Nanoenzyme-Reinforced Injectable Hydrogel for Healing Diabetic Wounds Infected with Multidrug Resistant Bacteria

Multifunctional photothermally responsive hydrogel as an effective whole-process management platform to accelerate chronic diabetic wound healing

The management of chronic diabetic wounds is a complex issue that requires wound repair, regulation of inflammatory levels, and intervention to prevent bacterial infection. To address this issue, we developed a multifunctional photothermally responsive hydrogel (PAG-CuS) as an effective platform for managing the entire wound-healing process, including promoting wound healing, providing anti-inflammatory therapy, and performing photothermal sterilization. Constructed through copolymerization of acrylic acid (AA), methacrylic anhydride-modified gelatin (GelMA), and lipoic acid sodium (LAS) coated copper sulfide nanoparticles (CuS@LAS), PAG-CuS possessed a porous three-dimensional structure that promoted cell adhesion and had a substantial water-holding capacity. Additionally, the internal CuS@LAS not only conferred photothermal antibacterial properties to the hydrogel but also served as physical cross-linking agents, thus enhancing its mechanical strength. Under the NIR-induced photothermal effect, the porous hydrogel liberates CuS@LAS, and later CuS@LAS expels LAS via micelle deassembly to eliminate intracellular ROS. This results in the down-regulation of MMP-9 expression, promoting ECM production and facilitating wound healing. Meanwhile, the release of Cu2+ from PAG-CuS could enhance CD31 expression in endothelial cells, promoting microvessel formation, which is crucial for wound healing. In the diabetic wound model of GK rats, the PAG-CuS hydrogel reduced ROS levels, increased microvessel count, improved epithelialization, and enhanced wound healing. Therefore, this versatile photothermal hydrogel has the potential to be applied in sterilization, scavenging free radicals, and promoting angiogenesis, making it an effective and comprehensive solution to manage the challenges of diabetic wounds. STATEMENT OF SIGNIFICANCE: Assessment of functional recovery and timely adjustment of treatment strategy is critical in the management of chronic diabetic wounds. In this work, we prepared PAG-CuS composite hydrogels by integrating in situ reduction, chemical crosslinking, and nanoenhancement techniques. The near-infrared light-induced photothermal effect of PAG-CuS gel rapidly kills bacteria at the lesion site, and the generated heat simultaneously promotes the multilevel release of LAS from the gel, which could regulate the levels of ROS and MMP-9 to promote extracellular matrix formation. In addition, the Cu2+ released from the gel can promote the formation of blood vessels to improve blood oxygenation. Therefore, this project proposes a synergistic solution to realize the whole process of management to accelerate chronic diabetic wound healing.

A Multifunctional Hydrogel for Simultaneous Visible H2 O2 Monitoring And Accelerating Diabetic Wound Healing

Diabetic wound is one of the chronic wounds that is difficult to heal, and effective treatment of it still confronts a great challenge. Monitoring the variation of diabetic wound microenvironment (such as hydrogen peroxide (H2 O2 )) can understand the wound state and guide the wound management. Herein, a multifunctional hydrogel with the abilities of monitoring the H2 O2 concentration, alleviating oxidative stress and promoting wound healing is developed, which is prepared by encapsulating manganese-containing bioactive glass (MnBG) and CePO4 :Tb in biocompatible gelatin methacryloyl (GelMA) hydrogel (CPT-MnBG-Gel). On the one hand, the H2 O2 -dependent fluorescence quenching effect of the CePO4 :Tb contributes to visible monitoring of the H2 O2 concentration of wounds via smartphone imaging, and the CPT-MnBG-Gel hydrogel can effectively monitor the H2 O2 level of 10.35-200 µmol L-1 . On the other hand, MnBG can alleviate oxidative stress and promote the proliferation, migration and differentiation of fibroblasts and endothelial cells in vitro owing to the bioactive Mn and Si ions, and in vivo evaluation also demonstrates that the CPT-MnBG-Gel hydrogels can effectively accelerate wound healing. Hence, such multifunctional hydrogel is promising for diabetic wound management and accelerating wound healing.

Multifunctional Hydrogels for the Healing of Diabetic Wounds

The healing of diabetic wounds is hindered by various factors, including bacterial infection, macrophage dysfunction, excess proinflammatory cytokines, high levels of reactive oxygen species, and sustained hypoxia. These factors collectively impede cellular behaviors and the healing process. Consequently, this review presents intelligent hydrogels equipped with multifunctional capacities, which enable them to dynamically respond to the microenvironment and accelerate wound healing in various ways, including stimuli -responsiveness, injectable self-healing, shape -memory, and conductive and real-time monitoring properties. The relationship between the multiple functions and wound healing is also discussed. Based on the microenvironment of diabetic wounds, antibacterial, anti-inflammatory, immunomodulatory, antioxidant, and pro-angiogenic strategies are combined with multifunctional hydrogels. The application of multifunctional hydrogels in the repair of diabetic wounds is systematically discussed, aiming to provide guidelines for fabricating hydrogels for diabetic wound healing and exploring the role of intelligent hydrogels in the therapeutic processes.

Multifunctional biomaterial hydrogel loaded with antler blood peptide effectively promotes wound repair

Diabetes is an epidemic in contemporary society, which seriously affects people's health. Therefore, it is imperative to develop a multifunctional wound dressing that can expedite the healing of diabetic wounds. In this study, quaternized oxidized sodium alginate (QOSA) and carboxymethyl chitosan (CMCS) formed hydrogel through Schiff base reaction, and the composite hydrogel was prepared by adding the antioxidant activity of deer antler blood polypeptide (D). The hydrogel exhibits favorable attributes, including a high swelling ratio, biocompatibility, and noteworthy antioxidant, antibacterial, and hemostatic properties. Finally, it was used to evaluate its effectiveness in repairing diabetic wounds. Upon evaluation, this hydrogel can effectively promote diabetic wound healing. It facilitates cell proliferation at the wound site, mitigates inflammatory responses, and enhances the expression of growth factors at the wound site. This suggests that this hydrogel holds significant promise as an ideal candidate for advanced wound dressings.

Microenvironmental dynamics of diabetic wounds and insights for hydrogel-based therapeutics

The rising prevalence of diabetes has underscored concerns surrounding diabetic wounds and their potential to induce disability. The intricate healing mechanisms of diabetic wounds are multifaceted, influenced by ambient microenvironment, including prolonged hyperglycemia, severe infection, inflammation, elevated levels of reactive oxygen species (ROS), ischemia, impaired vascularization, and altered wound physicochemical properties. In recent years, hydrogels have emerged as promising candidates for diabetic wound treatment owing to their exceptional biocompatibility and resemblance to the extracellular matrix (ECM) through a three-dimensional (3D) porous network. This review will first summarize the microenvironment alterations occurring in the diabetic wounds, aiming to provide a comprehensive understanding of its pathogenesis, then a comprehensive classification of recently developed hydrogels will be presented, encompassing properties such as hypoglycemic effects, anti-inflammatory capabilities, antibacterial attributes, ROS scavenging abilities, promotion of angiogenesis, pH responsiveness, and more. The primary objective is to offer a valuable reference for repairing diabetic wounds based on their unique microenvironment. Moreover, this paper outlines potential avenues for future advancements in hydrogel dressings to facilitate and expedite the healing process of diabetic wounds.

Oxygen-Generating Hydrogels as Oxygenation Therapy for Accelerated Chronic Wound Healing

Hypoxia in chronic wounds impairs the activities of reparative cells, resulting in tissue necrosis, bacterial infections, decreased angiogenesis, and delayed wound healing. To achieve effective oxygenation therapy and restore oxygen homeostasis, oxygen-generating hydrogels based on different oxygen sources have been developed to release dissolved oxygen in the wound bed, which not only alleviate hypoxia, but also accelerate chronic wound healing. This review first discusses the vital role of oxygen and hypoxia in the wound healing process. The advancements in oxygen-generating hydrogels, which produce oxygen through the decomposition of hydrogen peroxide, metal peroxides, glucose-activated cascade reactions, and photosynthesis of algae microorganisms for chronic wound healing, are discussed and summarized. The therapeutic effects and challenges of using oxygen-generating hydrogels for the clinical treatment of chronic wounds are concluded and prospected.

Mild hyperthermia-assisted chitosan hydrogel with photothermal antibacterial property and CAT-like activity for infected wound healing

Infected wounds pose a serious threat to public health and pose a significant challenge and financial burden worldwide. The treatment of infected wounds is now an urgent problem to be solved. Herein, mild hyperthermia-assisted hydrogels composed of carboxymethyl chitosan (CMCs), oxidized dextran (Odex), epigallocatechin gallate (EGCG) and PtNPs@PVP (CAT-like nanoenzymes) were proposed for the repair of infected wounds. The incorporation of PtNPs@PVP nanoenzymes give the hydrogels excellent photothermal property and CAT-like activity. When the temperature is maintained at 42-45 °C under 808 nm near infrared (NIR) exposure, the CMCs/Odex/EGCG/Nanoenzymes (COEN2) hydrogel demonstrated highly enhanced antibacterial ability (95.9 % in vivo), hydrogen peroxide (H2O2) scavenging ratio (85.1 % in vitro) and oxygen supply (20.7 mg/L in vitro). Furthermore, this mild-heat stimulation also promoted angiogenesis in the damaged skin area. Overall, this multifunctional hydrogel with antibacterial, antioxidant, oxygen supply, hemostasis, and angiogenesis capabilities has shown great promise in the repair of infected wounds. This study establishes the paradigm of enhanced infected wound healing by mild hyperthermia-assisted H2O2 scavenging, oxygen supplemental, and photothermal antibacterial hydrogels.

Hydrogen sulfide releasing poly(γ-glutamic acid) biocomposite hydrogel with monitoring, antioxidant, and antibacterial properties for diabetic wound healing

Adverse factors such as high levels of glucose, oxidative stress, inflammation, and bacterial infection impede diabetic wound healing and even worsen wounds. Owing to its outstanding anti-inflammatory and antioxidant properties as well as the potential to promote cell migration and proliferation, hydrogen sulfide(H2S) gas therapy is promising for chronic diabetic wound recovery. In this work, a multifunctional poly(γ-glutamic acid)(PGA) hydrogel encapsulated with keratin-based H2S donor(KTC), ciprofloxacin(Cip), and anthocyanins(Ant) was developed. The resultant hydrogel was capable of releasing H2S, thereby promoting cell proliferation and enhancing anti-inflammation and antioxidant activity. The release of antibiotic Cip was accelerated under a diabetic wound microenvironment, thereby enhancing the antibacterial activity of the hydrogel. The encapsulated Ant could serve as a pH monitor, sensitively indicating wound pH conditions in situ and indirectly reflecting wound infection. In vivo results in diabetic wound healing suggested that PGA/Ant/KTC/Cip hydrogel reduced inflammation and promoted angiogenesis and collagen deposition, thereby accelerating wound healing.

Microcurrent Cloth-Assisted Transdermal Penetration and Follicular Ducts Escape of Curcumin-Loaded Micelles for Enhanced Wound Healing

Purpose

Larger nanoparticles of bioactive compounds deposit high concentrations in follicular ducts after skin penetration. In this study, we investigated the effects of microcurrent cloth on the skin penetration and translocation of large nanoparticle applied for wound repair applications.

Methods

A self-assembly of curcumin-loaded micelles (CMs) was prepared to improve the water solubility and transdermal efficiency of curcumin. Microcurrent cloth (M) was produced by Zn/Ag electrofabric printing to facilitate iontophoretic transdermal delivery. The transdermal performance of CMs combined with M was evaluated by a transdermal system and confocal microscopy. The CMs/iontophoretic combination effects on nitric oxide (NO) production and inflammatory cytokines were evaluated in Raw 264.7 cells. The wound-healing property of the combined treatment was assessed in a surgically created full-thickness circular wound mouse model.

Results

Energy-dispersive X-ray spectroscopy confirmed the presence of Zn/Ag on the microcurrent cloth. The average potential of M was measured to be +214.6 mV in PBS. Large particle CMs (CM-L) prepared using surfactant/cosurfactant present a particle size of 142.9 nm with a polydispersity index of 0.319. The solubility of curcumin in CM-L was 2143.67 μg/mL, indicating 250-fold higher than native curcumin (8.68 μg/mL). The combined treatment (CM-L+M) demonstrated a significant ability to inhibit NO production and increase IL-6 and IL-10 secretion. Surprisingly, microcurrent application significantly improved 20.01-fold transdermal performance of curcumin in CM-L with an obvious escape of CM-L from follicular ducts to surrounding observed by confocal microscopy. The CM-L+M group also exhibited a better wound-closure rate (77.94% on day 4) and the regenerated collagen intensity was approximately 2.66-fold higher than the control group, with a closure rate greater than 90% on day 8 in vivo.

Conclusion

Microcurrent cloth play as a promising iontophoretic transdermal drug delivery accelerator that enhances skin penetration and assists CMs to escape from follicular ducts for wound repair applications.

Antibacterial, antioxidant and injectable hydrogels constructed using CuS and curcumin co-loaded micelles for NIR-enhanced infected wound healing

Constructing antibacterial and antioxidant hydrogels is critical for treating infected full-thickness skin wounds. Herein, we report a co-encapsulation strategy to load CuS nanoparticles and hydrophobic antioxidant curcumin (cur) in aldehyde-terminated F127 micelles, which are then cross-linked with carboxymethyl chitosan through a Schiff base reaction to form a functional composite hydrogel (CF-CuS-cur). Apart from its suitable swelling and degradation behavior, good biocompatibility, and injectability for treating irregular wounds, the CF-CuS-cur hydrogel displayed excellent photothermal antibacterial ability under 1064 nm NIR laser irradiation, and antioxidant activity to protect cells from excessive oxidative stress. Using a full-thickness infected wound model, we demonstrated that the CF-CuS-cur hydrogel accelerated the wound healing process by effective sterilization and decreased inflammation, under synergistic action from CuS, curcumin and NIR irradiation. Histological and immunohistochemistry analysis further revealed the promoted skin attachments and regeneration, collagen deposition, neovascularization, and early transition to anti-inflammatory M2 macrophages, when the wounds were treated with the CF-CuS-cur hydrogel. This work demonstrates a facile strategy to construct functional hydrogels with NIR-enhanced antibacterial and antioxidant properties, which can be potentially applied as wound dressings for treating chronic wounds.

pH-Responsive Injectable Multifunctional Pluronic F127/Gelatin-Based Hydrogels with Hydrogen Production for Treating Diabetic Wounds

Diabetic chronic wounds remain a major clinical challenge with long-term inflammatory responses and extreme oxidative damage. Hence, a pH-responsive injectable multifunctional hydrogel [Gel/CUR-FCHO/Mg (GCM) micromotors] via a Schiff base reaction between gelatin and benzaldehyde-grafted Pluronic F127 drug-loaded micelles (FCHO) was fabricated for the first time. Dynamic Schiff base linkage endowed the GCM hydrogel with the ability to be self-healing, injectable, and pH-responsive for on-demand drug delivery at the wound site. Curcumin (CUR), a hydrophobic drug with antioxidative, anti-inflammatory, and antibacterial activities, was encapsulated into the hydrogel matrix by micellization (CUR-FCHO micelles). Simultaneously, magnesium-based micromotors (Mg micromotors) were physically entrapped into the system for providing active hydrogen (H2) to scavenge reactive oxygen species and alleviate inflammatory responses. As a result, the GCM micromotor hydrogel displayed an inherent antibacterial property, extraordinary antioxidative performance, and remarkable biocompatibility. In the diabetic mouse with a full-thickness cutaneous defect wound, the GCM hydrogel could remodel the inflammatory microenvironment and stimulate vascularization and collagen deposition, thereby facilitating wound closure and enhancing tissue regeneration, which offered a promising therapeutic option for diabetic chronic wound management.

Extracellular vesicle biopotentiated hydrogels for diabetic wound healing: The art of living nanomaterials combined with soft scaffolds

Diabetic wounds (DWs) pose a major challenge for the public health system owing to their high incidence, complex pathogenesis, and long recovery time; thus, there is an urgent need to develop innovative therapies to accelerate the healing process of diabetic wounds. As natural nanovesicles, extracellular vesicles (EVs) are rich in sources with low immunogenicity and abundant nutritive molecules and exert potent therapeutic effects on diabetic wound healing. To avoid the rapid removal of EVs, a suitable delivery system is required for their controlled release. Owing to the advantages of high porosity, good biocompatibility, and adjustable physical and chemical properties of hydrogels, EV biopotentiated hydrogels can aid in achieving precise and favorable therapy against diabetic wounds. This review highlights the different design strategies, therapeutic effects, and mechanisms of EV biopotentiated hydrogels. We also discussed the future challenges and opportunities of using EV biopotentiated hydrogels for diabetic wound healing.

Antibacterial Broad-Spectrum Dendritic/Gellan Gum Hybrid Hydrogels with Rapid Shape-Forming and Self-Healing for Wound Healing Application

Treating wound infections is a difficult task ever since pathogenic bacteria started to develop resistance to common antibiotics. The present study develops hybrid hydrogels based on the formation of a polyelectrolyte complex between the anionic charges of dopamine-functionalized Gellan Gum (GG-DA) and the cationic moieties of the TMP-G2-alanine dendrimer. The hydrogels thus obtained can be doubly crosslinked with CaCl2 , obtaining solid hydrogels. Or, by oxidizing dopamine to GG-DA, possibly causing further interactions such as Schiff Base and Michael addition to take place, hydrogels called injectables can be obtained. The latter have shear-thinning and self-healing properties (efficiency up to 100%). Human dermal fibroblasts (HDF), human epidermal keratinocytes (HaCaT), and mouse monocyte cells (RAW 264.7), after incubation with hydrogels, in most cases show cell viability up to 100%. Hydrogels exhibit adhesive behavior on various substrates, including porcine skin. At the same time, the dendrimer serves to crosslink the hydrogels and endows them with excellent broad-spectrum microbial eradication activity within four hours, evaluated using Staphylococcus aureus 2569 and Escherichia coli 178. Using the same GG-DA/TMP-G2-alanine ratios hybrid hydrogels with tunable properties and potential for wound dressing applications can be produced.

Hypoxic Microenvironment Reconstruction with Synergistic Biofunctional Ions Promotes Diabetic Wound Healing

Chronic hypoxia and ischemia make diabetic wounds non-healing. Cellular functions of diabetic chronic wounds are inhibited under a pathological environment. Therefore, this work develops a composite hydrogel system to promote diabetic wound healing. The composite hydrogel system consists of ε-poly-lysine (EPL), calcium peroxide (CP), and borosilicate glass (BG). The hydrogel supplies continuous dissolved oxygen molecules to the wound that can penetrate the skin tissue to restore normal cellular function and promote vascular regeneration. Biofunctional ions released from BGs can recruit more macrophages through neovascularization and modulate macrophage phenotypic transformation. Combining oxygen-mediated vascular regeneration and ion-mediated inflammatory regulation significantly accelerated diabetic wound healing. These findings indicate that this composite hydrogel system holds promise as a novel tissue engineering material.

Potential mechanism of the AgNCs-hydrogel in promoting the regeneration of diabetic infectious wounds

Diabetic infectious wound treatment is challenging due to insistent wound infections. To treat such complicated pathological diabetic infectious wounds, multifunctional materials need to be developed, and their mechanisms need to be understood. Here, we developed a material termed AgNCs-hydrogel, which is a multifunctional DNA hydrogel used as dressings by integrating it with antibacterial silver nanoclusters. The AgNCs-hydrogel was applied to promote the regeneration of diabetic infectious wounds in mice because it exhibited superior antibacterial activity and effective ROS-scavenging properties. Based on skin proteomics, we explored the potential mechanism of the AgNCs-hydrogel in treating mouse skin wounds. We found that the AgNCs-hydrogel can regulate some key proteins located primarily in the extracellular exosomes, involved in the negative regulation of the apoptotic process, and perform ATP binding to accelerate diabetic infected wound closure. Therefore, this study provided a multifunctional AgNCs-hydrogel and revealed its potential mechanism in promoting the regeneration of diabetic infectious wounds.

Platelet Rich Plasma Loaded Multifunctional Hydrogel Accelerates Diabetic Wound Healing via Regulating the Continuously Abnormal Microenvironments

Continuous oxidative stress and cellular dysfunction caused by hyperglycemia are distinguishing features of diabetic wounds. It has been a great challenge to develop a smart dressing that can accelerate diabetic wound healing through regulating abnormal microenvironments. In this study, a platelet rich plasma (PRP) loaded multifunctional hydrogel with reactive oxygen species (ROS) and glucose dual-responsive property is reported. It can be conveniently prepared with PRP, dopamine (DA) grafted alginate (Alg-DA), and 6-aminobenzo[c][1,2]oxaborol-1(3H)-ol (ABO) conjugated hyaluronic acid (HA-ABO) through ionic crosslinks, hydrogen-bond interactions, and boronate ester bonds. The hydrogel possesses injectability, moldability, tissue adhesion, self-healing, low hemolysis, and hemostasis performances. Its excellent antioxidant property can create a low oxidative stress microenvironment for other biological events. Under an oxidative stress and/or hyperglycemia state, the hydrogel can degrade at an accelerated rate to release a variety of cytokines derived from activated blood platelets. The result is a series of positive changes that are favorable for diabetic wound healing, including fast anti-inflammation, activated macrophage polarization toward M2 phenotype, promoted migration and proliferation of fibroblasts, as well as expedited angiogenesis. This work provides an efficient strategy for chronic diabetic wound management and offers an alternative for developing a new-type PRP-based bioactive wound dressing.

Dynamic Microenvironment-Adaptable Hydrogel with Photothermal Performance and ROS Scavenging for Management of Diabetic Ulcer

Persistent bacterial infections and excessive oxidative stress prevent the healing of diabetic ulcers, leading to an increased disability rate. Current treatments fail to kill bacteria while simultaneously relieving oxidative stress. Herein, a dynamic microenvironment-adaptable hydrogel (BP@CAu) with photothermal performance and reactive oxygen species scavenging is presented for diabetic ulcer healing. This hydrogel prepared using a dynamic borate-ester could respond to acidity in the infection microenvironment for a controllable drug release. An excellent photothermal conversion effect was integrated in the hydrogel, which exhibited strong antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. The hydrogel attenuated intracellular oxidative stress and inflammation and promoted cell migration. In a full-thickness skin defect model of diabetic rats, the BP@CAu hydrogel contributed to the fastest wound closure, with ideal reepithelialization, granulation tissue formation, and regeneration of blood vessels. Further mechanistic studies revealed that the hydrogel relieved oxidative stress and downregulated the expression of inflammatory cytokines, resulting in dramatic therapeutic effects on diabetic wounds. Therefore, this study provides a synergistic therapeutic strategy for efficient photothermal performance and reactive oxygen species scavenging in diabetic ulcers.

An in situ dual-anchoring strategy for enhanced immobilization of PD-L1 to treat autoimmune diseases

Immune checkpoints play key roles in maintaining self-tolerance. Targeted potentiation of the checkpoint molecule PD-L1 through in situ manipulation offers clinical promise for patients with autoimmune diseases. However, the therapeutic effects of these approaches are often compromised by limited specificity and inadequate expression. Here, we report a two-step dual-anchor coupling strategy for enhanced immobilization of PD-L1 on target endogenous cells by integrating bioorthogonal chemistry and physical insertion of the cell membrane. In both type 1 diabetes and rheumatoid arthritis mouse models, we demonstrate that this approach leads to elevated and sustained conjugation of PD-L1 on target cells, resulting in significant suppression of autoreactive immune cell activation, recruitment of regulatory T cells, and systematic reshaping of the immune environment. Furthermore, it restores glucose homeostasis in type 1 diabetic mice for over 100 days. This specific in situ bioengineering approach potentiates the functions of PD-L1 and represents its translational potential.

Chitosan-based emulgel and xerogel film containing Thymus pubescens essential oil as a potential wound dressing

Controlling the wound exudates accompanied by microbial wound infections has still remained as one the most challenging clinical issues. Herein, a chitosan/gelatin/polyvinyl alcohol xerogel film containing Thymus pubescens essential oil is fabricated for antimicrobial wound dressing application. The chemical and physical characteristics of the devised formulation is characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscope, and tensile tests. Moreover, swelling capability, water vapour transmission rate, water contact angle, solubility, moisture content, and release properties are also studied. The antimicrobial and antibiofilm tests are performed using the broth microdilution and XTT assay, respectively. The produced formulation shows excellent antimicrobial efficacy against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida species. It is also demonstrated that the obtained film can reduce (∼80 %) Candida albicans biofilm formation, and its biocompatibility is confirmed with MTT (∼100 %) and hemolysis tests. The antimicrobial activity can be correlated to the microbial membrane attraction for Candida albicans cells, illustrated by flow cytometry. This proposed film with appropriate mechanical strength, high swelling capacity in different pH values (∼200-700 %), controlled release property, and antimicrobial and antioxidant activities as well as biocompatibility can be used as a promising candidate for antimicrobial wound dressing applications.

Tailoring the Surface and Composition of Nanozymes for Enhanced Bacterial Binding and Antibacterial Activity

With the advantages of diverse structures, tunable enzymatic activity, and high stability, nanozymes are widely used in medicine, chemistry, food, environment, and other fields. As an alternative to traditional antibiotics, nanozymes attract more and more attention from the scientific researchers in recent years. Developing nanozymes-based antibacterial materials opens up a new avenue for the bacterial disinfection and sterilization. In this review, the classification of nanozymes and their antibacterial mechanisms are discussed. The surface and composition of nanozymes are critical for the antibacterial efficacy, which can be tailored to enhance both the bacterial binding and the antibacterial activity. On the one hand, the surface modification of nanozymes enables binding and targeting of bacteria that improves the antibacterial performance of nanozymes including the biochemical recognition, the surface charge, and the surface topography. On the other hand, the composition of nanozymes can be modulated to achieve enhanced antibacterial performance including the single nanozyme-mediated synergistic and multiple nanozymes-mediated cascade catalytic antibacterial applications. In addition, the current challenges and future prospects of tailoring nanozymes for antibacterial applications are discussed. This review can provide insights into the design of future nanozymes-based materials for the antibacterial treatments.

Chitosan based macromolecular hydrogel loaded total glycosides of paeony enhances diabetic wound healing by regulating oxidative stress microenvironment

Oxidative stress microenvironment caused by reactive oxygen species (ROS) accumulation seriously hinders wound healing in diabetes, which brings great burden to global health. Various wound dressings on the market focus on delivering active substances to promote wound healing in diabetes. However, the complex pathological microenvironment of diabetic wounds often leads to the inactivation of delivery factors, which often leads to treatment failure, and thus, emerging therapeutic approaches are urgently needed. In this study, a macromolecular hydrogel synthesized by crosslinking N-carboxyethyl chitosan, hyaluronic acid-aldehyde, and adipic acid dihydrazide, with self-healing and injectable abilities was used to deliver total glycosides of paeony (TGP). The TGP incorporated hydrogel could obviously induce fibroblasts proliferation and secretion of various extracellular matrix proteins and growth factors, induce migration and angiogenesis of vein endothelial cells, and enhance macrophages polarization to M2 phenotype by eliminating accumulated ROS. In diabetic wound models, the ROS-scavenging hydrogel efficiently enhanced proliferation, re-epithelialization, collagen deposition, as well as angiogenesis in the wound area. Besides, the dressing induced the macrophages polarization from M1 phenotype (pro-inflammatory) to M2 phenotype (anti-inflammatory) and decreased the levels of inflammatory cytokines, thereby enhancing the diabetic wound healing. The wounds treated with TGP incorporated hydrogel almost completely healed 16 days after treatment. However, the residual wound areas in the groups of Con, INTRA, and Gel are 55.2 ± 4.6 %, 33.7 ± 6.5 %, and 34.9 ± 6.1 % on the 16th day, respectively. This hydrogel with pathological microenvironment improvement ability affords a novel therapeutic strategy for enhancing healing of chronic diabetic wound.

Injectable antibacterial tissue-adhesive hydrogel based on biocompatible o-phthalaldehyde/amine crosslinking for efficient treatment of infected wounds

Injectable antibacterial hydrogels have attracted considerable attention in wound management. However, the development of injectable hydrogels with excellent antibacterial activity, good biocompatibility, and strong tissue adhesion remains a challenge. In this study, an antibacterial tissue-adhesive hydrogel was developed based on a catalyst-free o-phthalaldehyde (OPA)/amine reaction by simply mixing OPA-terminated four-arm poly(ethylene glycol) (4aPEG-OPA) and ε-poly-l-lysine (ε-PLL) solutions. The hydrogel showed tunable gelation time, storage moduli, and degradation rate depending on the polymer concentration and 4aPEG-OPA/ε-PLL mass ratio. The hydrogel exhibited nearly 100% bacterial inhibition rates in-vitro against Gram-negative E. coli and Gram-positive S. aureus, while maintaining good biocompatibility. The hydrogel matched well in shape and tightly adhered to the tissue after in-situ formation at the wound sites. Following the treatment of rat models of full-thickness skin incisions and round wounds, the hydrogel effectively closed the wounds and promoted wound healing. Moreover, after administering to S. aureus infected full-thickness skin wounds, the hydrogel exhibited remarkable efficacy in inhibiting wound infection with a bacterial inhibition rate over 99.94%, achieving a significantly accelerated wound healing compared with the commercially available Prontosan® gel. Therefore, the hydrogel exhibits great potential as a wound dressing for infection prevention and promotion of healing.

Fe(III)-incorporated porphyrin-based conjugated organic polymer as a peroxidase mimic for the sensitive determination of glucose and H2O2

Nanozymes, i.e., nanomaterials that possess intrinsic enzyme-like behaviour, have thrived over the past few decades owing to their advantages of superior stability and effortless storage. Such artificial enzymes can be a perfect alternative to naturally occurring enzymes, which have disadvantages of high cost and limited functionality. In this work, we present the fabrication of an Fe(III)-incorporated porphyrin-based conjugated organic polymer as a nanozyme for the efficient detection of glucose through its intrinsic peroxidase activity and the amperometric detection of hydrogen peroxide. The iron-incorporated porphyrin-based conjugated organic polymer (Fe-DMP-POR) possesses a spherical morphology with high chemical and thermal stability. Exploiting the peroxidase-mimicking activity of the material for the determination of glucose, a detection limit of 4.84 μM is achieved with a linear range of 0-0.15 mM. The Fe-DMP-POR also exhibits a reasonable recovery range for the detection of human blood glucose. The as-synthesized material can also act as an H2O2 sensor, with a sensitivity of 947.67 μA cm-2 mM-1 and a limit of detection of 3.16 μM.

DNA-Based Hydrogels with Multidrug Sequential Release for Promoting Diabetic Wound Regeneration

Diabetic wound (DW) regeneration is highly challenging due to persistent bacterial infection, excessive production of reactive oxygen species (ROS), prolonged inflammatory response, and insufficient angiogenesis. Ideal management requires the integration and sequential release of bactericidal, antioxidative, anti-inflammatory, and angiogenic agents during DW repair. Here, we develop a DNA-based multidrug hydrogel, termed Agilegel, to promote the efficient healing of DW. Hierarchically structured Agilegel can precisely control the sequential release of vascular endothelial growth factor-alpha (VEGF-α), silver nanoclusters (AgNCs), and interleukin-10 (IL-10) through covalent bonds in its primary structure (phosphate backbone), noncovalent bonds in its secondary structure (base pairs), and physical encapsulation in its advanced structure (pores), respectively. We demonstrate that Agilegel can effectively eliminate bacterial infection through AgNCs and mitigate ROS production through DNA scaffolds. Moreover, during the inflammatory phase, Agilegel promotes the polarization of macrophages from pro-inflammatory M1 to anti-inflammatory M2 phenotype using IL-10. Subsequently, Agilegel stimulates cell proliferation, angiogenesis, and extracellular matrix formation through the action of VEGF-α, thereby accelerating the closure of DW. Our results indicate that DNA hydrogels confer the capacity to regulate the sequential release of drugs, enabling them to effectively manage the phased intervention of multiple drugs in the treatment of complex diseases within physiological environments.

Multifunctional nanozyme-reinforced copper-coordination polymer nanoparticles for drug-resistance bacteria extinction and diabetic wound healing

BACKGROUND

Drug-resistant bacterial infections in chronic wounds are a persistent issue, as they are resistant to antibiotics and can cause excessive inflammation due to generation of reactive oxygen species (ROS). An effective solution would be to not only combat bacterial infections but also scavenge ROS to relieve inflammation at the wound site. Scaffolds with antioxidant properties are attractive for their ability to scavenge ROS, and there is medical demand in developing antioxidant enzyme-mimicking nanomaterials for wound healing.

METHODS

In this study, we fabricated copper-coordination polymer nanoparticles (Cu-CPNs) through a self-assembly process. Furthermore, ε-polylysine (EPL), an antibacterial and cationic polymer, was integrated into the Cu-CPNs structure through a simple one-pot self-assembly process without sacrificing the glutathione peroxidase (GPx) and superoxide dismutase (SOD)-mimicking activity of Cu-CPNs.

RESULTS

The resulting Cu-CPNs exhibit excellent antioxidant propertiesin mimicking the activity of glutathione peroxidase and superoxide dismutase and allowing them to effectively scavenge harmful ROS produced in wound sites. The in vitro experiments showed that the resulting Cu-CPNs@EPL complex have superior antioxidant properties and antibacterial effects. Bacterial metabolic analysis revealed that the complex mainly affects the cell membrane integrity and nucleic acid synthesis that leads to bacterial death.

CONCLUSIONS

The Cu-CPNs@EPL complex has impressive antioxidant properties and antibacterial effects, making it a promising solution for treating drug-resistant bacterial infections in chronic wounds. The complex's ability to neutralize multiple ROS and reduce ROS-induced inflammation can help relieve inflammation at the wound site. Schematic illustration of the ROS scavenging and bacteriostatic function induced by Cu-CPNs@EPL nanozyme in the treatment of MRSA-infected wounds.

Biomimetic Nanozyme-Decorated Hydrogels with H2O2-Activated Oxygenation for Modulating Immune Microenvironment in Diabetic Wound

Diabetic foot ulcers (DFUs) remain a devastating threat to human health. While hydrogels are promising systems for DFU-based wound management, their effectiveness is often hindered by the immune response and hostile wound microenvironment associated with the uncontrollable accumulation of reactive oxygen species and hypoxia. Here, we develop a therapeutic wound dressing using a biomimetic hydrogel system with the decoration of catalase-mimic nanozyme, namely, MnCoO@PDA/CPH. The hydrogel can be designed to match the mechanical and electrical cues of skins simultaneously with H2O2-activated oxygenation ability. As a proof of concept, DFU-based rat models are created to validate the therapeutic efficacy of the MnCoO@PDA/CPH hydrogel in vivo. The results indicate that the developed hydrogel can promote DFU healing and improve the quality of the healed wound as featured by alleviated proinflammatory, increased re-epithelialization, highly ordered collagen deposition, and functional blood vessel growth.

Prussian blue nano-enzyme-assisted photodynamic therapy effectively eradicates MRSA infection in diabetic mouse skin wounds

Antibiotic therapy can induce the generation of severe bacterial resistance, further challenging the usability of currently available drugs and treatment options. Therefore, it is essential to develop new strategies to effectively eradicate drug-resistant bacteria. Herein, we have reported a combinational strategy for the eradication of drug-resistant bacteria by using chlorin e6 (Ce6) loaded Prussian blue nanoparticles (PB NPs). This nanocomplex showed strong catalase activity and photodynamic properties. In vitro experiments demonstrated that CPB-Ce6 NPs effectively kill MRSA by generating ROS under laser irradiation. Meanwhile, the nano-enzyme activity of CPB NPs can decompose H2O2 in the bacterial microenvironment to upregulate the O2 level, which in turn alleviates hypoxia in the microenvironment and improves the antibacterial effect of PDT. In vivo results demonstrated that CPB-Ce6 NPs with laser irradiation effectively cleared MRSA and promoted infected wound repair in a diabetic mouse model and normal mice through upregulating VEGF. Moreover, CPB-Ce6 NPs showed excellent biosafety profiles in vitro and in vivo. From our point of view, this PDT based on PB NPs with nano-enzyme activity may provide an effective treatment for infections associated with drug-resistant microbes and tissue repair.

Catechol-Modified and MnO2-Nanozyme-Reinforced Hydrogel with Improved Antioxidant and Antibacterial Capacity for Periodontitis Treatment

Periodontitis is an inflammatory disease characterized by tooth loss and alveolar bone resorption. Bacteria are the original cause of periodontitis, and excess reactive oxygen species (ROS) encourage and intensify inflammation. In this study, a mussel-inspired and MnO2 NPs-reinforced adhesive hydrogel capable of alleviating periodontitis with improved antibacterial and antioxidant abilities was developed. The hydrogel was created by combining polyvinyl alcohol (PVA), 3,4-dihydroxy-d-phenylalanine (DOPA), and MnO2 nanoparticles (NPs) (named PDMO hydrogel). The hydrogel was demonstrated to be able to scavenge various free radicals (including total ROS─O2•- and OH•) and relieve the hypoxia in an inflammatory microenvironment by scavenging excess ROS and generating O2 due to its superoxide dismutase (SOD)/catalase (CAT)-like activity. Besides, under 808 nm near-infrared (NIR) light, the photothermal performance of the PDMO hydrogel displayed favorable antibacterial and antibiofilm effects toward Escherichia coli, Staphylococcus aureus, and Porphyromonas gingivalis (up to nearly 100% antibacterial rate). Furthermore, the PDMO hydrogel exhibited favorable therapeutic efficacy in alleviating gingivitis in Sprague-Dawley rats, even comparable to or better than the commercial PERIO. In addition, in the periodontitis models, the PDMO2 group showed the height of the residual alveolar bone and the smallest shadow area of low density among other groups, indicating the positive role of the PDMO2 hydrogel in bone regeneration. Finally, the biosafety of the PDMO hydrogel was comprehensively investigated, and the hydrogel was demonstrated to have good biocompatibility. Therefore, the developed PDMO hydrogel provided an effective solution to resolve biofilm recolonization and oxidative stress in periodontitis and could be a superior candidate for local drug delivery system in the clinical management of periodontitis with great potential for future clinical translation.

Multifunctional Hyaluronic Acid Microneedle Patch Embedded by Cerium/Zinc-Based Composites for Accelerating Diabetes Wound Healing

Chronic nonhealing diabetic wounds are becoming increasingly severe, with high rates of mortality and disability, owing to the difficulty in wound healing caused by hyperglycemia, blocked angiogenesis, biofilm infection, and excessive oxidative stress. A multicomponent enzyme-responsive natural polymer, a hyaluronic acid (HA) microneedle, embedded in a cerium/zinc-based nanomaterial (ZCO) for the treatment of diabetic wounds is reported. ZCO-HA can destroy the oxidation balance of bacteria, kill bacteria, and scavenge reactive oxygen species (ROS) to alleviate oxidative stress via the adjustable release of Zn2+ and Ce3+ /4+ . Additionally, ZCO-HA exhibits good anti-inflammatory activity through the nuclear factor kappa-B (NF-κB) pathway, which reduces the inflammatory state of macrophages and promotes cell proliferation, migration, and angiogenesis. In vitro experiments shows that ZCO-HA accompanies mouse fibroblast migration, promoting human umbilical vein endothelial cell tube formation. In vivo studies in mice with streptozotocin-induced (STZ)-induced diabetes reveal that this microneedle accelerates wound healing without systemic toxicity. RNA transcriptome sequencing illustrates that the multicomponent HA microneedle accelerates wound healing in diabetes through cell migration and inhibits inflammatory reactions and oxidative damage in mice via the NF-κB signaling pathway.

Engineering core-shell chromium nanozymes with inflammation-suppressing, ROS-scavenging and antibacterial properties for pulpitis treatment

Oral diseases are usually caused by inflammation and bacterial infection. Reactive oxygen species (ROS), which come from both autologous inflammation tissue and bacterial infection, play an important role in this process. Thus, the elimination of excessive intracellular ROS can be a promising strategy for anti-inflammatory treatment. With the rapid development of nanomedicines, nanozymes, which can maintain the intracellular redox balance and protect cells against oxidative damage, have shown great application prospects in the treatment of inflammation-related diseases. However, their performance in pulpitis and their related mechanisms have yet to be explored. Herein, we prepared dozens of metallic nanoparticles with core-shell structures, and among them, chromium nanoparticles (NanoCr) were selected for their great therapeutic potential for pulpitis disease. NanoCr showed a broad antibacterial spectrum and strong anti-inflammatory function. Antibacterial assays showed that NanoCr could effectively inhibit a variety of common pathogens of oral infection. In vitro experiments offered evidence of the multienzyme activity of NanoCr and its function in suppressing ROS-induced inflammation reactions. The experimental results show that NanoCr has optimal antibacterial and anti-inflammatory properties in in vitro cell models, showing great potential for the treatment of pulpitis. Therefore, the use of NanoCr could become a new therapeutic strategy for clinical pulpitis.

An Antibacterial and Anti-Oxidative Hydrogel Dressing for Promoting Diabetic Wound Healing and Real-Time Monitoring Wound pH Conditions with a NIR Fluorescent Imaging System

The design and synthesis of multifunctional chitosan hydrogels based on polymerized ionic liquid and a near-infrared (NIR) fluorescent probe (PIL-CS) is a promising strategy, which not only prevents the transition from acute to chronic wounds, but also provides prompt measures regarding microenvironmental alterations in chronic wounds. PIL-CS hydrogel can real-time visualize wound pH through in vivo NIR fluorescent imaging and also feature the pH-responsive sustained drug release, such as antioxidant, to eliminate reactive oxygen species (ROS) and to boost diabetic wound healing. PIL-CS hydrogel is specific, sensitive, stable, and reversible in response to pH changes at the wound site. It, therefore, enables real-time monitoring for a dynamic pH change in the microenvironment of irregular wounds. PIL-CS hydrogel is also designed to possess many merits including high water containment and swelling rate, good biocompatibility, electrical conductivity, antifreeze, tissue adhesion, hemostatic performance, and efficient antibacterial activity against MRSA. In vivo studies showed that PIL-CS hydrogel provided fast diabetic wound healing support, promoted vascular endothelial growth factor (VEGF) production, and reduced ROS and tumor necrosis factor (TNF-α) generation. The results support that the hydrogels coupled with NIR fluorescent probes can be an excellent diabetic wound dressing for enhancing and real-time monitoring skin restoration and regeneration.

Research progress of nanoparticle targeting delivery systems in bacterial infections

Bacterial infection is a huge threat to the health of human beings and animals. The abuse of antibiotics have led to the occurrence of bacterial multidrug resistance, which have become a difficult problem in the treatment of clinical infections. Given the outstanding advantages of nanodrug delivery systems in cancer treatment, many scholars have begun to pay attention to their application in bacterial infections. However, due to the similarity of the microenvironment between bacterial infection lesions and cancer sites, the targeting and accuracy of traditional microenvironment-responsive nanocarriers are questionable. Therefore, finding new specific targets has become a new development direction of nanocarriers in bacterial prevention and treatment. This article reviews the infectious microenvironment induced by bacteria and a series of virulence factors of common pathogenic bacteria and their physiological functions, which may be used as potential targets to improve the targeting accuracy of nanocarriers in lesions.

In situ stimulus-responsive self-assembled nanomaterials for drug delivery and disease treatment

The individual motifs that respond to specific stimuli for the self-assembly of nanomaterials play important roles. In situ constructed nanomaterials are formed spontaneously without human intervention and have promising applications in bioscience. However, due to the complex physiological environment of the human body, designing stimulus-responsive self-assembled nanomaterials in vivo is a challenging problem for researchers. In this article, we discuss the self-assembly principles of various nanomaterials in response to the tissue microenvironment, cell membrane, and intracellular stimuli. We propose the applications and advantages of in situ self-assembly in drug delivery and disease diagnosis and treatment, with a focus on in situ self-assembly at the lesion site, especially in cancer. Additionally, we introduce the significance of introducing exogenous stimulation to construct self-assembly in vivo. Based on this foundation, we put forward the prospects and possible challenges in the field of in situ self-assembly. This review uncovers the relationship between the structure and properties of in situ self-assembled nanomaterials and provides new ideas for innovative drug molecular design and development to solve the problems in the targeted delivery and precision medicine.

Injectable, antibacterial, and oxygen-releasing chitosan-based hydrogel for multimodal healing of bacteria-infected wounds

Bacterial infection is one of the main challenges of wound healing. It imposes financial and healthcare costs. The emergence of antibiotic-resistant bacteria has increased concerns about this challenge, and made finding alternative solutions a crucial aim. We created a new, antibacterial, multifunctional hydrogel with synergistic chemodynamic and photothermal features for wound-healing applications. We fabricated a chitosan (CT)-based hydrogel containing tannic acid (TA), Fe, and MnO2 nanosheets (CT-TA-Fe-MnO2) via a simple method and characterized it. The antibacterial features (resulting from the production of reactive oxygen species within bacterial cells) and healing ability (via anti-inflammatory and hemostatic features) of the hydrogel were confirmed in vitro. In vivo results revealed the effectiveness of the CT-TA-Fe-MnO2 hydrogel in decreasing the hemostatic time, improving anti-inflammatory effects, and promoting wound healing during 14 days by enhancing the deposition and maturation of collagen fibers without affecting the vital organs. The fabricated CT-TA-Fe-MnO2 hydrogel could be a promising candidate with antibacterial and anti-inflammatory activities suitable for wound-healing applications.

Research advances in smart responsive-hydrogel dressings with potential clinical diabetic wound healing properties

The treatment of chronic and non-healing wounds in diabetic patients remains a major medical problem. Recent reports have shown that hydrogel wound dressings might be an effective strategy for treating diabetic wounds due to their excellent hydrophilicity, good drug-loading ability and sustained drug release properties. As a typical example, hyaluronic acid dressing (Healoderm) has been demonstrated in clinical trials to improve wound-healing efficiency and healing rates for diabetic foot ulcers. However, the drug release and degradation behavior of clinically-used hydrogel wound dressings cannot be adjusted according to the wound microenvironment. Due to the intricacy of diabetic wounds, antibiotics and other medications are frequently combined with hydrogel dressings in clinical practice, although these medications are easily hindered by the hostile environment. In this case, scientists have created responsive-hydrogel dressings based on the microenvironment features of diabetic wounds (such as high glucose and low pH) or combined with external stimuli (such as light or magnetic field) to achieve controllable drug release, gel degradation, and microenvironment improvements in order to overcome these clinical issues. These responsive-hydrogel dressings are anticipated to play a significant role in diabetic therapeutic wound dressings. Here, we review recent advances on responsive-hydrogel dressings towards diabetic wound healing, with focus on hydrogel structure design, the principle of responsiveness, and the behavior of degradation. Last but not least, the advantages and limitations of these responsive-hydrogels in clinical applications will also be discussed. We hope that this review will contribute to furthering progress on hydrogels as an improved dressing for diabetic wound healing and practical clinical application.

Mussel-inspired self-healing hydrogel form pectin and cellulose for hemostasis and diabetic wound repairing

Diabetic wound is considered as a kind of chronic wound prone to infection and difficult to repair due to high glucose level in the blood of patients. In this research, a biodegradable self-healing hydrogel with mussel inspired bioadhesion and anti-oxidation properties is fabricated based on Schiff-base cross-linking. The hydrogel was designed from dopamine coupled pectin hydrazide (Pec-DH) and oxidized carboxymethyl cellulose (DCMC) for mEGF loading as a diabetic wound repair dressing. The Pectin and CMC as natural feedstock endowed the hydrogel with biodegradability to avoid possible side effects, while the coupled catechol structure could enhance the tissue adhesion of the hydrogel for hemostasis. The results showed the Pec-DH/DCMC hydrogel formed fast and can cover irregular wounds with good sealing effect. The catechol structure also improved the reactive oxygen species (ROS) scavenging ability of the hydrogel, which can eliminate the negative effect of ROS during wound healing. The in vivo diabetic wound healing experiment revealed the hydrogel as mEGF loading vehicle greatly enhanced the diabetic wound repairing rate in mice model. As a result, the Pec-DH/DCMC hydrogel could show advantages as EGF carrier in wound healing applications.

Hyaluronic acid-based dual network hydrogel with sustained release of platelet-rich plasma as a diabetic wound dressing

In recent years, the incidence of diabetic skin ulcers has increased. Because of its extremely high disability and fatality rate, it brings a huge burden to patients and society. Platelet-rich plasma (PRP) contains a large number of biologically active substances and is of great clinical value in the treatment of various wounds. However, its weak mechanical properties and the consequent abrupt release of active substances greatly limit its clinical application and therapeutic efficacy. Here, we chose hyaluronic acid (HA) and ε-polylysine (ε-PLL) to prepare a hydrogel with the ability to prevent wound infection and promote tissue regeneration. At the same time, using the macropore barrier effect of the lyophilized hydrogel scaffold, platelets in PRP are activated with calcium gluconate in the macropores of the scaffold carrier, and fibrinogen from PRP is converted in a fibrin-packed network forming a gel that interpenetrates the hydrogel scaffold carrier, thus creating a double network hydrogel with slow-release of growth factors from degranulated platelets. The hydrogel not only showed better performance in functional assays in vitro, but also showed more superior therapeutic effects in reducing inflammatory response, promoting collagen deposition, facilitating re-epithelialization and angiogenesis in the treatment of full skin defects in diabetic rats.

Multifunctional chondroitin sulfate based hydrogels for promoting infected diabetic wounds healing by chemo-photothermal antibacterial and cytokine modulation

Diabetic foot (DF) is difficult to heal due to the formation of drug-resistant bacterial biofilms and dysregulation of the wound microenvironment. To solve this problem, multifunctional hydrogels were prepared by in situ or spraying with 3-aminophenylboronic acid modified oxidized chondroitin sulfate (APBA-g-OCS), polyvinyl alcohol (PVA) and black phosphorus/bismuth oxide/ε-polylysine (BP/Bi₂O₃/ε-PL) as precursors for promoting infected diabetic wounds healing. The hydrogels display multiple stimulus responsiveness, strong adhesion and rapid self-healing ability owing to the dynamic borate ester bonds, hydrogen bonds and π-π conjugation cross-link points, remain synergistic chemo-photothermal antibacterial effect and anti-biofilm formation ability due to the doping of BP/ Bi₂O₃/ε-PL into the hydrogel by dynamic imine bonds crosslinking and possess anti-oxidation and inflammatory chemokine adsorption ability attributing to the presence of APBA-g-OCS. Most importantly, as a result of the above functions, the hydrogels can not only respond to the wound microenvironment to conduct combined PTT and chemotherapy for efficient anti-inflammation, but also improve the wound microenvironment by scavenging ROS and regulating the expression of cytokines, thus further accelerating collagen deposition, promoting granulation tissue formation and angiogenesis, finally promoting the healing of infected wounds in diabetic rats.

Progress in Pluronic F127 Derivatives for Application in Wound Healing and Repair

Pluronic F127 hydrogel biomaterial has garnered considerable attention in wound healing and repair due to its remarkable properties including temperature sensitivity, injectability, biodegradability, and maintain a moist wound environment. This comprehensive review provides an in-depth exploration of the recent advancements in Pluronic F127-derived hydrogels, such as F127-CHO, F127-NH2, and F127-DA, focusing on their applications in the treatment of various types of wounds, ranging from burns and acute wounds to infected wounds, diabetic wounds, cutaneous tumor wounds, and uterine scars. Furthermore, the review meticulously examines the intricate interaction mechanisms employed by these hydrogels within the wound microenvironment. By elucidating the underlying mechanisms, discussing the strengths and weaknesses of Pluronic F127, analyzing the current state of wound healing development, and expanding on the trend of targeting mitochondria and cells with F127 as a nanomaterial. The review enhances our understanding of the therapeutic effects of these hydrogels aims to foster the development of effective and safe wound-healing modalities. The valuable insights provided this review have the potential to inspire novel ideas for clinical treatment and facilitate the advancement of innovative wound management approaches.

Glucose-Responsive Antioxidant Hydrogel Accelerates Diabetic Wound Healing

Diabetic complications can be ameliorated by inhibiting excessive oxidative stress with antioxidants. To enhance therapeutic intervention, it is crucial to develop intelligent scaffolds for efficient delivery of antioxidants to diabetic wounds. This study introduces reversible boronic bonds to create an intelligent antioxidant hydrogel scaffold. This study modifies gelatin methacryloyl (GelMA) with 4-carboxyphenyboronic acid (CPBA) to synthesize a derivative of GelMA (GelMA-CPBA), and then photo cross-links GelMA-CPBA with (-)-epigallocatechin-3-gallate (EGCG) to form GelMA-CPBA/EGCG (GMPE) hydrogel. The GMPE hydrogel responds to changes in glucose levels, and more EGCG is released as glucose level increases due to the dissociation of boronic ester bonds. The GMPE hydrogel shows good biocompatibility and biodegradability, and its mechanical property is similar to that of the skin tissue. Both in vitro and in vivo results demonstrate that the GMPE hydrogel scaffolds effectively eliminate reactive oxygen species (ROS), reduce the inflammation, and promote angiogenesis, thereby improve collagen deposition and tissue remodeling during diabetic wound healing. This strategy offers new insight into glucose-responsive scaffolds, and this responsive antioxidan hydrogel scaffold holds great potential for the treatment of chronic diabetic wounds.

Injectable chitosan/xyloglucan composite hydrogel with mechanical adaptivity and endogenous bioactivity for skin repair

Delayed or chronic wound healing is one of severe clinical issues. Developing scaffold materials capable of supporting cells and inducing tissue regeneration remains a challenge. Here, a polysaccharide-based hydrogel is constructed for promoting full-thickness skin wound healing in mouse model. The engineering hydrogel consists of a dynamic crosslinking network formed by the Schiff base reaction between aldehyde-containing xyloglucan and methacrylated chitosan. Its reversible gel-sol-gel transition upon shearing force is highly beneficial to completely cover and fill irregular wound shape. The second covalent cross-linking network achieved by photo-initiated polymerization offers a feasible way to tune the mechanical property of hydrogel after injection, with an ideal mechanical adaptivity for clinical application. Remarkably, both in vitro and in vivo evaluations demonstrate that the hydrogel with endogenously bioactive galactoside units can promote cell spheroid formation and accelerate wound healing by expediting re-epithelialization, collagen deposition, angiogenesis as well as the formation of hair follicles.

Stem cell niche-inspired microcarriers with ADSCs encapsulation for diabetic wound treatment

Stem cell therapies have made great progress in the treatment of diabetic wounds during recent decades, while their short in vivo residence, alloimmune reactions, undesired behaviors, and dramatic losses of cell functions still hinder the translation of them into clinic. Here, inspired by the natural components of stem cell niches, we presented novel microfluidic hydrogel microcarriers with extracellular matrix (ECM)-like composition and adipose-derived stem cells (ADSCs) encapsulation for diabetic wound healing. As the hydrogel was synthesized by conjugating hyaluronic acid methacryloyl (HAMA) onto the Fibronectin (FN) molecule chain (FN-HAMA), the laden ADSCs in the microcarriers showed improved bioactivities and pro-regenerative capabilities. Based on these features, we have demonstrated that these ADSCs microcarriers exhibited significant promotion of neovascularization, follicular rejuvenation, and collagen deposition in a mouse diabetic wound model. These results indicated that the stem cell niche-inspired FN-HAMA microcarriers with ADSCs encapsulation have great clinical potential for diabetic wound treatment.

Oxygenated Wound Dressings for Hypoxia Mitigation and Enhanced Wound Healing

Oxygen is a critical factor that can regulate the wound healing processes such as skin cell proliferation, granulation, re-epithelialization, angiogenesis, and tissue regeneration. However, hypoxia, a common occurrence in the wound bed, can impede normal healing processes. To enhance wound healing, oxygenation strategies that could effectively increase wound oxygen levels are effective. The present review summarizes wound healing stages and the role of hypoxia in wound healing and overviews current strategies to incorporate various oxygen delivery or generating materials for wound dressing, including catalase, nanoenzyme, hemoglobin, calcium peroxide, or perfluorocarbon-based materials, in addition to photosynthetic bacteria and hyperbaric oxygen therapy. Mechanism of action, oxygenation efficacy, and potential benefits and drawbacks of these dressings are also discussed. We conclude by highlighting the importance of design optimization in wound dressings to address the clinical needs to improve clinical outcomes.

Growth of spiral ganglion neurons induced by graphene oxide/oxidized bacterial cellulose composite hydrogel

The damage or degeneration of spiral ganglion neurons (SGNs) can impair the auditory signals transduction from hair cells to the central auditory system, and cause significant hearing loss. Herein, a new form of bioactive hydrogel incorporating topological graphene oxide (GO) and TEMPO-oxidized bacterial cellulose (GO/TOBC hydrogel) was developed to provide a favorable microenvironment for SGN neurite outgrowth. As the network structure of lamellar interspersed fiber cross-linked by GO/TOBC hydrogels well simulated the structure and morphology of ECM, with the controllable hydrophilic property and appropriate Young's modulus well met those requirements of SGNs microenvironment, the GO/TOBC hybrid matrix exhibited great potential to promote the growth of SGNs. The quantitative real-time PCR result confirmed that the GO/TOBC hydrogel can significantly accelerate the development of growth cones and filopodia, by increasing the mRNA expression levels of diap3, fscn2, and integrin β1. These results suggest that GO/TOBC hydrogel scaffolds have the potential to be used to construct biomimetic nerve grafts for repairing or replacing nerve defects.

Hydrogel with ROS scavenging effect encapsulates BR@Zn-BTB nanoparticles for accelerating diabetic mice wound healing via multimodal therapy

The strategies for eliminating excess reactive oxygen species (ROS) or suppressing inflammatory responses on the wound bed have proven effective for diabetic wound healing. In this work, a zinc-based nanoscale metal-organic framework (NMOF) functions as a carrier to deliver natural product berberine (BR) to form BR@Zn-BTB nanoparticles, which was, in turn, further encapsulated by hydrogel with ROS scavenging ability to yield a composite system of BR@Zn-BTB/Gel (denoted as BZ-Gel). The results show that BZ-Gel exhibited the controlled release of Zn²⁺ and BR in simulated physiological media to efficiently eliminated ROS and inhibited inflammation and resulted in a promising antibacterial effect. In vivo experiments further proved that BZ-Gel significantly inhibited the inflammatory response and enhanced collagen deposition, as well as to re-epithelialize the skin wound to ultimately promote wound healing in diabetic mice. Our results indicate that the ROS-responsive hydrogel coupled with BR@Zn-BTB synergistically promotes diabetic wound healing.

Scarless wound healing programmed by core-shell microneedles

Effective reprogramming of chronic wound healing remains challenging due to the limited drug delivery efficacy hindered by physiological barriers, as well as the inappropriate dosing timing in distinct healing stages. Herein, a core-shell structured microneedle array patch with programmed functions (PF-MNs) is designed to dynamically modulate the wound immune microenvironment according to the varied healing phases. Specifically, PF-MNs combat multidrug-resistant bacterial biofilm at the early stage via generating reactive oxygen species (ROS) under laser irradiation. Subsequently, the ROS-sensitive MN shell gradually degrades to expose the MN core component, which neutralizes various inflammatory factors and promotes the phase transition from inflammation to proliferation. In addition, the released verteporfin inhibits scar formation by blocking Engrailed-1 (En1) activation in fibroblasts. Our experiments demonstrate that PF-MNs promote scarless wound repair in mouse models of both acute and chronic wounds, and inhibit the formation of hypertrophic scar in rabbit ear models.

Cu-GA-coordination polymer nanozymes with triple enzymatic activity for wound disinfection and accelerated wound healing

During the past few years, bacterial infection and oxidative stress have become important issues for wound healing. However, the emergence of numerous drug-resistant superbugs has had a serious impact on the treatment of infected wounds. Presently, the development of new nanomaterials has become one of the most important approaches to the treatment of drug-resistant bacterial infections. Herein, coordination polymer copper-gallic acid (Cu-GA) nanorods with multi-enzyme activity is successfully prepared for efficient wound treatment of bacterial infection, which can effectively promote wound healing. Cu-GA can be efficiently prepared by a simple solution method and had good physiological stability. Interestingly, Cu-GA shows enhanced multienzyme activity (peroxidase, glutathione peroxidase, and superoxide dismutase), which can produce a large number of reactive oxygen species (ROS) under acidic conditions while scavenging ROS under neutral conditions. In acidic environment, Cu-GA possesses POD (peroxidase)-like and glutathione peroxidase (GSH-Px)-like catalytic activities that is capable of killing bacteria; but in neutral environment, Cu-GA exhibits superoxide dismutase (SOD)-like catalytic activity that can scavenge ROS and promote wound healing. In vivo studies show that Cu-GA can promote wound infection healing and have good biosafety. Cu-GA contributes to the healing of infected wounds by inhibiting bacterial growth, scavenging reactive oxygen species, and promoting angiogenesis. STATEMENT OF SIGNIFICANCE: Cu-GA-coordinated polymer nanozymes with multienzyme activity were successfully prepared for efficient wound treatment of bacterial infection, which could effectively promote wound healing. Interestingly, Cu-GA exhibited enhanced multienzyme activity (peroxidase, glutathione peroxidase, and superoxide dismutase), which could produce a large number of reactive oxygen species (ROS) under acidic conditions and scavenge ROS under neutral conditions. In vitro and in vivo studies demonstrated that Cu-GA was capable of killing bacteria, controlling inflammation, and promoting angiogenesis.

In situ photo-crosslinking silk fibroin based hydrogel accelerates diabetic wound healing through antibacterial and antioxidant

Bacterial infection and excessive reactive oxygen species (ROS) in diabetic wounds lead to a prolonged inflammatory phase, and injuries are highly susceptible to developing into chronic wounds. Improving the poor microenvironment is vital to achieving effective diabetic wound healing. In this work, methacrylated silk fibroin (SFMA) was combined with ε-polylysine (EPL) and manganese dioxide nanoparticles (BMNPs) to form an SF@(EPL-BM) hydrogel with in situ forming, antibacterial and antioxidant properties. EPL imparted high antibacterial activity (>96 %) to the hydrogel. BMNPs and EPL showed good scavenging activity against a variety of free radicals. SF@(EPL-BM) hydrogel had low cytotoxicity and could alleviate H₂O₂-induced oxidative stress in L929 cells. In diabetic wounds infected with Staphylococcus aureus (S. aureus), the SF@(EPL-BM) hydrogel exhibited better antibacterial properties and reduced wound ROS levels more significantly than that of the control in vivo. In this process, the pro-inflammatory factor TNF-α was down-regulated, and the vascularization marker CD31 was up-regulated. H&E and Masson staining showed a rapid transition from the inflammatory to the proliferative phase of the wounds, with significant new tissue and collagen deposition. These results confirm that this multifunctional hydrogel dressing holds well potential for chronic wound healing.

Multi-functional nanogel with cascade catalytic performance for treatment of diabetic oral mucosa ulcer

Introduction: Diabetic oral mucosa ulcers face challenges of hypoxia, hyperglycemia and high oxidative stress, which result in delayed healing process. Oxygen is regarded as an important substance in cell proliferation, differentiation and migration, which is beneficial to ulcer recovery. Methods: This study developed a multi-functional GOx-CAT nanogel (GCN) system for the treatment of diabetic oral mucosa ulcers. The catalytic activity, ROS scavenge and oxygen supply ability of GCN was validated. The therapeutic effect of GCN was verified in the diabetic gingival ulcer model. Results: The results showed that the nanoscale GCN was capable of significantly eliminating intracellular ROS, increasing intracellular oxygen concentration and accelerating cell migration of human gingival fibroblasts, which could promote diabetic oral gingival ulcer healing in vivo by alleviating inflammation and promoting angiogenesis. Discussion: This multifunctional GCN with ROS depletion, continuous oxygen supply and good biocompatibility, which might provide a novel therapeutic strategy for effective treatment of diabetic oral mucosa ulcers.

Near-Infrared Light-Responsive Hydrogels for Highly Flexible Bionic Photosensors

Soft biological tissues perform various functions. Sensory nerves bring sensations of light, voice, touch, pain, or temperature variation to the central nervous system. Animal senses have inspired tremendous sensors for biomedical applications. Following the same principle as photosensitive nerves, we design flexible ionic hydrogels to achieve a biologic photosensor. The photosensor allows responding to near-infrared light, which is converted into a sensory electric signal that can communicate with nerve cells. Furthermore, with adjustable thermal and/or electrical signal outputs, it provides abundant tools for biological regulation. The tunable photosensitive performances, high flexibility, and low cost endow the photosensor with widespread applications ranging from neural prosthetics to human-machine interfacing systems.