Glucose-responsive multifunctional metal-organic drug-loaded hydrogel for diabetic wound healing

Advancements in chitosan-based nanocomposites with ZIF-8 nanoparticles: multifunctional platforms for wound healing applications

The integration of chitosan and zeolitic imidazolate framework-8 (ZIF-8) nanoparticles has demonstrated significant potential in enhancing wound healing through their multifunctional capabilities. This review explores recent developments in chitosan-based nanocomposites incorporating ZIF-8 nanoparticles, emphasizing their antibacterial properties, pH-responsive drug release, angiogenesis promotion, and mechanical stability. Applications span hydrogel scaffolds, electrospun nanofibers, and sprayable membranes, all tailored for addressing challenges such as bacterial resistance, delayed tissue regeneration, and chronic wound management. Key findings highlight the synergistic benefits of ZIF-8's bioactivity with chitosan's biocompatibility, yielding innovative therapeutic strategies for complex wound healing scenarios. The discussed advancements not only underline their clinical relevance but also set a foundation for future explorations in regenerative medicine.

Konjac glucomannan/Bletilla striata polysaccharide composite hydrogel: A promising anti-inflammatory dressing for accelerated wound healing

A hydrogel with remarkable anti-inflammatory properties holds significant potential for accelerating wound healing. This study focuses on developing a safe and effective wound-healing hydrogel based on polysaccharides. The hydrogel was synthesized by cross-linking Konjac Glucomannan (KGM) and Bletilla Striata Polysaccharide (BSP) using 1,4-Butanediol Diglycidyl Ether (BDDE) and subsequently evaluated as a wound dressing. Compared to hydrogels cross-linked solely with KGM, the co-crosslinked KGM-BSP hydrogel demonstrated superior water retention, enhanced mechanical strength (maximum tensile stress: 6.6 kPa), excellent adhesive properties (maximum shear stress: 848.53 ± 31.4 Pa), and outstanding biocompatibility. Moreover, in vitro anti-inflammatory assays revealed that the KGM-BSP hydrogel effectively inhibited the activation of the TNF-α/NF-κB pathway while upregulating IL-10 expression, thereby mitigating inflammation and facilitating tissue repair during wound healing. Scratch and Western blot assays further indicated that the hydrogel significantly enhanced the migratory capacity of L929 cells by activating the Rho GTPase pathway. In a mouse wound model, the KGM-BSP hydrogel reduced inflammation, promoted angiogenesis, and stimulated collagen deposition, collectively accelerating wound closure. These findings suggest that the KGM-BSP composite hydrogel is a highly promising wound dressing with the potential to markedly enhance the wound healing process.

Bi2WO6@Cu2O-GOx bio-heterojunctionp-n spray for accelerating chronic diabetic wound repairment with bilaterally enhanced sono-catalysis and glycolytic inhibition antisepsis

Chronic diabetic wound poses a pressing global healthcare challenge, necessitating an approach to address issues such as pathogenic bacteria elimination, blood sugar regulation, and angiogenesis stimulation. Herein, we engineered a Bi2WO6@Cu2O-GOx bio-heterojunction (BWCG bio-HJ) with exceptional cascade catalytic performance and impressive sonosensitivity to remodel the wound microenvironment and expedite the diabetic wound healing. Specifically, the Z-scheme junctions of Bi2WO6@Cu2O significantly augmented carrier separation dynamics, leading to the highly efficient generation of reactive oxygen species (ROS) upon US irradiations. Furthermore, glucose oxidase (GOx) grafted on the Bi2WO6@Cu2O surface facilitated the conversion of glucose into H2O2 and glucuronic acid, providing a rich supply for Cu+-mediated Fenton-like reactions. The robust oxidation effect disrupted the bacteria's phosphotransferase system (PTS), hindering glucose uptake, glycolysis, and energy metabolism, ultimately inducing bacterial death and reshaping the diabetic wound microenvironment. The BWCG bio-HJ was formulated as an antibacterial spray for chronic diabetic wound repair. Extensive in vitro and in vivo experiments confirmed that the BWCG bio-HJ spray could eliminate pathogenic bacteria, consume local blood sugar, and promote angiogenesis, collagen deposition, and epithelialization, thereby accelerating the diabetic wound healing process. This bio-heterojunction spray comprehensively addressed the principal pathological factors associated with diabetic wounds, offering a promising strategy for combatting stubborn infections.

Smart hydrogel: A new platform for cancer therapy

Cancer is a significant contributor to mortality worldwide, posing a significant threat to human life and health. The unique bioactivity, ability to precisely control drug release, and minimally invasive properties of hydrogels are indispensable attributes that facilitate optimal performance in cancer therapy. However, conventional hydrogels lack the ability to dynamically respond to changes in the surrounding environment, withstand drastic changes in the microenvironment, and trigger drug release on demand. Therefore, this review focuses on smart-responsive hydrogels that are capable of adapting and responding to external stimuli. We comprehensively summarize the raw materials, preparation, and cross-linking mechanisms of smart hydrogels derived from natural and synthetic materials, elucidate the response principles of various smart-responsive hydrogels according to different stimulation sources. Further, we systematically illustrate the important role played by hydrogels in modern cancer therapies within the context of therapeutic principles. Meanwhile, the smart hydrogel that uses machine learning to design precise drug delivery has shown great prospects in cancer therapy. Finally, we present the outlook on future developments and make suggestions for future related work. It is anticipated that this review will promote the practical application of smart hydrogels in cancer therapy and contribute to the advancement of medical treatment.

A recent review on smart sensor-integrated wound dressings: Real-time monitoring and on-demand therapeutic delivery

Wound management is a critical aspect of healthcare, necessitating continuous monitoring and timely interventions to ensure optimal healing outcomes. In recent years, the integration of sensor technology into wound dressings has emerged as a transformative approach, enabling real-time monitoring of healing parameters and facilitating on-demand treatment delivery. Sensor-based wound dressings leverage various sensing modalities, including temperature, pH, moisture, oxygen, and other biochemical markers, to provide comprehensive insights into the wound microenvironment. These dressings are equipped with miniaturized sensors capable of transmitting the data wirelessly, facilitating remote monitoring and timely interventions. Moreover, some advanced dressings incorporate responsive drug delivery systems, enabling the on-demand release of therapeutics based on real-time sensor feedback. Additionally, the incorporation of on-demand treatment mechanisms allows targeted delivery of therapeutics based on the specific needs of the wound, further enhancing the efficacy of the healing process. This comprehensive approach improves patient outcomes by promoting faster and more effective wound healing and reducing the burden through streamlined monitoring and treatment protocols. This paper presents an overview of recent advancements in sensor technology applied to wound healing, focusing on their role in monitoring wound parameters and delivering targeted therapy. These sensors leverage temperature, pH, and glucose sensing modalities to provide comprehensive insights into the healing process.

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.

Nanofibrous membrane/self-healing hydrogel double-layer nanocomposite dressings based on oxidized dextran and carboxymethyl chitosan loading ZIF-nanozyme for enhanced bacterial-infected diabetic wound healing

Treatment of diabetic wounds at different stages remains a pressing challenge. By simulating the complex structure of natural skin, a multifunctional nanofibrous membrane/self-healing hydrogel double-layer nanocomposite dressing loading nanozyme was prepared to accelerate diabetic wound healing. The upper layer was prepared from a modified self-synthesized polyurethane (APU) nanofibrous membrane, and the bottom layer was made of an injectable self-healing hydrogel loaded with nanozyme based on oxidized dextran (ODex) and carboxymethyl chitosan (CMC). The APU nanofibrous membrane on the top can maintain a breathable and sterile environment, support the dressing, and promote cell proliferation and migration. Glucose oxidase (GOx) and l -arginine (L-Arg) at the bottom were co-doped with zinc-ZIF nanoparticles (GLZ) and acted as nanozymes for enzyme catalysis. Under the catalytic action of GOx, the high blood sugar in the wound was consumed, the pH of the microenvironment was reduced, and Zn2+ was released, achieving an effective antibacterial effect. L-Arg was catalyzed by H2O2 to generate NO in a lower pH environment, accelerating angiogenesis. Overall, the double-layer composite dressings loaded with ZIF-nanozyme exhibited comprehensive blood sugar regulation capabilities and antibacterial activity, which could promote angiogenesis and cell proliferation, and effectively treat chronic diabetic wounds.

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.

Dynamic Boronate Ester Based Hydrogel with Enhanced Mechanical Properties and Multi-Stimuli-Triggered Release for Tissue Repair and Antioxidant Therapy

Oxidative stress and chronic inflammation play pivotal roles in causing impaired tissue regeneration and delaying wound healing processes. Epigallocatechin gallate (EGCG) demonstrates robust anti-inflammatory and antioxidant characteristics, thereby emerging as a highly promising therapeutic substance for tissue repair applications. In order to counteract the pathological characteristics of the wound microenvironment, including increased levels of reactive oxygen species (ROS), low pH (weak acidic conditions), and elevated glucose concentrations, a hydrogel with pH/ROS/glucose-responsive properties was fabricated. This hydrogel was modified with phenylboronic acid (PBA) groups, which not only enhance its mechanical strength but also endow it with multi-stimuli responsiveness via dynamic boronate ester bonds. The impacts of grafting of PBA and loading of EGCG on the rheological and mechanical properties, as well as the network structure of the hydrogels, were systematically investigated. Moreover, in vitro experiments showed that the hydrogel could achieve excellent sustained and controlled release of both small-molecule and macromolecular drugs. Additionally, cell viability tests verified the hydrogel's outstanding biocompatibility, and antioxidant experiments demonstrated its efficient ability to scavenge intracellular ROS. In conclusion, this injectable and biodegradable hydrogel possesses multi-stimuli responsiveness, controllable drug release behavior, and antioxidant capacity, presenting a promising approach to alleviate oxidative damage and promote tissue repair. This study offers valuable perspectives for the design of advanced hydrogel materials aimed at treating wound healing.

H2S Donor Functionalized Molecular Machine for Combating Multidrug-Resistant Bacteria Infected Chronic Wounds

Chronic wounds are a worldwide medical challenge due to the complex and multifaceted etiologies, including bacterial infection, persistent inflammation, and impaired angiogenesis. Developing a comprehensive strategy integrating antibiosis and anti-inflammation to promote revascularization and accelerate wound healing is highly desirable. Nevertheless, current therapeutic methods still face two major challenges: 1) how to combat bacterial drug resistance, 2) how to achieve spatiotemporal control over bacterial elimination and inflammation reduction. To address these issues, a novel H2S donor functionalized molecular machine (MM), ACR-DM-HS, was developed. It selectively binds to and disturbs the bacterial membrane through a light-active vibronic-driven mechanochemical action (VDA), which synergizes with photodynamic therapy (PDT) to efficiently eradicate multidrug-resistant bacteria and biofilms, and conquers the evolution of bacterial resistance. Furthermore, it releases H2S in infected tissues to scavenge excess reactive oxygen species (ROS), inhibit the secretion of inflammatory factors, promote angiogenesis, and accelerate the healing of diabetic wounds in vivo. This work provides an integrated strategy combining antibiotics and anti-inflammation to treat with multidrug resistance bacterial-infected chronic wounds.

Hyaluronic acid/ε-polylysine hydrogel enriched with Saussurea involucrata polysaccharide for improved skin dryness induced by ultraviolet radiation

Ultraviolet B (UVB) radiation exposure is a major contributor to skin photoaging, ultimately resulting in dryness. Conventional treatments for this condition frequently exhibit limited efficacy due to poor skin penetration and are associated with significant side effects. Saussurea involucrate polysaccharide (SIP) has been shown to alleviate photoaging-induced dry skin; however, its effectiveness is limited due to low drug utilization and the need for frequent dosing. In this study, we developed hyaluronic acid (HA) and ε-polylysine (ε-PLL) hydrogels designed to enhance skin hydration and enable sustained drug release. The optimal formulation, designated A5E3, contained 5 % HA plus 3 % ε-PLL. The sustained release of SIP from A5E3 demonstrated superior therapeutic effects in a mouse model of skin photoaging, including reduced inflammation and apoptosis, as well as enhanced keratinocyte differentiation and lipid production. The A5E3 hydrogel not only enhanced the drug utilization of SIP but also provided a sustained moisturizing environment, promoting faster skin repair. These findings support the development of skincare products with superior moisturizing and reparative properties, underscoring the potential of hydrogels as effective carriers for treating UVB-induced skin dryness and damage.

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

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

Tri-Layered Bioactive Cutaneous Scaffold with Integrated Bioactive Metal Organic Frameworks to Promote Full-Thickness Infected Diabetic Wound Healing: Multifaceted Therapeutic Strategies

Chronic infected diabetic wounds are complex and often lead to severe clinical outcomes such as sepsis, gangrene, and amputation. To address these challenges, herein we developed a novel tri-layered scaffold to provide multi-functional therapeutic support. The bottom poly (lactic-co-glycolic acid) (PLGA) fibrous layer contains doxycycline loaded CuBDC nanosheets for rapid antibacterial action. The porous PLGA/gelatin middle layer offers mechanical support and γ-tocotrienol loaded ZIF-8 nanocrystals mitigates oxidative stress in the wound. The PLGA top sealing fibrous layer delivers insulin and Transforming growth factor beta (TGF-β1) from Zeolitic Imidazolate Framework-8 (ZIF-8) nanocrystals to promote epithelialization and modulate inflammation. Comprehensive in vitro and in vivo evaluations demonstrated that the scaffold effectively filled deep wounds, reduced bacterial load, controlled inflammation, and accelerated the tissue regeneration. Histopathological analyses showed enhanced epithelialization and partial granulation tissue remodeling. Biochemical assays indicated an increase in glutathione peroxidase (GPx) activity and a reduction in lipid peroxidation. Gene expression analysis revealed decreased levels of the pro-inflammatory TNF-α and increased levels of the anti-inflammatory IL-10, facilitating the transition to the proliferative phase. This multi-layered composite scaffold, with its antimicrobial, antioxidant, and anti-inflammatory activities, controlled release capabilities, presents a promising solution the healing process of deep, infected diabetic wounds.

Design and biofabrication of barnacle and spider silk protein decorated composite bacterial cellulose for diabetic wound healing

Delayed healing of wounds in diabetics is mainly due to tissue inflammation, poor vasculature, lack of neovascularization, and bacterial infection. Therefore, a therapeutic protocol that disrupts this cycle and speeds healing is urgently needed. Despite attempts to enhance wound dressing effectiveness through hydrogels with diverse complexes such as bacterial cellulose (BC) combined with chitosan, BC/ chitosan/hyaluronic acid, and BC/chitosan/collagen, the toughness and adhesion properties of hydrogel remain constrained, leading to inadequate and uncontrollable wound healing. To address the challenge, we have devised an innovative solution by integrating barnacle cement protein (cp19k) and spider silk protein (major ampullate spidroin 1, MaSp1) into a BC matrix, complemented by chitosan. This development has led to the creation of a novel BC-based composite hydrogel BC/cp19k-MaSp1/C150k. The composite hydrogel stands out with its remarkable mechanical (3.92 Mpa) and adhesion properties (8.4 kPa) compared to its BC/C150k counterpart. Meanwhile, the BC/cp19k-MaSp1/C150k hydrogel also demonstrated antimicrobial activity, coagulation, and biocompatibility. The BC/cp19k-MaSp1/C150k hydrogel showed an exceptional capacity to enhance wound healing in a diabetic rat model, achieving a significant wound closure rate of over 98 % on day 14 when compared to BC and commercially available dressing 3 M™ Tegaderm™. This advancement holds significant promise in revolutionizing wound management for diabetics.

Smart self-healing hydrogel wound dressings for diabetic wound treatment

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

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

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

Next-generation biopolymer gels: innovations in drug delivery and theranostics

Biopolymers or natural polymers like chitosan, cellulose, alginate, collagen, etc. have gained significant interest recently due to their remarkable tunable properties that make them appropriate for a variety of applications & play a crucial role in everyday life. The features of biopolymers which include biodegradability, biocompatibility, sustainability, affordability, & availability are vital for creating products for use in biomedical fields. Apart from these characteristics, smart or stimuli-responsive biopolymers also show a distinctive property of being susceptible to various factors like pH, temperature, light intensity, & electrical or magnetic fields. The current review would present a brief idea about smart biopolymer gels along with their biomedical applications. The use of smart biopolymers gels as theranostic agents are also discussed in the present review. This review also focuses on the application of biopolymers in the fields of drug delivery, cancer treatment, tissue engineering & wound healing. These areas demonstrate the development and utilization of different types of biopolymers in current biomedical applications.

Hydrogel Dressings as Insulin Delivery Systems for Diabetic Wounds

Diabetic wounds are one of the most common and challenging complications of diabetes. Similar to chronic wounds, diabetic wounds are difficult to treat due to prolonged inflammation, a lack of angiogenesis, abnormal differentiation of new scar tissue, and the occurrence of numerous bacterial infections. Moreover, elevated sugar levels in tissues disrupt the healing process by enhancing inflammatory reactions, disrupting signaling pathways, and leading to the production of abnormal biological structures, which contribute to improper cell differentiation. Traditional dressings, such as bandages, gauze, and semi-occlusive foams, are inadequate for diabetic wounds with high exudation; moreover, frequently changing the dressing can cause secondary irritation. Hence, innovative hydrogel dressings are being developed, which, thanks to their soft polymer matrix, provide an ideal substrate for regenerating tissue. Hydrogels also allow for the introduction and controlled release of growth factors, making them a promising solution for treating diabetic wounds. Recently, researchers have focused on insulin, a hormone secreted by the human body to lower blood sugar levels, due to its interesting characteristics, such as supporting anti-inflammatory and proangiogenic processes and stimulating cell migration and proper proliferation. This review discusses the most important aspects of diabetes and diabetic wounds and traditional and innovative treatment methods, particularly hydrogel dressings used as systems for insulin delivery in response to glucose concentration.

Advancements in Wound Dressing Materials: Highlighting Recent Progress in Hydrogels, Foams, and Antimicrobial Dressings

Recent advancements in wound dressing materials have significantly improved acute and chronic wound management by addressing challenges such as infection control, moisture balance, and enhanced healing. Important progress has been made, especially with hydrogels, foams, and antimicrobial materials for creating optimized dressings. Hydrogels are known for maintaining optimal moisture levels, while foam dressings are excellent exudate absorbents. Meanwhile, antimicrobial dressing incorporates various antimicrobial agents to reduce infection risks. These dressing options reduce wound healing time while focusing on customized patient needs. Therefore, this review highlights the newest research materials and prototypes for wound healing applications, emphasizing their particular benefits and clinical importance. Innovations such as stimuli-responsive hydrogels and hybrid bioengineered composites are discussed in relation to their enhanced properties, including responsiveness to pH, temperature, glucose, or enzymes and drug delivery precision. Moreover, ongoing clinical trials have been included, demonstrating the potential of emerging solutions to be soon translated from the laboratory to clinical settings. By discussing interdisciplinary approaches that integrate advanced materials, nanotechnology, and biological insights, this work provides a contemporary framework for patient-centric, efficient wound care strategies.

Hydrogel-based therapies for diabetic foot ulcers: recent developments and clinical implications

The diabetic foot ulcer is among the most serious diabetes-associated complications, with a long disease course considerably increasing the pain and economic burden of patients, leading to amputation and even death. High blood sugar is characteristic of diabetic foot ulcers, with insufficient blood supply, oxidative stress disorder, and high-risk bacterial infection posing great challenges for disease treatment. Advances in hydrogel dressings have shown potential for the management of diabetic foot ulcers involving multisystem lesions. This study comprehensively reviews the pathogenesis of diabetic foot ulcers and advances in hydrogel dressings in treating diabetic foot ulcers, providing innovative perspectives for assessing the nursing care requirements and associated clinical applications.

Glucose oxidase: An emerging multidimensional treatment option for diabetic wound healing

The healing of diabetic skin wounds is a complex process significantly affected by the hyperglycemic environment. In this context, glucose oxidase (GOx), by catalyzing glucose to produce gluconic acid and hydrogen peroxide, not only modulates the hyperglycemic microenvironment but also possesses antibacterial and oxygen-supplying functions, thereby demonstrating immense potential in the treatment of diabetic wounds. Despite the growing interest in GOx-based therapeutic strategies in recent years, a systematic summary and review of these efforts have been lacking. To address this gap, this review article outlines the advancements in the application of GOx and GOx-like nanozymes in the treatment of diabetic wounds, including reaction mechanisms, the selection of carrier materials, and synergistic therapeutic strategies such as multi-enzyme combinations, microneedle structures, and gas therapy. Finally, the article looks forward to the application prospects of GOx in aiding the healing of diabetic wounds and the challenges faced in translating these innovations to clinical practice. We sincerely hope that this review can provide readers with a comprehensive understanding of GOx-based diabetic treatment strategies, facilitate the rigorous construction of more robust multifunctional therapeutic systems, and ultimately benefit patients with diabetic wounds.

Multitasking Asynchronous Collaborative Nanosystem for Diabetic Wound Healing Based on Hypoglycemic, Antimicrobial, and Angiogenesis-Promoting Effects

A diabetic foot ulcer (DFU) is a common and serious complication of diabetes. This complication can result in amputation and death because of the several challenges associated with wound healing that can be attributed to the complex wound microenvironment, including biofilm infection, hyperglycemia, and diabetic angiopathy. Existing investigations on the wound-healing rate consider only one or two pathogenic factors, and therefore, despite the extensive research on these pathological microenvironments, there is an urgent need to optimize the wound-healing rate in patients with diabetic foot ulcers. To this end, a multitasking asynchronous collaborative nanosystem is designed in this study. The designed nanosystem can efficiently clear biofilm infections using optimized photodynamic therapy based on a poly photosensitizer ionic liquid (i.e., Ce6IL), reduce local blood glucose concentration using glucose oxidase, and reconstruct blood vessels by stimulating endothelial cell proliferation and migration using nitric oxide. The experimental results indicate that the three-step sequential collaboration strategy for clearing biofilm infections, reducing glucose concentrations, and reconstructing damaged blood vessels can help significantly accelerate wound healing rate in patients with diabetic foot ulcers.

VEGF loading heparinized hyaluronic acid macroporous hydrogels for enhanced 3D endothelial cell migration and vascularization

The formation of robust vascular systems within voluminous scaffolds remains a formidable barrier in the realm of tissue engineering. There is a growing interest in the integration of biomaterial scaffolds with multiple physical and chemical stimuli to augment the process of vascularization. This study aims to investigate the combined impact of macroporous structures and vascular endothelial growth factor (VEGF) on cell migration and vascularization. Heparinized hyaluronic acid (HepHA) macroporous hydrogels with differing pore sizes, composed by methacrylated hyaluronic acid (HAMA) and methacrylated heparin (HepMA), were fabricated by a gelatin microspheres (GMS) template leaching method. After characterization of their physical properties, VEGF was immobilized on the HepHA hydrogels. The in vitro release study indicated that the HepHA hydrogels can provide sustained release of VEGF. Subsequently, cells migration of human umbilical vein endothelial (HUVECs) assessment indicated that HUVECs cultured on VEGF-loaded HepHA hydrogels with larger pores (VEGF@HepHA250) migrated the furthest. Finally, the hydrogels were implanted and evaluated using a dorsal subcutaneous model. The histological analyses conducted in vivo were consistent with the in vitro results, VEGF@HepHA250 hydrogels exhibited the most pronounced vascularization four weeks post-implantation, indicating that hydrogels with expanded pores and an enriched VEGF promoted angiogenesis within the hydrogels. This study sheds light on the synergistic effects of VEGF release on 3D cell migration and vascularization within hydrogels of differing pore sizes, thus providing novel insights into the strategic design and fabrication of tissue-engineered scaffolds that are amenable to vascularization.

In-situ oxygen-supplying ROS nanopurifier for enhanced healing of MRSA-infected diabetic wounds via microenvironment modulation

Hypoxia, high ROS levels and chronic inflammation are the main factors that hinder the healing of diabetic wounds. Long-term exposed wounds are prone to bacterial infection, especially MRSA infection, which exacerbates the complex wound microenvironment of diabetes and threatens patients' lives. Here, we developed a ROS nanopurifier (CSVNP), which was prepared by loading superoxide dismutase (SOD), catalase (CAT) and vancomycin into nanogels through in-situ polymerization. CSVNP can effectively increase enzyme loading and stability, and improve cascade reaction efficiency between enzymes through nanosize effect, so that CSVNP can use a variety of ROS (H2O2 and ·O2-) as oxygen sources to generate much oxygen in situ, which can effectively alleviate the hypoxic environment and inflammatory response of diabetic tissues, theraby promoting cell migration and angiogenesis, and accelerating wound healing. In addition, the generated oxygen can further promote the transformation of pro-inflammatory M1 macrophages into anti-inflammatory M2 macrophages and reduce pro-inflammatory factors (TNF-α, IL-6, and IL-1β) release. CSVNP can also effectively eradicate MRSA by releasing vancomycin, preventing bacterial infection from exacerbating the deterioration of diabetic wounds. This multifunctional ROS nanopurifier with antiphlogosis, antibacterial and in-situ oxygen supply, provides a new strategy with universal and translational prospects for clinical diabetic tissue damage. STATEMENT OF SIGNIFICANCE: Methicillin-resistant staphylococcus aureus (MRSA)-infected diabetic wounds face significant challenges in clinical care, characterized by high ROS levels, acute inflammation, vascular lesions, and hypoxia, which impede healing and risk severe complications. Here, we originally developed a reactive oxygen species (ROS) nanopurifier prepared by in-situ polymerization of superoxide dismutase (SOD), catalase (CAT), and vancomycin. It uses SOD and CAT to continuously convert ROS (H2O2 and ·O2-) into O2 in diabetic tissues, effectively improving hypoxia and chronic inflammation, thereby promoting angiogenesis and cell proliferation and migration, and accelerating diabetic wound healing. Vancomycin can effectively kill MRSA bacteria, avoid bacterial infection spread, and reduce complications risk. This safe, efficient and easy-to-prepare ROS nanopurifier provides a general strategy for repairing MRSA-infected diabetic tissue damage.

Multifaceted Catalytic Glucose Depletion and Reactive Oxygen Species-Scavenging Nanoenzyme Composite Hydrogel for Facilitating Diabetic Bone Regeneration

Regeneration of diabetic bone defects remains a formidable challenge due to the chronic hyperglycemic state, which triggers the accumulation of advanced glycation end products (AGEs) and reactive oxygen species (ROS). To address this issue, we have engineered a bimetallic metal-organic framework-derived Mn@Co3O4@Pt nanoenzyme loaded with alendronate and Mg2+ ions (termed MCPtA) to regulate the hyperglycemic microenvironment and recover the osteogenesis/osteoclast homeostasis. Notably, the Mn atom substitution in the Co3O4 nanocrystalline structure could modulate the electronic structure and significantly improve the SOD/CAT catalytic activity for ROS scavenging. By integration with GOx-like Pt nanoparticles, the MCPtA achieved effective multiple cascade catalytic performance that facilitated the clearance of glucose and ROS. Furthermore, the MCPtA was encapsulated within a glucose-responsive hydrogel cross-linked via a borate ester bond, termed PAM, to evaluate the potential of the composite hydrogel for cranial defect repair in diabetic rats. The in vitro/vivo experiments as well as the RNA sequencing analysis demonstrated that the nanoenzyme composite hydrogel could disrupt the glucose-ROS-induced inflammation and promoted osteogenesis and angiogenesis, in consequence, improving the therapeutic effects for diabetic bone regeneration. This study provided crucial insights into nanoenzyme-mediated microenvironmental regulation for diabetic bone regeneration.

Isoferulic acid regulates CXCL12/CXCR4-mediated apoptosis and autophagy in podocyte and mice with STZ-induced diabetic nephropathy

Diabetic nephropathy (DN) is the most common microvascular complication of diabetes mellitus and a major cause of end-stage renal disease. Isoferulic acid (IFA) is a phenolic compound that has strong antioxidant, anti-inflammatory, and hypoglycemic effects. Researches and our previous study showed the potential anti-diabetic capacity and anti- oxidative stress damage targeting podocytes of IFA. The purpose of this study was to investigate whether IFA protects MPC5 podocytes from high glucose damage and alleviates DN symptoms in STZ-induced mice, as well as to explore the mechanism. The findings revealed that IFA (10, 25, 50 μM) significantly reduced high glucose-mediated toxicity, abnormal motility and morphology, ROS release, Ca2+ elevation with MPTP opening, apoptotic alterations with Caspase-3/7 activity increase and CXCL12 chemotaxis and interaction with CXCR4 in MPC5 podocytes. Furthermore, IFA increased Podocalyxin and LC3 II/I ratio. Meanwhile, IFA suppressed p53, mTOR, CASK, and p62. Furthermore, IFA has the ability to directly influence downstream mTOR, p53, and CASK apoptotic and podocyte motility regulatory targets when inhibiting the CXCL12/CXCR4 signaling pathway. In the sequent in vivo experiment, the results showed STZ-induced DN mice had higher kidney index, urination, UACR, lipid metabolism abnormalities and renal dysfunction, raised blood glucose, and podocyte damage than normal C57BL/6 mice. However, IFA treatment (50 mg/kg, 25 mg/kg, and 12.5 mg/kg) for 10 weeks restored the DN symptoms in the mice. IFA treatment elevated LC3B and LC3 II/I ratios and decreased p62 via suppressing chemokine axis CXCL12/CXCR4 with PI3K/Akt/mTOR, MMP9, and NF-κB p65 and activating podocyte markers WT1, nephrin, and Podocalyxin, thereby inducing autophagy and mitigating apoptosis in the DN mice kidneys. These findings suggest that IFA protective mechanism on kidney and podocytes simulating DN symptoms is primarily mediated by the CXCL12/CXCR4 pathways with the inactivation of apoptotic pathways and activation of autophagy.

Bioadhesive supramolecular polymer/hyaluronic acid hydrogel with sustained release of zinc ions and dexamethasone for diabetic wound healing

Diabetic patients often struggle with wound healing and are at higher risk of infections, necessitating the development of a stretchable, adhesive hydrogel dressing with antibacterial and angiogenesis-promoting properties. In this study, we synthesized a series of adhesive, antibacterial and anti-inflammatory hydrogels using free radical polymerization with materials including methacrylated hyaluronic acid (HAMA), N-[tris(hydroxymethyl)methyl]acrylamide (THMA), and 3-(bis(pyridin-2-ylmethyl)amino)propyl methacrylate (DPAMA). By leveraging the strong affinity of zinc(II)-dipicolylamine coordination complexes for the phosphorylated groups in dexamethasone sodium phosphate (DMSP), Zn2+ and DMSP were successfully incorporated into the hydrogel. The results demonstrated that the hydrogels possessed excellent adhesiveness and mechanical properties, enabling them to adhere closely to the skin while remaining easily removable without causing trauma. Antibacterial tests demonstrated significant inhibitory effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), attributed to the slow release of Zn2+, which effectively suppressed bacterial growth. Additionally, the slow release of DMSP provided strong anti-inflammatory effects. The DHTDZ2 hydrogel, containing 1.5 mg/mL Zn2+ and 4 mg/mL DMSP, significantly accelerated the healing of full-thickness skin wounds. In vitro angiogenesis, immunofluorescence, and immuno-histochemical results further confirmed that the DHTDZ2 hydrogel promoted angiogenesis and reduced the expression of pro-inflammatory factors. In summary, the hydrogel is an effective wound healing dressing that can reduce wound infections and inflammation.

Hydrogels and hydrogel-based drug delivery systems for promoting refractory wound healing: Applications and prospects

Refractory wounds represent a significant health concern that presents considerable challenges within clinical practice. The healing process of refractory wounds, which involves various cell types and biologically active molecules, is dynamically influenced by multiple factors, including diabetes, infections, and inflammation. Owing to their hydrophilicity, biocompatibility, and capacity for drug loading, hydrogels have emerged as promising and innovative biomaterials for enhancing wound healing. In recent decades, hydrogels with inherent therapeutic properties have been identified. Moreover, advanced hydrogel-based drug delivery systems have been developed to facilitate the sustained and controlled release of therapeutic agents at the site of refractory wounds. This review aims to summarize recent advancements and applications of hydrogels, including those with intrinsic therapeutic properties and hydrogel-based drug delivery systems, in the treatment of refractory wounds. Additionally, we discuss the limitations associated with hydrogel applications and propose future perspectives, which will lead to ongoing efforts to optimize hydrogels as ideal biomaterials for refractory wound healing.

Carboxyl-functionalized multifunctional red-emitting carbon quantum dots as an ideal biomaterial

Carbon quantum dots (CQDs) have been developed into a popular nanomaterial due to their abundant surface state, good biocompatibility, and excellent antimicrobial properties. However, CQDs with multiple functions, such as being red-emitting, having good antibacterial activity, and having excellent pH sensitivity, have rarely been reported. In this work, red-emitting CQDs (R-CQDs) with excellent optical properties and antimicrobial activity were prepared by a simple green hydrothermal method. In antimicrobial applications, the R-CQDs featured good antibacterial activity due to the generation of reactive oxygen species, indicating excellent photodynamic antimicrobial ability. In addition, the R-CQDs showed fine pH sensitivity, giving them potential as pH sensors to monitor the pH of wounds in real time. The promising potential application of R-CQDs for cell imaging was also demonstrated. In summary, we offer R-CQDs with good antibacterial and pH sensitivity as a potential nanomaterial for pH and antimicrobial monitoring of wounds, shedding light on the biomedical field.

Metal ion formulations for diabetic wound healing: Mechanisms and therapeutic potential

Metals are vital in human physiology, which not only act as enzyme catalysts in the processes of superoxide dismutase and glucose phosphorylation, but also affect the redox process, osmotic adjustment, metabolism and neural signals. However, metal imbalances can lead to diseases such as diabetes, which is marked by chronic hyperglycemia and affects wound healing. The hyperglycemic milieu of diabetes impairs wound healing, posing significant challenges to patient quality of life. Wound healing encompasses a complex cascade of hemostasis, inflammation, proliferation, and remodeling phases, which are susceptible to disruption in hyperglycemic conditions. In recent decades, metals have emerged as critical facilitators of wound repair by enhancing antimicrobial properties (e.g., iron and silver), providing angiogenic stimulation (copper), promoting antioxidant activity and growth factor synthesis (zinc), and supporting wound closure (calcium and magnesium). Consequently, research has pivoted towards the development of metal ion-based therapeutics, including innovative formulations such as nano-hydrogels, nano-microneedle dressings, and microneedle patches. Prepared by combining macromolecular materials such as chitosan, hyaluronic acid and sodium alginate with metals, aiming at improving the management of diabetic wounds. This review delineates the roles of key metals in human physiology and evaluates the application of metal ions in diabetic wound management strategies.

Multifunctional layered microneedle patches enable transdermal angiogenesis and immunomodulation for scarless healing of thermal burn injuries

Thermal burn injuries induce substantial alterations in the immune compositions and anatomical structures in the skin, which are characterized by strong inflammatory responses and thick eschar formation on the wound surface. These traits challenge current treatment paradigms due to insufficient drug penetration into affected tissues and the unsatisfactory wound regeneration. Herein, we report a layered microneedle (MN) patch for addressing these challenges in burn injury healing. The MN patch features a core/shell structure with methacrylated gelatin (GelMA) encapsulated with human umbilical vein endothelial cell (HUVECs)-derived hypoxia-induced exosomes (EXO-H) as the bottom layer and sodium alginate (SA) containing naringin (Nar)-loaded CaCO3 nanoparticles (CaCO3@Nar) as the top layer. Upon administration onto thermal burn injury site, the MN patches enable transdermal drug delivery by perforating the eschar. The spontaneous degradation of CaCO3@Nar in the interstitial fluid triggers sustained Nar release to alleviate local inflammation and scavenge excessive reactive oxygen species (ROS). Meanwhile, EXO-H significantly promote the migration and proliferation of HUVECs and enhance their angiogenesis capacity to support scarless wound tissue regeneration. The MN patch in this work successfully promoted scarless healing of skin burn injuries on rat models, providing an approach for thermal burn treatment in the clinics.

Antibacterial carboxymethyl chitosan hydrogel loaded with antioxidant cascade enzymatic system for immunoregulating the diabetic wound microenvironment

Diabetic wound healing faces several complex challenges, such as hypoxia, oxidative stress, and bacterial infections, which severely inhibit the wound-healing process. Herein, a quaternary ammonium salt-crosslinked carboxymethyl chitosan hydrogel (TPC) with excellent antioxidant and antibacterial properties was developed to immunoregulate the diabetic wound microenvironment. The TPC hydrogel was prepared by first mixing carboxymethyl chitosan (CMCS) and protocatechualdehyde (PA), followed by the addition of a quaternary ammonium cross-linker (TSPBA) and a superoxide dismutase (SOD)-catalase (CAT) cascade system. The immobilized SOD and CAT retained their activity, continuously converting endogenous ·O2- and H2O2 to O2 and H2O. PA also provided the TPC hydrogel excellent oxygen and nitrogen radical scavenging capacity. The quaternary ammonium groups in TSPBA significantly enhanced the inherent antibacterial ability of CMCS-based hydrogels. In diabetic wound-healing experiments, this porous and adhesive TPC hydrogel effectively closed wounds and regenerated skin tissue, resulting in shorter wound edges, thicker granulation, and higher collagen deposition levels compared with other groups. The TPC hydrogel also promoted macrophage polarization toward the M2 phenotype, accelerating wound healing by upregulating IL-10 expression, downregulating IL-6 expression, and enhancing angiogenesis. These results demonstrate the great potential of TPC hydrogel as a promising therapeutic dressing for treating diabetic wounds.

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.

Localized Surface Plasmon Resonance-Enhanced Photocatalytic Antibacterial of In Situ Sprayed 0D/2D Heterojunction Composite Hydrogel for Treating Diabetic Wound

Chronic diabetic wounds pose significant challenges due to uncontrolled bacterial infections, prolonged inflammation, and impaired angiogenesis. The rapid advancement of photo-responsive antibacterial therapy shows promise in addressing these complex issues, particularly utilizing 2D heterojunction materials, which offer unique properties. Herein, an in situ sprayed Bi/BiOCl 0D/2D heterojunction composite fibrin gel with the characteristics of rapid formation and effective near-infrared activation is designed for the treatment of non-healing diabetes-infected wounds. The sprayed composite gel can provide protective shielding for skin tissues and promote endothelial cell proliferation, vascularization, and angiogenesis. The Bi/BiOCl 0D/2D heterojunction, with its localized surface plasmon resonance (LSPR), can overcome the wide bandgap limitation of BiOCl, enhancing the generation of local heat and reactive oxygen species under near-infrared irradiation. This facilitates bacterial elimination and reduced inflammation, supporting the accelerated healing of diabetes-infected wounds. This study underscores the potential of LSPR-enhanced heterojunctions as advanced wound therapies for chronic diabetic wounds.

Fabrication of porcine acellular dermal matrix and oxidized hyaluronic acid conductive composite hydrogels for accelerating skin wound healing under electrical stimulation

Electrical stimulation (ES) of skin wounds can promote cell proliferation, protein synthesis, inflammatory response, and improve neurological function. In this study, the dynamical cross-linked conductive hydrogels have been developed by integration of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) into porcine acellular dermal matrix (PADM) and oxidized hyaluronic acid (OHA) using dopamine-Fe complex (DA@Fe) as cross-linking agent. The as-obtained conductive composite hydrogels have the characteristics of rapid gelation, excellent deformation ability, high water absorption, and suitable degradation rate. Four-point probes resistivity measurement system has been used to test the electrical properties of the as-obtained hydrogels, and showing their conductivity at 0.207-0.322 S/m. In addition, the developed dynamical cross-linked conductive hydrogels exhibit excellent biocompatibility, thereby inducing cells proliferation and migration. In vivo results show that the resultant composite hydrogel can accelerate wound healing with combination of electrical stimulation (ES) by promoting expression of vascular factor (CD31) and decreasing the expression of tumor necrosis factor-α (TNF-α).

A review of lignin application in hydrogel dressing

Lignin is the most abundant natural aromatic polymer in the world. Currently, researchers have developed a number of lignin-based composite materials that are widely used in various fields, including industry, agriculture and medicine. Especially in recent years, lignin has attracted great interest as a high-value product for biomedical applications. Due to its antioxidant, antibacterial, adhesive and other properties, lignin is a promising candidate for the development of hydrogel dressings. However, there is no comprehensive overview of the application of lignin-based hydrogel dressings. In this review, lignin-based hydrogel skin dressings were first presented, and the preparation methods of physical and chemical crosslinking in lignin-based hydrogel dressings were discussed. In addition, various functional and environmentally responsive lignin-based hydrogel dressings were primarily reviewed. Finally, the prospects for the development of novel multifunctional lignin-based hydrogel dressings in the future were presented. In conclusion, this review provided a timely and comprehensive summary of the latest advances in the use of lignin as a biomaterial for hydrogel dressings, which would provide valuable guidance for the further development of lignin-based hydrogels.

Recent Advances in the Drugs and Glucose-Responsive Drug Delivery Systems for the Treatment of Diabetes: A Systematic Review

Diabetes is a common chronic metabolic disease. Different types of drugs play important roles in controlling diabetes and its complications, but there are some limitations. The glucose-responsive drug delivery system is a novel technology with potential in diabetes treatment. It could automatically release drugs in response to changes in glucose levels in the body to maintain blood glucose within a normal range. The emergence of a glucose-sensitive drug delivery system provides a more intelligent and precise way to treat diabetes. The review is carried out according to the Preferred Reporting Items for Systematic Reviews (PRISMA 2020) guidelines This review focuses on the recent advances in the drugs and different systems of glucose-sensitive drug delivery, including glucose oxidase, phenylboronic acid, Concanavalin A, and other glucose-reactive systems. Furthermore, the glucose-responsive drug delivery system combined with the application applied in hydrogels, microneedles, and nanoparticles is also explored and summarized. The new platforms to sustain the release of anti-diabetic drugs could be desirable for patients. It could lead to increased adherence and glycemic outcomes for the detection and treatment of diabetes. Furthermore, given the limitations of glucose-responsive drug delivery systems, solutions and perspectives are proposed to help the understanding and application of these systems. This review will be helpful for drug discovery and treatment of diabetes from a new perspective.

Advances in Smart-Response Hydrogels for Skin Wound Repair

Hydrogels have emerged as promising candidates for biomedical applications, especially in the treatment of skin wounds, as a result of their unique structural properties, highly tunable physicochemical properties, and excellent biocompatibility. The integration of smart-response features into hydrogels allows for dynamic responses to different external or internal stimuli. Therefore, this paper reviews the design of different smart-responsive hydrogels for different microenvironments in the field of skin wound therapy. First, the unique microenvironments of three typical chronic difficult-to-heal wounds and the key mechanisms affecting wound healing therapeutic measures are outlined. Strategies for the construction of internal stimulus-responsive hydrogels (e.g., pH, ROS, enzymes, and glucose) and external stimulus-responsive hydrogels (e.g., temperature, light, electricity, and magnetic fields) are highlighted from the perspective of the wound microenvironment and the in vitro environment, and the constitutive relationships between material design, intelligent response, and wound healing are revealed. Finally, this paper discusses the severe challenges faced by smart-responsive hydrogels during skin wound repair and provides an outlook on the combination of smart-responsive hydrogels and artificial intelligence to give scientific direction for creating and using hydrogel dressings that respond to stimuli in the clinic.

Exudate Unidirectional Pump to Promote Glucose Catabolism Triggering Fenton-Like Reaction for Chronic Diabetic Wounds Therapy

The massive accumulation of exudate containing high concentrations of glucose causes wound infection and triggers the release of inflammatory factors, which in turn delays the closure of diabetic wounds. In this study, a Janus membrane is constructed by combining glucose oxidase (GOx) and copper ions (Cu2+) for the treatment of diabetic wounds, which is named as Janus@GOx/Cu2+. It consists of hydrophobic, transitional, and superhydrophilic layers in a three-layer structure with gradient hydrophilicity for self-pumping properties. The Janus@GOx/Cu2+ membrane triggers a series of cascading reactions while pumping out diabetic wound exudates. First, glucose oxidase loaded onto the hydrophilic layer of the Janus@GOx/Cu2+ membrane decomposes glucose into hydrogen peroxide (H2O2) and glucuronic acid, reducing the local glucose level. The generated glucuronic acid neutralizes the local alkaline environment of chronic wounds. Simultaneously, the H2O2 interacts with the Cu2+ contained in the hydrophobic layers of the Janus@GOx/Cu2+ membrane via a Fenton-like reaction, generating hydroxyl radicals with excellent bactericidal properties. Cu2+ promotes angiogenesis and wound healing in diabetic wounds. Under the action of multiple responses, the Janus@GOx/Cu2+ membrane promotes wound healing in diabetic infections.

Current progress of protein-based dressing for wound healing applications - A review

Protein-based wound dressings have garnered increasing interest in recent years owing to their distinct physical, chemical, and biological characteristics. The intricate molecular composition of proteins gives rise to unique characteristics, such as exceptional biocompatibility, biodegradability, and responsiveness, which contribute to the promotion of wound healing. Wound healing is an intricate and ongoing process influenced by multiple causes, and it consists of four distinct phases. Various treatments have been developed to repair different types of skin wounds, thanks to advancements in medical technology and the recognition of the diverse nature of wounds. This review has literature reviewed within the last 3-5 years-the recent progress and development of protein in wound dressings and the fundamental properties of an ideal wound dressing. Herein, the recent strides in protein-based state-of-the-art wound dressing emphasize the significant challenges and summarize future perspectives for wound healing applications.

LSPR-enhanced photoresponsive antibacterial efficiency of Bi/MoS2-loaded fibrin gel for management of diabetic wounds

Chronic diabetic wounds present formidable challenges, marked by uncontrolled bacterial infections, prolonged inflammation, and impaired angiogenesis. The evolving landscape of photo-responsive antibacterial therapy holds great promise in addressing these multifaceted issues, with a particular focus on leveraging the distinctive properties of 2D heterojunction materials. In this investigation, we engineered composite sprayed hydrogels, seamlessly integrating Bi/MoS2 nano-heterojunctions. Capitalizing on the synergistic interplay between photocatalytic antibacterial and photothermal antibacterial mechanisms, the Bi/MoS2 heterojunction, guided by its localized surface plasmon resonance, demonstrated outstanding antibacterial efficacy within a mere 10-minute exposure to 808 nm near-infrared light. This accelerated sterilization both in vitro and in vivo, consequently expediting wound healing. The sprayed composite gel not only furnishes protective shielding for skin tissues but also fosters endothelial cell proliferation, vascularization, and angiogenesis. This safe and ultrafast sterilizing hydrogel presents immense potential for application in antimicrobial dressings, thereby offering a promising avenue for diabetic wound healing.

Non-releasing poly (ionic liquid) based hydrogel accelerates diabetic wound healing

Persistent bacterial colonization, abnormal inflammatory responses, and impaired angiogenesis pose significant challenges to effective wound repair, particularly in diabetic wounds. Employing exogenous bioactive substances in wound dressings is a recognized approach to dynamically respond to the wound microenvironment and accelerate the repair process. However, this strategy can lead to the development of drug resistance and induce further tissue damage. To address these challenges, we are synthesizing a novel hydrogel for diabetic wound treatment using functional poly (ionic liquid) and modified dextran. The hydrogel is characterized by its excellent tissue adhesion, exceptional self-healing capacity, and substantial compressive deformation. It exhibits broad antibacterial activity, reduces the expression of pro-inflammatory cytokines and enhances the healing in diabetic wounds. Its efficacy is superior to that of the positive control group. This innovative non-releasing hydrogel presents as a promising alternative to conventional antibiotics, offering significant potential for the treatment and healing of diabetic chronic wounds.

Smart theranostics for wound monitoring and therapy

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

Enhanced diabetic wound healing with injectable hydrogel containing self-assembling nanozymes

To build a smart system in response to the variable microenvironment in infected diabetic wounds, a multifunctional wound dressing was constructed by co-incorporating glucose oxidase (GOx) and a pH-responsive self-assembly Cu2-xSe-BSA nanozyme into a dual-dynamic bond cross-linked hydrogel (OBG). This composite hydrogel (OBG@CG) can adhere to the wound site and respond to the acidic inflammatory environment, initiating the GOx-catalyzed generation of H2O2 and the self-assembly activated peroxidase-like property of Cu2-xSe-BSA nanozymes, resulting in significant hydroxyl radical production to attack the biofilm during the acute infection period and alleviate the high-glucose microenvironment for better wound healing. During the wound recovery phase, Cu2-xSe-BSA aggregates disassembled owing to the elevated pH, terminating catalytic reactive oxygen species generation. Simultaneously, Cu2+ released from the Cu2-xSe-BSA not only promotes the production of mature collagen but also enhances the migration and proliferation of endothelial cells. RNA-seq analysis demonstrated that OBG@CG exerted its antibacterial property by damaging the integrity of the biofilm by inducing radicals and interfering with the energy supply, along with destroying the defense system by disturbing thiol metabolism and reducing transporter activities. This work proposes an innovative glucose consumption strategy for infected diabetic wound management, which may inspire new ideas in the exploration of smart wound dressing.

Fast fabrication of "all-in-one" injectable hydrogels as antibiotic alternatives for enhanced bacterial inhibition and accelerating wound healing

Skin wound infection has become a notable medical threat. Herein, the polysaccharide-based injectable hydrogels with multifunctionality were developed by a simple and fast gelation process not only to inactivate bacteria but also to accelerate bacteria-infected wound healing. Sodium nitroprusside (SNP) loaded PCN-224 nanoparticles were introduced into the polymer matrix formed by the dynamic and reversible coordinate bonds between Ag+ with carboxyl and amino or hydroxyl groups on carboxymethyl chitosan (CMCS), hydrogen bonds and electrostatic interactions in the polymer to fabricate SNP@PCN@Gel hydrogels. SNP@PCN@Gel displayed interconnected porous structure, excellent self-healing capacity, low cytotoxicity, good blood compatibility, and robust antibacterial activity. SNP@PCN@Gel could produce reactive oxygen species (ROS) and NO along with Fe2+, and showed long-term sustained release of Ag+, thereby effectively killing bacteria by synergistic photothermal (hyperthermia), photodynamic (ROS), chemodynamic (Fenton reaction), gas (NO) and ion (Ag+ and -NH3+ in CMCS) therapy. Remarkably, the hydrogels significantly promoted granulation tissue formation, reepithelization, collagen deposition and angiogenesis as well as wound contraction in bacteria-infected wound healing. Taken together, the strategy represented a general method to engineer the unprecedented photoactivatable "all-in-one" hydrogels with enhanced antibacterial activity and paved a new way for development of antibiotic alternatives and wound dressing.

A TLR4-Targeting Bioactive Peptide Hydrogel to Regulate Immune-Microenvironment for Diabetic Wound Repair

Persistent inflammation and disrupted immunoregulation are critical factors in impeding diabetic wound healing. While immunoregulatory hydrogel dressings hold significant promise for clinical applications in diabetic wound healing, the current application often demands intricate interventions and high-cost treatments involving cytokines and cell therapies. The development of single component immunoregulatory hydrogels remains a complex challenge. To address this issue, an active peptide hydrogel with immunoregulatory properties targeting the TLR4/NF-kB pathway, aiming to promote rapid diabetic wound healing, is engineered. The hydrogel sequence comprises naphthalene derivative, phenylalanine, and glycine to modulate hydrophilic/hydrophobic characteristics. The amino group on arginine contributes to tissue adhesion and regulation of intermolecular forces, ultimately yielding stable gels. The results underscore the formation of the peptide hydrogel (NFA) via the physical crosslinking of self-assembled nanofibers in water, thereby affording both excellent injectability and tissue adhesion. Notably, NFA demonstrates significant potential in promoting wound healing in a mouse model with full-thickness wounds by regulating macrophage responses in the inflammatory microenvironment through the TLR4/NF-kB pathway.

A Zn-MOF-GOx-based cascade nanoreactor promotes diabetic infected wound healing by NO release and microenvironment regulation

Diabetic wound healing is a great clinical challenge due to the microenvironment of hyperglycemia and high pH value, bacterial infection and persistent inflammation. Here, we develop a cascade nanoreactor hydrogel (Arg@Zn-MOF-GOx Gel, AZG-Gel) with arginine (Arg) loaded Zinc metal organic framework (Zn-MOF) and glucose oxidase (GOx) based on chondroitin sulfate (CS) and Pluronic (F127) to accelerate diabetic infected wound healing. GOx in AZG-Gel was triggered by hyperglycemic environment to reduce local glucose and pH, and simultaneously produced hydrogen peroxide (H2O2) to enable Arg-to release nitric oxide (NO) for inflammation regulation, providing a suitable microenvironment for wound healing. Zinc ions (Zn2+) released from acid-responsive Zn-MOF significantly inhibited the proliferation and biofilm formation of S.aureus and E.coli. AZG-Gel significantly accelerated diabetic infected wound healing by down-regulating pro-inflammatory tumor necrosis factor (TNF)-α and interleukin (IL)-6, up-regulating anti-inflammatory factor IL-4, promoting angiogenesis and collagen deposition in vivo. Collectively, our nanoreactor cascade strategy combining "endogenous improvement (reducing glucose and pH)" with "exogenous resistance (anti-bacterial and anti-inflammatory)" provides a new idea for promoting diabetic infected wound healing by addressing both symptoms and root causes. STATEMENT OF SIGNIFICANCE: A cascade nanoreactor (AZG-Gel) is constructed to solve three key problems in diabetic wound healing, namely, hyperglycemia and high pH microenvironment, bacterial infection and persistent inflammation. Local glucose and pH levels are reduced by GOx to provide a suitable microenvironment for wound healing. The release of Zn2+ significantly inhibits bacterial proliferation and biofilm formation, and NO reduces wound inflammation and promotes angiogenesis. The pH change when AZG-Gel is applied to wounds is expected to enable the visualization of wound healing to guide the treatment of diabetic wound. Our strategy of "endogenous improvement (reducing glucose and pH)" combined with "exogenous resistance (anti-bacterial and anti-inflammatory)" provides a new way for promoting diabetic wound healing.

Reactive Oxygen-Correlated Photothermal Imaging of Smart COF Nanoreactors for Monitoring Chemodynamic Sterilization and Promoting Wound Healing

Chemodynamic therapy (CDT) has emerged as a promising approach for treating infected diabetic wounds, while reliable imaging technology for simultaneous monitoring of ROS and therapeutic processes is still a formidable challenge. Herein, smart covalent organic framework (COF) nanoreactors (COF NRs) are constructed by hyaluronic acid (HA) packaged glucose oxidase (GOx) covalently linked Fe-COF for diabetic wound healing. Upon the breakdown of the HA protective layer, GOx consumes glucose to produce gluconic acid and hydrogen peroxide (H2O2), resulting in decreased local pH and H2O2 supplementation. Density functional theory (DFT) calculations show that Fe-COF has high catalytic activity towards H2O2, leading to in situ generation of hydroxyl radicals (·OH) for sterilization, and the localized downregulation of glucose effectively improved the microenvironment of diabetic wounds. Meanwhile, based on the near-infrared photothermal imaging of oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB), the authors showed that TMB can be applied for the point-of-care testing of ·OH and glucose, and assessing the sterilization progress in vivo. More significantly, the facile photothermal signaling strategy can be extended to monitor various ROS-mediated therapeutic systems, enabling accurate prediction of treatment outcomes.

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.