Construction of multifunctional hydrogel with metal-polyphenol capsules for infected full-thickness skin wound healing

Near-infrared light-triggered silk fibroin hydrogels integrated with polydopamine-modified nanoparticles for enhanced wound healing and infection control

This study presents the development and evaluation of a novel silk fibroin (SF)-based hydrogel composite, SiPDA/Ag-C, enhanced with polydopamine (PDA)-modified silver nanoparticles (Ag@PDA) and PDA-modified curcumin (Cur-PDA), for skin wounds treatment and infection control. Dopamine readily oxidizes and reacts with SF to form hydrogels. By in-situ synthesizing silver nanoparticles (Ag NPs) on the surface of PDA nanospheres, Ag@PDA achieves a dual antibacterial effect. It combines the photothermal antibacterial property of PDA with the ability of Ag NPs to disrupt bacterial membranes and DNA. Coating PDA on the surface of curcumin creates Cur-PDA nanoparticles, which not only enhance curcumin's bioavailability but also integrate curcumin's anti-inflammatory and antioxidant properties with PDA's antioxidant and photothermal antibacterial capabilities. Combining Ag@PDA and Cur-PDA into the SF hydrogel matrix results in the SiPDA/Ag-C hydrogel. The hydrogel leverages the photothermal properties of PDA to achieve non-invasive wound healing under near-infrared (NIR) light irradiation. The SiPDA/Ag-C hydrogel could significantly inhibit the growth of Staphylococcus aureus and Escherichia coli in vitro and in vivo, and promote wound healing by reducing inflammation, enhancing antioxidant capacity, and stimulating tissue regeneration. In vivo study shows that compare with the treatment of SiPDA/Ag-C hydrogel alone, the combined treatment with NIR irradiation could significantly inhibit bacterial growth and improve tissue repair. The hydrogel also exhibited excellent biocompatibility, biodegradability, and minimal cytotoxic effects, making it a promising candidate for advanced wound care and tissue engineering applications.

Photo-generating Type-I ROS and aryl radicals by mitochondrial-targeting oxime-ester photogenerator for pyroptosis-mediated anti-hypoxia photoimmunotherapy

Pyroptosis is an inflammatory form of programmed cell death with great potential in cancer immunotherapies. Photodynamic therapy (PDT) represents a promising treatment modality to trigger pyroptosis. However, the hypoxic microenvironment inside the tumors often induces limited therapeutic efficacy. Herein, in this work, the first type of mitochondrial-targeting oxime-ester photogenerator (T-Oximer) was constructed to boost type-I ROS/aryl free radicals which could induce DNA damage by DNA cleaving and facilitate high-efficiency pyroptosis-mediated photoimmunotherapy. Detailed mechanism investigations revealed that T-Oximer could produce aryl free radicals via photolysis reaction and generate type-I ROS (O2 •- and •OH) based on the type-I electron transfer process. Meanwhile, T-Oximer could accumulate in the mitochondria, boost mitochondrial radicals, and damage mitochondria in hypoxic tumor cells. Of peculiar interest, T-Oixmer could bind with DNA and cleave DNA to induce DNA damage. Combined mitochondrial damage with DNA cleavage, T-Oximer can initiate pyroptosis, activate the ICD effect, and trigger robust systemic antitumor immunity for efficient tumor regression and metastasis suppression. Our finding provides a new strategy for constructing oxygen-independent photogenerator for high-efficiency pyroptosis-mediated anti-hypoxia photoimmunotherapy.

Cu-Intercalated MoS2 Nanosheets with Enhanced Antibacterial Activity for Treatment of Bacterial Keratitis

Bacterial keratitis (BK) is a critical and sight-threatening corneal infection that significantly impairs the quality of life. Due to the widespread antibiotic-resistant microbes and the slow development in antibiotics, there is an increasingly growing demand to create new antimicrobial agents for the treatment of BK. Herein, copper-intercalated molybdenum disulfide (Cu-MoS2) nanosheets are constructed by intercalating Cu into the interlayer structure of MoS2 via intercalation chemistry, which not only introduces the Fenton reaction but also modulates the electronic structure of MoS2. Cu-MoS2 can convert H2O2 into more toxic reactive oxygen species (ROS), thereby exhibiting excellent bactericidal performance against Staphylococcus aureus (S. aureus), methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) at room temperature in the dark. Animal experiments indicated that Cu-MoS2 can effectively treat BK caused by MRSA. This work demonstrates that intercalation chemistry as a novel and effective strategy to tune MoS2 as the antibacterial agent with no reliance on light that has great potential therapeutic effects on clinical drug-resistant BK.

Silk fibroin methacryloyl hydrogel loaded with silver-gallic acid nanoparticles for enhanced diabetic wound healing

Diabetic wound healing is hindered by oxidative stress, impaired angiogenesis, and inflammation. To address these issues, we developed a novel silver-gallic acid nanoparticle and incorporated it into a methacryloyl silk fibroin hydrogel (Ag@GA/Gel) based on the concept of polyphenol-metal nanoparticle networks for diabetic wound healing. In vitro experiments demonstrated that this hydrogel could promote macrophage polarization toward the M2 phenotype, scavenge reactive oxygen species, and exhibit pro-angiogenic and antibacterial properties. In vivo experiments showed that Ag@GA/Gel enhanced wound healing in diabetic mice, evidenced by a reduction in pro-inflammatory cytokine (IL-6) expression at the wound site. Additionally, levels of the anti-inflammatory factor (TGF-β), the M2 macrophage marker (CD206), and angiogenesis markers (VEGF, CD31) were elevated. The experimental results indicate that Ag@GA/Gel is a promising therapeutic approach for diabetic wound healing.

Anisotropic structure of nanofiber hydrogel accelerates diabetic wound healing via triadic synergy of immune-angiogenic-neurogenic microenvironments

Wound healing in chronic diabetic patients remains challenging due to the multiple types of cellular dysfunction and the impairment of multidimensional microenvironments. The physical signals of structural anisotropy offer significant potential for orchestrating multicellular regulation through physical contact and cellular mechanosensing pathways, irrespective of cell type. In this study, we developed a highly oriented anisotropic nanofiber hydrogel designed to provide directional guidance for cellular extension and cytoskeletal organization, thereby achieving pronounced multicellular modulation, including shape-induced polarization of macrophages, morphogenetic maturation of Schwann cells, oriented extracellular matrix (ECM) deposition by fibroblasts, and enhanced vascularization by endothelial cells. Additionally, we incorporated a VEGF-mimicking peptide to further reinforce angiogenesis, a pivotal phase that interlocks with immune regulation, neurogenesis, and tissue regeneration, ultimately contributing to optimized inter-microenvironmental crosstalk. In vivo studies validated that the anisotropic bioactive nanofiber hydrogel effectively accelerated diabetic wound healing by harnessing the triadic synergy of the immune-angiogenic-neurogenic microenvironments. Our findings highlight the promising potential of combining physical and bioactive signals for the modulation of various cell types and the refinement of the multidimensional microenvironment, offering a novel strategy for diabetic wound healing.

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

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

Antimicrobial Phenolic Materials: From Assembly to Function

Infectious diseases pose considerable challenges to public health, particularly with the rise of multidrug-resistant pathogens that globally cause high mortality rates. These pathogens can persist on surfaces and spread in public and healthcare settings. Advances have been made in developing antimicrobial materials to reduce the transmission of pathogens, including materials composed of naturally sourced polyphenols and their derivatives, which exhibit antimicrobial potency, broad-spectrum activity, and a lower likelihood of promoting resistance. This review provides an overview of recent advances in the fabrication of antimicrobial phenolic biomaterials, where natural phenolic compounds act as active antimicrobial agents or encapsulate other antimicrobial agents (e.g., metal ions, antimicrobial peptides, natural biopolymers). Various forms of phenolic biomaterials synthesized through these two strategies, including antimicrobial particles, capsules, hydrogels, and coatings, are summarized, with a focus on their application in wound healing, bone repair and regeneration, oral health, and antimicrobial coatings for medical devices. The potential of these advanced phenolic biomaterials provides a promising therapeutic approach for combating antimicrobial-resistant infections and reducing microbial transmission.

A multiple-crosslinked injectable hydrogel for modulating tissue microenvironment and accelerating infected diabetic wound repair

Elevated oxidative stress and inflammation, bacterial infections, and vascular impairment undoubtedly impede the normal diabetic wound healing process, which has encouraged the development of high-performance dressings for wound management. Herein, a new type of multiple-crosslinked injectable hydrogel, GCP, was developed via the radical polymerization of propenyl groups and the formation of copper‒polyphenol coordination bonds and Schiff base bonds. The copper‒polyphenol coordination and Schiff base bonds in the GCP hydrogel were disrupted in the acidic microenvironment of diabetic wound, resulting in the release of copper ions and protocatechualdehyde (PA) to scavenge reactive oxygen species (ROS), promote angiogenesis and cell migration, and exert antibacterial and anti-inflammatory activities via the CuPA complexes. Consequently, markedly accelerated infected diabetic wounds healing was achieved through this tissue microenvironment remodeling strategy. Moreover, the underlying mechanism of the antibacterial properties was investigated by 16S rRNA sequencing. The results indicated that the CuPA complexes can clearly inhibit the growth and reproduction of S. aureus by downregulating specific genes associated with ABC transporters, hindering bacterial protein synthesis, and enhancing oxidoreductase activity. This innovative hydrogel platform for wound management may inspire new methods for the preparation of high-performance biomedical materials and the treatment of other clinical diseases.

An antibacterial, antioxidant and hemostatic hydrogel accelerates infectious wound healing

Hydrogel drug-delivery system that can effectively load antibacterial drugs, realize the in-situ drug release in the microenvironment of wound infection to promote wound healing. In this study, a multifunctional hydrogel drug delivery system (HA@TA-Okra) was constructed through the integration of hyaluronic acid methacrylate (HAMA) matrix with tannic acid (TA) and okra extract. The composition and structural characteristics of HA@TA-Okra system and its unique advantages in the treatment of diverse wounds were systematically evaluated. TA, due to its unique chemical structure, is able to anchor within the HAMA network through interactions and cross-linking, conferring exceptional mechanical strength and stability to the hydrogel. Both TA and okra extract possess antioxidant and antibacterial properties, and when they two acts synergistically they can effectively scavenge free radicals, enhance antibacterial action, diminishing the risk of wound infection. In vitro experiments revealed that HA@TA-Okra system has superior properties, such as rapid gel response, remarkable swelling regulation, and potent antioxidant ability. Furthermore, the HA@TA-Okra system significantly outperformed conventional dressings in terms of hemostatic performance in a rat hemorrhage model. We further evaluated the repair role of HA@TA-Okra system in vivo by establishing an animal model of full-thickness skin defects and a model of infected total skin defects. The results confirmed its positive effects in fighting bacterial infection, reducing inflammation and promoting wound healing. In summary, the HA@TA-Okra system exhibits comprehensive properties such as antibacterial, antioxidant and hemostatic properties, which has a potential application in the field of tissue repair medicine.

Magnetic Nanoactuator-Protein Fiber Coated Hydrogel Dressing for Well-Balanced Skin Wound Healing and Tissue Regeneration

Despite significant progress in skin wound healing, it is still a challenge to construct multifunctional bioactive dressings based on a highly aligned protein fiber coated hydrogel matrix for antifibrosis skin wound regeneration that is indistinguishable to native skin. In this study, a "dual-wheel-driven" strategy is adopted to modify the surface of methacrylated gelatin (GelMA) hydrogel with highly aligned magnetic nanocomposites-protein fiber assemblies (MPF) consisting of photothermal responsive antibacteria superparamagnetic nanocomposites-fibrinogen (Fg) complexes as the building blocks. Whole-phase healing properties of the modified hydrogel dressing, GelMA-MPF (GMPF), stem from the integration of Fg protein with RGD peptide activity decorated on the surface of the antibacterial magnetic nanoactuator, facilitating facile and reproducible dressing preparation by self-assembly and involving biochemical, morphological, and biophysical cues. Payload and substantial release of copper ions for in situ catalytic production of nitric oxide (NO) from the fiber inorganic skeleton adsorbed by Fg molecules collectively regulate the proliferation, migration, reorganization, and transdifferentiation behavior of fibroblasts and fulfill antifibrosis in the process of skin wound healing and subcutaneous appendage regeneration. In full-thickness skin lesion mouse models, the complete regeneration of skin tissue with regenerated hair follicle cells and capillary blood vessels is realized in a temporally and spatially ordered manner.

An Immunomodulatory Hydrogel Featuring Antibacterial and Reactive Oxygen Species Scavenging Properties for Treating Periodontitis in Diabetes

Periodontal disease is a multifactorial, bacterially induced inflammatory disorder characterized by progressive destruction of periodontal tissues. Additionally, diabetes mellitus exacerbates periodontitis, resulting in expedited resorption of periodontal bone. However, methods such as mechanical debridement, anti-inflammatory medications, and surgical approaches often fail to eradicate local infections and inflammation, complicating the reconstruction of periodontal tissue structures. Consequently, there is an urgent need to devise a novel strategy for managing diabetic periodontal conditions. Here, a multifunctional controlled-release drug delivery system (GOE1) is developed by encapsulating self-assembled nanoparticles (consisting of chlorhexidine acetate and epigallocatechin-3-gallate) into a hydrogel matrix composed of gelatin methacryloyl and oxidized hyaluronic acid. In vitro experiments demonstrate that the GOE1 hydrogel possesses good antimicrobial, antioxidant and anti-inflammatory properties, and transgenic sequence genomics further illustrates that IL-17-producing RAW 264.7 macrophages are critical for mediating M1/M2 macrophage transition and provide favorable immune microenvironment. In addition, in vivo experiments reveal that GOE1 significantly ameliorates periodontal tissue inflammation and reduces the loss of alveolar bone by reducing inflammatory infiltration and collagen destruction. Overall, the GOE1 hydrogel offers a promising therapeutic option for managing diabetic periodontitis.

Hypericum Perforatum Callus Extract-Loaded Composite Hydrogel with Diverse Bioactivities for Enhanced Wound Healing and Fibrosis Prevention

Plant Callus are a valuable source of pluripotent stem cells and bioactive phytochemicals. Meanwhile, the Hypericum perforatum callus extract (HPCE) is particularly rich in compounds such as hyperforin, hypericin, quercetin, and other phenolic and flavonoid derivatives. These phytochemicals exhibit strong antibacterial, antioxidant, anti-inflammatory, and anti-fibrotic properties, making them promising for wound healing. One of the most critical challenges following wound healing is the formation of fibrosis, which can compromise the complex structural integrity of skin. To address this issue, a poly(vinyl alcohol)/chitosan/alginate (PCA) wound dressing loaded with HPCE is developed. This hydrogel dressing features a porous structure with suitable mechanical properties and a high swelling capacity, potentially enhancing its effectiveness in promoting tissue regeneration and wound healing. In vitro studies have confirmed its biocompatibility, cell proliferation, and cell adhesion properties. Additionally, the dressing has demonstrated the ability to inhibit the proliferation of certain antibiotic-resistant bacteria. The in vivo studies revealed the anti-inflammatory properties, promotion of angiogenesis, facilitation of re-epithelialization, and stimulation of collagen deposition of the dressing under investigation. Moreover, the immunohistochemistry analysis of the two key markers, p16 and p53, has shown that the application of the dressing helps prevent fibrosis after wound healing.

An advanced chitosan based sponges dressing system with antioxidative, immunoregulation, angiogenesis and neurogenesis for promoting diabetic wound healing

Promoting wound nerve regeneration and synchronously initiating angiogenesis are critical factors in the healing process of diabetic wounds. However, existing research on diabetic wounds mainly focuses on angiogenesis, bacterial infection and reactive oxygen species, often failing to coordinate neurogenesis and angiogenesis. To coordinate the symbiosis of nerves and blood vessels in the diabetic wounds, we successfully designed a multifunctional chitosan (CS)-based sponges by regulating the structure of CS specifically for diabetic wound healing. This sponge, which facilitates effective exudate transfer and modulates the wound microenvironment, was constructed using hydroxybutyl CS grafted with thioctic acid (TA), named as HCT sponge. When applied in a humid environment, the hydrophobic side chains of the HCT sponge interact with self-assembled hydrophobic domains, forming gel-sponge composite. Experimental results showed that the adhesion strength of the HCT sponge to wet porcine skin was 70.3 kPa. Additionally, the sponge exhibited favorable degradability, cytocompatibility and antioxidant properties. As it is shown in the experiments in vitro, sponge can not only promote cell proliferation, migration, and blood vessel formation, but also promote M2 macrophage polarization. Moreover, the rat liver and femoral artery injury model validated that the HCT sponge can effectively treat heavy bleeding from wounds efficacy through quickly sealing wounds and the formation of multiple hemostatic dams. In vivo studies indicated that the HCT sponge significantly accelerated the diabetic wound healing process compared to the recombinant bovine basic fibroblast growth factor gel, achieving a better recovery from the HCT sponge after 15 days. Pathological results show that the designed novel sponge holds considerable promise for treating diabetic wound, allowing regenerative neurogenesis and angiogenesis at the wound site, which provides a significant potential for further improving clinical applications.

Photo-crosslinking injectable Photothermal antibacterial hydrogel based on quaternary ammonium grafted chitosan and hyaluronic acid for infected wound healing

Antibacterial hydrogels not only provide a better environment for skin wounds to avoid infection but also accelerate wound healing. Herein, chitosan modified by a quaternary ammonium salt (CQ), and hyaluronic acid grafted with methacrylate (HM) were designed and synthesized to prepare an injectable photo-crosslinking hydrogel for wound dressing with inherent antibacterial and photothermal properties. CQ and HM exhibited excellent biocompatibility, improved water retention, and antibacterial activity, illustrating vast potential as an antibacterial material in various applications. MXene, a type of 2D nanomaterial, has been widely researched due to its photothermal properties. The CQ and HM polymer precursor could be mixed with Mxene and then crosslinked with 395 nm UV radiation under mild conditions to form a 3D network structure CQ-HM/MXene hydrogel. This hydrogel displayed an appropriate swelling ratio, elastic modulus, photothermal property and excellent biocompatibility. The injectable property of the hydrogel allowed it to easily cover the wound. In vitro and in vivo studies showed that the injectable hydrogel had low cytotoxicity and excellent antibacterial properties, which could help promote wound healing. In summary, this novel CQ-HA/MXene hydrogel has the potential for application in skin wound healing due to inherent antibacterial activity and photothermal effect.

Plant-inspired visible-light-driven bioenergetic hydrogels for chronic wound healing

Chronic bioenergetic imbalances and inflammation caused by hyperglycemia are obstacles that delay diabetic wound healing. However, it is difficult to directly deliver energy and metabolites to regulate intracellular energy metabolism using biomaterials. Herein, we propose a light-driven bioenergetic and oxygen-releasing hydrogel (PTKM@HG) that integrates the thylakoid membrane-encapsulated polyphenol nanoparticles (PTKM NPs) to regulate the energy metabolism and inflammatory response in diabetic wounds. Upon red light irradiation, the PTKM NPs exhibited oxygen generation and H2O2 deletion capacity through a photosynthetic effect to restore hypoxia-induced mitochondrial dysfunction. Meanwhile, the PTKM NPs could produce exogenous ATP and NADPH to enhance mitochondrial function and facilitate cellular anabolism by regulating the leucine-activated mTOR signaling pathway. Furthermore, the PTKM NPs inherited antioxidative and anti-inflammatory ability from polyphenol. Finally, the red light irradiated PTKM@HG hydrogel augmented the survival and migration of cells keratinocytes, and then accelerated angiogenesis and re-epithelialization of diabetic wounds. In short, this study provides possibilities for effectively treating diseases by delivering key metabolites and energy based on such a light-driven bioenergetic hydrogel.

An advanced hydrogel dressing system with progressive delivery and layer-to-layer response for diabetic wound healing

Wound healing in diabetic patients presents a significant challenge due to delayed inflammatory responses, which obstruct subsequent healing stages. In response, we have developed a progressive, layer-by-layer responsive hydrogel, specifically designed to meet the dynamic requirements of diabetic wounds throughout different healing phases. This hydrogel initiates with a glucose-responsive layer formed by boronate ester bonds between 4-arm-poly (ethylene glycol) succinimidyl glutarate (4arm-PEG-SG) and 3-aminophenylboronic acid. This configuration ensures precise control over the physicochemical properties, facilitating accurate drug release during the healing process. Furthermore, we have incorporated an active pharmaceutical ingredient ionic liquid (API) composed of diclofenac and L-carnitine. This combination effectively tackles the solubility and stability issues commonly associated with anti-inflammatory drugs. To further refine drug release, we integrated matrix metalloproteinase-9 (MMP-9)-sensitive gelatin microcapsules, ensuring a controlled release and preventing the abrupt, uneven drug distribution often seen in other systems. Our hydrogel's rheological properties closely resemble human skin, offering a more harmonious approach to diabetic wound healing. Overall, this progressive layer-by-layer responsive wound management system, which is a safe, efficient, and intelligent approach, holds significant potential for the clinical treatment of diabetic wounds. STATEMENT OF SIGNIFICANCE: The two main problems of diabetic wounds are the long-term infiltration of inflammation and the delayed repair process. In this experiment, a glucose-responsive hierarchical drug delivery system was designed to intelligently adjust gel properties to meet the needs of inflammation and repair stage of wound healing, accelerate the transformation of inflammation and repair stage, and accelerate the process of repair stage. In addition, in order to achieve accurate drug release in anti-inflammatory layer hydrogels and avoid sudden drug release due to poor solubility of anti-inflammatory small molecule drugs, we constructed a ionic liquid of active pharmaceutical ingredients (API-ILs) using diclofenac and L-carnitine as raw materials. It was wrapped in MMP-9 enzyme active gelatin microcapsule to construct a double-reaction anti-inflammatory layer gel to achieve accurate drug release. These findings highlight the potential of our system in treating diabetic wounds, providing a significant advance in wound treatment.

Copper hydrogen phosphate nanosheets functionalized hydrogel with tissue adhesive, antibacterial, and angiogenic capabilities for tracheal mucosal regeneration

Timely and effective interventions after tracheal mucosal injury are lack in clinical practices, which elevate the risks of airway infection, tracheal cartilage deterioration, and even asphyxiated death. Herein, we proposed a biomaterial-based strategy for the repair of injured tracheal mucosal based on a copper hydrogen phosphate nanosheets (CuHP NSs) functionalized commercial hydrogel (polyethylene glycol disuccinimidyl succinate-human serum albumin, PH). Such CuHP/PH hydrogel achieved favorable injectability, stable gelation, and excellent adhesiveness within the tracheal lumen. Moreover, CuHP NSs within the CuHP/PH hydrogel effectively stimulate the proliferation and migration of endothelial/epithelial cells, enhancing angiogenesis and demonstrating excellent tissue regenerative potential. Additionally, it exhibited significant inhibitory effects on both bacteria and bacterial biofilms. More importantly, when injected injured site of tracheal mucosa under fiberoptic bronchoscopy guidance, our results demonstrated CuHP/PH hydrogel adhered tightly to the tracheal mucosa. The therapeutic effects of the CuHP/PH hydrogel were further confirmed, which significantly improved survival rates, vascular and mucosal regeneration, reduced occurrences of intraluminal infections, tracheal stenosis, and cartilage damage complications. This research presents an initial proposition outlining a strategy employing biomaterials to mitigate tracheal mucosal injury, offering novel perspectives on the treatment of mucosal injuries and other tracheal diseases.

Seeking Cells, Targeting Bacteria: A Cascade-Targeting Bacteria-Responsive Nanosystem for Combating Intracellular Bacterial Infections

Intracellular bacteria pose a great challenge to antimicrobial therapy due to various physiological barriers at both cellular and bacterial levels, which impede drug penetration and intracellular targeting, thereby fostering antibiotic resistance and yielding suboptimal treatment outcomes. Herein, a cascade-target bacterial-responsive drug delivery nanosystem, MM@SPE NPs, comprising a macrophage membrane (MM) shell and a core of SPE NPs. SPE NPs consist of phenylboronic acid-grafted dendritic mesoporous silica nanoparticles (SP NPs) encapsulated with epigallocatechin-3-gallate (EGCG), a non-antibiotic antibacterial component, via pH-sensitive boronic ester bonds are introduced. Upon administration, MM@SPE NPs actively home in on infected macrophages due to the homologous targeting properties of the MM shell, which is subsequently disrupted during cellular endocytosis. Within the cellular environment, SPE NPs expose and spontaneously accumulate around intracellular bacteria through their bacteria-targeting phenylboronic acid groups. The acidic bacterial microenvironment further triggers the breakage of boronic ester bonds between SP NPs and EGCG, allowing the bacterial-responsive release of EGCG for localized intracellular antibacterial effects. The efficacy of MM@SPE NPs in precisely eliminating intracellular bacteria is validated in two rat models of intracellular bacterial infections. This cascade-targeting responsive system offers new solutions for treating intracellular bacterial infections while minimizing the risk of drug resistance.

Immunomodulatory Antibacterial Hydrogel for Wound Infection Management

Background

Wound healing has always been a focal point in clinical work. Bacterial infections and immune microenvironment disorders can both hinder normal wound healing. Current wound dressings only serve a covering function. Developing wound dressings with antibacterial and immunomodulatory functions is crucial for aiding wound healing. To address this issue, we have developed a hydrogel with antibacterial and immunomodulatory functions for managing infected wounds.

Methods

The present study describes a photo-crosslinked antibacterial hydrogel composed of curcumin, silver nanoparticles-loaded reduced graphene oxide, and silk fibroin methacryloyl for the treatment of infected wounds. The study assessed its antibacterial properties and its capacity to induce macrophage M2 polarization through in vitro and in vivo experiments.

Results

The hydrogel demonstrates robust antibacterial properties and enhances macrophage M2 polarization in both in vitro and in vivo settings. Moreover, it accelerates the healing of infected wounds in vivo by stimulating collagen deposition and angiogenesis.

Conclusion

Overall, this hydrogel shows great potential in managing wound infections.

An Immune-Regulating Polysaccharide Hybrid Hydrogel with Mild Photothermal Effect and Anti-Inflammatory for Accelerating Infected Wound Healing

Bacterial infections and excessive inflammation present substantial challenges for clinical wound healing. Hydrogels with mild photothermal (PTT) effects have emerged as promising agents owing to their dual actions: positive effects on cells and negative effects on bacteria. Here, an injectable self-healing hydrogel of oxidized konjac glucomannan/arginine-modified chitosan (OKGM/CS-Arg, OC) integrated with protocatechualdehyde-@Fe (PF) nanoparticles capable of effectively absorbing near-infrared radiation is synthesized successfully. The OC/PF hydrogels exhibit excellent mechanical properties, biocompatibility, and antioxidant activity. Moreover, in synergy with PTT, OC/PF demonstrates potent antibacterial effects while concurrently stimulating cell migration and new blood vessel formation. In methicillin-resistant Staphylococcus aureus-infected full-thickness mouse wounds, the OC/PF hydrogel displays remarkable antibacterial and anti-inflammatory activities, and accelerates wound healing by regulating the wound immune microenvironment and promoting M2 macrophage polarization. Consequently, the OC/PF hydrogel represents a novel therapeutic approach for treating multidrug-resistant bacterial infections and offers a technologically advanced solution for managing infectious wounds in clinical settings.

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.

Tetrahedral framework nucleic acids/hyaluronic acid-methacrylic anhydride hybrid hydrogel with antimicrobial and anti-inflammatory properties for infected wound healing

Bacterial resistance and excessive inflammation are common issues that hinder wound healing. Antimicrobial peptides (AMPs) offer a promising and versatile antibacterial option compared to traditional antibiotics, with additional anti-inflammatory properties. However, the applications of AMPs are limited by their antimicrobial effects and stability against bacterial degradation. TFNAs are regarded as a promising drug delivery platform that could enhance the antibacterial properties and stability of nanodrugs. Therefore, in this study, a composite hydrogel (HAMA/t-GL13K) was prepared via the photocross-linking method, in which tFNAs carry GL13K. The hydrogel was injectable, biocompatible, and could be instantly photocured. It exhibited broad-spectrum antibacterial and anti-inflammatory properties by inhibiting the expression of inflammatory factors and scavenging ROS. Thereby, the hydrogel inhibited bacterial infection, shortened the wound healing time of skin defects in infected skin full-thickness defect wound models and reduced scarring. The constructed HAMA/tFNA-AMPs hydrogels exhibit the potential for clinical use in treating microbial infections and promoting wound healing.

Antibacterial, Fatigue-Resistant, and Self-Healing Dressing from Natural-Based Composite Hydrogels for Infected Wound Healing

The treatment of infected wounds faces substantial challenges due to the high incidence and serious infection-related complications. Natural-based hydrogel dressings with favorable antibacterial properties and strong applicability are urgently needed. Herein, we developed a composite hydrogel by constructing multiple networks and loading ciprofloxacin for infected wound healing. The hydrogel was synthesized via a Schiff base reaction between carboxymethyl chitosan and oxidized sodium alginate, followed by the polymerization of the acrylamide monomer. The resultant hydrogel dressing possessed a good self-healing ability, considerable compression strength, and reliable compression fatigue resistance. In vitro assessment showed that the composite hydrogel effectively eliminated bacteria and exhibited an excellent biocompatibility. In a model of Staphylococcus aureus-infected full-thickness wounds, wound healing was significantly accelerated without scars through the composite hydrogel by reducing wound inflammation. Overall, this study opens up a new way for developing multifunctional hydrogel wound dressings to treat wound infections.

Antibacterial Micelles-Loaded Carboxymethyl Chitosan/Oxidized Konjac Glucomannan Composite Hydrogels for Enhanced Wound Repairing

Antibacterial hydrogels have emerged as a promising approach for effective wound treatment. However, despite extensive research on the fabrication of antibacterial hydrogels, it remains challenging to develop injectable, biocompatible, transparent, and mass-producible hydrogels with antibacterial properties. In this study, we successfully fabricated an antibacterial drug-loaded composite hydrogel, named CC45/OKG40/HS, through a Schiff base reaction between carboxymethyl chitosan (CC) and oxidized konjac glucomannan (OKG), followed by the encapsulation of stevioside-stabilized honokiol (HS) micelles. The CC45/OKG40/HS hydrogel exhibited several favorable properties, including a short gel time (<10 min), high water content (>92%), injectability, good adhesiveness, self-healing ability, and high transparency. In vitro experiments confirmed its excellent antibacterial properties, antioxidant activities, and high biocompatibility (no cytotoxicity, hemolysis ratio <5%). Furthermore, in vivo evaluation demonstrated that the CC45/OKG40/HS0.5 hydrogel accelerated wound healing by relieving inflammatory responses and enhancing re-epithelization. Given its feasibility for mass production, the findings showed that the CC45/OKG40/HS hydrogel has the potential as an advanced antibacterial wound dressing for commercial use.

Copper Nanodots-Based Hybrid Hydrogels with Multiple Enzyme Activities for Acute and Infected Wound Repair

Effectively controlling bacterial infection, reducing the inflammation and promoting vascular regeneration are all essential strategies for wound repair. Nanozyme technology has potential applications in the treatment of infections because its non-antibiotic dependent, topical and noninvasive nature. In wound management, copper-based nanozymes have emerged as viable alternatives to antibiotics. In this study, an ultrasmall cupric enzyme with high enzymatic activity is synthesized and added to a nontoxic, self-healing, injectable cationic guar gum (CG) hydrogel network. The nanozyme exhibits remarkable antioxidant properties under neutral conditions, effectively scavenging reactive nitrogen and oxygen species (RNOS). Under acidic conditions, Cu NDs have peroxide (POD) enzyme-like activity, which allows them to eliminate hydrogen peroxides and produce free radicals locally. Antibacterial experiments show that they can kill bacteria and remove biofilms. It reveals that low concentrations of Cu ND/CG decrease the expression of the inflammatory factors in cells and tissues, effectively controlling inflammatory responses. Cu ND/CG hydrogels also inhibit HIF-1α and promote VEGF expression in the wound with the ability to promote vascular regeneration. In vivo safety assessments reveal a favorable biosafety profile. Cu ND/CG hydrogels offer a promising solution for treating acute and infected wounds, highlighting the potential of innovative nanomaterials in wound healing.

A Multifunctional, Tough, Stretchable, and Transparent Curcumin Hydrogel with Potent Antimicrobial, Antioxidative, Anti-inflammatory, and Angiogenesis Capabilities for Diabetic Wound Healing

The treatment of diabetic chronic wounds is still faced with great challenges, mainly due to wound infection, excessive inflammation, and peripheral vascular disease in the wound area. Therefore, it is of great importance to develop a novel multifunctional hydrogel with high efficiency to accelerate diabetic wound healing. Curcumin (Cur), a Chinese herbal, has shown great potential in enhancing the healing of diabetic chronic wounds because of its immunomodulatory and pro-angiogenic properties. However, its low aqueous solubility, poor bioavailability, and chemical instability have limited its clinical applications. To address these current bottlenecks, novel poly(vinyl alcohol) (PVA)-chitosan (CS)/sodium alginate (SA)-Cur (PCSA) hydrogels were prepared for the first time, and they demonstrated all of the above intriguing performances by the Michael addition reaction of CS and Cur. PCSA hydrogels show multiple dynamic bonds, which possess strong mechanical properties (tensile stress: ∼0.980 MPa; toughness: ∼258.45 kJ/m3; and compressive strength: ∼7.38 MPa at strain of 80%). These intriguing performances provided an optimal microenvironment for cell migration and proliferation and also promoted the growth of blood vessels, leading to early angiogenesis. Importantly, the experimental results demonstrated that PCSA hydrogels can effectively transform pro-inflammatory M1 macrophages into anti-inflammatory M2 macrophages without the need for additional ingredients in vitro. Benefiting from these characteristics, a full-thickness diabetic wound in a rat model demonstrated that PCSA hydrogels can effectively accelerate wound healing via ROS-scavenging, downregulation of IL-1β, and upregulation of CD31 expression, resulting in angiogenesis and collagen deposition. This strategy not only provides a simple and safe Cur-based hydrogel for diabetic wound healing but also highlights the significant potential for the development of high-performance biomaterials for promoting diabetic wound healing using traditional Chinese medicine.

Injectable hydrogels doped with PDA nanoparticles for photothermal bacterial inhibition and rapid wound healing in vitro

The difficulty of wound healing due to skin defects has been a great challenge due to the complex inflammatory microenvironment. Delayed wound healing severely affects the quality of life of patients and represents a significant economic burden for public health systems worldwide. Therefore, there is an urgent need for the development of novel wound dressings that can efficiently resist drug-resistant bacteria and have superior wound repair capabilities in clinical applications. In this study, we designed an adhesive antimicrobial hydrogel dressing (GMH) based on methacrylic-anhydride-modified gelatin and oxidized hyaluronic acid formed by Schiff base and UV-induced double cross-linking for infected wound repair. By inserting PDA nanoparticles into the hydrogel (GMH/PDA), the hydrogel has the capability of photothermal conversion and exhibits good photothermal antimicrobial properties under near-infrared (NIR) light irradiation, which helps to reduce the inflammatory response and avoid bacterial infections during the wound healing process. In addition, GMH/PDA hydrogel exhibits excellent injectability, allowing the hydrogel dressings to be adapted to complex wound surfaces, making them promising candidates for wound therapy. In conclusion, the multifunctional injectable GMH/PDA hydrogel possesses high antimicrobial efficiency, antioxidant properties and good biocompatibility, making them promising candidates for the treatment of infected skin wounds.

Recent advances in photo-crosslinkable methacrylated silk (Sil-MA)-based scaffolds for regenerative medicine: A review

Silks fibroin can be chemically modified through amino acid side chains to obtain methacrylated silk (Sil-MA). Sil-MA could be processed into a variety of scaffold forms and combine synergistically with other biomaterials to form composites vehicle. The advent of Sil-MA material has enabled impressive progress in the development of various scaffolds based on Sil-MA type to imitate the structural and functional characteristics of natural tissues. This review highlights the reasonable design and bio-fabrication strategies of diverse Sil-MA-based tissue constructs for regenerative medicine. First, we elucidate modification methodology and characteristics of Sil-MA. Next, we describe characteristics of Sil-MA hydrogels, and focus on the design approaches and formation of different types of Sil-MA-based hydrogels. Thereafter, we present an overview of the recent advances in the application of Sil-MA based scaffolds for regenerative medicine, including detailed strategies for the engineering methods and materials used. Finally, we summarize the current research progress and future directions of Sil-MA in regenerative medicine. This review not only delineates the representative design strategies and their application in regenerative medicine, but also provides new direction in the fabrication of biomaterial constructs for the clinical translation in order to stimulate the future development of implants.

Bilayer wound dressing composed of asymmetric polycaprolactone membrane and chitosan-carrageenan hydrogel incorporating storax balsam

A comprehensive approach is needed to develop multifunctional wound dressing that is simple yet efficient. In this work, Liquidambar orientalis Mill. storax loaded hydroxyethyl chitosan (HECS)-carrageenan (kC) based hydrogel (HECS-kC) and polydopamine coated asymmetric polycaprolactone membrane (PCL-DOP) were used to develop a multifunctional and modular bilayer wound dressing. Asymmetric PCL-DOP membrane was prepared by non-solvent induced phase separation (NIPS) followed by polydopamine coating and demonstrated an excellent barrier against bacteria while allowing permeability for 5.45 ppm dissolved‑oxygen and 2130 g/m2 water vapor transmission in 24 h in addition to 805 kPa tensile strength. Storax loaded HECS-kC hydrogel, on the other hand, demonstrated a pH-responsive degradation and swelling to provide necessary conditions to facilitate wound healing. The hydrogels showed stretchability above 140 %, mild adhesive strength on sheep skin and PCL-DOP membrane, while the storax incorporation enhanced antibacterial and antioxidant activity. Furthermore, rat full-thickness skin defect model showed that the developed bilayer wound dressing could significantly facilitate wound healing compared to Tegaderm™ and control groups. This study shows that the bilayered wound dressing has the potential to be used as a simple and effective wound care system.

Metal-Phenolic Networks for Chronic Wounds Therapy

Chronic wounds are recalcitrant complications of a variety of diseases, with pathologic features including bacterial infection, persistent inflammation, and proliferation of reactive oxygen species (ROS) levels in the wound microenvironment. Currently, the use of antimicrobial drugs, debridement, hyperbaric oxygen therapy, and other methods in clinical for chronic wound treatment is prone to problems such as bacterial resistance, wound expansion, and even exacerbation. In recent years, researchers have proposed many novel materials for the treatment of chronic wounds targeting the disease characteristics, among which metal-phenolic networks (MPNs) are supramolecular network structures that utilize multivalent metal ions and natural polyphenols complexed through ligand bonds. They have a flexible and versatile combination of structural forms and a variety of formations (nanoparticles, coatings, hydrogels, etc.) that can be constructed. Functionally, MPNs combine the chemocatalytic and bactericidal properties of metal ions as well as the anti-inflammatory and antioxidant properties of polyphenol compounds. Together with the excellent properties of rapid synthesis and negligible cytotoxicity, MPNs have attracted researchers' great attention in biomedical fields such as anti-tumor, anti-bacterial, and anti-inflammatory. This paper will focus on the composition of MPNs, the mechanisms of MPNs for the treatment of chronic wounds, and the application of MPNs in novel chronic wound therapies.

Copper-Epigallocatechin Gallate Enhances Therapeutic Effects of 3D-Printed Dermal Scaffolds in Mitigating Diabetic Wound Scarring

Morbid dermal templates, microangiopathy, and abnormal inflammation are the three most critical reasons for the scarred healing and the high recurrence rate of diabetic wounds. In this present study, a combination of a methacrylated decellularized extracellular matrix (ECMMA, aka EM)-based hydrogel system loaded with copper-epigallocatechin gallate (Cu-EGCG) capsules is proposed to fabricate bio-printed dermal scaffolds for diabetic wound treatment. Copper ions act as a bioactive element for promoting angiogenesis, and EGCG can inhibit inflammation on the wound site. In addition to the above activities, EM/Cu-EGCG (E/C) dermal scaffolds can also provide optimized templates and nutrient exchange space for guiding the orderly deposition and remodeling of ECM. In vitro experiments have shown that the E/C hydrogel can promote angiogenesis and inhibit the polarization of macrophages to the M1 pro-inflammatory phenotype. In the full-thickness skin defect model of diabetic rats, the E/C dermal scaffold combined with split-thickness skin graft transplantation can alleviate pathological scarring via promoting angiogenesis and driving macrophage polarization to the anti-inflammatory M2 phenotype. These may be attributed to the scaffold-actuated expression of angiogenesis-related genes in the HIF-1α/vascular endothelial growth factor pathway and decreased expression of inflammation-related genes in the TNF-α/NF-κB/MMP9 pathway. The results of this study show that the E/C dermal scaffold could serve as a promising artificial dermal analogue for solving the problems of delayed wound healing and reulceration of diabetic wounds.

PGS/Gelatin Nanocomposite Electrospun Wound Dressing

Infectious diabetic wounds can result in severe injuries or even death. Biocompatible wound dressings offer one of the best ways to treat these wounds, but creating a dressing with a suitable hydrophilicity and biodegradation rate can be challenging. To address this issue, we used the electrospinning method to create a wound dressing composed of poly(glycerol sebacate) (PGS) and gelatin (Gel). We dissolved the PGS and Gel in acetic acid (75 v/v%) and added EDC/NHS solution as a crosslinking agent. Our measurements revealed that the scaffolds' fiber diameter ranged from 180.2 to 370.6 nm, and all the scaffolds had porosity percentages above 70%, making them suitable for wound healing applications. Additionally, we observed a significant decrease (p < 0.05) in the contact angle from 110.8° ± 4.3° for PGS to 54.9° ± 2.1° for PGS/Gel scaffolds, indicating an improvement in hydrophilicity of the blend scaffold. Furthermore, our cell viability evaluations demonstrated a significant increase (p < 0.05) in cultured cell growth and proliferation on the scaffolds during the culture time. Our findings suggest that the PGS/Gel scaffold has potential for wound healing applications.