One-Step Synthesis of Multifunctional Chitosan Hydrogel for Full-Thickness Wound Closure and Healing

Recent advances in smart hydrogels derived from polysaccharides and their applications for wound dressing and healing

Owing to their inherent biocompatibility and biodegradability, hydrogels derived from polysaccharides have emerged as promising candidates for wound management. However, the complex nature of wound healing often requires the development of smart hydrogels---intelligent materials capable of responding dynamically to specific physical or chemical stimuli. Over the past decade, an increasing number of stimuli-responsive polysaccharide-based hydrogels have been developed to treat various types of wounds. While a range of hydrogel types and their versatile functions for wound management have been discussed in the literature, there is still a need for a review of the crosslinking strategies used to create smart hydrogels from polysaccharides. This review provides a comprehensive overview of how stimuli-responsive hydrogels can be designed and made using five key polysaccharides: chitosan, hyaluronic acid, alginate, dextran, and cellulose. Various methods, such as chemical crosslinking, dynamic crosslinking, and physical crosslinking, which are used to form networks within these hydrogels, ultimately determine their ability to respond to stimuli, have been explored. This article further looks at different polysaccharide-based hydrogel wound dressings that can respond to factors such as reactive oxygen species, temperature, pH, glucose, light, and ultrasound in the wound environment and discusses how these responses can enhance wound healing. Finally, this review provides insights into how stimuli-responsive polysaccharide-based hydrogels can be developed further as advanced wound dressings in the future.

Five-In-One Hydrogel Integrating Bacteriostasis, Self-Healing Capability, Growth Factor Release, Electrical Stimulation, and Photothermal Stimulation Tailored for Complex Wound Repair

Complex wound management remains a significant global challenge, and the development of multifunctional wound dressings that can effectively promote wound healing remains an urgent clinical need. Herein, a kind of multifunctional hydrogel wound dressing that combines bacteriostasis, self-healing capability, growth factor release, electrical stimulation, and photothermal stimulation is developed. This kind of wound dressing is generated by adding protocatechualdehyde (protocatechuic aldehyde (PA)), short core-shell fibers loading with platelet-rich-plasma (platelet-rich plasma fibers), and polydopamine-coated carbon nanotubes (PDA@CNTs) into quaternary ammonium chitosan (QCS) solution to form a shear-reversibly cross-linked QCS/PA/PDA@CNTs-PRP hydrogel. The obtained hydrogels possess impressive properties, including high swelling capacity (445-852%), strong adhesion ability (16.4-36.7 kPa), self-healing ability, injectability, conductivity (0.24-0.46 S/m), and photothermal properties. Notably, under near-infrared irradiation, the hydrogel exhibits a highly efficient bactericidal activity. In vitro experiments demonstrated that the hydrogel exhibits excellent biocompatibility and anti-inflammatory capability as well as its ability to stimulate cell proliferation, migration, and tubule formation. Moreover, the in vivo studies further confirmed that with the additional assistance of near-infrared light and electrical stimulation, the hydrogel further promotes wound epithelization, angiogenesis, and collagen deposition. Consequently, this hydrogel provides a promising therapeutic strategy for complex wound healing.

Skin Barrier Restoration by Waste-Derived Multifunctional Adhesive Hydrogel Based on Tannin-Modified Chitosan

The development of multifunctional materials that actively enhance the wound healing process is critically important in addressing clinical and public healthcare challenges. Here, we report a multifunctional hydrogel obtained through physical cross-linking of chitosan and wood tannins for active wound management. Tannins, as polyphenolic wood-waste derivatives, act both as multifunctional additives and cross-linking agents, resulting in a stable and highly swellable hydrogel (>2000%·mg-1). The dressing is produced in the form of a dry and rigid film for easy transportation. After swelling, the material exhibits adequate Young's modulus (∼7 MPa, comparable to the stratum corneum's stiffness), improved flexibility, and suitable adhesion strength to adapt to joint movements. Polyphenolic tannins also provide the material with high antioxidant activity against DPPH radicals (100% RSA), showing potential for preventing complications during the inflammation phase. Moreover, tannins can completely block skin-damaging UV light without significantly altering the material's transparency, thus allowing constant visual wound monitoring. Wound healing investigations on abdominoplasty-derived skin demonstrated that tannins enhance the normal skin barrier restoration process, thereby facilitating the transition toward wound regeneration. This work offers a sustainable strategy for valorizing agri-food waste in a fully biobased material to address active wound management.

A preliminary study on the promotion of wound healing by paeoniflorin carbon dots loaded in chitosan hydrogel

Due to poor angiogenesis under the wound bed, wound treatment remains a clinical challenge. Therefore, there is an urgent need for new dressings to combat bacterial infections, accelerate angiogenesis, and accelerate wound healing. In this study, we prepared carbon dots nanomaterial (PF-CDs) derived from traditional Chinese medicine paeoniflorin using a simple green one pot hydrothermal method. The average particle size of the CSs we prepared was 4 nm, and a concentration of 200 μg ml-1was ultimately selected for experiments. Subsequently, PF-CDs were loaded into the chitosan hydrogel to form a new type of wound dressing CSMA@PF-CDs hydrogel. CSMA@PF-CDs demonstrated positive biocompatibility by promoting a 20% increase in cell proliferation and strong antibacterial activity. In comparison to the control group, CSMA@PF-CDs enhanced the expression level of anti-inflammatory factors by at least 2.5 times and reduces the expression level of pro-inflammatory factors by at least 3 times. Furthermore, CSMA@PF-CDs promoted the migration of Human umbilical vein endothelial cells and increased vascular endothelial growth factor expression by 5 times. The results ofin vivoexperiments indicate that CSMA@PF-CDs significantly promoted the healing of back wounds in rats. These characteristics make it a promising material for repairing infected wounds and a potential candidate for clinical skin regeneration applications.

Nano zero-valent iron driven sodium alginate/poly (acrylic acid) composite hydrogel powder for rapid hemostasis and wound healing

Uncontrollable bleeding resulting from warfare, traffic accidents, and various high-risk industries poses a serious issue. In this study, we develop a nano-zero-valent iron (nZVI)-driven sodium alginate (SA)/polyacrylic acid (PAA) composite hydrogel (SA/PAA/nZVI, SPI), which is subsequently fabricated into a powder to achieve rapid hemostasis and promote wound healing. The redox system comprising nZVI/ammonium persulfate (APS) efficiently generates significant quantities of free radicals and Fe3+ under both room and low temperatures (4 °C), thereby significantly accelerating hydrogel formation. The SPI hydrogel exhibits excellent mechanical properties and adhesion due to its interpenetrating network structure, enabling it to resist various degrees of bending and folding. Notably, the SPI hydrogel powder, obtained through drying and grinding processes, possesses self-gelling properties and can effectively adhere to wet tissues. This is attributed to the strong hygroscopic properties of the hydrogel and the abundant dynamic bonds within its structure. These powders can rapidly absorb significant volumes of blood, including blood cells and coagulation factors, and demonstrate superior hemostatic efficacy over commercial chitosan powders (CCS) in diverse bleeding scenarios. Furthermore, the SPI hydrogel powder markedly improved skin wound healing compared to CCS in a rat full-thickness skin wound model. In conclusion, the SA/PAA composite hydrogel, driven by nZVI, demonstrates significant potential for facilitating hemostasis and wound healing.

A sesbania gum/γ-polyglutamic acid photo-crosslinking composite hydrogel loaded with multi-component traditional Chinese medicine extract synergizes microenvironment amelioration in infected diabetic wound healing

The intricate physiological microenvironment of the diabetic wound characterized by overexpressed reactive oxygen species (ROS), persistent inflammation, angiogenetic dysfunction, and bacterial infection impeded the healing process. Herein, a photo-crosslinking composite hydrogel was fabricated based on the methacrylate modification of sesbania gum (SG) and γ-polyglutamic acid (γ-PGA), which could trigger free radical polymerization to form interpenetrating polymer network under 365 nm UV. Meanwhile, the micronized traditional Chinese medicine Huoxue Tongluo extract (HXTL) was encapsulated into the hydrogel to prepare the wound dressing (H-SGPGA). The 1H NMR and FT-IR successfully confirmed the synthesis of the methacrylate SG (SGMA) and γ-PGA (γ-PGAMA). Then, the enhanced mechanical properties, ROS scavenging (DPPH: 88.2 % ± 0.9 %; ABTS+: 90.5 % ± 0.4 %) and the antibacterial capacity (97.04 % ± 0.58 % against S. aureus) of H-SGPGA was investigated and confirmed in vitro. Finally, in the S. aureus infected diabetic wound model, the in vivo result demonstrated that the H-SGPGA significantly accelerated the diabetic wound repair process (8.31 % ± 5.54 % wound area on day 12) by promoting epidermis regeneration (79.13 % ± 5.99 %), collagen deposition (71.4 % ± 9.1 %), and angiogenesis (294.1 % ± 29.6 % of control group). Therefore, the composite H-SGPGA provided a potential treatment as the hydrogel dressing for the diabetic wound.

Hemostatic and antimicrobial properties of chitosan-based wound healing dressings: A review

Uncontrolled bleeding and microbial infections pose significant hurdles in wound healing, and the use of specialized functional dressings is pivotal in overcoming these obstacles. Among the various wound dressings currently under investigation, those based on chitosan and its derivatives have garnered significant attention due to their superior biocompatibility, antimicrobial properties, hemostatic capabilities, and healing promoting ability. In this comprehensive review, we initially delve into the hemostatic capabilities of chitosan, elucidating its interactions with blood cells and plasma proteins. We also dissect the intricate antimicrobial mechanisms of chitosan, which operate through both intracellular and extracellular pathways. The centerpiece of this review is the systematic classification of dressings based on chitosan and its derivatives, across various forms, such as hydrogels, sponges, membranes, fibers, and powders. This is followed by an exhaustive analysis of their hemostatic and antibacterial efficacy in wound healing, providing a robust foundation for further research and the advancement of clinical applications in the field.

Photothermal antimicrobial guar gum hydrogel cross-linked by bioactive small molecule lysine for infected wound healing

The healing of bacteria-infected wounds has long posed a significant clinical challenge. Traditional hydrogel wound dressings often lack self-healing properties and effective antibacterial characteristics, making wound healing difficult. In this study, a bioactive small molecule cross-linking agent 4-FPBA/Lys/4-FPBA (FLF) composed of 4-formylphenylboronic acid (4-FPBA) and lysine (Lys) was utilized to cross-link guar gum (GG) and a tannic acid/iron (TA/Fe3+) chelate through multiple dynamic bonds, leading to the formation of a novel self-healing hydrogel dressing GG-FLF/TA/Fe. The hydrogel exhibited excellent stretchability and self-healing ability, which enabled it to adapt to irregular wound sites. Meanwhile, the hydrogel demonstrated remarkable antibacterial efficacy (>99 %) facilitated by the synergistic effects of photothermal properties and aromatic Schiff bases. Additionally, it had adjustable rheological properties, good mechanical characteristics, conductivity, antioxidant characteristics and biocompatibility. Notably, the GG-FLF/TA/Fe hydrogel dressing irradiated with NIR displayed superior therapeutic effects in a mouse wound infection model (wound healing rate: 94.8 %), promoting recovery from bacterially infected wounds by enhancing collagen deposition, facilitating the formation of skin appendages and blood vessels, and regulating inflammatory factors. In summary, this study presented a novel approach to prepare biologically active antibacterial polysaccharide hydrogels and highlighted the substantial potential of this hydrogel as a biomedical antibacterial dressing.

Glucose-triggered NIR-responsive photothermal antibacterial gelatin/dextran hydrogel simultaneously targeting the high glucose and infection microenvironment in diabetic wound

The treatment of diabetic wounds with bacterial infection is a major challenge in the medical field. Microenvironment-responsive hydrogel dressings have shown great advantages, and photothermal antibacterial therapy is a potential antimicrobial strategy to avoid the generation of resistant bacteria. In this work, a glucose-triggered near-infrared (NIR)-responsive photothermal antibacterial hydrogel was designed and named GOGD based on a cascade reaction of glucose oxidation and polyphenol polymerization. The GOGD hydrogel was composed of gelatin and oxidized dextran (Odex), and loaded with a natural plant polyphenol gallic acid (GA) and the dual-biological enzymes (glucose oxidase GOx and horseradish peroxidase HRP). In response to the high glucose environment, GOx in the hydrogel decomposed glucose to produce hydrogen peroxide, which further catalyzed GA polymerization with HRP to produce poly-GA possessing NIR photothermal capability, thus endow GOGD hydrogel with glucose-triggered NIR responsive photothermal antibacterial property simultaneously targeting the high glucose and infection microenvironment in diabetic wounds. Furthermore, the GOGD hydrogel demonstrated good biocompatibility and a strong ability to scavenge reactive oxygen species (ROS), thereby protecting cells from oxidative damage. In a mouse model, this hydrogel not only displayed excellent hemostatic properties but also significantly enhanced the healing of Staphylococcus aureus-infected diabetic wounds by regulating inflammation and promoting angiogenesis. Therefore, the proposed GOGD hydrogel provides a novel approach to diabetic wound treatment by utilizing its unique glucose-responsive mechanism combined with integrated NIR-photothermal bacterial inhibition. This well-designed material holds great promise for significantly improving the healing of infected diabetic wounds and offers new prospects for future advancements in wound therapy.

Hydrogel inspired by "adobe" with antibacterial and antioxidant properties for diabetic wound healing

With the aging population, the incidence of diabetes is increasing. Diabetes often leads to restricted neovascularization, antibiotic-resistant bacterial infections, reduced wound perfusion, and elevated reactive oxygen species, resulting in impaired microenvironments and prolonged wound healing. Hydrogels are important tissue engineering materials for wound healing, known for their high water content and good biocompatibility. However, most hydrogels suffer from poor mechanical properties and difficulty in achieving sustained drug release, hindering their clinical application. Inspired by the incorporation of fibers to enhance the mechanical properties of "adobe," core-shell fibers were introduced into the hydrogel. This not only improves the mechanical strength of the hydrogel but also enables the possibility of sustained drug release. In this study, we first prepared core-shell fibers with PLGA (poly(lactic-co-glycolic acid)) and PCL (polycaprolactone). PLGA was loaded with P2 (Parathyroid hormone-related peptides-2), developed by our group, which promotes angiogenesis and cell proliferation. We then designed a QTG (QCS/TA/Gel, quaternary ammonium chitosan/tannic acid/gelatin) hydrogel, incorporating the core-shell fibers and the anti-inflammatory drug celecoxib into the QTG hydrogel. This hydrogel exhibits excellent antibacterial properties and biocompatibility, along with good mechanical performance. This hydrogel demonstrates excellent water absorption and swelling capabilities. In the early stages of wound healing, the hydrogel can absorb the wound exudate, maintaining the stability of the wound microenvironment. This hydrogel promotes neovascularization and collagen deposition, accelerating the healing of diabetic wounds, with a healing rate exceeding 95 % by day 14. Overall, this study provides a promising strategy for developing tissue engineering scaffolds for diabetic wound healing.

A Semi-Interpenetrating Network Hydrogel with Excellent Photothermal Antibacterial and ROS Scavenging Activities for MRSA-Infected Wounds

The prolonged infection of bacteria at the wound site may lead to serious physical problems. Herein, a multifunctional macroporous hydrogel with superior photothermal antibacterial and ROS scavenging activity (denoted as M-XG gel) was designed for the treatment of MRSA-infected wounds. The M-XG gels are composed of embedding Prussian blue nanoparticles (PBNPs) as photothermal converters and chelating ferric ions with xanthan gum (XG) and dopamine (DA) to form a semipermeable network. The introduction of DA occupies the cross-link sites of ferric ions, further increasing the pore size (200-500 μm open macropores) and endowing the hydrogel with ideal adhesion. The increase of cross-link sites in PBNPs formed a promising equilibrium M-XG gel with identical macroporous structures and toughened mechanical performance. The metal ligands between ferric ions and catechols, as well as the unique photothermal response of PBNPs, endow the hydrogels with a fast and stable near-infrared (NIR) photothermal conversion efficiency (48%). In the MRSA-infected SD rat trauma model, wounds treated with the M-XG gel group had completely closed after 14 days, effectively controlling wound bacterial infection and accelerating angiogenesis and collagen deposition, synergistically promoting infected wound healing. Therefore, the photothermal hydrogel with a semi-interpenetrating network demonstrates its great potential for infected wound tissue engineering.

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

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

Using Three-Dimensional Bioprinting to Generate Realistic Models of Wound Healing

Significance: The skin serves as the primary defense against external stimuli, making it vulnerable to damage. Injuries can cause a dysregulated environment, resulting in chronic inflammation and inhibition of cell proliferation and migration, which delays recovery. Innovative approaches, such as three-dimensional (3D) bioprinting, can foster a controlled healing environment by promoting synergy between the skin microbiome and cells. Recent Advances: Traditional approaches to wound healing have focused on fostering an environment conducive to the interplay between cells, extracellular proteins, and growth factors. 3D bioprinting, a manufacturing technology with applications in tissue engineering, deposits biomaterial-based bioink containing living cells to fabricate custom-designed tissue scaffolds in a layer-by-layer fashion. This process controls the architecture and composition of a construct, producing multilayered and complex structures such as skin. Critical Issues: The selection of biomaterials for scaffolds has been a challenge when 3D skin tissue engineering. While prioritizing mechanical properties, current biomaterials often lack the ability to interact with environmental stimuli such as pH, temperature, or oxygen levels. Employing smart biomaterials that integrate bioactive molecules and adapt to external conditions could overcome these limitations. This innovation would enable scaffolds to create a sustainable wound-healing environment, fostering microbiome balance, reducing inflammation, and facilitating cellular recovery and tissue restoration, addressing critical gaps in existing wound care solutions. Future Directions: Novel bioink formulations for skin injury recovery are focused on improving long-term cell viability, proliferation, vascularization, and immune integration. Efficient recovery of the skin microbiome using bioactive molecules has the potential to create microenriched environments that support the recovery of the skin microbiome and restore immune regulation. This promising direction for future research aims to improve patient outcomes in wound care.

Nanomedicine's shining armor: understanding and leveraging the metal-phenolic networks

Metal-phenolic networks (MPNs), which comprise supramolecular amorphous networks formed by interlinking polyphenols with metal ions, garner escalating interest within the realm of nanomedicine. Presently, a comprehensive synthesis of the cumulative research advancements and utilizations of MPNs in nanomedicine remains absent. Thus, this review endeavors to firstly delineate the characteristic polyphenols, metal ions, and their intricate interaction modalities within MPNs. Subsequently, it elucidates the merits and demerits of diverse synthesis methodologies employed for MPNs, alongside exploring their potential functional attributes. Furthermore, it consolidates the diverse applications of MPNs across various nanomedical domains encompassing tumor therapy, antimicrobial interventions, medical imaging, among others. Moreover, a meticulous exposition of the journey of MPNs from their ingress into the human body to eventual excretion is provided. Lastly, the persistent challenges and promising avenues pertaining to MPNs are delineated. Hence, this review offering a comprehensive exposition on the current advancements of MPNs in nanomedicine, consequently offering indirect insights into their potential clinical implementation.

An injectable in situ-forming hydrogel with self-activating genipin-chitosan (GpCS) cross-linking and an O2/Ca2+ self-supplying capability for wound healing and rapid hemostasis

Severe traumatic bleeding and chronic diabetic wounds require rapid hemostasis and multifunctional dressings, which remain particularly challenging, especially for non-compressible trauma and irregular wounds with dysregulated microenvironments. Chitosan (CS) can be easily cross-linked with genipin to form GpCS hydrogels. However, developing injectable GpCS hydrogels for biomedical applications faces challenges, particularly in enhancing rapid gel formation and optimizing physical properties. In this study, we present an innovative approach to improve these aspects by designing a novel injectable GpCS hydrogel, strategically enhanced through a calcium peroxide (CaO2)-activated cross-linking reaction. CaO2 played a pivotal role in promoting in situ cross-linking of the GpCS hydrogel, leading to significant improvements in its injectable in situ gel-forming ability, mechanical strength, and self-healing and bioadhesive properties. CaO2 incorporated in the hydrogels rapidly converted to oxygen when combined with catalase (CAT), thereby establishing a self-sustaining oxygen/calcium release system. This system not only promoted hyperoxia and activated the coagulation cascade, facilitating rapid blood clotting, but also significantly accelerated wound healing through enhanced angiogenesis, collagen deposition, and M2 macrophage polarization. These attributes significantly enhanced the capacity of the hydrogel to facilitate wound closure and hemostasis, highlighting its therapeutic value in accelerating recovery and improving healing outcomes in clinical wound care.

Formulation of Asiatic acid-loaded polymeric chitosan-based hydrogel for effective MRSA infection control and enhanced wound healing in zebrafish models

BACKGROUND

Wound healing relies on a controlled inflammatory process vital for tissue regeneration. Chronic wounds, characterized by persistent inflammation and high infection risk, pose significant challenges in healthcare. Hydrogel dressings offer promise in wound care; however, the understanding of their role in managing inflammation and infection remains unclear. This study aimed to elucidate these processes and assess the efficacy of Asiatic acid (AA)-infused hydrogels in reducing inflammation and preventing infection. The unique properties of AA suggest its potential to modulate inflammation, promote tissue regeneration, and inhibit microbial colonization, thereby paving the way for specialized dressings that optimize healing outcomes.

METHODS

The investigation encompassed the antibacterial, anti-biofilm, antioxidant activity, and biocompatibility of AA using a fibroblast cell line. A hydrogel incorporating AA was developed and characterized through scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), contact angle analysis, tensile testing, swelling capacity, and thermal stability assessments. Biodegradability was evaluated via enzymatic degradation, alongside controlled drug release and antibacterial efficacy against MRSA. In vivo studies using a zebrafish model examined wound healing and immune response.

RESULTS

Results confirmed AA's potent antibacterial activity against MRSA and its effectiveness in disrupting mature biofilms. Additionally, AA exhibited strong antioxidant activity and biocompatibility. Morphological analysis revealed a pore structure conducive to wound healing, and the hydrogel demonstrated enhanced tensile strength, swelling properties, and thermal stability. In vivo, the AA-infused hydrogel accelerated wound closure, re-epithelialization, and immune response, supporting its potential for advanced wound care applications. In conclusion, the AA-infused chitosan hydrogel emerges as a promising candidate for advanced wound care therapies.

Enhanced hemostatic efficacy of cryogel with copper ion-loaded mesoporous bioactive glasses for acute and persistent bleeding

Uncontrolled acute and persistent bleeding, as well as with infection, is a great challenge because of the high mortality during treating the patients with injuries, complex surgery or bone marrow failure. Here, we develop an external form of natural components which is based on phosphorylated methacrylated gelatin (GelMA, G) cryogel (GP) loaded with tannic acid (TA)-mixed copper ion (Cu2+) mesoporous bioactive glasses (MBG), named after GP@MBG-Cu-TA cryogel, to address the goals of reduce persistent bleeding and enhance antibacterial activity. Structurally, GP@MBG-Cu-TA cryogel is based on GP, MBG loaded with TA and Cu2+ adheres to GP via hydrogen bonding. In vitro, GP@MBG-Cu-TA cryogel displays a good biocompatibility, hemostatic and antimicrobial capability. In vivo studies, GP@MBG-Cu-TA cryogel can enhance the hemostatic effect in the liver injury in SD rats for the acute bleeding, as well as in the aplastic anemia and hemophilia A mice with tail amputation for the persistent bleeding. In addition, GP@MBG-Cu-TA cryogel accelerates the skin wound repair in the mice with the bacterial contamination at the injury site. In sum, GP@MBG-Cu-TA cryogel is not only endowed with dual function of hemostatic and antimicrobial capability, but also can stop bleeding of the objects with either normal or abnormal coagulation function. Thus, GP@MBG-Cu-TA cryogel provides a promising candidate dressing for managing bleeding and bacterial complications in clinic.

Injectable and self-healing carboxymethyl chitosan/carboxymethyl cellulose/marine snail peptide hydrogel for infected wound healing

Treatment of bacterial infected full-thickness wounds remains a great challenge in clinic. Herein, a HYP hydrogel was prepared using carboxymethyl chitosan, dialdehyde carboxymethyl cellulose, and marine snail peptide (Tyr-Ile-Ala-Glu-Asp-Ala-Glu-Arg) as starting materials. The marine snail peptide with good antioxidant activity could remove the reactive oxygen species in wound sites, thereby alleviating the excessive inflammatory response. The dynamic Schiff-base bonds endowed HYP with good injectable and self-healing abilities. HYP exhibited suitable gelation time, good rheological properties, and unique porosity structure, which were conducive to wound healing. In vitro biological studies indicated that HYP showed good biocompatibility, low hemolysis ratio, and improved antibacterial and antioxidant activities. In vivo study revealed that HYP could promote wound healing in a bacterial infected full-thickness skin defect rat model. The wound tissues showed reduced number of inflammatory cells, newly formed hair follicles, and obvious collagen deposition. The expression of inflammatory and angiogenesis related biomarkers (IL-6, IL-10, CD31, and α-SMA) significantly improved. Therefore, HYP hydrogel showed great application prospect as a wound dressing for bacterial infected wound.

Injectable dual-network hyaluronic acid nanocomposite hydrogel for prevention of postoperative breast cancer recurrence and wound healing

High locoregional recurrence rates and potential wound infections remain a significant challenge for postoperative breast cancer patients. Herein, we developed a dual-network hyaluronic acid (HA) nanocomposite hydrogel composed of herring sperm DNA (hsDNA) bridged methacrylated HA (HAMA) and FeMg-LDH-ppsa nanohybrid chelated catechol-modified HA (HADA) for the prevention of breast cancer recurrent, anti-infection, and promoting wound healing. Dynamic reversible hsDNA cross-linking combined with metal-catechol chelating renders the hydrogel injectability, rapid self-healing ability, and enhanced mechanical properties. FeMg-LDH-ppsa nanohybrids obtained by in situ polymerization of aniline derivatives in the FeMg-LDH interlayer exhibited excellent photothermal effect. Upon near-infrared (NIR) irradiation, the photothermal effect mediated by FeMg-LDH-ppsa can unwind the hsDNA duplex, enabling the controlled release of preloaded DOX for synergistic photothermal-chemotherapy antitumor. Meanwhile, the catechol-metal (Fe3+/Mg2+) moieties in the hydrogel enhanced tissue adhesion and exhibited intrinsic antimicrobial and bioactive properties, which in combination with the NIR-assisted photothermal effect, significantly accelerated infected wound healing through sterilizing microorganisms, alleviating inflammation, re-epithelialization, and angiogenesis. Overall, this multifunctional hydrogel represented a promising candidate in postoperative wound management for simultaneous tumor elimination, antiinfection, and wound repair.

Construction of chitosan/carboxylated polyvinyl alcohol/poly(N-isopropylacrylamide) composite antibacterial hydrogel for rapid wound healing

In the realm of skin injury management, the expedited closure of wounds, prevention of scar formation, and enhancement of the healing process are of critical significance. The creation of economical dressings that effectively facilitate swift wound sealing in the initial phase of skin trauma while curbing scar development represents a promising avenue for clinical utility. Within the context of this investigation, we synthesized a novel hydrogel composed of chitosan (CS), carboxylated poly(vinyl alcohol) (PVA-COOH) via a Schiff base reaction between carboxylated PVA and chitosan, yielding networks abundant in amide bonds. Following this, a chitosan/carboxylated PVA/poly(N-isopropylacrylamide) hydrogel (CNP) was engineered by incorporating poly-N-isopropylacrylamide chains for interpenetration at ambient temperature. Our findings indicate that the CNP hydrogel exhibits favorable degradability and swelling characteristics. Moreover, it possesses favorable antimicrobial efficacy and biocompatibility. In a murine full-thickness skin injury model, the hydrogel was found to expedite wound healing by augmenting granulation tissue formation, mitigating wound inflammation, and promoting angiogenesis.

Double-alternating injectable multifunctional hydrogel based on chitosan for skin wound repair

Injectable hydrogels can be suitable for any irregular wounds to play an important role in wound healing, which have attracted much attention from researchers. Here, a chitosan-based double alternating injectable hydrogel had been proposed, which aligned with characteristics of wound healing. First of all, carboxymethyl chitosan (CMCS) and oxidized gellant (OGG) were used to fabricate above double-alternating injectable hydrogel skeleton (COG) through Schiff base bond. Then, dipotassium glycyrrhizinate (DPG) and bioactive glass (BG) were loaded respectively into COG, forming COG2-D10 and COG2-B0.5 hydrogel. Various properties of above hydrogels such as rheological behaviors, injectable capability, cytocompatibility, antibacterial and anti-inflammatory activity were systematically investigated. The results indicated that above hydrogel not only had a stable network structure, good toughness, injectability, and excellent adhesive properties, but also exhibited efficient antibacterial, anti-inflammatory, hemostatic, and biocompatible properties. The investigation of in vivo full-thickness skin wound healing showed that compared with COG2-D10 or COG2-B0.5 hydrogel alone, the double-alternating COG2-D10/COG2-B0.5 hydrogel could better enhance the efficacy of drugs, promote cell migration and proliferation, accelerate collagen fiber deposition and neovascularization, and significantly improve wound healing (p < 0.01). Therefore, the double-alternating therapy strategy of hydrogel will provide a new approach for the clinical treatment of skin wound healing.

Nanozyme-chitosan-aerogel immobilized enzyme-driven biocatalytic cascade for therapeutic engineering of diabetic wounds

A novel strategy that has emerged in recent years involves the use of aerogels for anti-inflammatory treatment, which has been extensively studied for its powerful application prospects in wound healing, diabetic complications, and tissue regeneration. However, the therapeutic efficacy of aerogels alone is compromised due to bacterial infections at the wound site. Therefore, it is necessary to incorporate effective antibacterial systems onto the aerogels to enhance their efficacy against bacterial infections. For instance, the design of cascade reactions targeting specific disease biomarkers for diagnostic and therapeutic purposes holds promise for enhancing treatment efficacy and precision. In this study, we successfully achieved the immobilization of glucose oxidase within an aerogel prepared from nanozymes, demonstrating remarkable catalytic activity and high-temperature stability. The cascade catalytic system comprising nanozymes and glucose oxidase was applied to combat Methicillin-resistant Staphylococcus aureus (MASR) bacterial infections, exhibiting effective biofilm removal capabilities. In therapeutic experiments on ulcerated wounds in diabetic mice, the cascade catalytic system demonstrated outstanding efficacy with excellent biocompatibility. The therapeutic effects were primarily manifested in the rapid clearance of biofilms formed by MASR, achieved by locally depleting glucose in the wound area, thereby promoting the healing process of ulcerated wounds.

Sustained Release of Curcumin from Cur-LPs Loaded Adaptive Injectable Self-Healing Hydrogels

Biological tissue defects are typically characterized by various shaped defects, and they are prone to inflammation and the excessive accumulation of reactive oxygen species. Therefore, it is still urgent to develop functional materials which can fully occupy and adhere to irregularly shaped defects by injection and promote the tissue repair process using antioxidant and anti-inflammatory mechanisms. Herein, in this work, phenylboronic acid modified oxidized hyaluronic acid (OHAPBA) was synthesized and dynamically crosslinked with catechol group modified glycol chitosan (GCHCA) and guar gum (GG) into a hydrogel loaded with curcumin liposomes (Cur-LPs) which were relatively uniformly distributed around 180 nm. The hydrogel possessed rapid gelation within 30 s, outstanding injectability and tissue-adaptive properties with self-healing properties, and the ability to adhere to biological tissues and adapt to tissue movement. Moreover, good biocompatibility and higher DPPH scavenging efficiency were illustrated in the hydrogel. And a more sustainable release of curcumin from Cur-LPs-loaded hydrogels, which could last for 10 days, was achieved to improve the bioavailability of curcumin. Finally, they might be injected to fully occupy and adhere to irregularly shaped defects and promote the tissue repair process by antioxidant mechanisms and the sustained release of curcumin for anti-inflammation. And the hydrogel would have potential application as candidates in tissue defect repair.

An injectable epoxidized soybean oil/gelatin-based photothermal biogel with remarkable rapid hemostasis capability for wound repair

The development of wound dressings with rapid hemostasis, antibacterial activity without the addition of antibiotics and on-demand removability that effectively avoid secondary damage to the wound during replacement still faces significant challenges. Herein, injectable epoxidized soybean oil/gelatin-based photothermal biogel with outstanding tissue adhesion, on-demand removability, shape-adaptability, and antibacterial performance is prepared as a removable wound dressing for wound repair. The biogel is composed of two types of hydrophilic/hydrophobic three-dimensional network structures, which interweave together through dynamic imine bonds, coordination bonds and numerous hydrogen bonds to synergistically improve injectability, self-healing, tissue adhesion, and compressive performance of the biogel. Moreover, the prepared EG-02 biogel not only has excellent thermal stability, biodegradability, hemocompatibility, and RBCs and platelet adhesion properties, but also displays outstanding cytocompatibility and the ability to promote cell migration. Furthermore, the EG-02 biogel treated with a near-infrared (NIR) laser (808 nm, 0.2 W·cm-2) exhibits prominent photothermal cycling stability and antibacterial performance. Notably, the EG-02 biogel presents remarkable rapid hemostasis capability, with the hemostatic time greatly shortened to 40 s and the blood loss significantly reduced to 89.2 mg. Therefore, the injectable photothermal biogel, as a fascinating candidate for on-demand removable wound dressing, has shown promising application prospects in wound repair.

Advances of biomacromolecule-based antibacterial hydrogels and their performance evaluation for wound healing: A review

Biomacromolecule hydrogels possess excellent mechanical properties and biocompatibility, but their inability to combat bacteria restricts their application in the biomedical field. With the increasing requirements and demands for hydrogel dressings, wound dressings with antibacterial properties of biomacromolecule hydrogels reinforced by adding antibacterial agents have attracted much attention, and related reviews are emerging. In this paper, the advances of biomacromolecule antibacterial hydrogels (including chitosan, sodium alginate, Hyaluronic acid, cellulose and gelatin) were first overviewed, and the antibacterial agents incorporated into hydrogels were classified (including metals and their derivatives, carbon-based materials, and native compounds). A series of performance evaluations of antibacterial hydrogels in the process of promoting wound healing were then reviewed, including basic properties (mechanical, rheological, injectable and self-healing, etc.), in vitro experiments (hemostasis, antibacterial, anti-inflammatory, anti-oxidation, biocompatibility) and in vivo experiments (in vivo model, histomorphology analysis, cytokines). Finally, the future development of biomacromolecule-based antibacterial hydrogels for wound healing is prospected. This work can provide a useful reference for researchers to prepare practical new wound hydrogel dressings.

Highly biocompatible, antioxidant and antibacterial gelatin methacrylate/alginate - Tannin hydrogels for wound healing

Gelatin (Gel) hydrogels are widely utilized in various aspects of tissue engineering, such as wound repair, due to their abundance and biocompatibility. However, their low strength and limited functionality have constrained their development and scope of application. Tannic acid (TA), a naturally occurring polyphenol found in plants and fruits, has recently garnered interest as a crosslinking, anti-inflammatory, and antioxidant agent. In this study, we fabricated novel multifunctional gelatin methacrylate/alginate-tannin (GelMA/Alg-TA) hydrogels using chemical and physical crosslinking strategies with gelatin methacrylate (GelMA), alginate (Alg), and TA as the base materials. The GelMA/Alg-TA hydrogels maintained a stable three-dimensional porous structure with appropriate water content and exhibited excellent biocompatibility. Additionally, these hydrogels demonstrated significant antioxidant and antibacterial properties and substantially promoted wound healing in a mouse model of full-thickness skin defects by modulating inflammatory responses and enhancing granulation formation. Therefore, our study offers valuable insights into the design principles of novel multifunctional GelMA/Alg-TA hydrogels, highlighting their exceptional biocompatibility, antioxidant, and antibacterial properties. GelMA/Alg-TA hydrogels are promising candidates for wound healing applications.

Hericium erinaceus β-glucan/tannic acid hydrogels based on physical cross-linking and hydrogen bonding strategies for accelerating wound healing

The majority of natural fungal β-glucans exhibit diverse biological functionalities, such as immunomodulation and anti-inflammatory effects, attributed to their distinctive helix or highly branched conformation This study utilized β-glucan with helix conformation and high-viscosity extracted from Hericium erinaceus, employing freeze-thaw and solvent exchange strategies to induce multiple hydrogen bonding between molecules, thereby initiating the self-assembly process of β-glucan from random coil to stable helix conformation without chemical modifications. Subsequently, the natural bioactive compound tannic acid was introduced through physical entanglement, imparting exceptional antioxidant properties to the hydrogel. The HEBG/TA hydrogel exhibited injectable properties, appropriate mechanical characteristics, degradability, temperature-responsive tannic acid release, antioxidant activity, and hemostatic potential. In vivo experiments using skin full-thickness defect and deep second-degree burn wound models demonstrated significant therapeutic efficacy, including neovascularization, and tissue regeneration. Moreover, the HEBG/TA hydrogel demonstrated its ability to regulate cytokines by effectively inhibiting the production of inflammatory mediators (TNF-α, IL-6), while simultaneously enhancing the expression of cell proliferation factor KI-67 and markers associated with angiogenesis such as CD31 and α-SMA. This study highlights the potential of combining natural β-glucan with bioactive molecules for skin repair.

Multifunctional chitosan-based hydrogels loaded with iridium nanoenzymes for skin wound repair

Hemostasis, infection, oxidative stress, and inflammation still severely impede the wound repair process. It is significant to develop multifunctional wound dressings that can function as needed in various stages of wound healing. In this study, iridium nanoparticles (IrNPs) with multi-enzyme mimetic activity were complexed with chitosan (CS) and fucoidan (FD) for the first time to make a multifunctional CS/FD/IrNPs hydrogel with excellent antioxidant effect. The hydrogel has excellent physicochemical properties. In particular, the incorporation of IrNPs imparts excellent antioxidant properties to the hydrogel, which could scavenge reactive oxygen species (ROS). In addition, the hydrogel shows excellent hemostatic and antibacterial properties. The CS/FD/IrNPs hydrogel performs fast and efficient hemostasis in 21 s. Moreover, the blood loss of the CS/FD/IrNPs hydrogel group was approximately 10% of that in the control group and the antibacterial rate of CS/FD/IrNPs hydrogel against E. coli and S. aureus was up to 95 %. In vivo results demonstrate that CS/FD/IrNPs hydrogel promotes wound healing by attenuating ROS levels, reducing oxidative damage, mitigating inflammation, and accelerating angiogenesis. To summarize, the CS/FD/IrNPs hydrogel system, with hemostatic, antibacterial, antioxidant, anti-inflammatory and pro-healing activities, can be a promising and effective strategy for the treatment of clinically difficult-to-heal wounds.

Spray-assisted layer-by-layer deposition of quaternized chitosan/tannic acid for the construction of multifunctional bio-based nonwoven dressings

Gauze wound dressings have received considerable attention due to their cost-effectiveness, excellent mechanical properties, and widespread applications. However, their inability to actively combat microorganisms and effectively scavenge free radicals results in suboptimal wound management. In this study, a novel nonwoven-based gauze dressing coated with quaternized chitosan/tannic acid (QCS/TA), based on electrostatic interaction and hydrogen bonding, was successfully prepared using a spray-assisted layer-by-layer assembly method. The bio-based nonwoven dressing, assembled with multiple interlacing bilayers, demonstrated outstanding antimicrobial properties, eliminating 99.99 % of Staphylococcus aureus (S. aureus) and 85 % of Escherichia coli (E. coli). Compared to the pristine nonwoven dressing, the QCS/TA-coated nonwoven dressing scavenged >85 % of the surrounding radicals within 2 h. Additionally, the nonwoven dressing exhibits excellent coagulation properties. Notably, the facile spraying procedure preserved most of the softness and breathability of the nonwoven substrate. After the deposition of seven bilayers, the bending stiffness and drape coefficient increased by only 37.63 % and 3.85 %, respectively, while the air permeability and moisture permeability reached 1712 mm/s and 3683.58 g/m2/d, respectively. This bio-based nonwoven dressing, derived from safe and non-toxic ingredients, holds promise as the next generation of multifunctional gauze dressings.

Chitosan-based self-healing hydrogel dressing for wound healing

Skin has strong self-regenerative capacity, while severe skin defects do not heal without appropriate treatment. Therefore, in order to cover the wound sites and hasten the healing process, wound dressings are required. Hydrogels have emerged as one of the most promising candidates for wound dressings because of their hydrated and porous molecular structure. Chitosan (CS) with biocompatibility, oxygen permeability, hemostatic and antimicrobial properties is beneficial for wound treatment and it can generate self-healing hydrogels through reversible crosslinks, from dynamic covalent bonding, such as Schiff base bonds, boronate esters, and acylhydrazone bonds, to physical interactions like hydrogen bonding, electrostatic interaction, ionic bonding, metal-coordination, host-guest interactions, and hydrophobic interaction. Therefore, various chitosan-based self-healing hydrogel dressings have been prepared in recent years to cope with increasingly complex wound conditions. This review's objective is to provide comprehensive information on the self-healing mechanism of chitosan-based hydrogel wound dressings, discuss their advanced functions including antibacterial, conductive, anti-inflammatory, anti-oxidant, stimulus-responsive, hemostatic/adhesive and controlled release properties, further introduce their applications in the promotion of wound healing in two categories: acute and chronic (infected, burn and diabetic) wounds, and finally discuss the future perspective of chitosan-based self-healing hydrogel dressings for wound healing.

Accelerated, injectable, self-healing, scarless wound dressings using rGO reinforced dextran/chitosan hydrogels incorporated with PDA-loaded asiaticoside

The process of wound healing is intricate and complex, necessitating the intricate coordination of various cell types and bioactive molecules. Despite significant advances, challenges persist in achieving accelerated healing and minimizing scar formation. Herein, a multifunctional hydrogel engineered via dynamic Schiff base crosslinking between oxidized dextran and quaternized chitosan, reinforced with reduced graphene oxide (rGO) is reported. The resulting OQG hydrogels demonstrated injectability to aid in conforming to irregular wound geometries, rapid self-healing to maintain structural integrity and adhesion for intimate integration with wound beds. Moreover, the developed hydrogels possessed antioxidant and antibacterial activities, mitigating inflammation and preventing infection. The incorporation of conductive rGO further facilitated the transmission of endogenous electrical signals, stimulating cell migration and tissue regeneration. In addition, the polydopamine-encapsulated asiaticoside (AC@PDA) nanoparticles were encapsulated in OQG hydrogels to reduce scar formation during in vivo evaluations. In vitro results confirmed the histocompatibility of the hydrogels to promote cell migration. The recovery of the full-thickness rat wounds revealed that these designed OQG hydrogels with the incorporation of AC@PDA nanoparticles could accelerate wound healing, reduce inflammation, facilitate angiogenesis, and minimize scarring when implemented. This multifunctional hydrogel system offers a promising strategy for enhanced wound management and scarless tissue regeneration, addressing the multifaceted challenges in wound care.

Polyphenol-hyaluronic acid-based hydrogel remodels the wound microenvironment and eliminates bacterial infection for accelerating wound healing

The wound microenvironment, often characterized by alkaline pH and severe hypoxia, presents significant challenges to the healing of bacterial-infected wounds. While considerable research has focused on improving wound healing through effective bacterial elimination using advanced therapeutic approaches, the importance of regulating the wound microenvironment has received less emphasis. In this work, we developed a biocompatible hydrogel, HTFC, by incorporating CaO2 nanoparticles (CaO2 NPs) into a gel formed by tannic acid (TA), hyaluronic acid (HA), and Fe3+. The HA and TA in HTFC hydrogel help to create a slightly acidic microenvironment, facilitating the decomposition of CaO2 NPs to release H2O2 for chemodynamic therapy (CDT). The reduction properties of TA promote the recycling of Fe3+/Fe2+, enhancing CDT efficacy and partially converting H2O2 to O2, thereby alleviating hypoxia. Additionally, FeIIITA complexes in HTFC enhance CDT through photothermal therapy (PTT)-induced improvement of the Fenton reaction. This multifunctional hydrogel, with its synergistic effects of PTT and CDT, along with its ability to remodel the wound microenvironment from hypoxic and alkaline to normoxic and acidic, accelerates the bacterial-infected wound healing process.

Facile fabrication of quaternized chitosan-incorporated biomolecular patches for non-compressive haemostasis and wound healing

Cell-free wound dressings (WDs) with desirable effectiveness and safety have received much attention in the field of regenerative medicine. However, the weak linkages between bioactive polymers and the spatial structure of WDs frequently result in interventional treatment failure. Herein, we create a series of quaternized chitosan (QCS)-incorporated composite hydrogels (referred to as GHCH-n) by UV cross-linking and then convert them into microneedle patches (MNPs). QCS, which is positively charged and amphiphilic, is essential for broad-spectrum antibacterial and haemostatic activities. QCS is proven to be slightly toxic, so it is immobilized into the methacrylate gelatine (GelMA) molecular cage to minimize adverse effects. A polydimethylsiloxane micro-mould is used to shape the MNPs. MNPs can pierce tissue, seal off bleeding sites, and cling to wounds securely. Thus, MNPs can cooperate with GHCH-n hydrogels to halt bleeding and accelerate wound healing. This study recommends GHCH-10 MNPs as an advanced biomaterial. Several preclinical research models have thoroughly validated the application effect of GHCH-10 MNPs. This research also proposes a novel strategy for integrating the nature of bioactive polymers and the structure of composite biomaterials. This strategy is not only applicable to the fabrication of next-generation WDs but also shows great potential in expanding interdisciplinary domains.

Preparation of Multifunctional Hydrogels with In Situ Dual Network Structure and Promotion of Wound Healing

As an emerging biomedical material, wound dressings play an important therapeutic function in the process of wound healing. It can provide an ideal healing environment while protecting the wound from a complex external environment. A hydrogel wound dressing composed of tilapia skin gelatin (Tsg) and fucoidan (Fuc) was designed in this article to enhance the microenvironment of wound treatment and stimulate wound healing. By mixing horseradish peroxidase (HRP), hydrogen peroxide (H2O2), tilapia skin gelatin-tyramine (Tsg-Tyr), and carboxylated fucoidan-tyramine in agarose (Aga), using the catalytic cross-linking of HRP/H2O2 and the sol-gel transformation of Aga, a novel gelatin-fucoidan (TF) double network hydrogel wound dressing was constructed. The TF hydrogels have a fast and adjustable gelation time, and the addition of Aga further enhances the stability of the hydrogels. Moreover, Tsg and Fuc are coordinated with each other in terms of biological efficacy, and the TF hydrogel demonstrated excellent antioxidant properties and biocompatibility in vitro. Also, in vivo wound healing experiments showed that the TF hydrogel could effectively accelerate wound healing, reduce wound microbial colonization, alleviate inflammation, and promote collagen deposition and angiogenesis. In conclusion, TF hydrogel wound dressings have the potential to replace traditional dressings in wound healing.

Laponite/lactoferrin hydrogel loaded with eugenol for methicillin-resistant Staphylococcus aureus-infected chronic skin wound healing

Severe bacterial infections can give rise to protracted wound healing processes, thereby posing a significant risk to a patient's well-being. Consequently, the development of a versatile hydrogel dressing possessing robust bioactivity becomes imperative, as it holds the potential to expedite wound healing and yield enhanced clinical therapeutic outcomes. In this context, the present study involves the formulation of an injectable multifunctional hydrogel utilizing laponite (LAP) and lactoferrin (LF) as foundational components and loaded with eugenol (EG). This hydrogel is fabricated employing a straightforward one-pot mixing approach that leverages the principle of electrostatic interaction. The resulting LAP/LF/EG2% composite hydrogel can be conveniently injected to address irregular wound geometries effectively. Once administered, the hydrogel continually releases lactoferrin and eugenol, mitigating unwarranted oxidative stress and eradicating bacterial infections. This orchestrated action culminates in the acceleration of wound healing specifically in the context of MRSA-infected wounds. Importantly, the LAP/LF/EG2% hydrogel exhibits commendable qualities including exceptional injectability, potent antioxidant attributes, and proficient hemostatic functionality. Furthermore, the hydrogel composition notably encourages cellular migration while maintaining favorable cytocompatibility. Additionally, the hydrogel manifests noteworthy bactericidal efficacy against the formidable multidrug-resistant MRSA bacterium. Most significantly, this hydrogel formulation distinctly expedites the healing of MRSA-infected wounds by promptly inducing hemostasis, curbing bacterial proliferation, and fostering angiogenesis, collagen deposition, and re-epithelialization processes. As such, the innovative hydrogel material introduced in this investigation emerges as a promising dressing for the facilitation of bacterial-infected wound healing and consequent tissue regeneration.

An artificial liquid-liquid phase separation-driven silk fibroin-based adhesive for rapid hemostasis and wound sealing

The powerful adhesion systems of marine organisms have inspired the development of artificial protein-based bioadhesives. However, achieving robust wet adhesion using artificial bioadhesives remains technically challenging because the key element of liquid-liquid phase separation (LLPS)-driven complex coacervation in natural adhesion systems is often ignored. In this study, mimicking the complex coacervation phenomenon of marine organisms, an artificial protein-based adhesive hydrogel (SFG hydrogel) was developed by adopting the LLPS-mediated coacervation of the natural protein silk fibroin (SF) and the anionic surfactant sodium dodecylbenzene sulfonate (SDBS). The assembled SF/SDBS complex coacervate enabled precise spatial positioning and easy self-adjustable deposition on irregular substrate surfaces, allowing for tight contact. Spontaneous liquid-to-solid maturation promoted the phase transition of the SF/SDBS complex coacervate to form the SFG hydrogel in situ, enhancing its bulk cohesiveness and interfacial adhesion. The formed SFG hydrogel exhibited intrinsic advantages as a new type of artificial protein-based adhesive, including good biocompatibility, robust wet adhesion, rapid blood-clotting capacity, and easy operation. In vitro and in vivo experiments demonstrated that the SFG hydrogel not only achieved instant and effective hemostatic sealing of tissue injuries but also promoted wound healing and tissue regeneration, thus advancing its clinical applications. STATEMENT OF SIGNIFICANCE: Marine mussels utilize the liquid-liquid phase separation (LLPS) strategy to induce the supramolecular assembly of mussel foot proteins, which plays a critical role in strong underwater adhesion of mussel foot proteins. Herein, an artificial protein-based adhesive hydrogel (named SFG hydrogel) was reported by adopting the LLPS-mediated coacervation of natural protein silk fibroin (SF) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS). The assembled SFG hydrogel enabled the precise spatial positioning and easy self-adjustable deposition on substrate surfaces with irregularities, allowing tight interfacial adhesion and cohesiveness. The SFG hydrogel not only achieved instant and effective hemostatic sealing of tissue injuries but also promoted wound healing and tissue regeneration, exhibiting intrinsic advantages as a new type of artificial protein-based bioadhesives.

A Novel Coacervate Embolic Agent for Tumor Chemoembolization

Transcatheter arterial chemoembolization (TACE) has proven effective in blocking tumor-supplied arteries and delivering localized chemotherapeutic treatment to combat tumors. However, traditional embolic TACE agents exhibit certain limitations, including insufficient chemotherapeutic drug-loading and sustained-release capabilities, non-biodegradability, susceptibility to aggregation, and unstable mechanical properties. This study introduces a novel approach to address these shortcomings by utilizing a complex coacervate as a liquid embolic agent for tumor chemoembolization. By mixing oppositely charged quaternized chitosan (QCS) and gum arabic (GA), a QCS/GA polymer complex coacervate with shear-thinning property is obtained. Furthermore, the incorporation of the contrast agent Iohexol (I) and the chemotherapeutic doxorubicin (DOX) into the coacervate leads to the development of an X-ray-opaque QCS/GA/I/DOX coacervate embolic agent capable of carrying drugs. This innovative formulation effectively embolizes the renal arteries without recanalization. More importantly, the QCS/GA/I/DOX coacervate can successfully embolize the supplying arteries of the VX2 tumors in rabbit ear and liver. Coacervates can locally release DOX to enhance its therapeutic effects, resulting in excellent antitumor efficacy. This coacervate embolic agent exhibits substantial potential for tumor chemoembolization due to its shear-thinning performance, excellent drug-loading and sustained-release capabilities, good biocompatibility, thrombogenicity, biodegradability, safe and effective embolic performance, and user-friendly application.

Hybrid Hydrogels for Immunoregulation and Proangiogenesis through Mild Heat Stimulation to Accelerate Whole-Process Diabetic Wound Healing

Intense and persistent oxidative stress, excessive inflammation, and impaired angiogenesis severely hinder diabetic wound healing. Bioactive hydrogel dressings with immunoregulatory and proangiogenic properties have great promise in treating diabetic wounds. However, the therapeutic effects of dressings always depend on drugs with side effects, expensive cytokines, and cell therapies. Herein, a novel dynamic borate-bonds crosslinked hybrid multifunctional hydrogel dressings with photothermal properties are developed to regulate the microenvironment of diabetic wound sites and accelerate the whole process of its healing without additional medication. The hydrogel is composed of phenylboronic acid-modified chitosan and hyaluronic acid (HA) crosslinked by tannic acid (TA) through borate bonds and Prussian blue nanoparticles (PBNPs) with photothermal response characteristics are embedded in the polymer networks. The results indicate hydrogels show inherent broad-spectrum antioxidative activities through the integrated interaction of borate bonds, TA, and PBNPs. Meanwhile, combined with the regulation of macrophage phenotype by HA, the inflammatory microenvironment of diabetic wounds is transformed. Moreover, the angiogenesis is then enhanced by the mild photothermal effect of PBNPs, followed by promoted epithelialization and collagen deposition. In summary, this hybrid hydrogel system accelerates all stages of wound repair through antioxidative stress, immunomodulation, and proangiogenesis, showing great potential applications in diabetic wound management.

Chondroitin sulfate/silk fibroin hydrogel incorporating graphene oxide quantum dots with photothermal-effect promotes type H vessel-related wound healing

Chronic wounds with bacterial infection present formidable clinical challenges. In this study, a versatile hydrogel dressing with antibacterial and angiogenic activity composite of silk fibroin (SF), chondroitin sulfate (CS), and graphene oxide quantum dots (GOQDs) is fabricated. GOQDs@SF/CS (GSC) hydrogel is rapidly formed through the enzyme catalytic action of horseradish peroxidase. With the incorporation of GOQDs both gelation speed and mechanical properties have been enhanced, and the photothermal characteristics of GOQDs in GSC hydrogel enabled bacterial killing through photothermal treatment (PTT) at ∼51 °C. In vitro studies show that the GSC hydrogels demonstrate excellent antibacterial performance and induce type H vessel differentiation of endothelial cells via the activated ERK1/2 signaling pathway and upregulated SLIT3 expression. In vivo results show that the hydrogel significantly promotes type H vessels formation, which is related to the collagen deposition, epithelialization and, ultimately, accelerates the regeneration of infected skin defects. Collectively, this multifunctional GSC hydrogel, with dual action of antibacterial efficacy and angiogenesis promotion, emerges as an innovative skin dressing with the potential for advancing in infected wound healing.

Bioinspired wet adhesive carboxymethyl cellulose-based hydrogel with rapid shape adaptability and antioxidant activity for diabetic wound repair

Currently, adhesive hydrogels have shown promising effect in chronic diabetic wound repair. However, there are issues and challenges in treating diabetic wounds due to inadequate wet adhesion, unable to fill irregular and deep wounds, and oxidative stress. Herein, a mussel-inspired naturally hydrogel dressing with rapid shape adaptability, wet adhesion and antioxidant abilities for irregular, deep and frequently movement diabetic wounds repair was constructed by comprising catechol modified carboxymethyl cellulose (CMC-DA) and tannic acid. Benefiting from the reversible hydrogen bonding, the resulting hydrogels exhibited injectability, remarkable self-healing ability, rapid shape adaptability and strong tissue adhesion (45.9 kPa), thereby contributing to self-adaptive irregular-shaped wounds or moving joint parts. Especially, the adhesion strength of the hydrogel on wet tissue still remained at 14.9 kPa. Besides, the hydrogels could be easily detached from the skin by ice-cooling that avoided secondary damage caused by dressing change. Remarkably, the hydrogels possessed excellent antioxidant, satisfactory biocompatibility, efficient hemostasis and antibacterial properties. The in vivo evaluation further demonstrated that the hydrogel possessed considerable wound-healing promotion effect by regulating diabetic microenvironment, attributed to that the hydrogel could significantly reduce inflammatory response, alleviate oxidative stress and regulate neovascularization. Overall, this biosafe adhesive hydrogel had great potentials for diabetic wound management.

An adhesion-switchable hydrogel dressing for painless dressing removal without secondary damage

Hydrogels with strong adhesion to wet tissues are considered promising for wound dressings. However, the clinical application of adhesive hydrogel dressing remains a challenge due to the issues of secondary damage during dressing changes. Herein, we fabricated an adhesion-switchable hydrogel formed with poly(acrylamide)-co-poly(N-isopropyl acrylamide), quaternary ammonium chitosan and tannic acid. This hydrogel forms instant and robust adhesion to the skin at body temperature. However, as the temperature rises above the lower critical solution temperature (LCST), the hydrogel loses its adhesion towards the wound area due to the temperature-dependent volume phase transition of the copolymer, occurring around 45 °C. Consequently, the designed hydrogel can be easily detached from adhered tissues upon demand, providing a facile and effective method for painless dressing changes without secondary damage. This hydrogel holds great promise for long-term application in wound dressings.

Bletilla striata Polysaccharide-/Chitosan-Based Self-Healing Hydrogel with Enhanced Photothermal Effect for Rapid Healing of Diabetic Infected Wounds via the Regulation of Microenvironment

The management of diabetic ulcers poses a significant challenge worldwide, and persistent hyperglycemia makes patients susceptible to bacterial infections. Unfortunately, the overuse of antibiotics may lead to drug resistance and prolonged infections, contributing to chronic inflammation and hindering the healing process. To address these issues, a photothermal therapy technique was incorporated in the preparation of wound dressings. This innovative solution involved the formulation of a self-healing and injectable hydrogel matrix based on the Schiff base structure formed between the oxidized Bletilla striata polysaccharide (BSP) and hydroxypropyltrimethylammonium chloride chitosan. Furthermore, the introduction of CuO nanoparticles encapsulated in polydopamine imparted excellent photothermal properties to the hydrogel, which promoted the release of berberine (BER) loaded on the nanoparticles and boosted the antibacterial performance. In addition to providing a reliable physical protection to the wound, the developed hydrogel, which integrated the herbal components of BSP and BER, effectively accelerated wound closure via microenvironment regulation, including alleviated inflammatory reaction, stimulated re-epithelialization, and reduced oxidative stress based on the promising results from cell and animal experiments. These impressive outcomes highlighted their clinical potential in safeguarding the wound against bacterial intrusion and managing diabetic ulcers.

Antibacterial adhesive based on oxidized tannic acid-chitosan for rapid hemostasis

Currently, bacterial infections and bleeding interfere with wound healing, and multifunctional hydrogels with appropriate blood homeostasis, skin adhesion, and antibacterial activity are desirable. In this study, chitosan-based hydrogels were synthesized using oxidized tannic acid (OTA) and Fe3+ as cross-linkers (CS-OTA-Fe) by forming covalent, non-covalent, and metal coordination bonds between Fe3+ and OTA. Our results demonstrated that CS-OTA-Fe hydrogels showed antibacterial properties against Gram-positive bacteria (Staphylococcus aureus)and Gram-negative bacteria (Escherichia coli), low hemolysis rate (< 2 %), rapid blood clotting ability, in vitro (< 2 min), and in vivo (90 s) in mouse liver bleeding. Additionally, increasing the chitosan concentration from 3 wt% to 4.5 wt% enhanced cross-linking in the network, leading to a significant improvement in the strength (from 106 ± 8 kPa to 168 ± 12 kPa) and compressive modulus (from 50 ± 9 kPa to 102 ± 14 kPa) of hydrogels. Moreover, CS-OTA-Fe hydrogels revealed significant adhesive strength (87 ± 8 kPa) to the cow's skin tissue and cytocompatibility against L929 fibroblasts. Overall, multifunctional CS-OTA-Fe hydrogels with tunable mechanical properties, excellent tissue adhesive, self-healing ability, good cytocompatibility, and fast hemostasis and antibacterial properties could be promising candidates for biomedical applications.

Chitosan-based injectable hydrogel with multifunction for wound healing: A critical review

Different types of clinical wounds are difficult to treat while infected by bacteria. Wound repair involves multiple cellular and molecular interactions, which is a complicated process. However, wound repair often suffers from abnormal cellular functions or pathways that result in unavoidable side effects, so there is an urgent need for a material that can heal wounds quickly and with few side effects. Based on these needs, hydrogels with injectable properties have been confirmed to be able to undergo self-healing, which provides favorable conditions for wound healing. Notably, as a biopolymer with excellent easy-to-modify properties from a wide range of natural sources, chitosan can be used to prepare injectable hydrogel with multifunction for wound healing because of its outstanding flowability and injectability. Especially, chitosan-based hydrogels with marked biocompatibility, non-toxicity, and bio-adhesion properties are ideal for facilitating wound healing. In this review, the characteristics and healing mechanisms of different wounds are briefly summarized. In addition, the preparation and characterization of injectable chitosan hydrogels in recent years are classified. Additionally, the bioactive properties of this type of hydrogel in vitro and in vivo are demonstrated, and future trend in wound healing is prospected.

Mussel-inspired tissue adhesive composite hydrogel with photothermal and antioxidant properties prepared from pectin for burn wound healing

Biodegradable self-healing hydrogels with antibacterial property attracted growing attentions in biomedication as wound dressings since they can prevent bacterial infection and promote wound healing process. In this research, a biodegradable self-healing hydrogel with ROS scavenging performance and enhanced tissue adhesion was fabricated from dopamine grafted oxidized pectin (OPD) and naphthoate hydrazide terminated PEO (PEO NH). At the same time, Fe3+ ions were incorporated to endow the hydrogel with near-infrared (NIR) triggered photothermal property to obtain antibacterial activity. The composite hydrogel showed good hemostasis performance based on mussel inspired tissue adhesion with biocompatibility well preserved. As expected, the composition of FeCl3 improved conductivity and endowed photothermal property to the hydrogel. The in vivo wound repairing experiment revealed the 808 nm NIR light triggered photothermal behavior of the hydrogel reduced the inflammation response and promoted wound repairing rate. As a result, this composite FeCl3/hydrogel shows great potential to be an excellent wound dressing for the treatment of infection prong wounds with NIR triggers.

Expansion-clotting chitosan fabrics based on unidirectional fast-absorption fibers for rapid hemorrhage control

The rapid absorption of water from the blood to concentrate erythrocytes and platelets, thus triggering quick closure, is important for hemostasis. Herein, expansion-clotting chitosan fabrics are designed and fabricated by ring spinning of polylactic acid (PLA) filaments as the core layer and highly hydrophilic carboxyethyl chitosan (CECS) fibers as the sheath layer, and subsequent knitting of obtained PLA@CECS core spun yarns. Due to the unidirectional fast-absorption capacity of CECS fibers, the chitosan fabrics can achieve erythrocytes and platelets aggregate quickly by concentrating blood, thus promoting the formation of blood clots. Furthermore, the loop structure of coils formed in the knitted fabric can help them to expand by absorbing water to close their pores, providing effective sealing for bleeding. Besides, They have enough mechanical properties, anti-penetrating ability, and good tissue-adhesion ability in wet conditions, which can form a physical barrier to resist blood pressure during hemostasis and prevent them from falling off the wound, thus enhancing hemostasis synergistically. Therefore, the fabrics exhibit superior hemostatic performance in the rabbit liver, spleen, and femoral artery puncture injury model compared to the gauze group. This chitosan fabric is a promising hemostatic material for hemorrhage control.

Incorporation of Resveratrol-Hydroxypropyl-β-Cyclodextrin Complexes into Hydrogel Formulation for Wound Treatment

Resveratrol could be applied in wound healing therapies because of its antioxidant, anti-inflammatory and antibacterial effects. However, the main limitation of resveratrol is its low aqueous solubility. In this study, resveratrol was included in hydroxypropyl-β-cyclodextrin complexes and further formulated in Pluronic F-127 hydrogels for wound treatment therapy. IR-spectroscopy and XRD analysis confirmed the successful incorporation of resveratrol into complexes. The wound-healing ability of these complexes was estimated by a scratch assay on fibroblasts, which showed a tendency for improvement of the effect of resveratrol after complexation. The antimicrobial activity of resveratrol in aqueous dispersion and in the complexes was evaluated on methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Candida albicans strains. The results revealed a twofold decrease in the MIC and stronger inhibition of the metabolic activity of MRSA after treatment with resveratrol in the complexes compared to the suspended drug. Furthermore, the complexes were included in Pluronic hydrogel, which provided efficient drug release and appropriate viscoelastic properties. The formulated hydrogel showed excellent biocompatibility which was confirmed via skin irritation test on rabbits. In conclusion, Pluronic hydrogel containing resveratrol included in hydroxypropyl-β-cyclodextrin complexes is a promising topical formulation for further studies directed at wound therapy.

A novel injectable thermo/photo dual-crosslinking hydrogel based on modified chitosan for fast sealing open globe injury

Open globe injuries (OGIs) demand immediate attention to prevent further complications and improve vision prognosis. Herein, we developed a thermo/photo dual-crosslinking injectable hydrogel, HBC_m_Arg, for rapidly sealing OGIs in emergency ophthalmic cases. HBC_m_Arg was prepared with arginine and methacrylic anhydride modified hydroxybutyl chitosan (HBC). HBC_m_Arg was initially in liquid form at 25 °C, enabling easy injection at the injury site. After reaching the ocular surface temperature, it underwent reversible heat-induced gelation to achieve in situ transformation. Further, HBC_m_Arg was capable of rapid photocrosslinking under UV light, forming a dual network structure to bolster mechanical strength, thereby facilitating effective OGI closure. Biocompatibility assessments, including in vitro studies with three ocular cell types and in vivo experiments on rabbit eyes, confirmed the safety profile of HBC_m_Arg. Ex vivo and in vivo burst pressure tests demonstrated the hydrogel's ability to promptly restore intraocular pressure and withstand elevated pressures, underscoring its potential for OGI stabilization. Additionally, the suitable degradation of HBC_m_Arg within ocular tissues, coupled with its stability in ex vivo assessments, presented a delicate balance between stability and biodegradability. In conclusion, HBC_m_Arg holds promise for improving emergency ophthalmic care by providing a rapid, effective, and safe way to seal OGIs in critical situations.

Preparation of nano-silver containing black phosphorus based on quaternized chitosan hydrogel and evaluating its effect on skin wound healing

Hydrogels with favorable biocompatibility and antibacterial properties are essential in postoperative wound hemorrhage care, facilitating rapid wound healing. The present investigation employed electrostatic adsorption of black phosphorus nanosheets (BPNPs) and nano‑silver (AgNPs) to cross-link the protonated amino group NH3+ of quaternized chitosan (QCS) with the hydroxyl group of hyaluronic acid (HA). The electrostatic interaction between the two groups resulted in the formation of a three-dimensional gel network structure. Additionally, the hydrogel containing AgNPs deposited onto BPNPs was assessed for its antibacterial properties and effects on wound healing. Hydrogel demonstrated an outstanding drug-loading capacity and could be employed for wound closure. AgNPs loaded on the BPNPs released silver ions and exhibited potent antibacterial properties when exposed to 808 nm near-infrared (NIR) radiation. The ability of the hydrogel to promote wound healing in an acute wound model was further evaluated. The BPNPs were combined with HA and QCS in the aforementioned hydrogel system to improve adhesion, combine the photothermal and antibacterial properties of the BPNPs, and promote wound healing. Therefore, the reported hydrogels displayed excellent biocompatibility and hold significant potential for application in the field of tissue engineering for skin wound treatment.