A functional chitosan-based hydrogel as a wound dressing and drug delivery system in the treatment of wound healing

Revolutionizing pressure ulcer regeneration: Unleashing the potential of extracellular matrix-derived temperature-sensitive injectable antioxidant hydrogel for superior stem cell therapy

Pressure ulcers are a common issue in elderly and medically compromised individuals, posing significant challenges in healthcare. Human umbilical cord mesenchymal stem cells (HUMSCs) offer therapeutic benefits like inflammation modulation and tissue regeneration, yet challenges in cell survival, retention, and implantation rates limit their clinical application. Hydrogels in three-dimensional (3D) stem cell culture mimic the microenvironment, improving cell survival and therapeutic efficacy. A thermosensitive injectable hydrogel (adEHG) combining gallic acid-modified hydroxybutyl chitosan (HBC-GA) with soluble extracellular matrix (adECM) has been developed to address these challenges. The hybrid hydrogel, with favorable physical and chemical properties, shields stem cells from oxidative stress and boosts their therapeutic potential by clearing ROS. The adEHG hydrogel promotes angiogenesis, cell proliferation, and collagen deposition, further enhancing inflammation modulation and wound healing through the sustained release of therapeutic factors and cells. Additionally, the adEHG@HUMSC composite induces macrophage polarization towards an M2 phenotype, which is crucial for wound inflammation inhibition and successful healing. Our research significantly propels the field of stem cell-based therapies for pressure ulcer treatment and underscores the potential of the adEHG hydrogel as a valuable tool in advancing regenerative medicine.

Physicochemically Cross-linked Injectable Hydrogel: an Adhesive Skin Substitute for Burned Wound Therapy

Burns carry a large surface area, varying in shapes and depths, and an elevated risk of infection. Regardless of the underlying etiology, burns pose significant medical challenges and a high mortality rate. Given the limitations of current therapies, tissue-engineering-based treatments for burns are inevitable. Herein, we developed a natural physicochemically cross-linked adhesive injectable skin substitute (SS) comprising chitosan (Ch) and silk fibroin (SF), cross-linked with tannic acid (TA) through hydrogen bonding, and incorporated with fresh platelet-rich fibrin (FPRF). SF was also chimerically cross-linked with riboflavin (RF) under visible light to ensure desirable biodegradability rate and nontoxicity. Double cross-linked SS exhibited a semibilayer (SBSS) structure with smaller pores in the upper layer. In the CaCl2-treated FPRF, the activated platelets augmented vascular endothelial growth factor (VEGF) and platelet-derived GF (PDGF) release. The resultant SBSS possessed optimal adhesion, hemocompatibility, and significant antibacterial and antioxidant activities (P ≤ 0.05). The rat liver injury model confirmed the rapid hemostatic effect of SBSS. Furthermore, the bottom layer of SBSS promoted L929 fibroblast growth, proliferation, and migration. SBSS-treated wounds showed lower inflammatory cells, earlier epithelialization, significant angiogenesis, and faster healing. The proposed SBSS could be an ideal remedy for burn wound therapy.

Preparation of a chitosan/polyvinyl alcohol-based dual-network hydrogel for use as a potential wound-healing material for the sustainable release of drugs

Treating chronic wounds poses significant challenges in clinical medicine due to bacterial infection, reactive oxygen species (ROS) accumulation, and excessive inflammation. This study aimed to address these issues by developing a wound dressing with antibacterial, antioxidant, and anti-inflammatory properties. Chitosan was functionally modified with acrolein to covalently bind to epigallocatechin gallate (EGCG), enabling a high EGCG load. Subsequently, polyvinyl alcohol (PVA) and EGCG-modified chitosan were crosslinked to prepare a new double-network hydrogel with added cysteine (CSAEC/P50). CSAEC/P50 demonstrated optimal mechanical properties (low swelling rate, high water retention, and optimal flexibility), low hemolysis, high coagulation properties, and antibacterial and antioxidant activities. Cell scratch tests indicated that CSAEC/P50 can promote NIH3T3 cell migration. Immunofluorescence results showed that CSAEC/P50 promoted the transformation of proinflammatory M1 macrophages to anti-inflammatory M2 macrophages. These findings suggest that CSAEC/P50 has significant potential for use in wound dressing applications.

Development of HEMA-Succinic Acid-PEG Bio-Based Monomers for High-Performance Hydrogels in Regenerative Medicine

In recent years, hydrogels have found a special place in regenerative medicine for tissue repair, rehabilitation, and drug delivery. To be used in regenerative medicine, hydrogels must have desirable physical, chemical, and biological properties. In this study, a new biomonomer based on hydroxyethyl methacrylate-succinic acid-polyethylene glycol 200 (HEMA-Suc-PEG) was synthesized and characterized. Then, using the synthesized monomers and different ratios of polyethylene glycol diacrylate (PEGDA) as a crosslinker, biocompatible hydrogels were synthesized through thermal and UV curing methods. The mechanical, physical, chemical, and biological properties of the hydrogels and the behavior of endothelial cells, an essential component of the cardiovascular system, were evaluated. The results showed that the hydrogel synthesized with 0.2 g of PEGDA (UV curing) has desirable mechanical and physical properties. Biological tests showed that these hydrogels are not only nontoxic to cells but also enhance cell adhesion. Therefore, the hydrogel containing the synthesized monomer HEMA-Suc-PEG and 0.2 g of PEGDA has the potential to be used in the cardiovascular system.

Tissue adhesive hyaluronan-quercetin (Ago)@halloysite-fungal carboxymethyl chitosan nanocomposite hydrogels for wound dressing applications

This study investigates nanocomposite hydrogels reinforced with hyaluronan-quercetin‑silver nanoparticles intercalated halloysite clay (HAQ-Hal-Ag) for potential application as wound dressings. HAQ-Hal-Ag (at 1, 3, and 5 wt%) was incorporated into a fungal carboxymethyl chitosan (FC)/polyacrylamide (PAM) network (FC-PAM) using methylene bisacrylamide (MBA) as the crosslinker and ammonium persulfate (APS) as the initiator. Various physicochemical analyses were performed to characterize the resulting hydrogels. The compressive strength of the nanocomposite hydrogels exhibited a proportional increase with increasing HAQ-Hal-Ag content, reaching a remarkable 1.04 MPa for hydrogels containing 5 wt% HAQ-Hal-Ag. Additionally, the hydrogels displayed highly porous structures with excellent swelling capacity. Importantly, they exhibited exceptional antibacterial efficacy against Escherichia coli and Staphylococcus aureus. Furthermore, cytotoxicity assays revealed high cell viability and proliferation rates, confirming the biocompatibility of these hydrogels with human dermal fibroblasts. These findings suggest significant promise for the nanocomposite hydrogels as wound dressing materials due to their outstanding biocompatibility, impressive compressive strength, and potent antibacterial activity.

Green synthesized ZnO and ZnO-based composites for wound healing applications

In recent years, zinc oxide nanoparticles (ZnO NPs) have gained much attention in biomedical applications because of their distinctive physicochemical features such as low toxicity and biocompatible properties. Traditional methods to produce ZnO NPs sometimes include harmful substances and considerable energy consumption, causing environmental issues and potential health risks. Nowadays, the concern of ZnO production has moved toward environmentally friendly and sustainable synthesis methods, using natural extracts or plant-based precursors. This review discusses the green synthesis of ZnO NPs utilizing various plant extracts for wound healing applications. Moreover, ZnO NPs have antibacterial characteristics, which can prevent infection, a substantial obstacle in wound healing. Their ability to maintain inflammation, proliferation, oxidative stress, and promote angiogenesis proves their critical role in wound closure. In addition, ZnO NPs can also be easily and ideally incorporated with wound dressings and scaffolds such as hydrogel, chitosan, cellulose, alginate, and other materials, due to their exceptional mechanical properties. The latest publication of green synthesis of ZnO NPs and their applications for wound healing has been discussed. Therefore, this review provides a current update of knowledge on the sustainable and biocompatible ZnO NPs for specific applications, i.e., wound healing applications. In addition, the green synthesis of ZnO NPs using plant extracts also provides a particular approach in terms of material preparation, which is different from previous review articles.

The Paradoxical Immunomodulatory Effects of Chitosan in Biomedicine

Chitosan is widely explored in the field of biomedicine due to its abundance and reported properties, including biocompatibility, biodegradability, non-toxicity, mucoadhesion, and anti-microbial activity. Although our understanding of the immune response to chitosan has evolved, confusion remains regarding whether chitosan is a pro- or anti-inflammatory biomaterial. Tackling this knowledge gap is essential for the translation of chitosan-based biomaterials to clinical use. Herein, we provide an overview of the immune responses to chitosan, exploring the roles of endotoxin contamination and physiochemical properties in immunomodulation. Ultimately, this literature review concludes that various physiochemical properties, including molecular weight, degree of deacetylation and polydispersity, endotoxin contamination, and cellular environment, interplay in the complex process of chitosan immunomodulation, which can lead to both pro- and anti-inflammatory effects.

A novel sustained-release agent based on disulfide-induced recombinant collagen hydrogels for the prevention and treatment of Schistosoma infections

Schistosomiasis is commonly managed using the praziquantel, but it is only effective against adult worms and duration of action is short. Liver fibrosis will worsen if eggs are still present after stopping treatment. Therefore, this study aimed to develop a sustained drug release system for effectively preventing and treating schistosomiasis. A disulfide bond-induced three-dimensional (3D) recombinant collagen hydrogel was developed for sustained praziquantel release. Three collagen sequences were developed based on the sequence for Scl2 of S. pyogene, with different substitutions of residues for cysteine (S-VCL-S1, S-VCL-S2, and S-VCL-S3). Their properties were tested. Mice were infected with Schistosoma japonicum cercariae and treated either with praziquantel collagen hydrogel or niclosamide collagen hydrogel. The worm-killing effect was examined. The application of hydrogel-niclosamide on the skin for 24 h effectively prevented Schistosome cercariae from infecting mice and showed 70.95% and 81.73% reduction in the number of eggs and worms, respectively. The combined use of niclosamide and anti-cercariae cream showed 100% protection after 24 h. The hydrogel-praziquantel also showed a 100% reduction of worms and eggs after 24 h of subcutaneous injection. The subcutaneous injection of praziquantel after 28 days of infection showed 95.19% and 80.12% reduction of worm and egg counts, respectively, and the development of larvae was significantly slowed down. Liver analysis showed no infection after 7 days of treatment. These results suggest developing a novel type of sustained-release agent against schistosomiasis based on the recombinant collagen hydrogel that provides a potential new treatment for schistosomiasis.IMPORTANCEThis study introduces an new way for treating schistosomiasis: a special collagen hydrogel that gradually releases medication to treat schistosomiasis effectively. This innovation provides a promising way to treat schistosomiasis. It represents a significant step forward in the fight against this disease and offers hope for more effective and safer treatments in the future.

Physicochemical characteristics of chitosan molecules: Modeling and experiments

Chitosan, a biocompatible polysaccharide, finds a wide range of applications, inter alia as an antimicrobial agent, stabilizer of food products, cosmetics, and in the targeted delivery of drugs and stem cells. This work represents a comprehensive review of the properties of chitosan molecule and its aqueous solutions uniquely combining theoretical modeling and experimental results. The emphasis is on physicochemical aspects which were sparsely considered in previous reviews. Accordingly, in the first part, the explicit solvent molecular dynamics (MD) modeling results characterizing the conformations of chitosan molecule, the contour length, the chain diameter and the density are discussed. These MD data are used to calculate several parameters for larger chitosan molecules using a hybrid approach based on continuous hydrodynamics. The dependencies of hydrodynamic diameter, frictional ratio, radius of gyration, and intrinsic viscosity on the molar mass of molecules are presented and discussed. These theoretical predictions, comprising useful analytical solutions, are used to interpret and rationalize the extensive experimental data acquired by advanced experimental techniques. In the final part, the molecule charge, acid-base, and electrokinetic properties, comprising the electrophoretic mobility and the zeta potential, are reviewed. Future research directions are defined and discussed.

Smart hydrogels for rapid wound repair: Chitosan-PVP matrices empowered by bimetallic MOF nanocages

In wound treatment, sustainable and effective dressings are crucial for rapid healing without scarring. Antimicrobial transparent hydrogel dressings were fabricated by grafting chitosan with polyvinyl pyrrolidone and impregnating it with zinc or zinc-silver metal-organic framework nanocages (30-50 nm). Characterization confirmed the hydrogels' excellent physical and chemical integrity. Comprehensive antibacterial, antifungal, and ion-release evaluations validated their efficacy, demonstrating remarkable results. These dressings also promoted a moisture-balanced environment ideal for wound healing. Comprehensive evaluations of these hydrogel dressings' antibacterial, antifungal, and ion-release properties confirmed their efficacy, demonstrating remarkable results. The dressings also promoted a moisture-balanced environment optimal for wound healing. Cytotoxicity tests on skin cells indicated that the hydrogels were safe and enhanced cell proliferation. Notably, CS/PVP hydrogels with bimetallic nanocages (CS/PVP4) achieved up to 69 % healing within 7 days. This rapid healing occurred due to the reduction of inflammation and IL-1 content in the dermis; the downregulation of MMP9 halted the breakdown of the extracellular matrix (ECM); the upregulation of TGF accelerated cell growth and raised the levels of collagen 1 and -SMA in the ECM. These findings suggest that the developed hydrogel dressings will provide sustainable wound healing, thereby increasing patient satisfaction.

Sustainable lignin-based composite hydrogels for controlled drug release and self-healing in antimicrobial wound dressing

Bacterial infections pose a significant threat to global public health, demanding innovative solutions in biomedical field. Lignin is a naturally abundant polyphenol-rich polymer, offer promising potential to fabricate advance biomaterials for biomedical applications. Hence, a composite hydrogel with antimicrobial and antioxidant activities based on the development of dynamic covalent bonds among sodium alginate, lignin and epigallocatechin-3-gallate (EGCG) was designed. Lignin provides structural integrity to hydrogel backbone as well as released synergistically with the drug. This synergistic effect of the pH-responsive controlled release of both EGCG and lignin improved the releasing ability and bioactivity of the hydrogels. In in vitro antimicrobial experiments, the addition of 3.08 wt% lignin significantly enhanced bactericidal efficacy against Escherichia coli and Staphylococcus aureus, raising the killing rate from 20 % to over 96 %. The dynamic borate bond allows hydrogel network to repair itself when it is disrupted. Its self-healing ability, pH-responsive drug delivery, biocompatibility and strong antimicrobial and antioxidant effects make it a promising candidate for chronic wound management. This lignin-based hydrogel marks a significant innovation in sustainable, multifunctional biomedical materials.

All-aqueous microfluidic fabrication of calcium alginate/alkylated chitosan core-shell microparticles with time-sequential functions for promoting whole-stage wound healing

Wound healing comprises a series of complex physiological processes, including hemostasis, inflammation, cell proliferation, and tissue remodeling. Designing new functional biomaterials by biological macromolecules with tailored therapeutic effects to precisely match the unique requirements of each stage is cherished but rarely discussed. Here, we employ all-aqueous microfluidics to fabricate multifunctional core-shell microparticles aimed at promoting whole-stage wound healing. These microparticles feature a core comprising calcium alginate, cellulose nanocrystals and epidermal growth factor, surrounded by a shell made of alkylated chitosan, alginate, and ciprofloxacin (EGF + CNC@Ca-ALG/CIP@ACS core-shell microparticles, D-CSMP). Response surface methodology (RSM) with a combination of central composite rotatable design (CCRD) is used to meticulously optimize the fabrication processes, endowing the resulting D-CSMP with superior capabilities for efficiently encapsulating and controlled releasing CIP and EGF tailored to each stage aligning the healing timeline. The developed D-CSMP demonstrate notable time-sequential functionalities, including promoting blood coagulation, enhancing hemostasis, and exerting antibacterial effects. Furthermore, in a skin injury model, D-CSMP significantly expedite and enhance the chronic wound healing process. In conclusion, our core-shell microparticles with notable time-sequential functions present a versatile and robust approach for wound treatment and related biomedical applications.

Progress in the Application of Hydrogels in Intervertebral Disc Repair: A Comprehensive Review

PURPOSE OF REVIEW

Intervertebral disc degeneration (IVDD) is a common orthopaedic disease and an important cause of lower back pain, which seriously affects the work and life of patients and causes a large economic burden to society. The traditional treatment of IVDD mainly involves early pain relief and late surgical intervention, but it cannot reverse the pathological course of IVDD. Current studies suggest that IVDD is related to the imbalance between the anabolic and catabolic functions of the extracellular matrix (ECM). Anti-inflammatory drugs, bioactive substances, and stem cells have all been shown to improve ECM, but traditional injection methods face short half-life and leakage problems.

RECENT FINDINGS

The good biocompatibility and slow-release function of polymer hydrogels are being noticed and explored to combine with drugs or bioactive substances to treat IVDD. This paper introduces the pathophysiological mechanism of IVDD, and discusses the advantages, disadvantages and development prospects of hydrogels for the treatment of IVDD, so as to provide guidance for future breakthroughs in the treatment of IVDD.

The interplay of skin architecture and cellular dynamics in wound healing: Insights and innovations in care strategies

Wound healing involves complex interactions among skin layers: the epidermis, which epithelializes to cover wounds; the dermis, which supports granulation tissue and collagen production; and the hypodermis, which protects overall skin structure. Key factors include neutrophils, activated by platelet degranulation and cytokines, and fibroblasts, which aid in collagen production during proliferation. The healing process encompasses inflammation, proliferation, and remodeling, with angiogenesis, fibroplasia, and re-epithelialization crucial for wound closure. Angiogenesis is characterized by the creation of collateral veins, the proliferation of endothelial cells, and the recruitment of perivascular cells. Collagen is produced by fibroblasts in granulation tissue, aiding in the contraction of wounds. The immunological response is impacted by T cells and cytokines. External topical application of various formulations and dressings expedites healing and controls microbial contamination. Polymeric materials, both natural and synthetic, and advanced dressings enhance healing by providing biodegradability, biocompatibility, and infection control, thus addressing tissue regeneration challenges. Numerous dressings promote healing, including films, hydrocolloids, hydrogels, foams, alginates, and tissue-engineered substitutes. Wound dressings are treated with growth factors, particularly PDGF, and antibacterial drugs to prevent infection. The challenges of tissue regeneration and infection control are evolving along with the field of wound care.

Enhancing Wound Healing With Sprayable Hydrogel Releasing Multi Metallic Ions: Inspired by the Body's Endogenous Healing Mechanism

In the pursuit of new wound care products, researchers are exploring methods to improve wound healing through exogenous wound healing products. However, diverging from this conventional approach, this work has developed an endogenous support system for wound healing, drawing inspiration from the body's innate healing mechanisms governed by the sequential release of metal ions by body at wound site to promote different stages of wound healing. This work engineers a multi-ion-releasing sprayable hydrogel system, to mimic this intricate process, representing the next evolutionary step in wound care products. It comprises Alginate (Alg) and Fibrin (Fib) hydrogel infused with Polylactic acid (PLA) polymeric microcarriers encapsulating multi (calcium, copper, and zinc) nanoparticles (Alg-Fib-PLA-nCMB). Developed sprayable Alg-Fib-PLA-nCMB hydrogel show sustained release of beneficial multi metallic ions at wound site, offering a range of advantages including enhanced cellular function, antibacterial properties, and promotion of crucial wound healing processes like cell migration, ROS mitigation, macrophage polarization, collagen deposition, and vascular regeneration. In a comparative study with a commercial product (Midstress spray), developed Alg-Fib-PLA-nCMB hydrogel demonstrates superior wound healing outcomes in a rat model, indicating its potential for next generation wound care product, addressing critical challenges and offering a promising avenue for future advancements in the wound management.

Recent advancements in bioadhesive self-healing hydrogels for effective chronic wound care

Chronic wounds are a critical and costly complication that affects millions of patients each year, especially patients suffering from diabetes, and constitute a serious global healthcare problem that needs immediate attention. In this direction, novel dressings that can integrate appropriate physicochemical and biological features, mechanical durability, and the capacity for therapy are of great clinical importance. For instance, self-healable hydrogels, with antibacterial activity and high tissue adhesion, have attracted increasing attention for wound management applications. Despite their potential, existing self-healable hydrogel networks exhibit limitations in mechanical strength and adhesion, tissue regeneration, antibacterial efficacy, and scalability, indicating a need for further improvement in the field. This review focuses on exactly these recent advances in the field with a special focus on self-healing adhesive hydrogel-based wound dressings as well as their structures, construction strategies, adhesion mechanisms, and emerging usage in the wound healing field. By shedding light on these developments, we aim to contribute to the ongoing pursuit of enhanced solutions for chronic wound care.

Stability, challenges, and prospects of chitosan for the delivery of anticancer drugs and tissue regenerative growth factors

Chitosan, a biopolymer derived from chitin, offers significant potential for regulated anticancer drug administration and tissue regeneration growth factors, owing to its biocompatibility, low toxicity, biodegradability, and little immunogenicity. Moreover, its structure can be extensively modified, for example, to create scaffolds, hydrogels, nanoparticles, and membranes, allowing it to be engineered precisely to achieve specific outcomes However, the therapeutic utilisation of chitosan is impeded by significant challenges, such as its inadequate hemocompatibility, durability, and uniformity in commercial manufacturing. Additionally, there is insufficient research offering a thorough examination of the capabilities, limitations, and challenges related to chitosan as carriers for anticancer drugs and growth factors. This article examines the stability, challenges, and advanced application of chitosan as a drug carrier in anti-cancer therapy and growth factor delivery. The problems of unregulated chitosan degradation arising from unsuitable storage conditions are considered and potential solutions, and areas for future research, are proposed to deal with such problems. Consequently, this review is expected to be highly valuable for aspiring scientists studying chitosan-related systems for delivery of anti-cancer drugs and growth factors.

New insights into the role of cellular senescence and chronic wounds

Chronic or non-healing wounds, such as diabetic foot ulcers (DFUs), venous leg ulcers (VLUs), pressure ulcers (PUs) and wounds in the elderly etc., impose significant biological, social, and financial burdens on patients and their families. Despite ongoing efforts, effective treatments for these wounds remain elusive, costing the United States over US$25 billion annually. The wound healing process is notably slower in the elderly, partly due to cellular senescence, which plays a complex role in wound repair. High glucose levels, reactive oxygen species, and persistent inflammation are key factors that induce cellular senescence, contributing to chronic wound failure. This suggests that cellular senescence may not only drive age-related phenotypes and pathology but also be a key mediator of the decreased capacity for trauma repair. This review analyzes four aspects: characteristics of cellular senescence; cytotoxic stressors and related signaling pathways; the relationship between cellular senescence and typical chronic non-healing wounds; and current and future treatment strategies. In theory, anti-aging therapy may influence the process of chronic wound healing. However, the underlying molecular mechanism is not well understood. This review summarizes the relationship between cellular senescence and chronic wound healing to contribute to a better understanding of the mechanisms of chronic wound healing.

A comprehensive review of the application of 3D-bioprinting in chronic wound management

INTRODUCTION

Chronic wounds require more sophisticated care than standard wound care because they are becoming more severe as a result of diseases like diabetes. By resolving shortcomings in existing methods, 3D-bioprinting offers a viable path toward personalized, mechanically strong, and cell-stimulating wound dressings.

AREAS COVERED

This review highlights the drawbacks of traditional approaches while navigating the difficulties of managing chronic wounds. The conversation revolves around employing natural biomaterials for customized dressings, with a particular emphasis on 3D-bioprinting. A thorough understanding of the uses of 3D-printed dressings in a range of chronic wound scenarios is provided by insights into recent research and patents.

EXPERT OPINION

The expert view recognizes wounds as a historical human ailment and emphasizes the growing difficulties and expenses related to wound treatment. The expert acknowledges that 3D printing is revolutionary, but also points out that it is still in its infancy and has the potential to enhance mass production rather than replace it. The review highlights the benefits of 3D printing for wound dressings by providing instances of smart materials that improve treatment results by stimulating angiogenesis, reducing pain, and targeting particular enzymes. The expert advises taking action to convert the technology's prospective advantages into real benefits for patients, even in the face of resistance to change in the healthcare industry. It is believed that the increasing evidence from in-vivo studies is promising and represents a positive change in the treatment of chronic wounds toward sophisticated 3D-printed dressings.

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.

A review of lignin application in hydrogel dressing

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