Absorbable Thioether Grafted Hyaluronic Acid Nanofibrous Hydrogel for Synergistic Modulation of Inflammation Microenvironment to Accelerate Chronic Diabetic Wound Healing

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

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

ROS-responsive hydrogels: from design and additive manufacturing to biomedical applications

Hydrogels with intricate 3D networks and high hydrophilicity have qualities resembling those of biological tissues, making them ideal candidates for use as smart biomedical materials. Reactive oxygen species (ROS) responsive hydrogels are an innovative class of smart hydrogels, and are cross-linked by ROS-responsive modules through covalent interactions, coordination interactions, or supramolecular interactions. Due to the introduction of ROS response modules, this class of hydrogels exhibits a sensitive response to the oxidative stress microenvironment existing in organisms. Simultaneously, due to the modularity of the ROS-responsive structure, ROS-responsive hydrogels can be manufactured on a large scale through additive manufacturing. This review will delve into the design, fabrication, and applications of ROS-responsive hydrogels. The main goal is to clarify the chemical principles that govern the response mechanism of these hydrogels, further providing new perspectives and methods for designing responsive hydrogel materials.

Immunomodulatory poly(L-lactic acid) nanofibrous membranes promote diabetic wound healing by inhibiting inflammation, oxidation and bacterial infection

Background

Given the significant impact on human health, it is imperative to develop novel treatment approaches for diabetic wounds, which are prevalent and serious complications of diabetes. The diabetic wound microenvironment has a high level of reactive oxygen species (ROS) and an imbalance between proinflammatory and anti-inflammatory cells/factors, which hamper the healing of chronic wounds. This study aimed to develop poly(L-lactic acid) (PLLA) nanofibrous membranes incorporating curcumin and silver nanoparticles (AgNPs), defined as PLLA/C/Ag, for diabetic wound healing.

Methods

PLLA/C/Ag were fabricated via an air-jet spinning approach. The membranes underwent preparation and characterization through various techniques including Fourier-transform infrared spectroscopy, measurement of water contact angle, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, assessment of in vitro release of curcumin and Ag+, testing of mechanical strength, flexibility, water absorption and biodegradability. In addition, the antioxidant, antibacterial and anti-inflammatory properties of the membranes were evaluated in vitro, and the ability of the membranes to heal wounds was tested in vivo using diabetic mice.

Results

Loose hydrophilic nanofibrous membranes with uniform fibre sizes were prepared through air-jet spinning. The membranes enabled the efficient and sustained release of curcumin. More importantly, antibacterial AgNPs were successfully reduced in situ from AgNO3. The incorporation of AgNPs endowed the membrane with superior antibacterial activity, and the bioactivities of curcumin and the AgNPs gave the membrane efficient ROS scavenging and immunomodulatory effects, which protected cells from oxidative damage and reduced inflammation. Further results from animal studies indicated that the PLLA/C/Ag membranes had the most efficient wound healing properties, which were achieved by stimulating angiogenesis and collagen deposition and inhibiting inflammation.

Conclusions

In this research, we successfully fabricated PLLA/C/Ag membranes that possess properties of antioxidants, antibacterial agents and anti-inflammatory agents, which can aid in the process of wound healing. Modulating wound inflammation, these new PLLA/C/Ag membranes serve as a novel dressing to enhance the healing of diabetic wounds.

Improving dermal fibroblast-to-epidermis communications and aging wound repair through extracellular vesicle-mediated delivery of Gstm2 mRNA

Skin aging is characterized by the disruption of skin homeostasis and impaired skin injury repair. Treatment of aging skin has long been limited by the unclear intervention targets and delivery techniques. Engineering extracellular vesicles (EVs) as an upgraded version of natural EVs holds great potential in regenerative medicine. In this study, we found that the expression of the critical antioxidant and detoxification gene Gstm2 was significantly reduced in aging skin. Thus, we constructed the skin primary fibroblasts-derived EVs encapsulating Gstm2 mRNA (EVsGstm2), and found that EVsGstm2 could significantly improve skin homeostasis and accelerate wound healing in aged mice. Mechanistically, we found that EVsGstm2 alleviated oxidative stress damage of aging dermal fibroblasts by modulating mitochondrial oxidative phosphorylation, and promoted dermal fibroblasts to regulate skin epidermal cell function by paracrine secretion of Nascent Polypeptide-Associated Complex Alpha subunit (NACA). Furthermore, we confirmed that NACA is a novel skin epidermal cell protective molecule that regulates skin epidermal cell turnover through the ROS-ERK-ETS-Cyclin D pathway. Our findings demonstrate the feasibility and efficacy of EVs-mediated delivery of Gstm2 for aged skin treatment and unveil novel roles of GSTM2 and NACA for improving aging skin.

Injectable hydrogel harnessing foreskin mesenchymal stem cell-derived extracellular vesicles for treatment of chronic diabetic skin wounds

Chronic skin wounds are a serious complication of diabetes with a high incidence rate, which can lead to disability or even death. Previous studies have shown that mesenchymal stem cells derived extracellular vesicles (EVs) have beneficial effects on wound healing. However, the human foreskin mesenchymal stem cell (FSMSCs)-derived extracellular vesicle (FM-EV) has not yet been isolated and characterized. Furthermore, the limited supply and short lifespan of EVs also hinder their practical use. In this study, we developed an injectable dual-physical cross-linking hydrogel (PSiW) with self-healing, adhesive, and antibacterial properties, using polyvinylpyrrolidone and silicotungstic acid to load FM-EV. The EVs were evenly distributed in the hydrogel and continuously released. In vivo and vitro tests demonstrated that the synergistic effect of EVs and hydrogel could significantly promote the repair of diabetic wounds by regulating macrophage polarization, promoting angiogenesis, and improving the microenvironment. Overall, the obtained EVs-loaded hydrogels developed in this work exhibited promising applicability for the repair of chronic skin wounds in diabetes patients.

Spermidine-Functionalized Injectable Hydrogel Reduces Inflammation and Enhances Healing of Acute and Diabetic Wounds In Situ

The inflammatory response is a key factor affecting tissue regeneration. Inspired by the immunomodulatory role of spermidine, an injectable double network hydrogel functionalized with spermidine (DN-SPD) is developed, where the first and second networks are formed by dynamic imine bonds and non-dynamic photo-crosslinked bonds respectively. The single network hydrogel before photo-crosslinking exhibits excellent injectability and thus can be printed and photo-crosslinked in situ to form double network hydrogels. DN-SPD hydrogel has demonstrated desirable mechanical properties and tissue adhesion. More importantly, an "operando" comparison of hydrogels loaded with spermidine or diethylenetriamine (DETA), a sham molecule resembling spermidine, has shown similar physical properties, but quite different biological functions. Specifically, the outcomes of 3 sets of in vivo animal experiments demonstrate that DN-SPD hydrogel can not only reduce inflammation caused by implanted exogenous biomaterials and reactive oxygen species but also promote the polarization of macrophages toward regenerative M2 phenotype, in comparison with DN-DETA hydrogel. Moreover, the immunoregulation by spermidine can also translate into faster and more natural healing of both acute wounds and diabetic wounds. Hence, the local administration of spermidine affords a simple but elegant approach to attenuate foreign body reactions induced by exogenous biomaterials to treat chronic refractory wounds.

Deep Red Light Driven Hydrogen Evolution by Heterojunction Polymer Dots for Diabetic Wound Healing

We describe small heterojunction polymer dots (Pdots) with deep-red light catalyzed H2 generation for diabetic skin wound healing. The Pdots with donor/acceptor heterojunctions showed remarkably enhanced photocatalytic activity as compared to the donor or acceptor nanoparticles alone. We encapsulate the Pdots and ascorbic acid into liposomes to form Lipo-Pdots nanoreactors, which selectively scavenge ⋅OH radicals in live cells and tissues under 650 nm light illumination. The antioxidant capacity of the heterojunction Pdots is ~10 times higher than that of the single-component Pdots described previously. Under a total light dose of 360 J/cm2, the Lipo-Pdots nanoreactors effectively scavenged ⋅OH radicals and suppressed the expression of pro-inflammatory cytokines in skin tissues, thereby accelerating the healing of skin wounds in diabetic mice. This study provides a feasible solution for safe and effective treatment of diabetic foot ulcers.

Hyaluronidase-Responsive Bactericidal Cryogel for Promoting Healing of Infected Wounds: Inflammatory Attenuation, ROS Scavenging, and Immune Regulation

Wounds infected with multidrug-resistant (MDR) bacteria are increasingly threatening public health and challenging clinical treatments because of intensive bacterial colonization, excessive inflammatory responses, and superabundant oxidative stress. To overcome this malignant burden and promote wound healing, a multifunctional cryogel (HA/TA2/KR2) composed of hyaluronic acid (HA), tannic acid (TA), and KR-12 peptides is designed. The cryogel exhibited excellent shape-memory properties, strong absorption performance, and hemostatic capacity. In vitro experiments demonstrated that KR-12 in the cryogel can be responsively released by stimulation with hyaluronidase produced by bacteria, reaching robust antibacterial activity against Escherichia coli (E. coli), MDR Pseudomonas aeruginosa (MDR-PA), and methicillin-resistant Staphylococcus aureus (MRSA) by disrupting bacterial cell membranes. Furthermore, the synergetic effect of KR-12 and TA can efficiently scavenge ROS and decrease expression of pro-inflammatory cytokines (tumor necrosis factor (TNF)-α & interleukin (IL)-6), as well as modulate the macrophage phenotype toward the M2 type. In vivo animal tests indicated that the cryogel can effectively destroy bacteria in the wound and promote healing process via accelerating angiogenesis and re-epithelialization. Proteomic analysis revealed the underlying mechanism by which the cryogel mainly reshaped the infected wound microenvironment by inhibiting the Nuclear factor kappa B (NF-κB) signaling pathway and activating the Janus kinase-Signal transducer and activator of transcription (JAK-STAT6) signaling pathway. Therefore, the HA/TA2/KR2 cryogel is a promising dressing candidate for MDR bacteria-infected wound healing.

An Antioxidative and Active Shrinkage Hydrogel Integratedly Promotes Re-Epithelization and Skin Constriction for Enhancing Wound Closure

Delayed re-epithelization and weakened skin contractions are the two primary factors that hinder wound closure in large-scale acute or chronic wounds. However, effective strategies for targeting these two aspects concurrently are still lacking. Herein, an antioxidative active-shrinkage hydrogel (AHF@AS Gel) is constructed that can integratedly promote re-epithelization and skin constriction to accelerate large-scale acute and diabetic chronic wound closure. The AHF@AS Gel is encapsulated by antioxidative amino- and hydroxyl-modified C70 fullerene (AHF) and a thermosensitive active shrinkage hydrogel (AS Gel). Specifically, AHF relieves overactivated inflammation, prevents cellular apoptosis, and promotes fibroblast migration in vitro by reducing excessive reactive oxygen species (ROS). Notably, the AHF@AS Gel achieved ≈2.7-fold and ≈1.7-fold better re-epithelization in acute wounds and chronic diabetic wounds, respectively, significantly contributing to the promotion of wound closure. Using proteomic profiling and mechanistic studies, it is identified that the AHF@AS Gel efficiently promoted the transition of the inflammatory and proliferative phases to the remodeling phase. Notably, it is demonstrated that AS Gel alone activates the mechanosensitive epidermal growth factor receptor/Akt (EGFR/Akt) pathway and promotes cell proliferation. The antioxidative active shrinkage hydrogel offers a comprehensive strategy for acute wound and diabetic chronic wound closure via biochemistry regulation integrating with mechanical forces stimulation.

Chemical Modifications in Hyaluronic Acid-Based Electrospun Scaffolds

Hyaluronic acid (HA) is a natural, non-sulfated glycosaminoglycan (GAG) present in ECM. It is involved in different biological functions with appealing properties in cosmetics and pharmaceutical preparations as well as in tissue engineering. Generally, HA has been electrospun in blends with natural or synthetic polymers to produce fibers having diameters in the order of nano and micro-scale whose pores can host cells able to regenerate damaged tissues. In the last decade, a rich literature on electrospun HA-based materials arose. Chemical modifications were generally introduced in HA scaffolds to favour crosslinking or conjugation with bioactive molecules. Considering the high solubility of HA in water, HA-based electrospun scaffolds are cross-linked to increase the stability in biological fluids. Crosslinking is necessary also to avoid the release of HA from the hybrid scaffold when implanted in-vivo. Furthermore, to endow the HA based scaffolds with new chemical or biological properties, conjugation of bioactive molecules to HA was widely reported. Herein, we review the existing research classifying chemical modifications on HA and HA-based electrospun fibers into three categories: i) in-situ crosslinking of electrospun HA-based scaffolds ii) off-site crosslinking of electrospun HA-based scaffolds; iii) conjugation of biofunctional molecules to HA with focus on peptides.

A ferrocene-based hydrogel as flexible electrochemical biosensor for oxidative stress detection and antioxidation treatment

Real-time sensing of reactive oxygen species (ROS) and timely scavenging of excessive ROS in physiological environments are critically important in the diagnosis and prevention of ROS-related diseases. To solve the mismatch problem between conventional rigid ROS biosensors and biological tissues in terms of both modulus and composition, here, we present a flexible ferrocene-based hydrogel biosensor designed for oxidative stress detection and antioxidation treatment. The hydrogel was fabricated through a supramolecular assembly of ferrocene-grafted polyethylenimine (PEI-Fc), sodium alginate (SA), and polyvinyl alcohol (PVA). Multiple non-covalent interactions, including electrostatic interactions between PEI-Fc and SA, hydrophobic interactions and π-π stacking among ferrocene groups, and the PVA crystalline domain, synergistically improve the mechanical properties of the PVA/SA/PEI-Fc hydrogel. The flexible PVA/SA/PEI-Fc hydrogel biosensor exhibited a broad detection range for hydrogen peroxide (H2O2), from 0 to 120 μM, using the differential pulse voltammetry method. Furthermore, the hydrogel demonstrated effective ROS scavenging and oxygen generation performance, desirable biocompatibility, and satisfactory antibacterial activity, making it suitable for biological interfaces. In vitro studies revealed that the PVA/SA/PEI-Fc hydrogel could monitor H2O2 concentration in the proximity of inflammatory cells, and effectively scavenge ROS to protect cells from oxidative stress damage. This all-in-one multifunctional hydrogel, integrating both sensing and treatment functions, holds great promise for clinical applications in the diagnosis and management of ROS-related diseases.

Transparent injectable sericin-honey hydrogel with antioxidant and antibacterial activities combined with feeding sericin accelerates diabetic wound healing

Wound healing in diabetics is often impaired or delayed due to the presence of high reactive oxygen species and low antioxidant levels. Here, a sericin-honey semi-interpenetrating network hydrogel with excellent antioxidant activity was prepared. Besides, the sericin-honey hydrogel is transparent, injectable, sticky, highly porous, and has good swelling properties, antibacterial activity, and cell compatibility. Based on its good performancein vitro, sericin-honey hydrogel achieved effectivein vivotreatment on a mouse diabetic wound model, significantly accelerating the wound healing process. Furthermore, the combined effect of feeding sericin solution played a positive role in strengthening the effect of diabetic wound repair.

The synergetic effect of alginate-derived hydrogels and metal-phenolic nanospheres for chronic wound therapy

Management of diabetic wounds presents a global health challenge due to elevated levels of ROS in the wound microenvironment, persistent dysregulation of inflammation modulation, and limitations in commercially available dressings. Addressing this issue, we have developed a pH-responsive and glucose-sensitive multifunctional hydrogel dressing that dynamically responds to the wound microenvironment and enables on-demand drug release. The dressing incorporates a matrix material based on aminophenylboronic acid-functionalized alginate and a polyhydroxy polymer, alongside an enhancer phase consisting of self-assembled metal-phenol coordination nanospheres formed by tannic acid and iron ions. Using the dynamic borate ester bonds and catechol-metal ion coordination bonds, the dressing exhibits remarkable shape adaptability, self-healing capability, tissue adhesiveness, antioxidant activity, and photothermal responsiveness, without additional curatives or crosslinking agents. As a wound dressing, it elicits macrophage polarization towards an anti-inflammatory phenotype while maintaining long-lasting antimicrobial effects. In a diabetic mouse model of full-thickness wound infections, it effectively mitigated inflammation and vascular damage, significantly expediting the wound healing process with a commendable 97.7% wound closure rate. This work provides a new direction for developing multifunctional smart hydrogel dressings that can accelerate diabetic wound healing for human health.

Injective Programmable Proanthocyanidin-Coordinated Zinc-Based Composite Hydrogel for Infected Bone Repair

Effectively integrating infection control and osteogenesis to promote infected bone repair is challenging. Herein, injective programmable proanthocyanidin (PC)-coordinated zinc-based composite hydrogels (ipPZCHs) are developed by compositing antimicrobial and antioxidant PC-coordinated zinc oxide (ZnO) microspheres with thioether-grafted sodium alginate (TSA), followed by calcium chloride (CaCl2 ) crosslinking. Responsive to the high endogenous reactive oxygen species (ROS) microenvironment in infected bone defects, the hydrophilicity of TSA can be significantly improved, to trigger the disintegration of ipPZCHs and the fast release of PC-coordinated ZnOs. This together with the easily dissociable PC-Zn2+ coordination induced fast release of antimicrobial zinc (Zn2+ ) with/without silver (Ag+ ) ions from PC-coordinated ZnOs (for Zn2+ , > 100 times that of pure ZnO) guarantees the strong antimicrobial activity of ipPZCHs. The exogenous ROS generated by ZnO and silver nanoparticles during the antimicrobial process further speeds up the disintegration of ipPZCHs, augmenting the antimicrobial efficacy. At the same time, ROS-responsive degradation/disintegration of ipPZCHs vacates space for bone ingrowth. The concurrently released strong antioxidant PC scavenges excess ROS thus enhances the immunomodulatory (in promoting the anti-inflammatory phenotype (M2) polarization of macrophages) and osteoinductive properties of Zn2+ , thus the infected bone repair is effectively promoted via the aforementioned programmable and self-adaptive processes.

Development of a Sprayable Hydrogel-Based Wound Dressing: An In Vitro Model

Hydrogel-based dressings can effectively heal wounds by providing multiple functions, such as antibacterial, anti-inflammatory, and preangiogenic bioactivities. The ability to spray the dressing is important for the rapid and effective coverage of the wound surface. In this study, we developed a sprayable hydrogel-based wound dressing using naturally derived materials: hyaluronic acid and gelatin. We introduced methacrylate groups (HAMA and GelMA) to these materials to enable controllable photocrosslinking and form a stable hydrogel on the wound surface. To achieve sprayability, we evaluated the concentration of GelMA within a range of 5-15% (w/v) and then incorporated 1% (w/v) HAMA. Additionally, we incorporated calcium peroxide into the hydrogel at concentrations ranging from 0 to 12 mg/mL to provide self-oxygenation and antibacterial properties. The results showed that the composite hydrogels were sprayable and could provide oxygen for up to two weeks. The released oxygen relieved metabolic stress in fibroblasts and reduced cell death under hypoxia in in vitro culture. Furthermore, calcium peroxide added antibacterial properties to the wound dressing. In conclusion, the developed sprayable hydrogel dressing has the potential to be advantageous for wound healing due to its practical and conformable application, as well as its self-oxygenating and antibacterial functions.

Developing natural polymers for skin wound healing

Natural polymers are complex organic molecules that occur in the natural environment and have not been subjected to artificial synthesis. They are frequently encountered in various creatures, including mammals, plants, and microbes. The aforementioned polymers are commonly derived from renewable sources, possess a notable level of compatibility with living organisms, and have a limited adverse effect on the environment. As a result, they hold considerable significance in the development of sustainable and environmentally friendly goods. In recent times, there has been notable advancement in the investigation of the potential uses of natural polymers in the field of biomedicine, specifically in relation to natural biomaterials that exhibit antibacterial and antioxidant characteristics. This review provides a comprehensive overview of prevalent natural polymers utilized in the biomedical domain throughout the preceding two decades. In this paper, we present a comprehensive examination of the components and typical methods for the preparation of biomaterials based on natural polymers. Furthermore, we summarize the application of natural polymer materials in each stage of skin wound repair. Finally, we present key findings and insights into the limitations of current natural polymers and elucidate the prospects for their future development in this field.

Thermo-sensitive hydroxybutyl chitosan/diatom biosilica hydrogel with immune microenvironment regulatory for chronic wound healing

This study proposes a chronic wound therapeutic strategy based on extracellular matrix (ECM) biomimetics and immune regulation. The hydroxybutyl chitosan/diatom biosilica hydrogel (H/D) which can regulate the immune microenvironment, is prepared from hydroxybutyl chitosan (HBC) as matrix to construct the bionic ECM and diatom biosilica (DB) as structural active unit. The hierarchical porous structure of DB provides strong anchoring interface effect to enhance the mechanical strength of hydrogel, while maintaining its favorable temperature phase transition behavior, improving the material's fit to the wound and convenience of clinical use. Silicates released from DB in H/D accelerate the transition of wounds from inflammation to proliferation and remodeling. In cellular and diabetic rat models, H/D reduces inflammation (induces conversion of M1-type macrophages to M2-type), induces angiogenesis (1.96-fold of control), promotes fibroblast proliferation (180.36 % of control), collagen deposition, keratinocyte migration (47.34 % more than control), and re-epithelialization. This study validates a possible biological mechanism for H/D bioactive hydrogel-mediated regulation of the immune microenvironment and provides a simple synergistic dressing strategy.

Programmed microalgae-gel promotes chronic wound healing in diabetes

Chronic diabetic wounds are at lifelong risk of developing diabetic foot ulcers owing to severe hypoxia, excessive reactive oxygen species (ROS), a complex inflammatory microenvironment, and the potential for bacterial infection. Here we develop a programmed treatment strategy employing live Haematococcus (HEA). By modulating light intensity, HEA can be programmed to perform a variety of functions, such as antibacterial activity, oxygen supply, ROS scavenging, and immune regulation, suggesting its potential for use in programmed therapy. Under high light intensity (658 nm, 0.5 W/cm2), green HEA (GHEA) with efficient photothermal conversion mediate wound surface disinfection. By decreasing the light intensity (658 nm, 0.1 W/cm2), the photosynthetic system of GHEA can continuously produce oxygen, effectively resolving the problems of hypoxia and promoting vascular regeneration. Continuous light irradiation induces astaxanthin (AST) accumulation in HEA cells, resulting in a gradual transformation from a green to red hue (RHEA). RHEA effectively scavenges excess ROS, enhances the expression of intracellular antioxidant enzymes, and directs polarization to M2 macrophages by secreting AST vesicles via exosomes. The living HEA hydrogel can sterilize and enhance cell proliferation and migration and promote neoangiogenesis, which could improve infected diabetic wound healing in female mice.

A carboxymethyl chitosan/oxidized hyaluronic acid composite hydrogel dressing loading with stem cell exosome for chronic inflammation wounds healing

Stem cell exosomes (Exo) play an important role in the transformation of macrophages, but the rapid clearance of Exo in vivo limits their therapeutic effects for chronic inflammation wounds healing. Here, stem cell Exo was isolated and introduced to a composite hydrogel including carboxymethyl chitosan (CMCS) and oxidized hyaluronic acid (OHA) through chemical cross-linking, which formed an Exo-loaded (CMCS/OHA/Exo) hydrogel. The CMCS/OHA/Exo hydrogel exhibited a function of Exo sustained release and an Exo protection within 6 days. This CMCS/OHA/Exo hydrogel was much better than CMCS/OHA hydrogel or Exo solution in macrophage cell phagocytosis, proliferation and migration in vitro, especially, played an obviously positive role in the transformation of macrophages compared with the reference groups. For the treatment of the chronic inflammation wounds in vivo, the CMCS/OHA/Exo hydrogel had the best results at wound heal rate and inhibiting the secretion of inflammatory factors, and it was far superior to reference groups in wound re-epithelization and collagen production. CMCS/OHA/Exo hydrogels can promote Exo release based on hydrogel degradation to regulate macrophages transformation and accelerate chronic wound healing. The study offers a method for preparing Exo-loaded hydrogels that effectively promote the transformation of macrophages and accelerate chronic inflammatory wound healing.

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.

Unimolecular Cascaded Multienzyme Conjugates Modulate the Microenvironment of Diabetic Wound to Promote Healing

An abnormal microenvironment underlies poor healing in chronic diabetic chronic wounds. However, effectively modulating the microenvironment of the diabetic wound remains a great challenge due to sustained oxidative stress and chronic inflammation. Here, we present a unimolecular enzyme-polymer conjugate that demonstrates excellent multienzymatic cascade activities. The cascaded enzyme conjugates (CECs) were synthesized by grafting poly(N-acryloyl-lysine) (pLAAm) from the glycan moieties of glucose oxidase (GOx) via glycan-initiated polymerization. The resulting CECs exhibited multiple enzymatic properties of GOx, superoxide dismutase mimic, and catalase mimic activities simultaneously. The CECs facilitated the depletion of high blood glucose, ROS scavenging, bacteria-killing, anti-inflammatory effects, and sustained oxygen generation, which restored the microenvironment in diabetic wounds. In vivo results from a diabetic mouse model confirmed the capacity and efficiency of the cascade reaction for diabetic wound healing. Our findings demonstrate that the three-in-one enzyme-polymer conjugates alone can modulate the diabetic microenvironment for 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.

ε-Poly-l-lysine-hydroxyphenyl propionic acid/IL-4 composite hydrogels with inflammation regulation and antibacterial activity for improving integration stability of soft tissues and orthopedic implants

The failure of orthopedic implants is usually caused by inflammation, poor tissue integration, and infection, which can lead to pain, limited mobility, dysfunction of patients. This may require additional surgical interventions, such as removal, replacement, or repair of implants, as well as related treatment measures such as antibiotic therapy, physical therapy. Here, an injectable hydrogel carrier was developed for the steady release of inflammatory regulators to reduce the surface tissue inflammatory response of orthopedic implants and induce soft tissue regeneration, ultimately achieving the promotion of implants stability. The hydrogels carrier was prepared by hydroxyphenyl propionic acid-modified ε-Poly-l-lysine (EPA), hydrogen peroxide and horseradish peroxidase, which showed antibacterial bioactive and stable factor release ability. Due to the introduction of IL-4, EPA@IL-4 hydrogels showed good inflammatory regulation. EPA@IL-4 hydrogels regulated the differentiation of macrophages into M2 in inflammatory environment in vitro, and promoted endothelial cells to show a more obvious trend of tube formation. The composite hydrogels reduced the inflammation on the surface of the implants in vivo, induced local endothelial cell angiogenesis, and had more collagen deposition and new granulation tissue. Therefore, EPA hydrogels based on IL-4 release are promising candidates for promoting of implants surface anti-inflammatory, soft tissue regeneration, and anti-infection.

Croconaine conjugated cationic polymeric nanoparticles for NIR enhanced bacterial killing

Light-triggered treatment approach has been regarded as an effective option for sterilization due to noninvasiveness, limited drug resistance, and minimized adverse effects. Herein, we designed and synthesized a functionalized cationic polymer, CR-PQAC, with croconaine bridging agent and quaternary ammonium groups for photothermal enhanced antimicrobial therapy under near-infrared irradiation. The quaternary ammonium group on the pendent chain endowing CR-PQAC the ability to effectively bind to bacteria. The CR-PQAC could self-assembles into micellar nanoparticles in aqueous solution, which exhibited strong absorption in the near-infrared (NIR) region, excellent photostability, and photothermal conversion efficiency of up to 43.8 %. Notably, the CR-PQAC nanoparticles presented remarkable antibacterial activity against both methicillin-resistant Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria with 808 nm laser irradiation. Moreover, the developed CR-PQAC has negligible dark cytotoxicity and good hemolytic compatibility against mammalian cells. Both in vitro and in vivo studies have demonstrated that the desirable antibacterial efficacy of CR-PQAC was obtained. Therefore, the proposed CR-PQAC may be a promising antimicrobial agent for NIR-enhanced killing bacterial.

Marine-derived polysaccharides and their therapeutic potential in wound healing application - A review

Polysaccharides originating from marine sources have been studied as potential material for use in wound dressings because of their desirable characteristics of biocompatibility, biodegradability, and low toxicity. Marine-derived polysaccharides used as wound dressing, provide several benefits such as promoting wound healing by providing a moist environment that facilitates cell migration and proliferation. They can also act as a barrier against external contaminants and provide a protective layer to prevent further damage to the wound. Research studies have shown that marine-derived polysaccharides can be used to develop different types of wound dressings such as hydrogels, films, and fibres. These dressings can be personalised to meet specific requirements based on the type and severity of the wound. For instance, hydrogels can be used for deep wounds to provide a moist environment, while films can be used for superficial wounds to provide a protective barrier. Additionally, these polysaccharides can be modified to improve their properties, such as enhancing their mechanical strength or increasing their ability to release bioactive molecules that can promote wound healing. Overall, marine-derived polysaccharides show great promise for developing effective and safe wound dressings for various wound types.

A focused review on hyaluronic acid contained nanofiber formulations for diabetic wound healing

The significant clinical challenge presented by diabetic wounds is due to their impaired healing process and increased risk of complications. It is estimated that a foot ulcer will develop at some point in the lives of 15-25 % of diabetic patients. Serious complications, including infection and amputation, are often led to by these wounds. In the field of tissue engineering and regenerative medicine, nanofiber-based wound dressings have emerged in recent years as promising therapeutic strategies for diabetic wound healing. Hyaluronic acid (HA), among various nanofiber materials, has gained considerable attention due to its unique properties, including biocompatibility, biodegradability, and excellent moisture retention capacity. By promoting skin hydration and controlling inflammation, a crucial role in wound healing is played by HA. Wounds are also helped to heal faster by HA through the regulation of inflammation levels and signaling the body to build more blood vessels in the damaged area. Great potential in various applications, including wound healing, has been shown by the development and use of nanofiber formulations in medicine. However, challenges and limitations associated with nanofibers in medicine exist, such as reproducibility, proper characterization, and biological evaluation. By providing a biomimetic environment that enhances re-epithelialization and facilitates the delivery of active substances, nanofibers promote wound healing. In accelerating wound healing, promising results have been shown by HA-contained nanofiber formulations in diabetic wounds. Key strategies employed by these formulations include revascularization, modulation of the inflammation microenvironment, delivery of active substances, photothermal nanofibers, and nanoparticle-loaded fabrics. Particularly crucial is revascularization as it restores blood flow to the wound area, promoting healing. Wound healing can also be enhanced by modulating the inflammation microenvironment through controlling inflammation levels. Future perspectives in this field involve addressing the current challenges and limitations of nanofiber technology and further optimizing HA-contained nanofiber formulations for improved efficacy in diabetic wound healing. This includes exploring new fabrication techniques, enhancing the biocompatibility and biodegradability of nanofibers, and developing multifunctional nanofibers for targeted drug delivery. Not only does writing a review in the field of nanofiber-based wound dressings, particularly those containing hyaluronic acid, allow us to consolidate our current knowledge and understanding but also broadens our horizons. An opportunity is provided to delve deeper into the intricacies of this innovative therapeutic strategy, explore its potential and limitations, and envision future directions. By doing so, a contribution can be made to the ongoing advancements in tissue engineering and regenerative medicine, ultimately improving the quality of life for patients with diabetic wounds.

Fabrication of an Adhesive Small Intestinal Submucosa Acellular Matrix Hydrogel for Accelerating Diabetic Wound Healing

The treatment of diabetic skin defects comes with enormous challenges in the clinic due to the disordered metabolic microenvironment. In this study, we therefore designed a novel composite hydrogel (SISAM@HN) with bioactive factors and tissue adhesive properties for accelerating chronic diabetic wound healing. Hyaluronic acid (HA) modified by N-(2-aminoethyl)-4-(4-(hydroxymethyl)-2-methoxy-5-nitrosophenoxy) butanamide (NB) held the phototriggering tissue adhesive capacity. Decellularized small intestinal submucosa (SIS) was degreased and digested to form the acellular matrix, which facilitated bioactive factor release. The results of the burst pressure test demonstrated that the in situ formed hydrogel possessed a tissue adhesive property. In vitro experiments, based on bone marrow stromal cells, revealed that the SIS acellular matrix-containing hydrogel contributed to promoting cell proliferation. In vivo, a diabetic mouse model was created and used to evaluate the tissue regeneration function of the obtained hydrogel, and our results showed that the synthesized hydrogel could assist collagen deposition, attenuate inflammation, and foster vascular growth during the wound healing process. Overall, the SIS acellular matrix-containing HA hydrogel was able to adhere to the wound sites, promote cell proliferation, and facilitate angiogenesis, which would be a promising biomaterial for wound dressing in clinical therapy of diabetic skin defects.

Antibacterial conductive self-healing hydrogel wound dressing with dual dynamic bonds promotes infected wound healing

In clinical applications, there is a lack of wound dressings that combine efficient resistance to drug-resistant bacteria with good self-healing properties. In this study, a series of adhesive self-healing conductive antibacterial hydrogel dressings based on oxidized sodium alginate-grafted dopamine/carboxymethyl chitosan/Fe3+ (OSD/CMC/Fe hydrogel)/polydopamine-encapsulated poly(thiophene-3-acetic acid) (OSD/CMC/Fe/PA hydrogel) were prepared for the repair of infected wound. The Schiff base and Fe3+ coordination bonds of the hydrogel structure are dynamic bonds that can be repaired automatically after the hydrogel network is disrupted. Macroscopically, the hydrogel exhibits self-healing properties, allowing the hydrogel dressing to adapt to complex wound surfaces. The OSD/CMC/Fe/PA hydrogel showed good conductivity and photothermal antibacterial properties under near-infrared (NIR) light irradiation. In addition, the hydrogels exhibit tunable rheological properties, suitable mechanical properties, antioxidant properties, tissue adhesion properties and hemostatic properties. Furthermore, all hydrogel dressings improved wound healing in the infected full-thickness defect skin wound repair test in mice. The wound size repaired by OSD/CMC/Fe/PA3 hydrogel + NIR was much smaller (12%) than the control group treated with Tegaderm™ film after 14 days. In conclusion, the hydrogels have high antibacterial efficiency, suitable conductivity, great self-healing properties, good biocompatibility, hemostasis and antioxidant properties, making them promising candidates for wound healing dressings for the treatment of infected skin wounds.

Reactive oxygen species (ROS) scavenging biomaterials for anti-inflammatory diseases: from mechanism to therapy

Inflammation is a fundamental defensive response to harmful stimuli, but the overactivation of inflammatory responses is associated with most human diseases. Reactive oxygen species (ROS) are a class of chemicals that are generated after the incomplete reduction of molecular oxygen. At moderate levels, ROS function as critical signaling molecules in the modulation of various physiological functions, including inflammatory responses. However, at excessive levels, ROS exert toxic effects and directly oxidize biological macromolecules, such as proteins, nucleic acids and lipids, further exacerbating the development of inflammatory responses and causing various inflammatory diseases. Therefore, designing and manufacturing biomaterials that scavenge ROS has emerged an important approach for restoring ROS homeostasis, limiting inflammatory responses and protecting the host against damage. This review systematically outlines the dynamic balance of ROS production and clearance under physiological conditions. We focus on the mechanisms by which ROS regulate cell signaling proteins and how these cell signaling proteins further affect inflammation. Furthermore, we discuss the use of potential and currently available-biomaterials that scavenge ROS, including agents that were engineered to reduce ROS levels by blocking ROS generation, directly chemically reacting with ROS, or catalytically accelerating ROS clearance, in the treatment of inflammatory diseases. Finally, we evaluate the challenges and prospects for the controlled production and material design of ROS scavenging biomaterials.

Nature-Derived Polysaccharide-Based Composite Hydrogels for Promoting Wound Healing

Numerous innovative advancements in dressing technology for wound healing have emerged. Among the various types of wound dressings available, hydrogel dressings, structured with a three-dimensional network and composed of predominantly hydrophilic components, are widely used for wound care due to their remarkable capacity to absorb abundant wound exudate, maintain a moisture environment, provide soothing and cooling effects, and mimic the extracellular matrix. Composite hydrogel dressings, one of the evolved dressings, address the limitations of traditional hydrogel dressings by incorporating additional components, including particles, fibers, fabrics, or foams, within the hydrogels, effectively promoting wound treatment and healing. The added elements enhance the features or add specific functionalities of the dressings, such as sensitivity to external factors, adhesiveness, mechanical strength, control over the release of therapeutic agents, antioxidant and antimicrobial properties, and tissue regeneration behavior. They can be categorized as natural or synthetic based on the origin of the main components of the hydrogel network. This review focuses on recent research on developing natural polysaccharide-based composite hydrogel wound dressings. It explores their preparation and composition, the reinforcement materials integrated into hydrogels, and therapeutic agents. Furthermore, it discusses their features and the specific types of wounds where applied.

Immune-microenvironment modulatory polyurethane-hyaluronic acid hybrid hydrogel scaffolds for diabetic wound treatment

The healing of wounds in diabetic patients is a huge challenge issue in clinical medicine due to the disordered immune. Recruiting endogenous cells to play a role in the early stage and timely reducing inflammation to promote healing in the middle or late of injuring are both prerequisites for effective treatment. Here, inspired by natural extracellular matrix, three-dimensional porous polyurethane-hyaluronic acid hybrid hydrogel scaffolds (PUHA) were prepared to repair diabetic wound through activate cell immunity by moderate foreign body reaction, provide cell adhesion growth extracellular matrix of hyaluronic acid (HA) and exhibit anti-inflammatory effect of polyurethane (PU). The interaction between PU and HA alters the compact PU hydrogel into macroporous PUHA hydrogel scaffolds with super-swelling, elastic mechanical properties, and controllable degradation, which are suitable for endogenous cells infiltration, growth and immune activation. Additionally, incorporating with RGD, PUHA hydrogel scaffolds with bioactive physicochemical features can evidently reduce the inflammation and modulate the polarization of macrophage apparently both in vitro and in vivo, mainly through downregulation of cytokine-cytokine receptor interaction genes, leading to reprogramming immune-microenvironment and rapid diabetic wound healing. This method of gathering cells initially and intervening immune-microenvironment in time provides an expected way to design biomaterials for chronic wound healing.

Drug in Therapeutic Polymer: Sinomenine-Loaded Oxidation-Responsive Polymeric Nanoparticles for Rheumatoid Arthritis Treatment

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease that frequently involves cartilage damage and the destruction of the bone structure, ultimately resulting in disability and long-term pain. It is clear that overexpression of reactive oxygen species (ROS) and the complex inflammatory microenvironment are the main causes of RA pathogenesis; thereby, the efficacy of any single-drug treatment is limited. Herein, we formulated a therapeutic hyaluronic acid derivative (PAM-HA) with adsorption capacity to the subchondral bone, a long retention time within inflamed joints, and ROS-scavenging capacity, which was used as a drug carrier for realizing the controlled release of sinomenine (Sin) within arthritic joints. This "drug in therapeutic polymer" design strategy was aimed at realizing antioxidant and anti-inflammatory combination therapy for RA. In vivo experiments suggest that PAM-HA@Sin NPs can be retained in the inflamed joints of rats for a long time compared with commercially available free Sin injections. As expected, therapeutic PAM-HA polymeric carriers can increase joint lubrication and reduce oxidative stress, while the released Sin induces downregulation of proinflammatory factors (TNF-α and IL-1β) and upregulation of anti-inflammatory factors (Arg-1 and IL-10) via the NF-κB pathway. In summary, a ROS-scavenging hyaluronic acid (HA) derivative was developed as the nanocarrier for Sin delivery to simultaneously remodel the oxidative/inflammatory microenvironment in RA, which opens up new horizons for the development of therapeutic polymers and the combined therapeutic strategies.

Recent Advances in Electrospun Nanofiber-Based Strategies for Diabetic Wound Healing Application

Diabetic ulcers are the second largest complication caused by diabetes mellitus. A great number of factors, including hyperchromic inflammation, susceptible microbial infection, inferior vascularization, the large accumulation of free radicals, and other poor healing-promoting microenvironments hold back the healing process of chronic diabetic ulcer in clinics. With the increasing clinical cases of diabetic ulcers worldwide, the design and development of advanced wound dressings are urgently required to accelerate the treatment of skin wounds caused by diabetic complications. Electrospinning technology has been recognized as a simple, versatile, and cost-reasonable strategy to fabricate dressing materials composed of nanofibers, which possess excellent extracellular matrix (ECM)-mimicking morphology, structure, and biological functions. The electrospinning-based nanofibrous dressings have been widely demonstrated to promote the adhesion, migration, and proliferation of dermal fibroblasts, and further accelerate the wound healing process compared with some other dressing types like traditional cotton gauze and medical sponges, etc. Moreover, the electrospun nanofibers are commonly harvested in the structure of nonwoven-like mats, which possess small pore sizes but high porosity, resulting in great microbial barrier performance as well as excellent moisture and air permeable properties. They also serve as good carriers to load various bioactive agents and/or even living cells, which further impart the electrospinning-based dressings with predetermined biological functions and even multiple functions to significantly improve the healing outcomes of different chronic skin wounds while dramatically shortening the treatment procedure. All these outstanding characteristics have made electrospun nanofibrous dressings one of the most promising dressing candidates for the treatment of chronic diabetic ulcers. This review starts with a brief introduction to diabetic ulcer and the electrospinning process, and then provides a detailed introduction to recent advances in electrospinning-based strategies for the treatment of diabetic wounds. Importantly, the synergetic application of combining electrospinning with bioactive ingredients and/or cell therapy was highlighted. The review also discussed the advantages of hydrogel dressings by using electrospun nanofibers. At the end of the review, the challenge and prospects of electrospinning-based strategies for the treatment of diabetic wounds are discussed in depth.

Double-network hydrogel enhanced by SS31-loaded mesoporous polydopamine nanoparticles: Symphonic collaboration of near-infrared photothermal antibacterial effect and mitochondrial maintenance for full-thickness wound healing in diabetes mellitus

Diabetic wound healing has become a serious healthcare challenge. The high-glucose environment leads to persistent bacterial infection and mitochondrial dysfunction, resulting in chronic inflammation, abnormal vascular function, and tissue necrosis. To solve these issues, we developed a double-network hydrogel, constructed with pluronic F127 diacrylate (F127DA) and hyaluronic acid methacrylate (HAMA), and enhanced by SS31-loaded mesoporous polydopamine nanoparticles (MPDA NPs). As components, SS31, a mitochondria-targeted peptide, maintains mitochondrial function, reduces mitochondrial reactive oxygen species (ROS) and thus regulates macrophage polarization, as well as promoting cell proliferation and migration, while MPDA NPs not only scavenge ROS and exert an anti-bacterial effect by photothermal treatment under near-infrared light irradiation, but also control release of SS31 in response to ROS. This F127DA/HAMA-MPDA@SS31 (FH-M@S) hydrogel has characteristics of adhesion, superior biocompatibility and mechanical properties which can adapt to irregular wounds at different body sites and provide sustained release of MPDA@SS31 (M@S) NPs. In addition, in a diabetic rat full thickness skin defect model, the FH-M@S hydrogel promoted macrophage M2 polarization, collagen deposition, neovascularization and wound healing. Therefore, the FH-M@S hydrogel exhibits promising therapeutic potential for skin regeneration.

NIR-responsive carrier-free nanoparticles based on berberine hydrochloride and indocyanine green for synergistic antibacterial therapy and promoting infected wound healing

Bacterial infections cause severe health conditions, resulting in a significant economic burden for the public health system. Although natural phytochemicals are considered promising anti-bacterial agents, they suffer from several limitations, such as poor water solubility and low bioavailability in vivo, severely restricting their wide application. Herein, we constructed a near-infrared (NIR)-responsive carrier-free berberine hydrochloride (BH, phytochemicals)/indocyanine green (ICG, photosensitizer) nanoparticles (BI NPs) for synergistic antibacterial of an infected wound. Through electrostatic interaction and π-π stacking, the hydrophobic BH and amphiphilic ICG are initially self-assembled to generate carrier-free nanoparticles. The obtained BI NPs demonstrated NIR-responsive drug release behavior and better photothermal conversion efficiency of up to 36%. In addition, BI NPs stimulated by NIR laser exhibited remarkable antibacterial activity, which realized the synergistic antibacterial treatment and promoted infected wound healing. In summary, the current research results provided a candidate strategy for self-assembling new BI NPs to treat bacterial infections synergistically.

Marine Biomaterials: Hyaluronan

The marine-derived hyaluronic acid and other natural biopolymers offer exciting possibilities in the field of biomaterials, providing sustainable and biocompatible alternatives to synthetic materials. Their unique properties and abundance in marine sources make them valuable resources for various biomedical and industrial applications. Due to high biocompatible features and participation in biological processes related to tissue healing, hyaluronic acid has become widely used in tissue engineering applications, especially in the wound healing process. The present review enlightens marine hyaluronan biomaterial providing its sources, extraction process, structures, chemical modifications, biological properties, and biocidal applications, especially for wound healing/dressing purposes. Meanwhile, we point out the future development of wound healing/dressing based on hyaluronan and its composites and potential challenges.

Self-powered enzyme-linked microneedle patch for scar-prevention healing of diabetic wounds

Diabetic wounds with complex pathological features and a difficult-to-heal nature remain a formidable challenge. To address this challenge, we design and fabricate a self-powered enzyme-linked microneedle (MN) patch composed of anode and cathode MN arrays, which respectively contain glucose oxidase (GOx) and horseradish peroxidase (HRP) encapsulated in ZIF-8 nanoparticles. The enzymatic cascade reaction in the MN patch can effectively reduce local hyperglycemia in diabetic wounds while generating stable microcurrents to promote rapid healing of diabetic wounds. Therefore, the diabetic wounds treated with this MN patch exhibit rapid, complete, and scar-preventative healing, which can be attributed to the synergistic actions of hypoglycemic, antibacterial, anti-inflammatory, and bioelectrical stimulation. In brief, the self-powered MN patch is an effective method to rapidly promote diabetic wound healing and prevent scar formation.

Immunomodulatory Nanosystems: Advanced Delivery Tools for Treating Chronic Wounds

The increasingly aging society led to a rise in the prevalence of chronic wounds (CWs), posing a significant burden to public health on a global scale. One of the key features of CWs is the presence of a maladjusted immune microenvironment characterized by persistent and excessive (hyper)inflammation. A variety of immunomodulatory therapies have been proposed to address this condition. Yet, to date, current delivery systems for immunomodulatory therapy remain inadequate and lack efficiency. This highlights the need for new therapeutic delivery systems, such as nanosystems, to manage the pathological inflammatory imbalance and, ultimately, improve the treatment outcomes of CWs. While a plethora of immunomodulatory nanosystems modifying the immune microenvironment of CWs have shown promising therapeutic effects, the literature on the intersection of immunomodulatory nanosystems and CWs remains relatively scarce. Therefore, this review aims to provide a comprehensive overview of the pathogenesis and characteristics of the immune microenvironment in CWs, discuss important advancements in our understanding of CW healing, and delineate the versatility and applicability of immunomodulatory nanosystems-based therapies in the therapeutic management of CWs. In addition, we herein also shed light on the main challenges and future perspectives in this rapidly evolving research field.

Functional carbohydrate-based hydrogels for diabetic wound therapy

Diabetes wound are grave and universal complications of diabetes. Owing to poor treatment course, high amputation rate and mortality, diabetes wound treatment and care have become a global challenge. Wound dressings have received much attention due to their ease of use, good therapeutic effect, and low costs. Among them, carbohydrate-based hydrogels with excellent biocompatibility are considered to be the best candidates for wound dressings. Based on this, we first systematically summarized the problems and healing mechanism of diabetes wounds. Next, common treatment methods and wound dressings were discussed, and the application of various carbohydrate-based hydrogels and their corresponding functionalization (antibacterial, antioxidant, autoxidation and bioactive substance delivery) in the treatment of diabetes wounds were emphatically introduced. Ultimately, the future development of carbohydrate-based hydrogel dressings was proposed. This review aims to provide a deeper understanding of wound treatment and theoretical support for the design of hydrogel dressings.

Polymers and Bioactive Compounds with a Macrophage Modulation Effect for the Rational Design of Hydrogels for Skin Regeneration

The development of biomaterial platforms for dispensing reagents of interest such as antioxidants, growth factors or antibiotics based on functional hydrogels represents a biotechnological solution for many challenges that the biomedicine field is facing. In this context, in situ dosing of therapeutic components for dermatological injuries such as diabetic foot ulcers is a relatively novel strategy to improve the wound healing process. Hydrogels have shown more comfort for the treatment of wounds due to their smooth surface and moisture, as well as their structural affinity with tissues in comparison to hyperbaric oxygen therapy, ultrasound, and electromagnetic therapies, negative pressure wound therapy or skin grafts. Macrophages, one of the most important cells of the innate immune system, have been described as the key not only in relation to the host immune defense, but also in the progress of wound healing. Macrophage dysfunction in chronic wounds of diabetic patients leads to a perpetuating inflammatory environment and impairs tissue repair. Modulating the macrophage phenotype from pro-inflammatory (M1) to anti-inflammatory (M2) could be a strategy for helping to improve chronic wound healing. In this regard, a new paradigm is found in the development of advanced biomaterials capable of inducing in situ macrophage polarization to offer an approach to wound care. Such an approach opens a new direction for the development of multifunctional materials in regenerative medicine. This paper surveys emerging hydrogel materials and bioactive compounds being investigated to induce the immunomodulation of macrophages. We propose four potential functional biomaterials for wound healing applications based on novel biomaterial/bioactive compound combination that are expected to show synergistic beneficial outcomes for the local differentiation of macrophages (M1-M2) as a therapeutic strategy for chronic wound healing improvement.

A conductive multifunctional hydrogel dressing with the synergistic effect of ROS-scavenging and electroactivity for the treatment and sensing of chronic diabetic wounds

Chronic diabetic wound with persistent inflammatory responses is still a serious threat to human health and life. Ideal wound dressings can be applied not only for covering the injury area, but also for regulating the inflammation to accelerate the wound healing and long-term monitoring of wound condition. However, there remains a challenge to design a multifunctional wound dressing for simultaneous treatment and monitoring of wound. Herein, an ionic conductive hydrogel with intrinsic reactive oxygen species (ROS)-scavenging properties and good electroactivity was developed for achieving the synergetic treatment and monitoring of diabetic wounds. In this study, we modified dextran methacrylate with phenylboronic acid (PBA) to prepare a ROS-scavenging material (DMP). Then the hydrogel was constructed by phenylboronic ester bonds induced dynamic crosslinking network, photo-crosslinked DMP and choline-based ionic liquid as the second network, and the crystallized polyvinyl alcohol as the third network, realizing good ROS-scavenging performance, high electroactivity, durable mechanical properties, and favorable biocompatibility. In vivo results showed that the hydrogel combined with electrical stimulation (ES) demonstrated good performance in promoting re-epithelization, angiogenesis and collagen deposition in chronic diabetic wound treatment by alleviating inflammation. Notably, with desirable mechanical properties and conductivity, the hydrogel could also precisely monitor movements of human body and possible tensile and compressive stresses of the wound site, providing timely alerts of excessive mechanical stress applied to the wound tissue. Thus, this "all-in-one" hydrogel exhibits great potential in constructing the next generation flexible bioelectronics for wound treatment and monitoring. STATEMENT OF SIGNIFICANCE: : Chronic diabetic wounds characterized by overexpressed reactive oxygen species (ROS) are still a serious threat to human health and life. However, there remains a challenge to design a multifunctional wound dressing for simultaneous wound treatment and monitoring. Herein, a flexible conductive hydrogel dressing with intrinsic ROS-scavenging properties and electroactivity was developed for the combined treatment and monitoring of the wound. The antioxidant hydrogel combined with electrical stimulation synergistically accelerated chronic diabetic wound healing by regulating oxidative stress, alleviating inflammation, promoting re-epithelization, angiogenesis and collagen deposition. Notably, with desirable mechanical properties and conductivity, the hydrogel also presented great potential in monitoring possible stresses of the wound site. The "all-in-one" bioelectronics integrating the treatment and monitoring functions present great application potential for accelerating chronic wound healing.

Composite nanofibrous dressing loaded with Prussian blue and heparin for anti-inflammation therapy and diabetic wound healing

Diabetic ulcer is a severe complication of diabetes that can lead to amputation due to the overproduction of pro-inflammatory factors and reactive oxygen species (ROS). In this study, a composite nanofibrous dressing was developed by combining Prussian blue nanocrystals (PBNCs) and heparin sodium (Hep) through electrospinning, electrospraying, and chemical deposition. The nanofibrous dressing (PPBDH) was designed to take advantage of the excellent pro-inflammatory factor-adsorbing capability of Hep and the ROS-scavenging capabilities of PBNCs, resulting in synergistic treatment. It is worth noting that the nanozymes were firmly anchored to the fiber surfaces through slight polymer swelling caused by the solvent during electrospinning, thereby guaranteeing the preservation of the enzyme-like activity levels of PBNCs. The PPBDH dressing was found to be effective in reducing intracellular ROS levels, protecting cells from ROS-induced apoptosis, and capturing excessive pro-inflammatory factors, including chemoattractant protein-1 (MCP-1) and interleukin-1β (IL-1β). Furthermore, a chronic wound healing evaluation conducted in vivo demonstrated that the PPBDH dressing was able to effectively alleviate the inflammatory response and accelerate wound healing. This research presents an innovative approach to fabricate nanozyme hybrid nanofibrous dressings, which have great potential in accelerating the healing of chronic and refractory wounds with uncontrolled inflammation.

Photodynamic Alginate Zn-MOF Thermosensitive Hydrogel for Accelerated Healing of Infected Wounds

Antibiotic resistance reduces the effectiveness of infected wound healing, and it is necessary to develop a new strategy to promote infected wound healing without using antibiotics. Here, we develop a Chlorin e6 (Ce6)-loaded zinc-metal-organic framework (MOF) thermosensitive hydrogel (Ce6@MOF-Gel) based on alginate and poly(propylene glycol) 407, which enhances antibacterial effects and promotes infected wound healing by a novel strategy of combining zinc-MOF with photodynamic therapy (PDT). Zinc-MOF can realize acid-responsive release of Ce6 and improve antibacterial performance without drug resistance by destroying the integrity of bacterial cell membranes and enhancing the production of bacterial reactive oxygen species (ROS). Additionally, Ce6@MOF-Gel enhances the stability, solubility, and photodynamic properties of Ce6. More importantly, Ce6@MOF-Gel reduces inflammation and promotes collagen deposition and re-epithelialization to facilitate infected wound healing. Collectively, the photodynamic MOF-based hydrogel provides a new, efficient, and safe way for accelerated healing of infected wounds.

A Self-Healing Multifunctional Hydrogel System Accelerates Diabetic Wound Healing through Orchestrating Immunoinflammatory Microenvironment

Developing an effective treatment strategy of drug delivery to improve diabetic wound healing remains a major challenge in clinical practice nowadays, due to multidrug-resistant bacterial infections, angiopathy, and oxidative damage in the wound microenvironment. Herein, an effective and convenient strategy was designed through a self-healing multiple-dynamic-bond cross-linked hydrogel with interpenetrating networks, which was formed by multiple-dynamic-bond cross-linking of reversible catechol-Fe³⁺ coordinate bonds, hydrogen bonding, and Schiff base bonds. The excellent autonomous healing of the hydrogel was initiated and accelerated by Schiff bonds with reversible breakage between 3,4-dihydroxybenzaldehyde containing catechol and aldehyde groups and chitosan chains, and further consolidated by the co-optation of other noncovalent interactions contributed of hydrogen bonding and Fe³⁺ coordinate bonds. Intriguingly, cathelicidin LL-37 was introduced and uniformly dispersed in the dynamic interpenetrating networks of the hydrogel as a bioactive molecular to orchestrate the diabetic wound healing microenvironment. This multifunctional wound dressing can significantly promote diabetic wound healing by antibacterial activity, immunomodulation, anti-inflammation, neovascularization, and antioxidant activity. Therefore, this study provided an effective and safe strategy for guiding the diabetic wound treatment in clinical applications.

Hyaluronic Acid-Based Nanosystems for CD44 Mediated Anti-Inflammatory and Antinociceptive Activity

The nervous and immune systems go hand in hand in causing inflammation and pain. However, the two are not mutually exclusive. While some diseases cause inflammation, others are caused by it. Macrophages play an important role in modulating inflammation to trigger neuropathic pain. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan that has a well-known ability to bind with the cluster of differentiation 44 (CD44) receptor on classically activated M1 macrophages. Resolving inflammation by varying the molecular weight of HA is a debated concept. HA-based drug delivery nanosystems such as nanohydrogels and nanoemulsions, targeting macrophages can be used to relieve pain and inflammation by loading antinociceptive drugs and enhancing the effect of anti-inflammatory drugs. This review will discuss the ongoing research on HA-based drug delivery nanosystems regarding their antinociceptive and anti-inflammatory effects.

From crosslinking strategies to biomedical applications of hyaluronic acid-based hydrogels: A review

Hyaluronic acid (HA) is not only a natural anionic polysaccharide with excellent biocompatibility, biodegradability, and moisturizing effect, but also an essential factor that can affect angiogenesis, inflammation, cell behavior, which has a wide range of applications in the biomedical field. Among them, HA-based hydrogels formed by various physical or chemical crosslinking strategies are particularly striking. They not only retain the physiological function of HA, but also have the skeleton function of hydrogel, which further expands the application of HA. However, HA-based natural hydrogels generally have problems such as insufficient mechanical strength and susceptibility to degradation by hyaluronidase, which limits their application to a certain extent. To solve such problems, researchers have prepared a variety of HA-based multifunctional hydrogels with remarkable properties in recent years by adopting various structural modification methods or novel crosslinking strategies, as well as introducing functionally reactive molecules or moieties, which have extended the application scope. This manuscript systematically introduced common crosslinking strategies of HA-based hydrogels and highlighted the development of novel HA-based hydrogels in anticancer drug delivery, cartilage repair, three-dimensional cell culture, skin dressing and other fields. We hope to provide some references for the subsequent development of HA-based hydrogels in the biomedical field.

Synergy of antioxidant and M2 polarization in polyphenol-modified konjac glucomannan dressing for remodeling wound healing microenvironment

Effective skin wound healing and tissue regeneration remain a challenge. Excessive/chronic inflammation inhibits wound healing, leading to scar formation. Herein, we report a wound dressing composed of KGM-GA based on the natural substances konjac glucomannan (KGM) and gallic acid (GA) that accelerates wound healing without any additional drugs. An in vitro study showed that KGM-GA could not only stimulate macrophage polarization to the anti-inflammatory M2 phenotype but also decrease reactive oxygen species (ROS) levels, indicating excellent anti-inflammatory properties. Moreover, in vivo studies of skin wounds demonstrated that the KGM-GA dressing significantly improved wound healing by accelerating wound closure, collagen deposition, and angiogenesis. In addition, it was observed that KGM-GA regulated M2 polarization, reducing the production of intracellular ROS in the wound microenvironment, which was consistent with the in vitro experiments. Therefore, this study designed a multifunctional biomaterial with biological activity, providing a novel dressing for wound healing.

Bimetal-organic framework/GOx-based hydrogel dressings with antibacterial and inflammatory modulation for wound healing

Antibiotic resistance of bacteria and persistent inflammation are critical challenges in treating bacteria infected wounds. Thus, it is urgent to develop versatile wound dressings that possess high-efficiency antibacterial performance and inflammation regulation. Herein, we have successfully constructed a hydrogel wound dressing consisting of the bimetallic metal-organic framework (MOF) loaded with glucose oxidase (GOx), termed as MOF(Fe-Cu)/GOx-polyacrylamide (PAM) gel. Hydrogel dressings can provide an efficient cascade-catalyzed system to accelerate wound healing via synergistic antibacterial and inflammatory modulation. Importantly, the catalytic property of the bimetallic MOF(Fe-Cu) is about five times that of the monometallic MOF(Fe). Based on such a cascade-catalyzed system, the abundant gluconic acid and H₂O₂ can be continuously produced by decomposing glucose via GOx. Such gluconic acid can notably improve the peroxidase performance of MOF(Fe-Cu), which can further efficiently decompose H₂O₂ to achieve the antibacterial. Meanwhile, MOF (Fe Cu)/GOx PAM gel can induce macrophages to change into an M2 phenotype, which can accelerate the transformation of the wound microenvironment to a remodeling state and then accelerate angiogenesis and neurogenesis. This work provides multifunctional bioactive materials for accelerating wound healing and will have great potential in clinical applications. STATEMENT OF SIGNIFICANCE: Antibiotic resistance and persistent inflammation are still the critical reasons for the slow healing of bacteria infected wounds. Herein, we prepared a hydrogel wound dressing composed of bimetallic metal organic framework (MOF) loaded with glucose oxidase (GOx). The catalytic activity of the bimetallic MOF(Fe-Cu) is significantly enhanced due to doping of copper, which makes it possess outstanding antibacterial ability based on cascade catalysis. Such dressing can promote the remodeling of inflammatory immunity by regulating macrophage polarization to suppress over-reactive inflammation, further accelerating the healing of bacteria-infected wounds. This study provides an innovative and effective way to accelerate the healing of bacteria infected wound by combining bacteria killing and inflammation modulation.

A Sustainable Solution to Skin Diseases: Ecofriendly Transdermal Patches

Skin is the largest epithelial surface of the human body, with a surface area of 2 m2 for the average adult human. Being an external organ, it is susceptible to more than 3000 potential skin diseases, including injury, inflammation, microbial and viral infections, and skin cancer. Due to its nature, it offers a large accessible site for administrating several medications against these diseases. The dermal and transdermal delivery of such medications are often ensured by utilizing dermal/transdermal patches or microneedles made of biocompatible and biodegradable materials. These tools provide controlled delivery of drugs to the site of action in a rapid and therapeutically effective manner with enhanced diffusivity and minimal side effects. Regrettably, they are usually fabricated using synthetic materials with possible harmful environmental effects. Manufacturing such tools using green synthesis routes and raw materials is hence essential for both ecological and economic sustainability. In this review, natural materials including chitosan/chitin, alginate, keratin, gelatin, cellulose, hyaluronic acid, pectin, and collagen utilized in designing ecofriendly patches will be explored. Their implementation in wound healing, skin cancer, inflammations, and infections will be discussed, and the significance of these studies will be evaluated with future perspectives.

Gold@Halloysite nanotubes-chitin composite hydrogel with antibacterial and hemostatic activity for wound healing

Infection and healing of wounds after injury has always been an unavoidable problem in daily life, so design of a biomaterial with antibacterial and good wound healing properties is highly needed. Herein, a wound healing hydrogel dressing with halloysite clay and chitin as the main components was prepared, which combines the advantages of the biomacromolecule and clay. Halloysite nanotubes (HNTs) are extremely biocompatible clay materials with a hollow tubular structure, and the inner and outer surfaces of HNTs are composed of SiOx and AlOx layers with different charges. Au nanoparticles with diameter in 5–10 nm were filled into the HNTs' lumen to endow photothermal effect of the clay materials. Au@HNTs was then mixed with chitin solution to prepare flexible composite hydrogel by crosslinking by epichlorohydrin. The antibacterial properties, biocompatibility and hemostatic properties of the hydrogel material were investigated by antibacterial experiments, cell experiments, mouse liver and tail hemostatic experiments. After infecting the back wound of mice with Staphylococcus aureus, the hydrogel was applied to the wound to further verify the killing effect on bacteria and wound healing effect of the hydrogel material in vivo. The Au@HNTs-chitin composite hydrogel exhibits high antibacterial and hemostatic activity as well as promoting wound healing function with low cytotoxicity. This study is significant for the development of high-performance wound dressings based on two commonly used biocompatible materials, which shows promising application in wound sterilization and healing.

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Au particles with diameter of 5–10 nm are filled into the lumen of halloysite.

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Au@HNTs enhanced the mechanical and anti-bacterial properties of chitin.

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Au@HNTs-chitin hydrogels exhibit photothermal effect with good compatibility.

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Hydrogel dressing shows hemostasis and promoting wound healing performance.