their mechanical properties and drug release behavior largely dependent on the type and degree of crosslinking. In this study, the effects of anhydrous ferrous chloride (Fe2+), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS), and polyvinyl alcohol/borax (PVA/Borax) on the properties of carboxymethyl chitosan (CMCS) and glycyrrhizic acid (GA) hydrogels were investigated. The GA-CMCS-based hydrogels (GFC, GEDC, GPBC) were prepared and their Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and rheological properties were analyzed. The results showed that GFC excelled in self-healing, swelling, and water retention. Furthermore, hydrogels with varying GA concentrations crosslinked by Fe2+ were tested for antibacterial activity and cellular nitric oxide (NO) levels, and were compared to GEDC and GPBC. Notably, Fe2+-crosslinked hydrogels demonstrated significant antibacterial efficacy, the antibacterial rate of 3 % GFC reached 93 %. When compared to the LPS group, which had an inflammatory NO level of 30.58 ± 0.95 μM, the 3 % GFC group demonstrated a notable reduction to 12.88 ± 1.04 μM. In contrast, GEDC and GPBC showed limited antibacterial and anti-inflammatory properties. In brief, hydrogels' physical, chemical, and biological properties were notably affected by various crosslinking agents. This study provides valuable insights for designing hydrogels tailored to specific application requirements.

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.

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.

Tailored Metal-Phenolic Network with Hypoglycemic Polyphenol for Promoting Diabetic Wound Healing

Diabetic foot ulcer is a common and serious complication of diabetes, with a high risk of amputation, recurrence, and mortality. Aiming at the characteristics of diabetic wounds and based on the result of network pharmacology, a tailored ligand cyanidin-3-O-glucoside (C3G) was selected to construct a metal-phenolic network (CM) through the self-assembly reaction with manganese ions. CM integrates the pharmacological advantages of C3G in antidiabetes and the anti-inflammatory activity of metal-phenolic networks by simulating the metal coordination structure of antioxidant enzymes. Reasonably, the wound areas of db/db mice with CM treatment rapidly decreased to 3.06% at day 14, accompanied by the improvement of tissue microenvironment. Mechanism investigation indicated that CM can not only reduce inflammation activation and immunoreaction but also increase gene transcripts in glucose metabolism, response to hypoxia, and angiogenesis. It is believed that this work opens a way for designing disease-specific metal-phenolic networks, and the CM with high biosafety promotes the clinical treatment of diabetic wounds.

Applications and prospects of biomaterials in diabetes management

Diabetes is a widespread metabolic disorder that presents considerable challenges in its management. Recent advancements in biomaterial research have shed light on innovative approaches for the treatment of diabetes. This review examines the role of biomaterials in diabetes diagnosis and treatment, as well as their application in managing diabetic wounds. By evaluating recent research developments alongside future obstacles, the review highlights the promising potential of biomaterials in diabetes care, underscoring their importance in enhancing patient outcomes and refining treatment methodologies.

All-in-One: A Multifunctional Composite Biomimetic Cryogel for Coagulation Disorder Hemostasis and Infected Diabetic Wound Healing

Traditional hemostatic materials are difficult to meet the needs of non-compressible bleeding and for coagulopathic patients. In addition, open wounds are susceptible to infection, and then develop into chronic wounds. However, the development of integrated dressings that do not depend on coagulation pathway and improve the microenvironment of chronic wounds remains a challenge. Inspired by the porous structure and composition of the natural extracellular matrix, adipic dihydrazide modified gelatin (GA), dodecylamine-grafted hyaluronic acid (HD), and MnO2 nanozyme (manganese dioxide)@DFO (deferoxamine)@PDA (polydopamine) (MDP) nanoparticles were combined to prepare GA/HD/MDP cryogels through amidation reaction and hydrogen bonding. These cryogels exhibited good fatigue resistance, photothermal antibacterial (about 98% killing ratios of both Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) after 3 min near-infrared irradiation), reactive oxygen species scavenging, oxygen release, and angiogenesis properties. Furthermore, in the liver defect model of rats with coagulopathy, the cryogel displayed less bleeding and shorter hemostasis time than commercial gelatin sponge. In MRSA-infected diabetic wounds, the cryogel could decrease wound inflammation and oxidative stress, alleviate the hypoxic environment, promote collagen deposition, and induce vascular regeneration, showing a better repair effect compared with the Tegaderm™ film. These results indicated that GA/HD/MDP cryogels have great potential in non-compressible hemorrhage for coagulopathic patients and in healing infected wounds for diabetic patients.

Design and characterization of a ROS-responsive antibacterial composite hydrogel for advanced full-thickness wound healing

Full-thickness skin wounds remian a significant and pressing challenge. In this study, we introduce a novel composite hydrogel, CS + GA + Zn-HA. This hydrogel is formulated by incorporating 1 % (1 g/100 mL) of bioactive Zinc-substituted hydroxyapatite nanoparticles (Zn-HA) and 0.2 % (0.2 g/100 mL) of Gallic acid (GA) into chitosan (CS) hydrogels. A 56 % β-glycerophosphate sodium (β-GP) solution serves as the cross-linking agent, and the hydrogel is formed at 37 °C. This composite hydrogel can effectively modulate the wound microenvironment, facilitating comprehensive skin wound healing within two weeks. Physicochemical characterization demonstrates that this hydrogel is thermosensitive, with remarkable swelling behavior, mechanical strength, and drug-delivery performance. In vitro, the GA-incorporated hydrogels possess outstanding reactive oxygen species (ROS) scavenging and antioxidant properties, protecting L929 cells from hydrogen peroxide-induced oxidative damage. The combination of Zn-HA nanoparticles and GA not only augments the functionality of the hydrogel and decreases its degradation rate but also enables the controlled release of curcumin. Moreover, it provides a suitable immune microenvironment in terms of biological effects and significantly boosts the hydrogel's antibacterial ability, as demonstrated by an 89.2 % reduction in E. coli and a 53.6 % reduction in S. aureus. Benefiting from these properties, the CS + GA + Zn-HA composite hydrogel significantly promotes granulation tissue formation, re-epithelialization, angiogenesis, and wound closure in vivo. In conclusion, our research highlights the potential of the CS + GA + Zn-HA hydrogel as a multifunctional scaffold in tissue engineering, providing valuable insights for the design of future wound dressings for diverse wound types.

Chitosan and gelatin based sprayable hydrogels incorporating photothermal and long-acting antibiotic sterilization for infected wound management with shape adaptability

Severe skin damage resulting from acute trauma is often accompanied by uncontrolled bleeding, microbial infections, and delayed wound healing. Herein, multifunctional sprayable hydrogels (CT-CS-ZIF@CIP Gel) were developed for wound management by incorporating antibacterial nanoplatforms (CT-CS-ZIF@CIP) into photocurable gels consisting of chitosan methacrylate and gallic acid grafted gelatin. The nanoplatform was initially constructed by sequentially loading Cu2Se (CS) and ciprofloxacin-decorated zeolitic imidazolate framework-8 (ZIF@CIP) onto Cu-doped Ti MOF (CT), in which CS served as a photothermal agent, ZIF enabled pH-responsive release of CIP, and CT acted as carriers for CS and ZIF@CIP. The hydrogel precursor can be sprayed onto wound surface and photocured quickly, allowing hydrogel to fit the wound shape and form a protective barrier onsite. The resultant hydrogel exhibited excellent hemostatic ability, adhesion properties, cytocompatibility and toxin adsorption capacity. By integrating CS for short-term photothermal therapy with CIP for long-acting chemotherapy, the CT-CS-ZIF@CIP Gel demonstrated 100 % sterilization of three bacterial strains. Furthermore, moderate release of zinc and copper ions promoted wound healing. The therapeutic efficacy of hydrogel was validated in an infected cutaneous mouse model. Overall, this work presents a versatile sprayable hydrogel that can be flexibly applied to irregular dynamic wounds for safe and effective wound management.

Thermosensitive-based synergistic antibacterial effects of novel LL37@ZPF-2 loaded poloxamer hydrogel for infected skin wound healing

Trauma healing is the process of healing after the body has been subjected to an external force and the skin and other tissues have become dissected or defective, showing the synergistic effect of various processes. Therefore, the investigation of innovative wound dressings has significant research and clinical implications. In this study, we constructed a zinc based metal-organic framework (MOF) and loaded with antimicrobial peptide LL37 to prepare LL37@ZPF-2 (ZPF = zeolite pyrimidine backbone), which was subsequently integrated with Poloxamer 407 to fabricate LL37@ZPF-2 thermosensitive hydrogel. Our study showed that in-situ packaging method can achieve encapsulation rate of 98 % and 15 % of drug loading for LL37. LL37@ZPF-2 demonstrated a higher inhibitory potency against S.aureus compared to E.coli. The Poloxamer 407-gel exhibits thermo-responsive sol-to-gel phase transition behaviors with a phase transition temperature (Tsol/gel) of ∼ 28.01℃, making it an appropriate material for wound healing. The composite hydrogel has excellent biocompatibility and hemocompatibility. A full-thickness skin defect model was built to confirm that LL37@ZPF-2 thermosensitive hydrogel dressing could inhibit bacterial growth, reduce the risk of wound infection, and stimulate angiogenesis and collagen deposition, resulting in a wound healing rate of 94.4 % on day 7 and complete healing on day 10. Our findings demonstrate that the novel thermosensitive LL37@ZPF-2 hydrogel confers good antibacterial activity, promoting cell migration and infected-wound healing properties, providing a promising platform for wound healing.

Development and Characterization of a Gelatin-Based Photoactive Hydrogel for Biomedical Application

Photoactive hydrogels facilitate light-triggered photochemical processes, positioning them as innovative solutions in biomedical applications, especially in antimicrobial photodynamic therapy. This study presents a novel methylene blue-based photoactive hydrogel designed as a topical gel solution to overcome the limitations of traditional pad-based systems by offering enhanced adaptability to irregular wound surfaces, uniform photosensitizer distribution, and deeper therapeutic light penetration. This study investigated the development of hydrogels by cross-linking gelatin with glutaraldehyde (GA) and incorporating methylene blue (MB) to investigate the effects of cross-linking density, network structure, and small molecule inclusion on hydrogel properties. The results showed that while glutaraldehyde concentration influenced swelling behavior and network structure, the inclusion of MB altered these properties, particularly reducing swelling and MB retention at higher GA concentrations. Rheological and thermal analyses confirmed that higher GA concentrations made the hydrogels more rigid, with MB influencing both mechanical and thermal properties. Additionally, the hydrogels exhibited enhanced antimicrobial properties through increased reactive oxygen species production, particularly in light-activated conditions, demonstrating the potential of MB-based photoactive hydrogels for improving antimicrobial efficacy, especially against S. aureus, E. coli, and C. albicans, offering as a possible alternative to traditional antimicrobial treatments.

An injectable, self-healing, anti-infective, and anti-inflammatory novel glycyrrhizic acid hydrogel for promoting acute wound healing and regeneration

Introduction

Bacterial infection, a complex wound microenvironment, and a persistent inflammatory response in acute wounds can result in delayed healing and abnormal scar formation, thereby compromising the normal function and aesthetic appearance of skin tissue. This issue represents one of the most challenging problems in clinical practice. This study aims to develop a hydrogel dressing specifically designed for the treatment of acute wounds, providing immediate and effective protection for the affected areas. This innovation seeks to offer a novel and advanced solution for the management of acute wounds.

Methods

In this study, a composite hydrogel scaffold was synthesized through the reaction between oxidized glycyrrhizic acid and carboxymethyl chitosan Schiff base. The material properties of the hydrogel were systematically characterized, and its biocompatibility and antibacterial efficacy were rigorously evaluated. A rat wound model was established to compare multiple groups, thereby assessing the impact of the hydrogel on the wound microenvironment and wound repair.

Results

The results demonstrated that the OGA-CMCS hydrogel exhibited excellent injectability, biocompatibility, and antibacterial properties. It was capable of enhancing the wound microenvironment, which in turn influenced the polarization of macrophages from the M1 to the M2 phenotype, thereby mitigating the inflammatory response, promoting angiogenesis and granulation tissue regeneration, and accelerating wound healing.

Discussion

This study successfully developed a novel glycyrrhizin-based hydrogel dressing, which not only introduces innovative approaches for the emergency management of acute surface wound defects but also provides an experimental foundation. It is anticipated to contribute significantly to addressing relevant clinical challenges.

Enhanced diabetic foot ulcer treatment with a chitosan-based thermosensitive hydrogel loaded self-assembled multi-functional nanoparticles for antibacterial and angiogenic effects

Inhibiting bacterial growth and promoting angiogenesis are essential for enhancing wound healing in diabetic patients. Excessive oxidative stress at the wound site can also lead to an accumulation of reactive oxygen species. To address these challenges, a smart thermosensitive hydrogel loaded with therapeutic agents was developed. This formulation features self-assembled nanoparticles named CIZ, consisting of chlorogenic acid (CA), indocyanine green (ICG), and zinc ions (Zn2+). These nanoparticles are loaded into a chitosan-β-glycerophosphate hydrogel, named CIZ@G, which enables rapid gel formation under photothermal effects. The hydrogel demonstrates good biocompatibility and effectively releases drugs into diabetic foot ulcers (DFU) wound. Benefiting from the dual actions of CA and zinc ions, the hydrogel exhibits potent antioxidative and anti-inflammatory effects, enhances the expression of vascular endothelial growth factor (VEGF) and Platelet endothelial cell adhesion molecule-1 (CD31), and promotes angiogenesis. Both in vitro and in vivo experiments confirm that CIZ@G can effectively inhibit the growth of Staphylococcus aureus post-laser irradiation and accelerate wound remodeling within 14 days. This approach offers a new strategy for the treatment of diabetic foot ulcers (DFU), potentially transforming patient care in this challenging clinical area.

Sustained Release of Curcumin from Cur-LPs Loaded Adaptive Injectable Self-Healing Hydrogels

Biological tissue defects are typically characterized by various shaped defects, and they are prone to inflammation and the excessive accumulation of reactive oxygen species. Therefore, it is still urgent to develop functional materials which can fully occupy and adhere to irregularly shaped defects by injection and promote the tissue repair process using antioxidant and anti-inflammatory mechanisms. Herein, in this work, phenylboronic acid modified oxidized hyaluronic acid (OHAPBA) was synthesized and dynamically crosslinked with catechol group modified glycol chitosan (GCHCA) and guar gum (GG) into a hydrogel loaded with curcumin liposomes (Cur-LPs) which were relatively uniformly distributed around 180 nm. The hydrogel possessed rapid gelation within 30 s, outstanding injectability and tissue-adaptive properties with self-healing properties, and the ability to adhere to biological tissues and adapt to tissue movement. Moreover, good biocompatibility and higher DPPH scavenging efficiency were illustrated in the hydrogel. And a more sustainable release of curcumin from Cur-LPs-loaded hydrogels, which could last for 10 days, was achieved to improve the bioavailability of curcumin. Finally, they might be injected to fully occupy and adhere to irregularly shaped defects and promote the tissue repair process by antioxidant mechanisms and the sustained release of curcumin for anti-inflammation. And the hydrogel would have potential application as candidates in tissue defect repair.

Immunomodulatory Hydrogel for Electrostatically Capturing Pro-inflammatory Factors and Chemically Scavenging Reactive Oxygen Species in Chronic Diabetic Wound Remodeling

Diabetic wound exhibits the complex characteristics involving continuous oxidative stress and excessive expression of pro-inflammatory cytokines to cause a long-term inflammatory microenvironment. The repair healing of chronic diabetic wounding is tremendously hindered due to persistent inflammatory reaction. To address the aforementioned issues, here, a dual-functional hydrogel is designed, consisting of N1-(4-boronobenzyl)-N3-(4-boronophenyl)-N1, N1, N3, N3-tetramethylpropane-1, 3-diaminium (TSPBA) modified polyvinyl alcohol (PVA) and methacrylamide carboxymethyl chitosan (CMCSMA) can not only electrostatically adsorb proinflammatory cytokines of IL1-β and TNF-α, but can also chemically scavenge the excessive reactive oxygen species (ROS) in situ. Both in vitro and in vivo evaluations verify that the negatively charged and ROS-responsive hydrogel (NCRH) can effectively modulate the chronic inflammatory microenvironment of diabetic wounds and significantly enhance wound remodeling. More importantly, the well-designed NCRH shows a superior skin recovery in comparison with the commercial competitor product of wound dressing. Consequently, the current work highlights the need for new strategies to expedite the healing process of diabetic wounds and offers a wound dressing material with immunomodulation.

LysSYL-Loaded pH-Switchable Self-Assembling Peptide Hydrogels Promote Methicillin-Resistant Staphylococcus Aureus Elimination and Wound Healing

Staphylococcus aureus (S. aureus), especially methicillin-resistant S. aureus (MRSA), causes wound infections, whose treatment remains a clinical challenge. Bacterium-infected wounds often create acidic niches with a pH 4.5-6.5. Endolysin LysSYL, which is derived from phage SYL, shows promise as an antistaphylococcal agent. However, endolysins generally exhibit instability and possess low bioavailability in acidic microenvironments. Here, an array of self-assembling peptides is designed, and peptide L5 is screened out based on its gel formation property and bioavailability. L5 exerted a pH-switchable antimicrobial effect (pH 5.5) and formed biocompatible hydrogels at neutral pH (pH 7.4). The LysSYL-loaded L5 can assemble L5@LysSYL hydrogels, increase thermal stability, and exhibit the slow-release effect of LysSYL. Effective elimination of S. aureus is achieved by L5@LysSYL through bacterial membrane disruption and cell separation inhibition. Moreover, L5@LysSYL hydrogels exhibit great potential in promoting wound healing in a mouse wound model infected by MRSA. Furthermore, L5@LysSYL hydrogels are safe and can decrease the cytokine levels and increase the number of key factors for vessel formation, which contribute to wound healing. Overall, the self-assembling L5@LysSYL can effectively clean MRSA and promote wound healing, which suggests its potential as a pH-sensitive wound dressing for the management of wound infections.

Endogenous/exogenous stimuli‐responsive smart hydrogels for diabetic wound healing

Diabetes significantly impairs the body's wound‐healing capabilities, leading to chronic, infection‐prone wounds. These wounds are characterized by hyperglycemia, inflammation, hypoxia, variable pH levels, increased matrix metalloproteinase activity, oxidative stress, and bacterial colonization. These complex conditions complicate effective wound management, prompting the development of advanced diabetic wound care strategies that exploit specific wound characteristics such as acidic pH, high glucose levels, and oxidative stress to trigger controlled drug release, thereby enhancing the therapeutic effects of the dressings. Among the solutions, hydrogels emerge as promising due to their stimuli‐responsive nature, making them highly effective for managing these wounds. The latest advancements in mono/multi‐stimuli‐responsive smart hydrogels showcase their superiority and potential as healthcare materials, as highlighted by relevant case studies. However, traditional wound dressings fall short of meeting the nuanced needs of these wounds, such as adjustable adhesion, easy removal, real‐time wound status monitoring, and dynamic drug release adjustment according to the wound's specific conditions. Responsive hydrogels represent a significant leap forward as advanced dressings proficient in sensing and responding to the wound environment, offering a more targeted approach to diabetic wound treatment. This review highlights recent advancements in smart hydrogels for wound dressing, monitoring, and drug delivery, emphasizing their role in improving diabetic wound healing. It addresses ongoing challenges and future directions, aiming to guide their clinical adoption.

Self-healing hydrogel from poly(aspartic acid) and dextran with antibacterial property for burn wound healing

Designing hydrogel dressing with intrinsic antibacterial property to promote skin injury recovery remains a significant challenge. In this research, poly(aspartic hydrazide) with grafted betaine (PAHB) was designed and reacted with oxidized dextran (OD) to fabricate biodegradable PAHB/OD hydrogel and its application as wound dressing was systematically investigated. The PAHB/OD hydrogels exhibited fast gelation, strong tissue adhesion, preferable mechanical properties and biocompatibility. The grafted betaine endowed the hydrogel with antibacterial property and antibacterial rate enhanced through photothermal performance of composited CuS nanoparticles under near infrared (NIR) radiation. The CuS composited PAHB/OD hydrogel (CuS/hydrogel) with microporous morphology was used as burn wound dressing with loaded anti-inflammatory drug diclofenac sodium (DS) in mouse model. The results showed the DS loaded CuS/hydrogel (CuS@DS/hydrogel) promoted the tissue regeneration and suppressed the inflammatory response. The histological analysis and immunohistochemical expression confirmed the CuS@DS/hydrogel promote angiogenesis of the burn wound by regulating the expression of inflammatory cytokines (IL-6 and CD68) and vascular endothelial growth factor (VEGF). Overall, the CuS@DS/hydrogel hydrogel is a promising candidate as wound dressing due to its tissue adhesive, antioxidant, antibacterial and anti-inflammatory activities.

Glucose and pH dual-responsive hydrogels with antibacterial, reactive oxygen species scavenging, and angiogenesis properties for promoting the healing of infected diabetic foot ulcers

The healing process of diabetic foot ulcers is challenging due to the presence of a complex and severe inflammatory microenvironment, characterized by hyperglycemia, low pH, susceptibility to infection, vascular dysfunction, and over-expression of reactive oxygen species (ROS), which can potentially lead to amputation or even mortality. Herein, a glucose and pH dual-responsive hydrogel was designed and prepared by crosslinking phenylboronic acid-grafted quaternary chitosan (QF, 4 wt%) with dopamine-grafted oxidized hyaluronic acid (OD, 5 wt%) through phenylboronation, schiff-base reaction, and other techniques. The multifunctional QO/@PV@AB7 hydrogel was prepared by incorporating pravastatin-loaded chitosan nanoparticles (CSNPs@PV, 2 mg/mL) and antimicrobial peptide AMP-AB7 loaded silica nanoparticles (SiO2NPs@AB7, 0.5 mg/mL). The results demonstrate that the QO/@PV@AB7 hydrogel exhibits good responsiveness to acidic conditions and high glucose levels, while effectively scavenging various types of ROS. Moreover, it exerted protective effects against oxidative stress on cells, enhanced HUVECs viability, and promoted angiogenesis. Notably, the QO/@PV@AB7 hydrogel displayed potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Additionally, in an MRSA-infected rat model of diabetic foot wounds, administration of the QO/@PV@AB7 hydrogel led to increased secretion of pro-angiogenic factors such as vascular endothelial nitric oxide synthase (eNOS), vascular endothelial-generating factor (VEGF), and endothelial cell adhesion molecule (CD31). Furthermore, the hydrogel significantly reduced the levels of inflammatory factors such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), while simultaneously increasing the levels of anti-inflammatory cytokines such as interleukin-10 (IL-10). The findings suggest that multifunctional hydrogels incorporating PV@CSNPs and SiO2NPs@AB7 demonstrate promising potential as a therapeutic approach for the treatment of diabetic foot. STATEMENT OF SIGNIFICANCE: Here, a glucose and pH dual-responsive QO/@PV@AB7 hydrogel with antimicrobial and angiogenesis-promoting properties was developed for the treatment of infected wounds in diabetic feet. Our findings demonstrate that the proposed hydrogel exhibits good responsiveness, effectively scavenges various types of reactive oxygen species (DPPH, O2-, -OH, and ABTS+), provides protection against oxidative stress, enhances HUVECs cell viability, and promotes angiogenesis. Notably, it also demonstrates potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and E. coli. Additionally, in vivo experiments demonstrated that the hydrogel exhibited accelerated wound healing in MRSA-infected diabetic foot ulcers, with a reduction of four days compared to the control group.

Accelerated, injectable, self-healing, scarless wound dressings using rGO reinforced dextran/chitosan hydrogels incorporated with PDA-loaded asiaticoside

The process of wound healing is intricate and complex, necessitating the intricate coordination of various cell types and bioactive molecules. Despite significant advances, challenges persist in achieving accelerated healing and minimizing scar formation. Herein, a multifunctional hydrogel engineered via dynamic Schiff base crosslinking between oxidized dextran and quaternized chitosan, reinforced with reduced graphene oxide (rGO) is reported. The resulting OQG hydrogels demonstrated injectability to aid in conforming to irregular wound geometries, rapid self-healing to maintain structural integrity and adhesion for intimate integration with wound beds. Moreover, the developed hydrogels possessed antioxidant and antibacterial activities, mitigating inflammation and preventing infection. The incorporation of conductive rGO further facilitated the transmission of endogenous electrical signals, stimulating cell migration and tissue regeneration. In addition, the polydopamine-encapsulated asiaticoside (AC@PDA) nanoparticles were encapsulated in OQG hydrogels to reduce scar formation during in vivo evaluations. In vitro results confirmed the histocompatibility of the hydrogels to promote cell migration. The recovery of the full-thickness rat wounds revealed that these designed OQG hydrogels with the incorporation of AC@PDA nanoparticles could accelerate wound healing, reduce inflammation, facilitate angiogenesis, and minimize scarring when implemented. This multifunctional hydrogel system offers a promising strategy for enhanced wound management and scarless tissue regeneration, addressing the multifaceted challenges in wound care.

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.

Fabrication of fiber-particle structures by electrospinning/electrospray combination as an intrinsic antioxidant and oxygen-releasing wound dressing

In this study, we employed a combination of electrospinning and electrospray techniques to fabricate wound dressings with a particle-fiber structure, providing dual characteristics of oxygen-releasing and intrinsic antioxidant properties, simultaneously. The electrospun part of the dressing was prepared from a blend of polycaprolactone/gallic acid-grafted-gelatin (GA-g-GE), enabling intrinsic ROS scavenging. To the best of our knowledge, this is the first time that PCL/GA-g-GE was fabricated by electrospinning. Furthermore, polyvinyl pyrrolidone (PVP) microparticles, containing calcium peroxide nanoparticles (CNPs), were considered as the oxygen production agent through the electrospray part. The CNP content was 1% and 3% w/w of PVP while biopolymer:PCL was 10% w/w. The fabricated structures were characterized in terms of fiber/particle morphology, elemental analysis, oxygen release behavior, ROS inhibition capacity, and water contact angle assessments. The covalent bonding of gallic acid to gelatin was confirmed by 1H-NMR, UV spectroscopy, and FTIR. According to the SEM results, the morphology of the prepared PCL/biopolymer fibers was bead-free and with a uniform average diameter. The analysis of released oxygen showed that by increasing the weight percentage of CNPs from 1 to 3 wt%, the amount of released oxygen increased from 120 mmHg to 195 mmHg in 24 h, which remained almost constant until 72 h. The obtained DPPH assay results revealed that the introduction of GA-g-GE into the fibrous structure could significantly improve the antioxidant properties of wound dressing compared to the control group without CNPs and modified gelatine. In vitro, the fabricated wound dressings were evaluated in terms of biocompatibility and the potential of the dressing to protect human dermal fibroblasts under oxidative stress and hypoxia conditions by an MTT assay. The presence of GA-g-GE led to remarkable protection of the cells against oxidative stress and hypoxia conditions. In vivo studies revealed that the incorporation of intrinsic ROS inhibition and oxygen-releasing properties could significantly accelerate the wound closure rate during the experimental period (7, 14, and 21 days). Additionally, histopathological investigations in terms of H&E and Masson's trichrome staining showed that the incorporation of the two mentioned capabilities remarkably facilitated the wound-healing process.

Acidic biofilm microenvironment-responsive ROS generation via a protein nanoassembly with hypoxia-relieving and GSH-depleting capabilities for efficient elimination of biofilm bacteria

Reactive oxygen species (ROS) are widely considered to the effective therapeutics for fighting bacterial infections especially those associated with biofilm. However, biofilm microenvironments including hypoxia, limited H2O2, and high glutathione (GSH) level seriously limit the therapeutic efficacy of ROS-based strategies. Herein, we have developed an acidic biofilm microenvironment-responsive antibacterial nanoplatform consisting of copper-dopped bovine serum albumin (CBSA) loaded with copper peroxide (CuO2) synthesized in situ and indocyanine green (ICG). The three-in-one nanotherapeutics (CuO2/ICG@CBSA) are capable of releasing Cu2+ and H2O2 in a slightly acidic environment, where Cu2+ catalyzes the conversion of H2O2 into hydroxyl radical (•OH) and consumes the highly expressed GSH to disrupt the redox homeostasis. With the assistance of an 808 nm laser, the loaded ICG not only triggers the production of singlet oxygen (1O2) by a photodynamic process, but also provides photonic hyperpyrexia that further promotes the Fenton-like reaction for enhancing •OH production and induces thermal decomposition of CuO2 for the O2-self-supplying 1O2 generation. The CuO2/ICG@CBSA with laser irradiation demonstrates photothermal-augmented multi-mode synergistic bactericidal effect and is capable of inhibiting biofilm formation and eradicating the biofilm bacteria. Further in vivo experiments suggest that the CuO2/ICG@CBSA can effectively eliminate wound infections and accelerate wound healing. The proposed three-in-one nanotherapeutics with O2/H2O2-self-supplied ROS generating capability show great potential in treating biofilm-associated bacterial infections. STATEMENT OF SIGNIFICANCE: Here, we have developed an acidic biofilm microenvironment-responsive nanoplatform consisting of copper-dopped bovine serum albumin (CBSA) loaded with copper peroxide (CuO2) synthesized in situ and indocyanine green (ICG). The nanotherapeutics (CuO2/ICG@CBSA) are capable of releasing Cu2+ and H2O2 in an acidic environment, where Cu2+ catalyzes the conversion of H2O2 into •OH and consumes the overexpressed GSH to improve oxidative stress. With the aid of an 808 nm laser, ICG provides photonic hyperpyrexia for enhancing •OH production, and triggers O2-self-supplying 1O2 generation. CuO2/ICG@CBSA with laser irradiation displays photothermal-augmented multi-mode antibacterial and antibiofilm effect. Further in vivo experiments prove that CuO2/ICG@CBSA effectively eliminates wound infection and promotes wound healing. The proposed three-in-one nanotherapeutics show great potential in treating biofilm-associated bacterial infections.

Poly-tannic acid coated PLGA nanoparticle decorated with antimicrobial peptide for synergistic bacteria treatment and infectious wound healing promotion

Bacterial infections pose a great threat to human health. Therefore, the development of new antibacterial agents or methods is in urgent need. In this study, we prepared polytannic acid (pTA)-coated PLGA nanoparticles decorated with Dermaseptin-PP (Der), an antimicrobial peptide (AMP), on the surface to obtain PLGA-pTA-Der. This nanoplatform could combine AMPs with photothermal treatment (PTT) mediated by pTA to achieve synergistic bacterial killing. The results of in vitro experiments showed that the PLGA-pTA-Der nanoparticles could eliminate nearly 99 % of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) upon near-infrared (NIR) laser irradiation (2.0 W·cm-2, 5 min), demonstrating excellent antibacterial properties. In addition, the results of atomic force microscopy (AFM) revealed that PLGA-pTA-Der with laser irradiation can greatly destroy the mechanical integrity of the bacterial outer membrane. And the presence of Der could exacerbate the heat damage caused by the PLGA-pTA NPs to the bacteria, which is helpful to reduce the critical temperature required for bacteria killing by PTT. In vivo experiments showed that PLGA-pTA-Der nanoparticles with laser irradiation significantly accelerated the wound healing process and inhibited the growth of bacterial. Moreover, it can achieve a strong photothermal antibacterial effect at a mild temperature (<45℃) and does not cause any obvious thermal damage to the surrounding normal skin tissues. Results of immunofluorescence staining showed that the expression of CD31 (a marker of new blood vessel formation) was significantly higher in the PLGA-pTA-Der + laser group than other groups, while the pro-inflammatory molecule TNF-α was significantly lower, indicating that PLGA-pTA-Der nanoparticles accelerated wound healing by enhancing angiogenesis and reducing the inflammatory response. In conclusion, PLGA-pTA-Der nanoparticles was a promising antimicrobial nanoplatform for treating bacterial infections and promoting wound healing.

A functional hydrogel of dopamine-modified gelatin with photothermal properties for enhancing infected wound healing

Infected skin wound has gradually become a prevalent injury that affects overall health. Currently, biomaterials with good adhesion, efficient antibacterial properties, and angiogenesis are considered as a suitable way to effectively heal infected wound. Herein, a multifunctional hydrogel comprising gelatin, dopamine (DA), and ferric ions (Fe3+) was developed for infected wound healing. The modified gelatin-dopamine (Gel-DA) enhanced adhesive capability. Subsequently introducing ferric ions (Fe3+) to form Gel-DA-Fe3+ hydrogels by Fe3+ and catechol coordination bonds. The designed hydrogels demonstrated multifaceted functionality, encompassing photothermal antibacterial, angiogenesis, and so on. The introduction of DA enhanced the adhesion of Gel-DA-Fe3+ to the skin surface and might serve as a physical barrier to seal wound. Meanwhile, DA and Fe3+ jointly endowed good photothermal effects to composite hydrogels, which could eliminate over 95 % of bacteria. In vitro results revealed that Gel-DA-Fe3+ hydrogels had good biocompatibility and promoted HUVECs migration and tube formation. Furthermore, in vivo studies confirmed that Gel-DA-Fe3+ hydrogels markedly expedited the wound healing of rats through eradicating bacteria, accelerating the deposition of collagen, and promoting angiogenesis. What's more, Gel-DA-Fe3+ hydrogels under near-infrared laser had a more pronounced ability for wound healing. Therefore, Gel-DA-Fe3+ hydrogels had great potential for application in bacteria-infected wound healing.

Green synthesis-inspired antibacterial, antioxidant and adhesive hydrogels with ultra-fast gelation and hemostasis for promoting infected skin wound healing

Bacterial infections are a serious threat to wound healing and skin regeneration. In recent years, photothermal therapy (PTT) has become one of the most promising tools in the treatment of infectious diseases. However, wound dressings with photo-responsive properties are currently still limited by the difficulties of biosafety and thermal stability brought by the introduction of photosensitizers or photothermal agents. Therefore, how to improve the therapeutic efficiency and biosafety from material design is still a major challenge at present. In this study, the carboxymethyl chitosan (CMCS) and protocatechuic aldehyde (PA) hydrogels based on horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) enzymatic catalysis was developed. Therein, HRP and H2O2 catalyzed cross-linking while polymerizing PA, which not only endowed the hydrogels with photothermal responsiveness but also with good biosafety through this enzyme-catalyzed green approach. Meanwhile, the hydrogels possessed highly efficient bacteriostatic ability with the assistance of near infrared (NIR). Moreover, the ultra-rapid gelation, strong tissue adhesion, high swelling ability, good antioxidant property and hemostatic property of the CMCS-PA hydrogels based on HRP/H2O2 enzymatic catalysis were suitable for the treatment of skin wounds. Meanwhile, NIR-assistant CMCS-PA hydrogels based on HRP/H2O2 enzymatic catalysis reduced inflammation, decreased bacterial infection, and promoted collagen deposition and angiogenesis, which showed remarkable therapeutic effects in a skin wound infection model. All results indicate that this green approach to introduce photothermal property by HRP-catalyzed PA polymerization endows the hydrogels with efficient photothermal conversion efficiency, suggesting that they are promising to provide new options for replacing photothermal agents and photosensitizers. STATEMENT OF SIGNIFICANCE: In recent years, wound dressings with photo-responsive properties are currently still limited by the difficulties of biosafety and thermal stability brought by the introduction of agent photosensitizers or photothermal agents. In this study, the carboxymethyl chitosan and protocatechuic aldehyde hydrogels based on horseradish peroxidase and hydrogen peroxide enzymatic catalysis was developed. The photothermal properties of hydrogels were transformed from absent to present just by horseradish peroxidase-catalyzed protocatechuic aldehyde polymerization in a green approach. Meanwhile, the hydrogels possessed highly efficient bacteriostatic ability with the assistance of near infrared. The green approach of introducing photothermal properties from material design solves the biosafety challenge. Therefore, this study is expected to provide new options for alternative photothermal agents and photosensitizers.

Polydopamine modified multifunctional carboxymethyl chitosan/pectin hydrogel loaded with recombinant human epidermal growth factor for diabetic wound healing

The development of a multifunctional wound dressing that can adapt to the shape of wounds and provide controlled drug release is crucial for diabetic patients. This study developed a carboxymethyl chitosan-based hydrogel dressing with enhanced mechanical properties and tissue adherence that were achieved by incorporating pectin (PE) and polydopamine (PDA) and loading the hydrogel with recombinant human epidermal growth factor (rhEGF). This EGF@PDA-CMCS-PE hydrogel demonstrated robust tissue adhesion, enhanced mechanical properties, and superior water retention and vapor permeability. It also exhibited significant antioxidant capacity. The results showed that EGF@PDA-CMCS-PE could effectively scavenge 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate)， (1,1-diphenyl-2-picrylhydrazyl), and superoxide anions and increase superoxide dismutase and catalase levels in vivo. In vitro cytotoxicity and antibacterial assays showed good biocompatibility and antimicrobial properties. The sustained release of EGF by the hydrogel was confirmed, with a gradual release profile over 120 h. In vivo studies in diabetic mice showed that the hydrogel significantly accelerated wound healing, with a wound contraction rate of 97.84% by day 14. Histopathological analysis revealed that the hydrogel promoted fibroblast proliferation, neovascularization, and orderly connective tissue formation, leading to a more uniform and compact wound-healing process. Thus, EGF@PDA-CMCS-PE hydrogel presents a promising tool for managing chronic diabetic wounds, offering a valuable strategy for future clinical applications.

Supramolecular Polymer Co-Assembled Multifunctional Chiral Hybrid Hydrogels with Adhesive, Self-Healing and Antibacterial Properties

Amino acid-derived self-assembled nanofibers comprising supramolecular chiral hydrogels with unique physiochemical characteristics are highly demanded biomaterials for various biological applications. However, their narrow functionality often limits practical use, necessitating the development of biomaterials with multiple features within a single system. Herein, chiral co-assembled hybrid hydrogel systems termed LPH-EGCG and DPH-EGCG were constructed by co-assembling L/DPFEG gelators with epigallocatechin gallate (EGCG) followed by cross-linking with polyvinyl alcohol (PVA) and hyaluronic acid (HA). The developed hybrid hydrogels exhibit superior mechanical strength, self-healing capabilities, and adhesive properties, owing to synergistic non-covalent interactions. Integrating hydrophilic polymers enhances the system's capacity to demonstrate favorable swelling characteristics. Furthermore, the introduction of EGCG facilitated the hybrid gels to display notable antibacterial properties against both Gram-positive and Gram-negative bacterial strains, alongside showcasing strong antioxidant capabilities. In vitro investigation demonstrated enhanced cell adhesion and migration with the LPH-EGCG system in comparison to DPH-EGCG, thus emphasizing the promising prospects of these hybrid hydrogels in advanced tissue engineering applications.

Multifunctional Microneedle Patch Based on Metal-Phenolic Network with Photothermal Antimicrobial, ROS Scavenging, Immunomodulatory, and Angiogenesis for Programmed Treatment of Diabetic Wound Healing

In diabetic patients with skin injuries, bacterial proliferation, accumulation of reactive oxygen species (ROS) in the tissues, and impaired angiogenesis make wound healing difficult. Therefore, eliminating bacteria, removing ROS, and promoting angiogenesis are necessary for treating acute diabetic wounds. In this study, benefiting from the ability of polyphenols to form a metal-phenolic network (MPN) with metal ions, TA-Eu MPN nanoparticles (TM NPs) were synthesized. The prepared photothermal agent CuS NPs and TM NPs were then loaded onto the supporting base and needle tips of PVA/HA (PH) microneedles, respectively, to obtain PH/CuS/TM microneedles. Antibacterial experiments showed that microneedles loaded with CuS NPs could remove bacteria by the photothermal effect. In vitro experiments showed that the microneedles could effectively scavenge ROS, inhibit macrophage polarization to the M1 type, and induce polarization to the M2 type as well as have the ability to promote vascular endothelial cell migration and angiogenesis. Furthermore, in vivo experiments showed that PH/CuS/TM microneedles accelerated wound healing by inhibiting pro-inflammatory cytokines and promoting angiogenesis in a diabetic rat wound model. Therefore, PH/CuS/TM microneedles have efficient antibacterial, ROS scavenging, anti-inflammatory, immunomodulatory, and angiogenic abilities and hold promise as wound dressings for treating acute diabetic wounds.

Self-Healing Conductive Hydrogels with Dynamic Dual Network Structure Accelerate Infected Wound Healing via Photothermal Antimicrobial and Regulating Inflammatory Response

Wound infections are an escalating clinical challenge with continuous inflammatory response and the threat of drug-resistant bacteria. Herein, a series of self-healing conductive hydrogels were designed based on carboxymethyl chitosan/oxidized sodium alginate/polymerized gallic acid/Fe3+ (CMC/OSA/pGA/Fe3+, COGFe) for promoting infected wound healing. The Schiff base and catechol-Fe3+ chelation in the dynamical dual network structure of the hydrogels endowed dressings with good toughness, conductivity, adhesion, and self-healing properties, thus flexibly adapting to the deformation of skin wounds. In terms of ultraviolet (UV) resistance and scavenging of reactive oxygen species (ROS), the hydrogels significantly reduced oxidative stress at the wound site. Additionally, the hydrogels with photothermal therapy (PTT) achieved a 95% bactericidal rate in 5 min of near-infrared (NIR) light radiation by disrupting the bacterial cell membrane structure through elevated temperature. Meanwhile, the inherent antimicrobial properties of GA could reduce healthy tissue damage caused by excessive heat. The composite hydrogels could effectively promote the proliferation and migration of fibroblasts and possess good biocompatibility and hemostatic effect. In full-thickness infected wound repair experiments in rats, the COGFe5 hydrogel combined with NIR effectively killed bacteria, modulated macrophage polarization (M1 to M2 phenotype) to improve the immune microenvironment of the wound, and shortened the repair time by accelerating the expression of collagen deposition (TGF-β) and vascular factors (CD31). This combined therapy might provide a prospective strategy for infectious wound treatment.

A nano-composite hyaluronic acid-based hydrogel efficiently antibacterial and scavenges ROS for promoting infected diabetic wound healing

Diabetic wound infection brings chronic pain to patients and the therapy remains a crucial challenge owing to the disruption of the internal microenvironment. Herein, we report a nano-composite hydrogel (ZnO@HN) based on ZnO nanoparticles and a photo-trigging hyaluronic acid which is modified by o-nitrobenzene (NB), to accelerate infected diabetic wound healing. The diameter of the prepared ZnO nanoparticle is about 50 nm. X-ray photoelectron spectroscopy (XPS) analysis reveals that the coordinate bond binds ZnO in the hydrogel, rather than simple physical restraint. ZnO@HN possesses efficient antioxidant capacity and it can scavenge DPPH about 40 % in 2 h and inhibit H2O2 >50 % in 8 h. The nano-composite hydrogel also exhibits satisfactory antibacterial capacity (58.35 % against E. coli and 64.03 % against S. aureus for 6 h). In vitro tests suggest that ZnO@HN is biocompatible and promotes cell proliferation. In vivo experiments reveal that the hydrogel can accelerate the formation of new blood vessels and hair follicles. Histological analysis exhibits decreased macrophages, increased myofibroblasts, downregulated TNF-α expression, and enhanced VEGFA expression during wound healing. In conclusion, ZnO@HN could be a promising candidate for treating intractable infected diabetic skin defection.

Bletilla striata Polysaccharide-/Chitosan-Based Self-Healing Hydrogel with Enhanced Photothermal Effect for Rapid Healing of Diabetic Infected Wounds via the Regulation of Microenvironment

The management of diabetic ulcers poses a significant challenge worldwide, and persistent hyperglycemia makes patients susceptible to bacterial infections. Unfortunately, the overuse of antibiotics may lead to drug resistance and prolonged infections, contributing to chronic inflammation and hindering the healing process. To address these issues, a photothermal therapy technique was incorporated in the preparation of wound dressings. This innovative solution involved the formulation of a self-healing and injectable hydrogel matrix based on the Schiff base structure formed between the oxidized Bletilla striata polysaccharide (BSP) and hydroxypropyltrimethylammonium chloride chitosan. Furthermore, the introduction of CuO nanoparticles encapsulated in polydopamine imparted excellent photothermal properties to the hydrogel, which promoted the release of berberine (BER) loaded on the nanoparticles and boosted the antibacterial performance. In addition to providing a reliable physical protection to the wound, the developed hydrogel, which integrated the herbal components of BSP and BER, effectively accelerated wound closure via microenvironment regulation, including alleviated inflammatory reaction, stimulated re-epithelialization, and reduced oxidative stress based on the promising results from cell and animal experiments. These impressive outcomes highlighted their clinical potential in safeguarding the wound against bacterial intrusion and managing diabetic ulcers.

Facile Solvent-Free Fabrication of All-Small-Molecule Supramolecular Photothermal Bioadhesive for Sutureless Wound Closure

Achieving underwater adhesion possesses a significant challenge, primarily due to the presence of interfacial water, which restricts the potential applications of adhesives. In this study, we present a straightforward and environmentally friendly one-pot approach for synthesizing a solvent-free supramolecular TPFe bioadhesive composed of thioctic acid, proanthocyanidins, and FeCl3. The bioadhesive exhibits excellent biocompatibility and photothermal antibacterial properties and demonstrates effective adhesion on various substrates in both wet and dry environments. Importantly, the adhesive strength of this bioadhesive on steel exceeds 1.2 MPa and that on porcine skin exceeds 100 kPa, which is greater than the adhesive strength of most reported bioadhesives. In addition, the bioadhesive exhibits the ability to effectively halt bleeding, close wounds promptly, and promote wound healing in the rat skin wound model. Therefore, the TPFe bioadhesive has potential as a medical bioadhesive for halting bleeding quickly and promoting wound healing in the biomedical field. This study provides a new idea for the development of bioadhesives with firm wet adhesion.

Natural blackcurrant extract contained gelatin hydrogel with photothermal and antioxidant properties for infected burn wound healing

Burns represent a prevalent global health concern and are particularly susceptible to bacterial infections. Severe infections may lead to serious complications, posing a life-threatening risk. Near-infrared (NIR)-assisted photothermal antibacterial combined with antioxidant hydrogel has shown significant potential in the healing of infected wounds. However, existing photothermal agents are typically metal-based, complicated to synthesize, or pose biosafety hazards. In this study, we utilized plant-derived blackcurrant extract (B) as a natural source for both photothermal and antioxidant properties. By incorporating B into a G-O hydrogel crosslinked through Schiff base reaction between gelatin (G) and oxidized pullulan (O), the resulting G-O-B hydrogel exhibited good injectability and biocompatibility along with robust photothermal and antioxidant activities. Upon NIR irradiation, the controlled temperature (around 45-50 °C) generated by the G-O-B hydrogel resulted in rapid (10 min) and efficient killing of Staphylococcus aureus (99 %), Escherichia coli (98 %), and Pseudomonas aeruginosa (82 %). Furthermore, the G-O-B0.5 hydrogel containing 0.5 % blackcurrant extract promoted collagen deposition, angiogenesis, and accelerated burn wound closure conclusively, demonstrating that this well-designed and extract-contained hydrogel dressing holds immense potential for enhancing the healing process of bacterial-infected burn wounds.

Mussel-inspired tissue adhesive composite hydrogel with photothermal and antioxidant properties prepared from pectin for burn wound healing

Biodegradable self-healing hydrogels with antibacterial property attracted growing attentions in biomedication as wound dressings since they can prevent bacterial infection and promote wound healing process. In this research, a biodegradable self-healing hydrogel with ROS scavenging performance and enhanced tissue adhesion was fabricated from dopamine grafted oxidized pectin (OPD) and naphthoate hydrazide terminated PEO (PEO NH). At the same time, Fe3+ ions were incorporated to endow the hydrogel with near-infrared (NIR) triggered photothermal property to obtain antibacterial activity. The composite hydrogel showed good hemostasis performance based on mussel inspired tissue adhesion with biocompatibility well preserved. As expected, the composition of FeCl3 improved conductivity and endowed photothermal property to the hydrogel. The in vivo wound repairing experiment revealed the 808 nm NIR light triggered photothermal behavior of the hydrogel reduced the inflammation response and promoted wound repairing rate. As a result, this composite FeCl3/hydrogel shows great potential to be an excellent wound dressing for the treatment of infection prong wounds with NIR triggers.

Enhanced osteogenic and ROS-scavenging MXene nanosheets incorporated gelatin-based nanocomposite hydrogels for critical-sized calvarial defect repair

The healing of critical-sized bone defects is a major challenge in the field of bone tissue engineering. Gelatin-related hydrogels have emerged as a potential solution due to their desirable properties. However, their limited osteogenic, mechanical, and reactive oxygen species (ROS)-scavenging capabilities have hindered their clinical application. To overcome this issue, we developed a biofunctional gelatin-Mxene nanocomposite hydrogel. Firstly, we prepared two-dimensional (2D) Ti3C2 MXene nanosheets using a layer delamination method. Secondly, these nanosheets were incorporated into a transglutaminase (TG) enzyme-containing gallic acid-imbedded gelatin (GGA) pre-gel solution to create an injectable GGA-MXene (GM) nanocomposite hydrogel. The GM hydrogels exhibited superior compressive strength (44-75.6 kPa) and modulus (24-44.5 kPa) compared to the GGA hydrogels. Additionally, the GM hydrogel demonstrated the ability to scavenge reactive oxygen species (OH- and DPPH radicals), protecting MC3T3-E1 cells from oxidative stress. GM hydrogels were non-toxic to MC3T3-E1 cells, increased alkaline phosphatase secretion, calcium nodule formation, and upregulated osteogenic gene expressions (ALP, OCN, and RUNX2). The GM400 hydrogel was implanted in critical-sized calvarial defects in rats. Remarkably, it exhibited significant potential for promoting new bone formation. These findings indicated that GM hydrogel could be a viable candidate for future clinical applications in the treatment of critical-sized bone defects.

Tannic acid and silicate-functionalized polyvinyl alcohol-hyaluronic acid hydrogel for infected diabetic wound healing

Healing of chronic diabetic wounds is challenging due to complications of severe inflammatory microenvironment, bacterial infection and poor vascular formation. Herein, a novel injectable polyvinyl alcohol-hyaluronic acid-based composite hydrogel was developed, with tannic acid (TA) and silicate functionalization to fabricate an 'all-in-one' hydrogel PTKH. On one hand, after being locally injected into the wound site, the hydrogel underwent a gradual sol-gel transition in situ, forming an adhesive and protective dressing for the wound. Manipulations of rheological characteristics, mechanical properties and swelling ability of PTKH could be performed via regulating TA and silicate content in hydrogel. On the other hand, PTKH was capable of eliminating reactive oxygen species overexpression, combating infection and generating a cell-favored microenvironment for wound healing acceleration in vitro. Subsequent animal studies demonstrated that PTKH could greatly stimulate angiogenesis and epithelization, accompanied with inflammation and infection risk reduction. Therefore, in consideration of its impressive in vitro and in vivo outcomes, this 'all-in-one' multifunctional hydrogel may hold promise for chronic diabetic wound treatment.

Preparation and Application of Hemostatic Hydrogels

Hemorrhage remains a critical challenge in various medical settings, necessitating the development of advanced hemostatic materials. Hemostatic hydrogels have emerged as promising solutions to address uncontrolled bleeding due to their unique properties, including biocompatibility, tunable physical characteristics, and exceptional hemostatic capabilities. In this review, a comprehensive overview of the preparation and biomedical applications of hemostatic hydrogels is provided. Particularly, hemostatic hydrogels with various materials and forms are introduced. Additionally, the applications of hemostatic hydrogels in trauma management, surgical procedures, wound care, etc. are summarized. Finally, the limitations and future prospects of hemostatic hydrogels are discussed and evaluated. This review aims to highlight the biomedical applications of hydrogels in hemorrhage management and offer insights into the development of clinically relevant hemostatic materials.

MG53/GMs/HA-Dex neural scaffold promotes the functional recovery of spinal cord injury by alleviating neuroinflammation

The adverse microenvironment, including neuroinflammation, hinders the recovery of spinal cord injury (SCI). Regulating microglial polarization to alleviate neuroinflammation at the injury site is an effective strategy for SCI recovery. MG53 protein exerts obvious repair ability on multiple tissues damage, but with short half-life. In this study, we composited an innovative MG53/GMs/HA-Dex neural scaffold using gelatin microspheres (GMs), hyaluronic acid (HA), and dextran (Dex) loaded with MG53 protein. This novel neural scaffold could respond to MMP-2/9 protein and stably release MG53 protein with good physicochemical properties and biocompatibility. In addition, it significantly improved the motor function of SCI mice, suppressed M1 polarization of microglia and neuroinflammation, and promoted neurogenesis and axon regeneration. Further mechanistic experiments demonstrated that MG53/GMs/HA-Dex hydrogel inhibited the JAK2/STAT3 signaling pathway. Thus, this MG53/GMs/HA-Dex neural scaffold promotes the functional recovery of SCI mice by alleviating neuroinflammation, which provides a new intervention strategy for the neural regeneration and functional repair of SCI.

Multifunctional 58S Bioactive Glass/Silver/Cerium Oxide-Based Biocomposites with Effective Antibacterial, Cytocompatibility, and Mechanical Properties

58S bioactive glass (BG) has effective biocompatibility and bioresorbable properties for bone tissue engineering; however, it has limitations regarding antibacterial, antioxidant, and mechanical properties. Therefore, we have developed BGAC biocomposites by reinforcing 58S BG with silver and ceria nanoparticles, which showed effective bactericidal properties by forming inhibited zones of 2.13 mm (against Escherichia coli) and 1.96 mm (against Staphylococcus aureus; evidenced by disc diffusion assay) and an increment in the antioxidant properties by 39.9%. Moreover, the elastic modulus, hardness, and fracture toughness were observed to be increased by ∼84.7% (∼51.9 GPa), ∼54.5% (∼3.4 GPa), and ∼160% (∼1.3 MPam1/2), whereas the specific wear rate was decreased by ∼55.2% (∼1.9 × 10-11 m3/Nm). X-ray diffraction, high-resolution transmission electron microscopy, and field emission scanning electron microscopy confirmed the fabrication of biocomposites and the uniform distribution of the nanomaterials in the BG matrix. The addition of silver nanoparticles in the 58S BG matrix (in BGA) increased mechanical properties by composite strengthening and bactericidal properties by damaging the cytoplasmic membrane of bacterial cells. The addition of nanoceria in 58S BG (BGC) increased the antioxidant properties by 44.5% (as evidenced by the 2,2-diphenyl-1-picrylhydrazyl assay). The resazurin reduction assay and MTT assay confirmed the effective cytocompatibility for BGAC biocomposites against mouse embryonic fibroblast cells (NIH3T3) and mouse bone marrow stromal cells. Overall, BGAC resulted in mechanical properties comparable to those of cancellous bone, and its effective antibacterial and cytocompatibility properties make it a good candidate for bone healing.

Nitric oxide-releasing multifunctional catechol-modified chitosan/oxidized dextran hydrogel with antibacterial, antioxidant, and pro-angiogenic properties for MRSA-infected diabetic wound healing

The study presents a multifunctional catechol-modified chitosan (Chi-Ca)/oxidized dextran (Dex-CHO) hydrogel (CDP-PB) that possesses antibacterial, antioxidant, and pro-angiogenic properties, aimed at improving the healing of diabetic wounds. The achievement of the as-prepared CDP-PB hydrogel with superb antibacterial property (99.9 %) can be realized through the synergistic effect of phenylboronic acid-modified polyethyleneimine (PEI-PBA) and photothermal therapy (PTT) of polydopamine nanoparticles loaded with the nitric oxide (NO) donor BNN6 (PDA@BNN6). Notably, CDP-PB hydrogel achieves ∼3.6 log10 CFU/mL MRSA of inactivation efficiency under 808 nm NIR laser irradiation. In order to mitigate oxidative stress, the Chi-Ca was synthesized and afterward subjected to a reaction with Dex-CHO via a Schiff-base reaction. The catechol-containing hydrogel demonstrated its effectiveness in scavenging DPPH, •OH, and ABTS radicals (> 85 %). In addition, the cellular experiment illustrates the increased migration and proliferation of cells by the treatment of CDP-PB hydrogel in the presence of oxidative stress conditions. Moreover, the findings from the animal model experiments provide evidence that the CDP-PB hydrogel exhibited efficacy in the eradication of wound infection, facilitation of angiogenesis, stimulation of granulation, and augmentation of collagen deposition. These results indicate the potential of the CDP-PB hydrogel for use in clinical applications.

Biodegradable and multifunctional black mulch film decorated with darkened lignin induced by iron ions for "green" agriculture

High-value utilization of bleached lignin has been widely used in different fields, whereas the investigation on darkened lignin in composite materials was often ignored. In this work, a sort of eco-friendly and structurally robust sodium carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA)/sodium lignosulfonate (SLS) black composite mulch film was elaborately designed. The chelation and redox reaction effect between Fe ions and SLS lead to the formation of a more quinones structure on lignin, darkening both lignin and the mulch films. The chelation effect between Fe ions and biopolymer formed three-dimensional structures, which can be used as sacrifice bonds to dissipate energy and improve the mechanical properties of the composite films. In particular, the maximum elongation at break and toughness increased from 48.4 % and 1141 kJ/m3 for the CMC/PVA film to 210.9 % and 1426 kJ/m3 for the optimized CMC/PVA/SLS/Fe black mulch film, respectively. In addition, the optimized black mulch film also possesses good soil water retention, thermal preservation effect, controlled urea release, and well biodegradability. This work offered a novel strategy for designing eco-friendly black mulch with reinforced mechanical strength, slow-release urea, soil moisture retention, and heat preservation performances.

Hybrid gelatin-ascorbyl phosphate scaffolds accelerate diabetic wound healing via ROS scavenging, angiogenesis and collagen remodeling

Skin wound healing, particularly diabetic wound healing, is challenging in clinical management. Impaired wound healing is associated with persistent oxidative stress, altered inflammatory responses, unsatisfactory angiogenesis and epithelialization. Magnesium ascorbyl phosphate (MAP), which is an ascorbic acid derivative and active ingredient in cosmetics, has been reported to scavenge reactive oxygen species (ROS), and is considered a potential therapeutic agent for diabetic wounds. Herein, we report a hybrid gelatin-MAP scaffolds that can reduces oxidative stress damage, enhances angiogenesis and collagen remodeling to accelerate diabetic wound repair. Preliminary insights based on network pharmacology indicate that MAP may accelerate wound repair through multiple biological pathways, including extracellular matrix remodeling and anti-apoptosis. In vitro studies showed that the hybrid hydrogel scaffold had suitable mechanical properties, excellent biocompatibility and bioactivity. Further animal experiments demonstrated that the hydrogel accelerated full-thickness wound repair in diabetic mice (repair rate MAP vs Control=91.791±3.306 % vs 62.962±6.758 %) through antioxidant, neuroangiogenesis, collagen remodeling, and up-regulated the expression of the related factors COL-1, CD31, VEGF, and CGRP. Overall, we developed a bioactive hybrid hydrogel encapsulating MAP that synergistically promotes diabetic wound repair through multiple biological effects. This potentially integrated therapeutic scaffold may enrich future surgical approaches for treating diabetic wounds.