Wound microenvironment self-adaptive hydrogel with efficient angiogenesis for promoting diabetic wound healing

Comparative efficacy of different functional hydrogel dressings in healing diabetic foot ulcer: A systematic review and network meta-analysis

AIMS

Functional hydrogel dressings offer a promising therapeutic approach, and optimizing their formulations is crucial for improving diabetic foot ulcers (DFUs) outcomes. This study explores the comparative efficacy of different functional hydrogel dressings in DFUs treatment.

MATERIALS AND METHODS

We conducted a systematic review and Bayesian network meta-analysis of randomized controlled trials evaluating functional hydrogel dressings for DFUs treatment. A comprehensive search was performed across PubMed, Embase, CENTRAL, CNKI and Web of Science from inception to June 2024. Bayesian network meta-analysis was employed to synthesize and compare the relative efficacy of hydrogel interventions, defined as the number of patients with complete wound closure.

RESULTS

In total, 23 studies involving 1671 patients with DFUs were included. The analysis revealed that immuno-regulating hydrogels (IRHs) had the highest effect estimate (2.2, 95% CI: 1.6, 3.2), compared with anti-bacterial hydrogels (ABHs) ranked last (1.3, 95% CI: 0.78, 2.3). Multi-functional hydrogels (MFHs) and proliferation-promoting hydrogels (PPHs) displayed intermediate effects (1.7, 95% CI: 1.2, 2.4). The relative efficacy ranking was IRH > MFH/PPH > ABH > placebo. The risk of adverse events was lower in functional hydrogel groups relative to placebo (0.75, 95% CI: 0.56, 0.96). Node-splitting analysis confirmed the consistency between direct and indirect evidence for IRH versus ABH. A funnel plot analysis indicated no significant publication bias, affirming the robustness of our findings.

CONCLUSION

This study provides a comprehensive evaluation of functional hydrogel dressings for DFUs treatment, highlighting the potential of IRH as the most effective option. These insights will guide future research and clinical applications to improve DFUs management.

An NIR-responsive "4A hydrogel" encapsulating wormwood essential oil: through antibacterial, antioxidant, anti-inflammation, and angiogenic to promote diabetic wound healing

The incorporation of hydrogels with biocompatible functional components to develop wound dressings exhibiting potent antibacterial, antioxidant, anti-inflammatory, and angiogenic properties to promote diabetic wound healing is highly desirable yet continues to pose a significant challenge. In this study, wormwood essential oil (WEO) is successfully encapsulated within black phosphorus (BP) using a physical extrusion technique. Subsequently, this composite is encapsulated within biocompatible gelatin methacrylate (GelMA) and hyaluronic acid methacrylate (HAMA) hydrogels to create multifunctional hydrogel dressing (WEO@BP/GH). In comparison to traditional hydrogels, BP enhances the encapsulation stability of WEO and improves the microenvironmental regulation capabilities through NIR-triggered release of WEO. Systemic in vitro experiments demonstrate that synergistic interaction between the diverse bioactive components of WEO and photothermal effects of BP results in highly effective antibacterial activities against S. aureus and E. coli, antioxidant of scavenging ROS, anti-inflammation of downregulating M1/M2 macrophages ratio, and angiogenic properties. Moreover, the in vivo tests demonstrate that WEO@BP/GH hydrogel significantly enhances high-performance diabetic wound repair through the acceleration of hemostasis, promotion of collagen deposition, regulation of inflammatory responses, and facilitation of vascularization. The findings indicate that WEO@BP/GH hydrogel holds considerable promise as a candidate for microenvironment regulation and effective diabetic wound healing across various clinical applications.

Dual-Network Hydrogel Loaded With ROS-activated Hydrogen Sulfide Donor to Accelerate Wound Healing and Inhibit Scar Production

The wound healing process consists of four continuous and overlapping stages-hemostasis, inflammation, proliferation, and remodeling-involving a variety of cells, growth factors, and the extracellular matrix. In recent years, growing evidence has shown that enhancing endogenous hydrogen sulfide (H2S) synthesis or providing exogenous H2S can promote angiogenesis, inhibit inflammation, reduce excessive oxidative stress, and support collagen deposition. However, the administration of exogenous H2S often presents challenges related to controlling its release duration and achieving targeted delivery. To achieve controlled and site-specific delivery of H2S to the wound area, a dual-network cross-linked injectable hydrogel formed by grafted ε-poly-L-lysine (designed as EG) and oxidized dextran (OD) (EGODF) loaded with a hydrogen sulfide donor (HSDF-NH2) to study its potential in wound healing is developed. The hydrogel exhibits excellent injectability, self-healing capability, and mechanical strength. Upon reactive oxygen species (ROS) stimulation, HSDF-NH2 releases both self-reporter fluorescence (HSDG-NH2) and H2S. Changes in the self-reporter fluorescence signal reflect H2S production and its entry into the body to exert therapeutic effects. Finally, using a wound model and a hypertrophic scar repair model, it is demonstrated that EGODF hydrogel is effective in promoting wound healing and inhibiting scar production.

Injectable hydrogels for treating skin injuries in diabetic animal models: a systematic review

Purpose

One of the main causes of chronic wounds is diabetes mellitus (DM), a metabolic disease characterized by chronic hyperglycemia. In this context, hydrogels have been used as a promising treatment for stimulating tissue ingrowth and healing in these injuries. This systematic review aimed to evaluate the findings of studies that investigated the effects of injectable hydrogels of various origins on skin wound healing using in vivo experimental models in diabetic rats.

Methods

This review was conducted in March 2023 using two databases, PubMed and Scopus, following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines and the SYRCLE (Systematic Review Centre for Laboratory Animal Experimentation). The following Medical Subject Headings (MeSH) descriptors were used: "hydrogels," "injectable," "in vivo," "diabetes mellitus," and "skin wound dressing."

Results

After the eligibility assessment, 12 studies were selected and analyzed from an initial 95 articles identified across databases. The studies demonstrated that a variety of injectable hydrogels showed biocompatibility and bioactivity, effectively interacting with skin tissue in diabetic wound models. These hydrogels were assessed for their compositions, structural properties, and in vivo effects on wound closure, inflammation reduction, and collagen deposition. Also, immunofluorescence analyses revealed increased expression of neoangiogenesis markers and reduced inflammatory factors in treated groups, highlighting the hydrogels potential for enhancing skin healing in diabetic wounds.

Conclusion

Injectable hydrogels show significant potential as an effective treatment for diabetic skin wounds, though further clinical studies are needed to fully assess their biological performance.

GLUT1-mediated HMGB1 O-GlcNAcylation drives hyperglycemia-Induced neutrophil extracellular trap networks formation via TLR4 signaling and exacerbates fibroblast inflammation

Neutrophil extracellular traps (NETs) exacerbate fibroblast inflammatory injury in hyperglycemic conditions, yet the role of glucose metabolism and O-linked N-acetylglucosamine (O-GlcNAc) glycosylation in this process remains unclear. Here, we investigate how glucose transporter protein 1 (GLUT1)-dependent glucose uptake regulates O-GlcNAcylation of high-mobility group box 1 (HMGB1) to drive NET formation and fibroblast inflammation. Mouse peripheral blood neutrophils (MPBN) were treated with high glucose (25 mM) and phorbol ester (PMA) to induce NETs. Co-culture of NETs with mouse fibroblasts (L929) reduced fibroblast viability by 1.1 fold and migration by 1.2 fold within 24 h, while upregulating pro-inflammatory cytokines (Tumor Necrosis Factor-α (TNF-α): +1.3-fold; Interleukin-1β (IL-1β): +1.1-fold; Interleukin-6 (IL-6): +1.1-fold) and suppressing collagen synthesis (Collagen I (COL-I): - 1.7-fold; Collagen III (COL-III): -2.5-fold). Critically, high glucose elevated GLUT1 expression in MPBN (+ 1.2-fold), further amplified under co-culture conditions(+ 1.2-fold). Functional assays using GLUT1 knockdown confirmed that GLUT1 activity was essential for glucose uptake and subsequent O-GlcNAc modification of HMGB1, stabilizing its expression. Enhanced O-GlcNAcylation of high-mobility group box 1 (HMGB1) directly promoted NET formation, evidenced by elevated markers (Citrullinated histone H3 (Cit-H3): +1.6-fold; Myeloperoxidase (MPO): +1.2-fold; Circulating free DNA (cfDNA): +2-fold) and activation of c-Jun N-terminal kinase (JNK)/p38 phosphorylation. These effects were abolished by toll-like receptor 4 (TLR4) inhibition, linking HMGB1-TLR4 signaling to NET-driven inflammation. Mechanistically, GLUT1 knockdown reduced HMGB1 O-GlcNAcylation and reversed NET-induced fibroblast dysfunction. Our findings provide direct evidence that hyperglycemia enhances GLUT1 expression and activity, driving HMGB1 O-GlcNAcylation to maintain NETs formation through TLR4, which promotes fibroblast inflammatory injury. This pathway highlights a metabolic-inflammation axis relevant to diabetic complications.

Baicalein based nano-delivery system restores mitochondrial homeostasis through PPAR signaling pathway to promote wound healing in diabetes

Wound healing in diabetes is a substantial clinical challenge due to the hyperglycemic microenvironment, high pH, bacterial infection, persistent inflammation, and impaired cellular functions, attributed to mitochondrial dysfunction. Here, we have developed an injectable photo-crosslinking nanocomposite hydrogel (BA/GOx@ZIF-8@GelMA, BGZ@GelMA) with baicalein (BA) and glucose oxidase (GOx) loaded Zinc metal-organic framework (ZIF-8) based on methacrylated gelatin (GelMA) to accelerate diabetic infected wound healing by regulating subcellular and cellular functions. The combination of ZIF-8 and BA gives the hydrogel excellent antibacterial properties. A high blood sugar environment triggers the release of GOx in BGZ@GelMA, reducing local glucose and pH, producing hydrogen peroxide (H2O2), and releasing BA and Zinc ions (Zn2+). This process provides a suitable microenvironment for wound healing. Zn2+ can significantly inhibit the proliferation of Staphylococcus aureus (S.aureus) and Escherichia coli (E.coli). The released BA can clear ROS in cells and mitochondria, restore mitochondrial function and stability, and make the hydrogel fundamentally improve the cell function damage induced by hyperglycemia, and ultimately promote cell proliferation, migration and angiogenesis. In general, our multifunctional nanocomposite hydrogel provides a new strategy for diabetes wound healing at the subcellular and cellular functional levels.

Injectable Hydrogel for Cardiac Repair via Dual Inhibition of Ferroptosis and Oxidative Stress

Ferroptosis plays a significant role in ischemic heart disease by exacerbating myocardial injury through oxidative stress, iron metabolism disorder, and inflammation. Herein, we develop an injectable hydrogel (HSD/DFO@GMs) with antiferroptosis and antioxidant properties for cardiac repair. The hydrogel is composed of dopamine-grafted oxidized hyaluronic acid, adipic acid dihydrazide grafted hyaluronic acid, and deferoxamine loaded gelatin microsphere, connected via a dynamic Schiff base bond. This hydrogel exhibits a favorable injectability and stable mechanical properties. It effectively chelates Fe2+ and scavenges the reactive oxygen species (ROS), creating a conducive microenvironment for cardiac repair. The dynamic Schiff base bond and gelatin matrix respond to the weakly acidic and MMP-2-rich microenvironment postinjury, enabling on-demand release of DFO in the injured myocardium. In vitro experiments indicate that the hydrogel significantly inhibits the ferroptosis and oxidative stress damage in H9C2 cardiomyocytes under a hypoxia/reoxygenation microenvironment. In an in vivo ischemia-reperfusion model, the HSD/DFO@GMs hydrogel reduces oxidative stress, modulates intracellular labile iron pool levels, and promotes revascularization, ultimately improving cardiac function. Overall, the HSD/DFO@GMs hydrogel provides a new strategy to improve cardiac repair by inhibiting ferroptosis and mitigating oxidative stress damage.

Electroactive Electrospun Nanofibrous Scaffolds: Innovative Approaches for Improved Skin Wound Healing

The incidence and burden of skin wounds, especially chronic and complex wounds, have a profound impact on healthcare. Effective wound healing strategies require a multidisciplinary approach, and advances in materials science and bioengineering have paved the way for the development of novel wound healing dressing. In this context, electrospun nanofibers can mimic the architecture of the natural extracellular matrix and provide new opportunities for wound healing. Inspired by the bioelectric phenomena in the human body, electrospun nanofibrous scaffolds with electroactive characteristics are gaining widespread attention and gradually emerging. To this end, this review first summarizes the basic process of wound healing, the causes of chronic wounds, and the current status of clinical treatment, highlighting the urgency and importance of wound dressings. Then, the biological effects of electric fields, the preparation materials, and manufacturing techniques of electroactive electrospun nanofibrous (EEN) scaffolds are discussed. The latest progress of EEN scaffolds in enhancing skin wound healing is systematically reviewed, mainly including treatment and monitoring. Finally, the importance of EEN scaffold strategies to enhance wound healing is emphasized, and the challenges and prospects of EEN scaffolds are summarized.

Resveratrol Promotes Wound Healing by Enhancing Angiogenesis via Inhibition of Ferroptosis

Diabetic wound healing critically depends on functional endothelial cells for angiogenesis, yet the hyperglycemic microenvironment induces endothelial dysfunction through oxidative stress, inflammation, and senescence. Although ferroptosis has been recognized as a critical pathological factor contributing to impaired diabetic wound healing, the therapeutic potential of resveratrol (Res), a natural polyphenol with well-documented antioxidant and anti-ferroptotic properties, remains underexplored in this context. This study aimed to investigate the protective effects of Res on endothelial cells and elucidate its underlying mechanisms in diabetic wound healing. In vitro experiments systematically evaluated Res's impact on cellular inflammatory responses, senescence levels, and angiogenic capacity. Subsequent in vivo studies assessed Res's therapeutic potential by monitoring diabetic wound healing progression and analyzing associated histological changes. To clarify the mechanisms underlying Res's promotion of diabetic wound healing, we conducted comprehensive analyses measuring intracellular reactive oxygen species, lipid peroxidation levels, mitochondrial membrane potential and morphology, ferroptosis-related marker expression, and upstream signaling pathway regulation. Res significantly reduced HG-induced inflammatory responses and cellular senescence in human umbilical vein endothelial cells while enhancing their angiogenic potential in vitro. In vivo results showed that Res not only markedly accelerated diabetic wound healing but also demonstrated multiple beneficial effects, including effective suppression of cellular senescence, decreased ferroptosis levels, and significantly promoted angiogenesis. Mechanistic investigations confirmed that Res achieves these effects by inhibiting ferroptosis through activation of the PI3K-AKT-Nrf2 signaling axis. Our results demonstrate that Res protects endothelial cells from HG-induced ferroptosis by activating PI3K-AKT-Nrf2 signaling, thereby promoting angiogenesis and diabetic wound healing. These findings highlight Res as a promising therapeutic candidate for impaired diabetic wound repair and justify further clinical investigation.

Regenerating Family Protein 3α-Loaded Responsive Hydrogel Accelerates Infected Diabetic Wound Healing

Chronic diabetic wounds are characterized by a persistent inflammatory response, severe oxidative stress, and excessive proteolysis, creating an inhibitory microenvironment that impedes tissue regeneration. Recent findings indicate that regenerating family protein 3α (Reg3α) can promote keratinocyte proliferation and epidermal neogenesis, while also exhibiting antimicrobial properties. However, the low bioavailability significantly limits the clinical use of Reg3α in the treatment of chronic diabetic wounds. This study presents a glucose and ROS dual-responsive hydrogel loaded with Reg3α, which is synthesized by phenylboronic acid-modified hyaluronic acid (HAP) and polyvinyl alcohol (PVA). The Reg3α-loaded hydrogel (HAP-PVA/Reg3α), which exhibits favorable viscoelastic properties to adapt to wound application, promotes cell proliferation and demonstrates antibacterial and anti-inflammatory activities without inducing cytotoxicity or hemolysis in vitro. In diabetic mice, HAP-PVA/Reg3α effectively accelerates Staphylococcus aureus (S. aureus)-infected wound healing by alleviating bacterial infection, reducing inflammation, and facilitating collagen deposition. The result of RNA-seq suggests a negative regulation of M0 macrophages in the HAP-PVA/Reg3α group, which is presumably associated with their transformation into anti-inflammatory M2 macrophages. Meanwhile, serum pro-inflammatory IL-6 level is significantly decreased in Reg3α and HAP-PVA/Reg3α groups. In conclusion, HAP-PVA/Reg3α as a multifunctional hydrogel has significant potential for the treatment of chronic infected diabetic wounds.

Polyphenol Conductive Nanozyme-Enhanced Redox Hydrogel Coupled with Vagus Nerve Electrical Stimulation for Diabetic Wound Repair

Diabetic wound repair is complicated by excessive oxidative reactions, bacterial infection, and persistent inflammation. Nanozyme-incorporated hydrogels have shown potential to facilitate diabetic wound repair. This study developed a polyphenol-conductive nanozyme-enhanced redox hydrogel composed of dopamine-grafted fish gelatin, methacrylated silk fibroin, and dopamine-mediated poly(3,4-ethylenedioxythiophene) (PDA-Fe-PEDOT) conductive nanozymes. The PDA-Fe-PEDOT conductive nanozyme confers electrical conductivity to the hydrogel, enabling it to couple endogenous electrical signals at the wound site and transmit exogenous electrical signals to the wound. Additionally, the PDA-Fe-PEDOT nanozyme also imparts hydrogel peroxidase-like activity, catalyzing hydrogen peroxide to generate hydroxyl radicals that effectively inhibit bacterial infection. The hydrogel also exhibits sustained antioxidant effects under exogenous electrical stimulation, reducing intracellular reactive oxygen species and protecting cells from oxidative stress. In vivo experiments demonstrated that vagus nerve electrical stimulation (VNS) regulates systemic inflammation, while the polyphenol-conductive nanozyme-enhanced redox hydrogel regulates local inflammation in diabetic wounds. The combination of polyphenol-conductive nanozyme-enhanced hydrogels and VNS synergistically promoted collagen deposition, angiogenesis, and nerve repair, leading to high-quality wound healing in diabetic wounds, offering an innovative tissue repair strategy that integrates natural dressings with exogenous stimulation.

Self-Powered Thermoelectric Hydrogels Accelerate Wound Healing

Electrical stimulation (ES) serves as a biological cue that regulates critical cellular processes, including proliferation and migration, offering an effective approach to accelerating wound healing. Thermoelectrics, capable of generating electricity by exploiting the temperature difference between skin and the surrounding environment without external energy input, present a promising avenue for ES-based therapies. Herein, we developed Ag2Se@gelatin methacrylate (Ag2Se@GelMA) thermoelectric hydrogels with high room-temperature thermoelectric performance and employed them as self-powered ES devices for wound repair. Systematic in vivo and in vitro investigations elucidated their biological mechanisms for enhancing wound healing. Our findings reveal that the Ag2Se@GelMA thermoelectric hydrogels can significantly accelerate the wound closure by amplifying the endogenous electric field, thereby promoting cell proliferation, migration, and angiogenesis. Comprehensive in vitro experiments demonstrated that ES generated by the hydrogels activates voltage-gated calcium ion channels, elevating intracellular Ca2+ levels and enhancing mitochondrial functions through the Ca2+/CaMKKβ/AMPK/Nrf2 pathway. This cascade improves mitochondrial dynamics and angiogenesis, thereby accelerating tissue regeneration. The newly developed Ag2Se@GelMA thermoelectric hydrogels represent a marked progress in wound dressing technology with the potential to improve clinical strategies in tissue engineering and regenerative medicine.

Chlorogenic acid-assisted dopamine‑sodium alginate composite nanofiber membranes for promoting wound healing

Developing safe and effective novel wound dressings to enhance full-thickness skin wound regeneration is highly desirable. In this study, we firstly incorporated chlorogenic acid (CA) into dopamine (DA) functionalized alginate (Alg-DA) conjugates and utilized polyvinyl alcohol (PVA) as the carrier polymer to fabricate a series of novel multifunctional composite nanofiber membranes (PVA/Alg-DA/CA) for promoting wound healing. These nanofiber membranes exhibited high water absorption, water vapor transmission rate, porosity, and hydrophilicity properties. The CA endowed the PVA/Alg-DA/CA membranes with excellent antibacterial properties, and the superior antioxidant activity to effectively protect cells from oxidative damage. Meanwhile, capitalizing on the unique nanofiber architecture, as well as the inherent biofunctional activities of CA and Alg-DA, these membranes exhibited remarkable biocompatibility, fostering a conducive environment for fibroblast adhesion and proliferation. Moreover, wound healing assessments and histopathological analyses revealed that composite membranes could promote neovascularization and tissue remodeling, and thus accelerating wound closure in the mouse full-thickness wound defect model. Additionally, the upregulation of key healing markers including CD31 and TGF-β1 protein expressions, further corroborated the ability of multifunctional membrane to stimulate the wound healing cascade. This multifunctional membranes with biosafety and therapeutic outcomes are a promising candidate for wound dressing to promote skin repair.

Multifunctional dynamic chitosan-guar gum nanocomposite hydrogels in infection and diabetic wound healing

Traditional wound care methods are less effective for infectious and diabetic wounds, highlighting an urgent need for effective strategies. The study aimed to design a self-healing hydrogel with antibacterial, antioxidant, and photothermal capabilities to treat infectious and diabetic wounds. Silver nanoparticles (AgNPs) were loaded into mesoporous polydopamine (MPDA) nanoparticles to form Ag@MPDA nanoparticles. Ag@MPDA was incorporated into the cationic guar gum-chitosan-boric acid (CCB) hydrogel to obtain the PA-CCB hydrogel. PA-CCB hydrogel exhibited excellent self-healing and adhesive properties, adapting well to the dynamic wound environment. PA-CCB hydrogel combined with photothermal therapy (PTT) could effectively eradicated E. coli (99.9 %) and S. aureus (99.7 %). The PA-CCB hydrogel reduced excessive reactive oxygen species and promoted the migration of fibroblasts in vitro. In the infected mouse wound models, the PA-CCB hydrogel effectively inhibited bacteria. After combining with PTT, the antibacterial ability of the PA-CCB hydrogel was further enhanced. In the diabetic mouse wound models, the PA-CCB hydrogel reduced the inflammatory level of wound tissue. In both models, after combining with PTT, the PA-CCB hydrogel exhibited further improvements in angiogenesis, collagen deposition, and re-epithelialization. By integrating multifunctional hydrogel with PTT, the PA-CCB hydrogel exhibited broad application potential for infectious and diabetic wounds.

Engineered Exosomes Loaded in Intrinsic Immunomodulatory Hydrogels with Promoting Angiogenesis for Programmed Therapy of Diabetic Wounds

Inducing rapid angiogenesis by delivering specific biological cues is critical for diabetic wound healing. Nevertheless, the angiogenesis is hindered by the inflammatory microenvironment, and the immune cells fail to orchestrate immune responses to wound healing. Herein, vascular endothelial growth factor (VEGF) plasmids-loaded macrophage exosomes (Exos) were fabricated and enfolded in injectable self-healing hydrogels for programmed therapy of diabetic wounds through sequentially intrinsically modulating the inflammatory microenvironment and promoting angiogenesis. The hydrogels, formed via dynamical Schiff base reactions using modified polysaccharides, intrinsically regulate the inflammatory microenvironment via broad-spectrum antioxidant activity and macrophage phenotype regulation, restoring tissue redox and immune homeostasis. Furthermore, the hydrogels can stabilize and release the engineered exosomes. By integration of generation and release of VEGF by plasmids-loaded macrophage Exos, VEGF secretion by M2 macrophages, and enhanced binding of VEGF to VEGF receptor 2 by high affinity of sulfated chitosan, the intrinsic immunomodulatory hydrogels effectively promote the angiogenesis and accelerate the diabetic wound healing process.

Mesenchymal stem cells and their exosomes: a novel approach to skin regeneration via signaling pathways activation

Accelerating wound healing is a crucial objective in surgical and regenerative medicine. The wound healing process involves three key stages: inflammation, cell proliferation, and tissue repair. Mesenchymal stem cells (MSCs) have demonstrated significant therapeutic potential in promoting tissue regeneration, particularly by enhancing epidermal cell migration and proliferation. However, the precise molecular mechanisms underlying MSC-mediated wound healing remain unclear. This review highlights the pivotal role of MSCs and their exosomes in wound repair, with a specific focus on critical signaling pathways, including PI3K/Akt, WNT/β-catenin, Notch, and MAPK. These pathways regulate essential cellular processes such as proliferation, differentiation, and angiogenesis. Moreover, in vitro and in vivo studies reveal that MSCs accelerate wound closure, enhance collagen deposition, and modulate immune responses, contributing to improved tissue regeneration. Understanding these mechanisms provides valuable insights into MSC-based therapeutic strategies for enhancing wound healing.

A 3D-printed grid-like hyaluronic acid based hydrogel loaded with deferoxamine as wound dressing promotes diabetic wound healing

The rigid inflammatory microenvironment and impaired vascular regeneration capability are two core barriers for diabetic wound healing. As hydrogels have unique 3D porous networks and hydrophilic structure, which can facilitate oxygen exchange and function as a functional delivery system for loading cells and other biomolecules, hydrogels have clinical potentials for treating diabetic wounds. Here we developed a 3D-printed grid-like hydrogel composed of hyaluronic acid-based acrylamide (HA-AM), oxidized mannan oligosaccharide (OMOS), and deferoxamine (DFO). We demonstrated that the developed hydrogel (HA-AM/OMOS@DFO) exhibited favorable swelling, reasonable degradation time, good biocompatibility and structural support strength. Moreover, the HA-AM/OMOS@DFO hydrogel exerted antioxidative effects and inflammatory regulation functions. In addition, the loaded DFO effectively promoted vascular regeneration in the wound, which facilitated the healing of chronic diabetic wounds. Findings suggested the developed material has potential for clinical application in treating diabetic wounds.

Recent advances in hyaluronic acid-based hydrogels for diabetic wound healing

Diabetic wound healing represents a complex biological challenge, often impeded by disrupted cellular processes and dysregulated inflammation, which can lead to chronic and non-healing wounds. Given the significant burden on patients and the healthcare system, there is an urgent need for advanced therapeutic strategies. Hyaluronic acid (HA)-based hydrogels have emerged as a promising solution due to their biocompatibility, biodegradability, and unique physiological functions. This review aims to provide a comprehensive overview of recent advances in HA-based hydrogels, highlighting their potential in addressing diabetic wound complications. Specifically, it examines challenges such as hyperglycemia-induced oxidative stress and impaired cellular signaling within the intricate diabetic wound microenvironment. Moreover, the review explores the composition and properties of HA, including its adhesive capabilities and role in reducing surgical trauma. Various crosslinking strategies and functional modifications are also discussed to endow HA-based hydrogels with antioxidant, antimicrobial, and growth factor-releasing capabilities. By summarizing the latest research and identifying areas for further exploration, this review contributes to the development of more effective HA-based hydrogel formulations for diabetic wound healing.

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.

Nature-derived microneedles with metal-polyphenolic networks encapsulation for chronic soft tissue defects repair: Responding and remodeling the regenerative microenvironment

The treatment outcomes of traditional patches for chronic soft tissue defects (CSTDs) are unsatisfactory in clinical, owing to the lack of intrinsic bioactivities to orchestrate the intricate regenerative process. To tackle this deficiency, nature-derived microneedles (NMs) composed of silk methacrylate and snail mucus are developed in this study. The resultant NMs have excellent mechanical strength and biological adhesiveness, ensuring suture-free but reliable fixation on implanted site. To enhance the intrinsic bioactivities, metal-polyphenolic networks (MPNs) coordinated from copper (Cu) and curcumin (Cur) are designed and encapsulated into NMs. Cu-Cur MPNs harness the anti-oxidative and anti-inflammatory properties of Cur with the pro-angiogenic properties of Cu, targeting different negative aspects in CSTDs repair. Furthermore, the pH-responsive disassembly of Cu-Cur MPNs can respond to the acidic microenvironment, allowing for burst-free and on-demand drug delivery. Both in-vitro and in-vivo experiments demonstrate that NMs with Cu-Cur MPNs encapsulation (Cu-Cur-NMs) can restore redox homeostasis, reduce inflammatory response, and promote blood vessel formation, thus remodeling the regenerative microenvironment to greatly improve the repair quality of CSTDs. Therefore, the combined advantages of microneedles-based patch system and MPNs-based nanotherapeutic agent are explored for the first time, and our proposed Cu-Cur-NMs represent a multifunctional and promising device for CSTDs repair.

Tissue-Adhesive and Antibacterial Hydrogel Promotes MDR Bacteria-Infected Diabetic Wound Healing via Disrupting Bacterial Biofilm, Scavenging ROS and Promoting Angiogenesis

Effective treatment of diabetic wounds remains challenging because of multidrug-resistant (MDR) bacterial infections, excessive oxidative stress, and impaired angiogenesis. In this study, a tissue-adhesive and antibacterial hydrogel incorporating MXene and deferoxamine (DFO)-loaded microspheres is developed for the treatment of MDR bacteria-infected diabetic wounds. The hydrogel is built based on covalent crosslinking between ε-poly(L-lysine) and o-phthalaldehyde-terminated four-arm poly(ethylene glycol). The hydrogel exhibited excellent mechanical properties, tissue adhesion strength, biocompatibility, and biodegradability. Under near-infrared (NIR) irradiation, the MXene converted light into heat and elevated the local temperature rapidly, enabling the rapid disintegration of MDR bacterial biofilms. Simultaneously, the hydrogel exerted inherent antibacterial activity, persistently killing planktonic bacteria, and effectively controlling wound infections. The encapsulated DFO is then released from the hydrogel in a sustained and controlled manner, and promoted angiogenesis during diabetic wound healing. Additionally, MXenes can scavenge excessive reactive oxygen species and alleviate wound inflammation. In the methicillin-resistant Staphylococcus aureus-infected diabetic wound model in mice, the composite hydrogel along with NIR irradiation efficiently reduced the infectious bacteria, and accelerated the wound healing by promoting angiogenesis and alleviating inflammation. This composite hydrogel has great clinical potential for the treatment of diabetic wounds, particularly in challenging healing environments involving motion and infection.

Proanthocyanidin capsules remodel the ROS microenvironment via regulating MAPK signaling for accelerating diabetic wound healing

Defective diabetic wound healing is a major clinical challenge, where hyperglycemia at the wound site induces excessive reactive oxygen species (ROS) which activate the MAPK pathway (particularly p38 MAPK), resulting in sustained release of inflammatory factors and cellular damage/apoptosis. Polyphenols are efficient ROS scavengers which reduce the level of inflammation at the wound site and promote wound healing, but the low bioavailability limits their biomedical application. This study developed a simple and highly efficient method for preparing proanthocyanidin (PC) capsules through hydrogen bonding and hydrophobic interactions among PC molecules. PC capsules can continuously scavenge free radicals and release proanthocyanidins, significantly enhancing their bioavailability. A single dose of PC capsules accelerates wound healing in diabetic mice by regulating the p38 MAPK signaling cascade, reducing inflammatory mediator concentration, inhibiting cell apoptosis, and remodeling the wound microenvironment. This research makes an important contribution to the field of enhancing polyphenol bioavailability for wound healing and reveals the potential of modulating the MAPK pathway for treating other inflammation and oxidative stress-related diseases.

Bioactivity and biomedical applications of pomegranate peel extract: a comprehensive review

Pomegranate peel is a by-product generated during the processing of pomegranate (Punica granatum L.) fruit, accounting for approximately 50% of the total mass of the fruit. Although pomegranate peel is usually regarded as waste, it is rich in various bioactive metabolites such as polyphenols, tannins, and flavonoids, demonstrating significant medicinal and nutritional value. In recent years, Pomegranate peel extract (PPE) has shown broad application prospects in the biomedical field due to its multiple effects, including antioxidant, anti-inflammatory, antibacterial, anti-apoptotic properties, and promotion of cell regeneration. This review consolidates the major bioactive metabolites of PPE and explores its applications in biomedical materials, including nanodrug carriers, hydrogels, and tissue engineering scaffolds. By synthesizing the existing literature, we delve into the potential value of PPE in biomedicine, the challenges currently encountered, and the future directions for research. The aim of this review is to provide a scientific basis for optimizing the utilization of PPE and to facilitate its broader application in the biomedical field.

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.

A Narrative Review of Bioactive Hydrogel Microspheres: Ingredients, Modifications, Fabrications, Biological Functions, and Applications

Hydrogel microspheres are important in regenerative medicine and tissue engineering, acting as cargos of cells, drugs, growth factors, bio-inks for 3D printing, and medical devices. The antimicrobial and anti-inflammatory characteristics of hydrogel microspheres are good for treating injured tissues. However, the biological properties of hydrogel microspheres should be modified for optimal treatment of various body parts with different physiological and biochemical environments. In addition, specific preparation methods are required to produce customized hydrogel microspheres with different shapes and sizes for various clinical applications. Herein, the advances in hydrogel microspheres for biomedical applications are reviewed. Synthesis methods for hydrogel precursor solutions, manufacturing methods, and strategies for enhancing the biological functions of these hydrogel microspheres are described. The involvement of bioactive hydrogel microspheres in tissue repair is also discussed. This review anticipates fostering more insights into the design, production, and application of hydrogel microspheres in biomedicine.

Optimizing risk management for post-amputation wound complications in diabetic patients: Focus on glycemic and immunosuppressive control

This study highlights the importance of identifying and addressing risk factors associated with wound complications following transtibial amputation in diabetic patients. These amputations, often necessitated by severe diabetic foot ulcers, carry significant risks of postoperative complications such as infection and delayed wound healing. Elevated hemoglobin A1c levels, indicative of poor glycemic control, and a history of kidney transplantation, due to required immunosuppressive therapy, are key factors influencing these outcomes. This paper emphasizes the need for enhanced glycemic management and personalized postoperative care, particularly for immunocompromised individuals, to minimize complications and improve patient prognosis. Future research should focus on prospective studies to validate targeted interventions and optimize care strategies, ultimately aiming to reduce the healthcare burden associated with diabetic foot complications.

Cellulose nanofiber-reinforced antimicrobial and antioxidant multifunctional hydrogel with self-healing, adhesion for enhanced wound healing

Current conventional wound dressings used for wound healing are often characterized by restricted bioactivity and devoid of multifunctionality resulting in suboptimal treatment and prolonged healing. Despite recent advances, the simultaneous incorporation of excellent flexibility, good mechanical performance, self-healing, bioactivity, and adhesion properties into the dressings without complicating their efficacy while maintaining simple synthesis remains a grand challenge. Herein, we effectively synthesized hybrid hydrogels of cellulose nanofiber (CNF), polyvinyl alcohol (PVA), and curcumin-modified silver nanoparticles (cAg) through a one-step synthesis method based on hydrogen bonds, dynamic boronic ester bonds, and coordinate covalent bonds. A flexible high mechanical strength (tensile stress (231 kPa) and compressive stress (1.23 MPa), self-healing, adhesive, yet highly antioxidant and antimicrobial hydrogel (with improved activity against C. albicans, S. aureus, and E. coli) is successfully obtained. Concentric structure of the micropores endows the hydrogels, good biodegradability, and sustained drug release of silver and curcumin. More remarkably, the designed hydrogel dressings not only significantly enhance cell viability (over 98 %) and cell proliferation but also promote angiogenesis, re-epithelialization, and deposition of collagen, all of which signal wound closure and substantiate the therapeutic effect of CNF/PB/cAg hydrogels in chronic wounds. These findings open up new perspectives for the design of wound healing hydrogels and beyond.

Catalase-like Nanozyme-Hybrid Hydrogels Utilizing Endogenous ROS as an Oxygen Source To Synergically Regulate Oxidative Stress and Hypoxia for Enhanced Diabetic Wound Healing

High levels of reactive oxygen species (ROS) and hypoxia in diabetic wounds significantly hinder the healing process. In this work, a kind of catalase-like nanozyme-hybrid hydrogel was developed to explore the potential of harnessing endogenous excessive ROS as an oxygen source to synergistically regulate oxidative stress and hypoxia, thereby enhancing diabetic wound healing. The hydrogels exhibited rapid degradation and controlled release of ferrihydrite nanozymes in response to oxidative stress, which continuously catalyzed the decomposition of H2O2 to generate oxygen, effectively scavenging ROS and reducing the risk of local oxygen toxicity. The hydrogels relieved intracellular oxidative stress and the hypoxic microenvironment simultaneously in vitro. The hydrogel dressings effectively inhibited oxidative damage at wound sites, promoted epidermis formation and collagen deposition, and significantly accelerated wound healing in db/db mice. Therefore, the catalase-like nanozyme-hybrid hydrogels represent a promising strategy for diabetic wound dressings, addressing both oxidative stress and hypoxia to improve healing outcomes.

Dual ROS/Glucose-Responsive Quercetin-Loaded Supramolecular Hydrogel for Diabetic Wound Healing

Diabetic wound healing remains a significant challenge due to complex pathological mechanisms, including prolonged inflammation, excessive reactive oxygen species (ROS) accumulation, angiogenesis dysfunction, and increased susceptibility to bacterial infection. In this study, we developed a dual ROS/glucose-responsive quercetin-loaded supramolecular hydrogel (GPQ hydrogel) for treating diabetic wounds. The hydrogel was fabricated by incorporating quercetin (QUE) into a guanosine-phenylboronic acid (GP) hydrogel network through dynamic borate ester bonds. Structural characterization revealed the formation of a typical G-quadruplex structure in the GPQ hydrogel. The dual responsiveness to ROS and glucose enabled the controlled release of QUE, effectively addressing the abnormal wound microenvironment in diabetes. In vitro studies demonstrated the excellent antibacterial, antioxidant, anti-inflammatory, and pro-angiogenic properties of the GPQ hydrogel. Furthermore, the in vivo diabetic wound healing study using a full-thickness wound model in streptozotocin-induced diabetic rats showed that the GPQ hydrogel significantly accelerated wound closure, enhanced re-epithelialization and collagen deposition, and promoted angiogenesis compared to the control and GP hydrogel groups. Immunofluorescence analysis confirmed the superior antioxidant and pro-angiogenic effects of the GPQ hydrogel in the wound microenvironment. This study presents a promising multifunctional biomaterial for effectively managing diabetic wounds.

An ATP-activated spatiotemporally controlled hydrogel prodrug system for treating multidrug-resistant bacteria-infected pressure ulcers

Adenosine triphosphate (ATP)-activated prodrug approaches demonstrate potential in antibacterial uses. However, their efficacy frequently faces obstacles due to uncontrolled premature activation and spatiotemporal distribution differences under physiological circumstances. Herein, we present an endogenous ATP-activated prodrug system (termed ISD3) consisting of nanoparticles (indole-3-acetic acid/zeolitic imidazolate framework-8@polydopamine@platinum, IZPP) embedded in a silk fibroin-based hydrogel, aimed at treating multidrug-resistant (MDR) bacteria-infected pressure ulcers. Initially, an ultraviolet-triggered adhesive ISD3 barrier is formed over the pressure ulcer wound by a simple local injection. Subsequently, the bacteria-secreted ATP prompts the degradation of IZPP, allowing the loaded IAA prodrug and nanozyme to encounter spatiotemporally on a single carrier, thereby efficiently generating reactive oxygen species (ROS). Exposure to 808 nm near-infrared light enhances the catalytic reaction speed, boosting ROS levels for stronger antibacterial action. Once optimal antibacterial action is reached, ISD3 switches to a dormant state, halting any further ROS production. Moreover, the bioactive components in ISD3 can exert anti-inflammatory functions, aiding in pressure ulcer recovery. Overall, our research introduces a hydrogel prodrug strategy activated by bacterial endogenous ATP, which precisely manages ROS generation and accelerates the recovery of MDR bacteria-infected pressure ulcers.

Nanoengineered Self-Assembling Peptides with Increased Proteolytic Stability Promote Wound Healing

The copper complex of the tripeptide glycine-histidine-lysine (GHK) has proven benefits in wound healing and tissue remodeling by promoting blood vessel growth and increasing skin oxygen levels, but its activity is reduced in body fluids due to fast proteolytic cleavage. Herein, we designed several peptides that bear the GHK sequence and can self-assemble into supramolecular nanostructures aiming for enhanced bioactivity. The design involves a phenylalanine (F) backbone known for its ability to form supramolecular assemblies. We tested either coassembly between the structural peptide F4D and the functional sequence GHK or assembly of covalently bound peptides, in which the GHK is bound via the glycine (F4D-GHK) or lysine (F4D-KHG, i.e., inverted GHK sequence). All tested peptides assembled into nanotapes, but their resistance to proteolytic degradation was different: covalently bound peptides generated more stable assemblies. Wound healing assays demonstrated that the supramolecular structures have enhanced bioactivity when compared to GHK alone. Multiplex immunoassay analyses demonstrated the secretion of key regulators of the healing process, such as cytokines, matrix metalloproteinases, and growth factors. Altogether our data show that incorporation of GHK/KHG into supramolecular structures improves its stability, bioactivity, and efficacy in promoting wound healing.

Angiogenesis during diabetic wound repair: from mechanism to therapy opportunity

Diabetes mellitus, a pervasive chronic metabolic disorder, is often associated with complications such as impaired wound healing. Various factors, most notably vascular deficiency, govern the wound repair process in diabetic patients, significantly impeding diabetic wound healing; therefore, angiogenesis and its role in diabetic wound repair have emerged as important areas of research. This review aims to delve into the mechanisms of angiogenesis, the effects of diabetes on angiogenesis, and the association between angiogenesis and diabetic wound repair. This will ultimately offer valuable guidance regarding the ideal timing of diabetic wound treatment in a clinical setting.

Neurovascularization inhibiting dual responsive hydrogel for alleviating the progression of osteoarthritis

Treating osteoarthritis (OA) associated pain is a challenge with the potential to significantly improve patients lives. Here, we report on a hydrogel for extracellular RNA scavenging and releasing bevacizumab to block neurovascularization at the osteochondral interface, thereby mitigating OA pain and disease progression. The hydrogel is formed by cross-linking aldehyde-phenylboronic acid-modified sodium alginate/polyethyleneimine-grafted protocatechuic acid (OSAP/PPCA) and bevacizumab sustained-release nanoparticles (BGN@Be), termed OSPPB. The dynamic Schiff base bonds and boronic ester bonds allow for injectability, self-healing, and pH/reactive oxygen species dual responsiveness. The OSPPB hydrogel can significantly inhibit angiogenesis and neurogenesis in vitro. In an in vivo OA model, intraarticular injection of OSPPB accelerates the healing process of condyles and alleviates chronic pain by inhibiting neurovascularization at the osteochondral interface. The injectable hydrogel represents a promising technique to treat OA and OA associated pain.

Injectable Nanocomposite Hydrogel for Accelerating Diabetic Wound Healing Through Inflammatory Microenvironment Regulation

Background

A paramount issue in the realm of chronic wound healing among diabetic patients is the pervasive inflammatory response that persistently thwarts angiogenesis, thereby precipitating protracted delays in the healing process of such wounds. Employing zeolitic imidazolate framework-8 (ZIF-8) as a drug delivery platform, integrated within a temperature-sensitive injectable hydrogel, presents an intriguing strategy for the closure of various irregular wounds, modulation of inflammatory responses, and promotion of angiogenesis.

Methods

Herein, ZIF-8 loaded with curcumin (Cur) combined with methylcellulose/carboxymethyl chitosan (MCC) thermosensitive hydrogel was described. The assessment encompassed the temperature-sensitive properties, pH-responsive release, antimicrobial activity, and ROS scavenging capabilities of the MCC@ZIF-8@Cur hydrogel. A series of studies were conducted to explore its biocompatibility, pro-angiogenic effects, and macrophage M2 polarization induction. Additionally, a full-thickness skin defect model of diabetic rat was established to investigate the hydrogel's multifaceted efficacy in facilitating wound repair, mitigating inflammatory responses, and fostering angiogenesis.

Results

The thermosensitive MCC@ZIF-8@Cur hydrogel possess the attribute of being injectable and capable of in situ formation (gelation temperature of ≥ 28 °C), thereby establishing an effective physical barrier for a multitude of irregular wound profiles. The incorporation of ZIF-8@Cur confers the hydrogel with exceptional antibacterial properties and the capability to eliminate reactive oxygen species (ROS). Moreover, the pH-responsive MCC@ZIF-8@Cur hydrogel continuously releases Cur and Zn2+, mitigating inflammation, inducing M2 polarization of macrophages, and promoting angiogenesis. This creates a favorable immune microenvironment conducive to skin regeneration, thereby accelerating the healing of diabetic wounds. In vivo studies have demonstrated a markedly accelerated wound healing ratio in rats within the hydrogel group compared to the Control group (p<0.001). By the 14th day of wound healing, the MCC@ZIF-8@Cur hydrogel group achieved a remarkable healing ratio of 97.22%, considerably surpassing the Control group (72.98%), showcasing remarkable potential for treating diabetic wounds.

Conclusion

The findings demonstrate the successful creation of a temperature-sensitive hydrogel that exhibits remarkable antibacterial properties and ROS scavenging capabilities. This hydrogel effectively suppresses inflammatory responses, modulates the polarization of macrophages towards the M2 phenotype, and promotes angiogenesis, thus fostering a favorable immune microenvironment for skin regeneration. These attributes collectively augur promising prospects and applications in the healing of diabetic wounds.

Injectable Silver Nanoparticle-Based Hydrogel Dressings with Rapid Shape Adaptability and Antimicrobial Activity

Burns and scalds often result in deep wounds that challenge adequate debridement and inflammation control using traditional sheet-like hydrogel dressings. Herein, we developed an antibacterial, injectable, and self-healing hydrogel (ADCM@Ag) by employing carboxymethyl chitosan (CMCS) for in situ green reduction of silver ions and utilizing a spontaneous Schiff base reaction with aldehyde-functionalized dextran (AD). SEM analysis revealed a porous structure within the hydrogel. Swelling and enzymatic degradation assays demonstrated that ADCM@Ag hydrogel possesses excellent fluid absorption capacity and biodegradability. Mechanical tests indicated good mechanical properties, allowing the hydrogel to withstand external forces when applied to animal wounds. The hydrogel exhibited good injectability, shape adaptability, and self-healing capability. Cell experiments showed that the ADCM@Ag hydrogel avoided the cytotoxicity caused by high concentrations of silver ions and had good cell compatibility. Antimicrobial assays showed that ADCM@Ag exhibited potent bactericidal effects against Gram-negative and Gram-positive bacteria, achieving at least 85% killing efficacy. Collectively, ADCM@Ag hydrogel has good potential for wound dressing applications.

Recent Advances and Challenges in Metal Halide Perovskite Quantum Dot-Embedded Hydrogels for Biomedical Application

Metal halide perovskite quantum dots (MHP QDs), as a kind of fluorescent material, have attracted much attention due to their excellent photoluminescence (PL) quantum yield (QY), narrow full width at half maximum (FWHM), broad absorption, and tunable emission wavelength. However, the instability and biological incompatibility of MHP QDs greatly hinder their application in the field of biomedicine. Hydrogels are three-dimensional polymer networks that are widely used in biomedicine because of their high transparency and excellent biocompatibility. This review not only introduces the latest research progress in improving the mechanical and optical properties of hydrogels/MHP QDs but also combines it with the existing methods for enhancing the stability of MHP QDs in hydrogels, aiming to provide new ideas for researchers in material selection and methods for constructing MHP QD-embedded hydrogels. Finally, their application prospects and future challenges are introduced.

Facile Formulation of a Resveratrol-Mediated Multibond Network Hydrogel with Efficient Sustainable Antibacterial, Reactive Oxygen Species Scavenging, Pro-Angiogenesis, and Immunomodulation Activities for Accelerating Infected Wound Healing

The management of chronic infected wounds remains a significant clinical challenge, largely due to the deficiency of optimal wound dressings with adequate mechanical strength, appropriate adhesiveness, and efficient sustainable antibacterial, reactive oxygen species (ROS) scavenging, pro-angiogenesis, and immunomodulation properties. To address such a dilemma, we employed a simple and facile strategy to utilize resveratrol (RSV) as a functional component to mediate hydrogel gelation in this study. The structure of this obtained hydrogel was supported by a multibond network, which not only endowed the resultant product with superior mechanical strength and moderate adhesiveness but also effectively prolonged the bioavailability of RSV. This strategy successfully integrated the entire system with sustainable antibacterial, ROS scavenging, pro-angiogenesis, and immunomodulation properties. Subsequent in vivo evidence has verified that this material was capable to accelerate the healing of chronic infected wounds. The underlying mechanism can be explained that this hydrogel is capable of propelling macrophage polarization from the M1 to M2 phenotype through modulating the PI3K/AKT signaling pathway to activate the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling as well as maintaining the mitochondrial membrane potential level in the normal state under excessive inflammatory and oxidative stimulus. In summary, this multifunctional hydrogel wound dressing provides a feasible way to promote the bioavailability of RSV, which is conducive for preparing a promising candidate for chronic infected wound healing. What is more important, it is also beneficial to reveal the correlative mechanisms to establish advanced therapeutic platform for targeting other complex infection microenvironment.

Rapid Fluid-Induced-Expanding Chitosan-Derived Hemostatic Sponges with Excellent Antimicrobial and Antioxidant Properties for Incompressible Hemorrhage and Wound Healing

Chitosan-based materials are known for their excellent biocompatibility and inherent hemostatic properties. However, their hemostatic efficiency is significantly affected by poor wettability and mechanical strength. Herein, we developed a novel hemostatic super elastic sponge from mussel-inspired chitosan modified with long alkyl and catechol functional groups (HMCC) via a simple freezing-drying procedure. The incorporation of decanal and catechol in the HMCC sponge significantly enhances its antimicrobial and antioxidant properties and facilitates multiple interactions with blood cells, thus promoting their enrichment for rapid hemostasis. Moreover, HMCC sponges exhibit high compressibility and rapid fluid-induced size recovery capacity, enabling wound shape adaptation to ensure minimizing irritation. In vivo experiments revealed that HMCC sponges possessed enhanced procoagulant, hemostasis abilities, and favorable degradability and could promote wound healing in a rat skin wound model. These results highlight the potential of the HMCC sponge as a promising solution for the clinical management of major bleeding.

Injectable Salecan/hyaluronic acid-based hydrogels with antibacterial, rapid self-healing, pH-responsive and controllable drug release capability for infected wound repair

Designing materials for wound dressings with superior therapeutic benefits, self-healing and injectable characteristics is important in clinical practice. Herein, a new self-healing injectable hydrogel was prepared via thermal treatment and dynamic Schiff base reaction by mixing oxidized hyaluronic acid (OHA) and hydrazided Salecan (Sal-ADH). The versatility of the wound dressing was confirmed by studying the inherent rheological properties, high swelling rate, sustained-release behavior of the drug, pH/hyaluronidase-dependent biodegradation, in vitro antimicrobial as well as in vivo wound healing performance. The presence of the antimicrobial drug polyhexamethylene biguanide (PHMB) conferred good antimicrobial properties to the Sal-ADH/OHA/PHMB (SOP) hydrogel, which could effectively prevent wound infection (the width of the inhibition circle of SOP-0.20 hydrogel was 4.97 mm, 5.93 mm for Staphylococcus aureus and Escherichia coli, respectively). The findings suggested that SOP hydrogel exhibited remarkable self-healing and injectability properties, as well as excellent hemostasis and biocompatibility. In vivo experiments indicated that the application of SOP hydrogels would obviously accelerate wound healing and attenuate the inflammatory response while increasing collagen deposition and angiogenesis. Altogether, antibacterial SOP hydrogels with moderate mechanical properties, pH-responsive release, excellent injectability, exceptional self-healing ability and anti-inflammatory effects could expand potential applications of injectable hydrogels in the biomedical field.

Multifunctional Adhesive Hydrogels: From Design to Biomedical Applications

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

Nanoscale Systems for Local Activation of Hypoxia-Inducible Factor-1 Alpha: A New Approach in Diabetic Wound Management

Chronic wounds in diabetic patients experience significant clinical challenges due to compromised healing processes. Hypoxia-inducible factor-1 alpha (HIF-1α) is a critical regulator in the cellular response to hypoxia, enhancing angiogenesis and tissue restoration. Nevertheless, the cellular response to the developed chronic hypoxia within diabetes is impaired, likely due to the destabilization of HIF-1α via degradation by prolyl hydroxylase domain (PHD) enzymes. Researchers have extensively explored HIF-1α activation as a potential pathway for diabetic wound management, focusing mainly on deferoxamine (DFO) as a potent agent to stabilize HIF-1α. This review provides an update of the other recent pharmacological agents managing HIF-1α activation, including novel PHD inhibitors (roxadustat and daprodustat) and Von Hippel-Lindau protein (VHL) antagonists, which could be potential alternatives for the local treatment of diabetic wounds. Furthermore, it highlights how localized delivery via advanced nanostructures can enhance the efficacy of these novel therapies. Importantly, by addressing these points, the current review can offer a promising area for research. Given that, these novel drugs have minimal applications in diabetic wound healing, particularly in the context of local application through nanomaterials. This gap presents an exciting opportunity for further investigation, as combining these drugs with localized nanotechnology could avoid undesired systemic side effects and sustain drug release within wound site, offering a transformative platform for diabetes wound treatment.

Injectable Nanocomposite Hydrogel with Synergistic Biofilm Eradication and Enhanced Re-epithelialization for Accelerated Diabetic Wound Healing

Diabetic wounds remain a critical clinical challenge due to their harsh microenvironment, which impairs cellular function, hinders re-epithelialization and tissue remodeling, and slows healing. Injectable nanocomposite hydrogel dressings offer a promising strategy for diabetic wound repair. In this study, we developed an injectable nanocomposite hydrogel dressing (HDL@W379) using LAP@W379 nanoparticles and an injectable hyaluronic acid-based hydrogel (HA-ADH-ODEX). This dressing provided a sustained, pH-responsive release of W379 antimicrobial peptides, effectively regulating the wound microenvironment to enhance healing. The HDL@W379 hydrogel featured multifunctional properties, including mechanical stability, injectability, self-healing, biocompatibility, and tissue adhesion. In vitro, the HDL@W379 hydrogel achieved synergistic biofilm elimination and subsequent activation of basal cell migration and endothelial cell tube formation. Pathway analysis indicated that the HDL@W379 hydrogel enhances basal cell migration through MEK/ERK pathway activation. In methicillin-resistant Staphylococcus aureus (MRSA)-infected diabetic wounds, the HDL@W379 hydrogel accelerated wound healing by inhibiting bacterial proliferation and promoting re-epithelialization, regenerating the granulation tissue, enhancing collagen deposition, and facilitating angiogenesis. Overall, this strategy of biofilm elimination and basal cell activation to continuously regulate the diabetic wound microenvironment offers an innovative approach to treating chronic wounds.

Bioprinted Symbiotic Dressings: A Lichen-Inspired Approach to Diabetic Wound Healing with Enhanced Bioactivity and Structural Integrity

Providing oxygen and preventing infection at wound sites are effective ways to heal diabetic chronic wounds. Inspired by natural lichens, a bioprinted biogenic hydrogel (BBH) containing microalgae and probiotics is developed for diabetic chronic wound therapeutics, which offers prolonged biogenetic oxygen supply by microalgae and infection inhibition by probiotics. The rational design of symbiotic BBH with customizable structure and microorganism composition enhances wound resilience against elevated glucose levels and hypoxia, leading to the increased migration ability of fibroblasts and the angiogenic potential of human umbilical vein endothelial cells. Notably, BBH-treated diabetic wounds exhibit dense vascular distribution, reduced hypoxia levels and inflammatory responses, and enhanced epithelial differentiation and keratinization abilities. Consequently, the BBH achieves rapid tissue repairing within 3 d and restores approximately 90% of the whole skin structure within 12 d. This work presents an engineered platform for regulating biological microenvironment of diabetic wounds and provides insights for developing bioprinted hybrid microorganism systems.

Chitosan-Based Hydrogels as Antibacterial/Antioxidant/Anti-Inflammation Multifunctional Dressings for Chronic Wound Healing

Due to repeated microbial infection, persistent inflammation, excessive oxidative stress, and cell dysfunction, chronic wounds are difficult to heal, posing a serious threat to public health. Therefore, developing multifunctional wound dressings that can regulate the complex microenvironment of chronic wounds and enhance cellular function holds great significance. Recently, chitosan has emerged as a promising biopolymer for wound healing due to its excellent biocompatibility, biodegradability, and versatile bioactivity. The aim of this review is to provide a comprehensive understanding of the mechanisms of delayed chronic wound healing and discuss the healing-promoting properties of chitosan and its derivatives, such as good biocompatibility, antibacterial activity, hemostatic capacity, and the ability to promote tissue regeneration. On this basis, the potential applications of chitosan-based hydrogels are summarized in chronic wound healing, including providing a suitable microenvironment, eliminating bacterial infections, promoting hemostasis, inhibiting chronic inflammation, alleviating oxidative stress, and promoting tissue regeneration. In addition, the concerns and perspectives for the clinical application of chitosan-based hydrogels are also discussed.

Photothermal enhanced antibacterial chitosan-based polydopamine composite hydrogel for hemostasis and burn wound repairing

Bleeding and bacterial infection are common problems associated with wound treatment, while effective blood clotting and vessel regeneration promotion are the primary considerations to design the wound dressing materials. This research presents a chitosan-based hydrogel with grafted quaternary ammonium and polyphosphate (QCSP hydrogel) as the antibacterial hemostatic dressing to achieve burn wound treatment. The tissue adhesion of the hydrogel sealed the blood flow and the polyphosphate grafted to the chitosan promoted the activation of coagulation factor V to enhance the hemostasis. At the same time, the grafted quaternary ammonium enhanced the antibacterial ability of the biodegradable hydrogel wound dressing. In addition, the polydopamine as a photothermal agent was composited into the hydrogel to enhance the antibacterial and reactive oxygen scavenging performance. The in vivo hemostasis experiment proved the polyphosphate enhanced the coagulation property. Moreover, this photothermal property of the composite hydrogel enhanced the burn wound repairing rate combined with the NIR stimulus. As a result, this hydrogel could have potential application in clinic as dressing material for hemostasis and infection prone would repairing.

Exploring the wound healing potential of dietary nitrate in diabetic rat model

Introduction

The wound healing in diabetes is hindered and prolonged due to long-term inflammation, oxidative stress damage, and angiogenesis disorders induced by high glucose status. The management of such difficult-to-treat wounds continues to pose a significant challenge in clinical treatment. Dietary nitrate, commonly found in greens such as beets and spinach, acts as a nutritional supplement and is metabolized in the body through the salivary nitrate-nitrite-NO pathway. This pathway plays a crucial role in various physiological functions, including enhancing blood flow and attenuating inflammation.

Methods

In this study, we established a diabetic rat wound model. Forty-eight rats were randomly divided into six groups (n = 8): the Con group, the Con + Nitrate group, the STZ group, the STZ + NaCl group, the STZ + rhEGF group, and the STZ + Nitrate group. Skin wound healing was assessed on the day of surgery and on postoperative days 3, 7, 10, and 14. Specimens were taken on days 7 and 14 post-surgery for relevant tests.

Results

We found that dietary nitrate could accelerate skin wound healing by promoting angiogenesis and increasing blood perfusion. Significantly, dietary nitrate also regulated glucose and lipid metabolism and exhibited anti-inflammatory and antioxidant properties.

Discussion

These findings provide a novel theoretical basis for managing wounds in diabetic individuals, indicating the broad potential of dietary nitrate in future clinical applications.

Microfluidic-engineered Chinese herbal nanocomposite hydrogel microspheres for diabetic wound tissue regeneration

Microfluidic-engineered hydrogel microspheres have emerged as a promising avenue for advancements in tissue engineering and regenerative medicine, particularly through the precise manipulation of fluids to achieve personalized composite biomaterials. In this study, we employed microfluidic technology to fabricate hydrogel microspheres (HMs) using Chinese herbal Bletilla striata polysaccharide (BSP) as the primary material. Concurrently, the natural active ingredient 20(S)-protopanaxadiol (PPD) was encapsulated within the HMs in the form of liposomes (PPD-Lipo), resulting in the formation of nanocomposite hydrogel microspheres (PPD-Lipo@HMs) intended for diabetic wound tissue repair. PPD-Lipo@HMs are characterized by the expansive specific surface area, adjustable mechanical properties, and exceptional biocompatibility. PPD-Lipo@HMs can stimulate the production of vascular endothelial factors, which in turn enhances the migration of endothelial cells, the creation of tubes, angiogenesis, and tissue repair. Moreover, the PPD-Lipo@HMs accumulation produces a microsphere scaffold that effectively covers damaged tissues, promoting the attachment, spread, and multiplication of fibroblast and endothelial cells. The polysaccharide material BSP within PPD-Lipo@HMs can modulate the immune microenvironment of the damaged tissue, reducing inflammation, encouraging re-epithelialization and granulation tissue formation, accelerating angiogenesis and collagen deposition, ultimately leading to tissue repair. The findings highlight the superior therapeutic efficacy of the microfluidic-engineered PPD-Lipo@HMs in addressing the complex challenges of diabetic wound tissue repair, thereby affirming the significant potential of microfluidic engineering technology in tissue repair applications.

Tunicate cellulose nanocrystals strengthened injectable stretchable hydrogel as multi-responsive enhanced antibacterial wound dressing for promoting diabetic wound healing

The intricate microenvironment of diabetic wounds characterized by hyperglycemia, intense oxidative stress, persistent bacterial infection and complex pH fluctuations hinders the healing process. Herein, an injectable multifunctional hydrogel (QPTx) was developed, which exhibited excellent mechanical performance and triple responsiveness to pH, temperature, and glucose due to dynamic covalent cross-linking involving dynamic Schiff base bonds and phenylboronate esters with phenylboronic-modified quaternized chitosan (QCS-PBA), polydopamine coated tunicate cellulose crystals (PDAn@TCNCs) and polyvinyl alcohol (PVA). Furthermore, the hydrogels can incorporate insulin (INS) drugs to adapt to the complex and variable wound environment in diabetic patients for on-demand drug release that promote diabetic wound healing. Based on various excellent properties of the colloidal materials, the hydrogels were evaluated for self-healing, rheological and mechanical properties, in vitro insulin response to pH/temperature/glucose release, antibacterial, antioxidant, tissue adhesion, coagulation, hemostasis in vivo and in vitro, and biocompatibility and biodegradability. By introducing PDAn@TCNCs particles, the hydrogel has photothermal antibacterial activity, enhanced adhesion and oxidation resistance. We further demonstrated that these hydrogel dressings significantly improved the healing process compared to commercial dressings (Tegaderm™) in full-layer skin defect models. All indicated that the glucose-responsive QPTx hydrogel platform has great potential for treating diabetic wounds.

Chitosan/rutin multifunctional hydrogel with tunable adhesion, anti-inflammatory and antibacterial properties for skin wound healing

Effective wound care remains a significant challenge due to the need for infection prevention, inflammation reduction, and minimal tissue damage during dressing changes. To tackle these issues, we have developed a multifunctional hydrogel (CHI/CPBA/RU), composed of chitosan (CHI) modified with 4-carboxyphenylboronic acid (CPBA) and the natural flavonoid, rutin (RU). This design endows the hydrogel with body temperature-responsive adhesion and low temperature-triggered detachment, thus enabling painless removal during dressing changes. The CHI/CPBA/RU hydrogels exhibit excellent biocompatibility, maintaining over 97 % viability of L929 cells. They also demonstrate potent intracellular free radical scavenging activity, with scavenging ratios ranging from 53 % to 70 %. Additionally, these hydrogels show anti-inflammatory effects by inhibiting pro-inflammatory cytokines (TNF-α, IL-6, and iNOS) and increasing anti-inflammatory markers (Arg1 and CD206) in RAW 264.7 macrophages. Notably, they possess robust antimicrobial properties, inhibiting over 99.9 % of the growth of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus growth. In vivo testing on a murine full-thickness skin defect model shows that the hydrogel significantly accelerates wound healing by reducing inflammation, increasing collagen deposition, and promoting angiogenesis, achieving 98 % healing by day 10 compared to 78 % in the control group. These attributes make the polysaccharide-based hydrogel a promising material for advanced wound care.

Supramolecular approach to the design of nanocarriers for antidiabetic drugs: targeted patient-friendly therapy

Diabetes and its complications derived are among serious global health concerns that critically deteriorate the quality of life of patients and, in some cases, result in lethal outcome. Herein, general information on the pathogenesis, factors aggravating the course of the disease and drugs used for the treatment of two types of diabetes are briefly discussed. The aim of the review is to introduce supramolecular strategies that are currently being developed for the treatment of diabetes mellitus and that present a very effective alternative to chemical synthesis, allowing the fabrication of nanocontainers with switchable characteristics that meet the criteria of green chemistry. Particular attention is paid to organic (amphiphilic and polymeric) formulations, including those of natural origin, due to their biocompatibility, low toxicity, and bioavailability. The advantages and limitations of different nanosystems are discussed, with emphasis on their adaptivity to noninvasive administration routes.<br>The bibliography includes 378 references.