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

Advanced healing potential of simple natural hydrogel loaded with sildenafil in combating infectious wounds

Infected wounds are common clinical injuries that often complicated by inflammation and oxidative stress due to bacterial invasion. These wounds typically suffer from impaired vascularization, which delays healing and increases the risk of complications such as sepsis and chronic wounds. Therefore, developing an effective treatment for infected wounds is highly necessary. Egg white can promote cell regeneration and repair, while chitosan is effective in resisting bacterial invasion. Sildenafil is believed to have the potential to promote angiogenesis. Based on these properties, we have prepared a new type of hydrogel using egg white and chitosan as the framework, loaded with sildenafil (CEHS). The hydrogel combines the benefits of its components, exhibiting good biocompatibility and promoting the proliferation and migration of NIH 3T3 (3T3) cells and human umbilical vein endothelial cells (HUVEC), as well as the angiogenesis in HUVEC. It also exhibits significant antioxidant, anti-inflammatory, and antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Additionally, in a mouse model of infected wounds, the CEHS effectively promoted wound healing through its excellent antioxidant and anti-inflammatory properties, antibacterial activity, and pro-angiogenic effects. In summary, this simple-to-prepare, multifunctional natural hydrogel shows great promise for the treatment of infected wounds.

Morphology and topography of chitosan-Zn complex/PEO fiber mats influence cell viability and attachment

Electrospun fiber mats with therapeutic potential show great promise as wound healing biomaterials. This study aims to compare the biophysical properties and biocompatibility of four different biodegradable fiber mats; namely chitosan and chitosan‑zinc complex (ChiZn)/(polyethylene oxide) PEO fibers, each with either nanometer-sized (~200 nm) or micron-sized (~1000 nm) diameters. Zn was incorporated to impact antibacterial properties of the fibers, ChiZn was synthesized using the in-situ precipitation method, and the influence of zinc chelation on the material structure and morphology was assessed using XRD, FTIR, XPS, and EDX, documenting the complexation and homogeneous distribution of zinc. ChiZn was then blended with PEO for electrospinning in a benign solvent system and crosslinked with glutaraldehyde vapor. SEM was used to examine fiber morphology while AFM documented a correlation between the roughness and fiber diameter. The effects of topography and composition on the viability, adhesion, and proliferation of stromal cells and mouse fibroblasts were investigated, showing higher cell viability on mats composed of nanosized fibers, whereas complex fiber mat composed of micron-sized fiber reduced their viability. SEM evaluations showed that cells spread only on the surface of the nanosized fibers, independently of the presence of Zn, while infiltration into the mat was observed for micron-sized fibers.

The design principle of natural polysaccharide hydrogels for promoting wound healing: a prospective review

Acute skin injuries and chronic non-healing wounds are common in daily life, posing significant physical trauma to patients and creating substantial social and economic burdens. Polysaccharide-based hydrogels not only maintain optimal moisture levels for wound recovery but also act as effective barriers against bacterial infection. Polysaccharides, with their unique properties such as biocompatibility, biodegradability, and non-toxicity, are promising materials for constructing hydrogels designed for wound healing. This review discusses wound physiology, key design factors for wound-healing hydrogels, and the fundamental principles of hydrogel gelation. It also provides an overview of the current applications of polysaccharide-based hydrogels-including those derived from hyaluronic acid, chitosan, sodium alginate, cellulose, glucose, and starch-as advanced wound dressings. Finally, the review outlines current challenges and future research directions for polysaccharide-based hydrogels in wound healing, aiming to inspire further exploration and innovation in this field.

Polymer Applied in Hydrogel Wound Dressing for Wound Healing: Modification/Functionalization Method and Design Strategies

Hydrogel wound dressings have emerged as a promising solution for wound healing due to their excellent mechanical and biochemical properties. Over recent years, there has been significant progress in expanding the variety of raw materials used for hydrogel formulation along with the development of advanced modification techniques and design approaches that enhance their performance. However, a comprehensive review encompassing diverse polymer modification strategies and design innovations for hydrogel dressings is still lacking in the literature. This review summarizes the use of natural polymers (e.g., chitosan, gelatin, sodium alginate, hyaluronic acid, and dextran) and synthetic polymers (e.g., poly(vinyl alcohol), polyethylene glycol, Pluronic F-127, poly(N-isopropylacrylamide), polyacrylamide, and polypeptides) in hydrogel wound dressings. We further explore the advantages and limitations of these polymers and discuss various modification strategies, including cationic modification, oxidative modification, double-bond modification, catechol modification, etc. The review also addresses design principles and synthesis methods, aligning polymer modifications with specific requirements in wound healing. Finally, we discuss future challenges and opportunities in the development of advanced hydrogel-based wound dressings.

Bioactive hydrogel formulations for regeneration of pathological bone defects

Bone defects caused by osteoporosis, infection, diabetes, post-tumor resection, and nonunion often cause severe pain and markedly increase morbidity and mortality, which remain a significant challenge for orthopedic surgeons. The precise local treatments for these pathological complications are essential to avoid poor or failed bone repair. Hydrogel formulations serve as injectable innovative platforms that overcome microenvironmental obstacles and as delivery systems for controlled release of various bioactive substances to bone defects in a targeted manner. Additionally, hydrogel formulations can be tailored for specific mechanical strengths and degradation profiles by adjusting their physical and chemical properties, which are crucial for prolonged drug retention and effective bone repair. This review summarizes recent advances in bioactive hydrogel formulations as three-dimensional scaffolds that support cell proliferation and differentiation. It also highlights their role as smart drug-delivery systems with capable of continuously releasing antibacterial agents, anti-inflammatory drugs, chemotherapeutic agents, and osteogenesis-related factors to enhance bone regeneration in pathological areas. Furthermore, the limitations of hydrogel formulations in pathological bone repair are discussed, and future development directions are proposed, which is expected to pave the way for the repair of pathological bone defects.

Innovating chitosan-based bioinks for dermal wound healing: Current progress and future prospects

The field of three-dimensional (3D) bio/printing, known as additive manufacturing (AM), heavily relies on bioinks possessing suitable mechanical properties and compatibility with living cells. Among the array of potential hydrogel precursor materials, chitosan (CS) has garnered significant attention due to its remarkable physicochemical and biological attributes. These attributes include biodegradability, nontoxicity, antimicrobial properties, wound healing promotion, and immune system activation, making CS a highly appealing hydrogel-based bioink candidate. This review explores the transformative potential of CS-based bioink for enhancing dermal wound healing therapies. We highlight CS's unique qualities that make it an optimal choice for bioink development. Advancements in 3D bio/printing technology for tissue engineering (TE) are discussed, followed by an examination of strategies for CS-based bioink formulation and their impacts on wound healing. To address the progress in translating advanced wound healing from lab to clinic, we highlight the current and ongoing research in CS-based bioink for 3D bio/printing in skin wound healing applications. Finally, we explore current evidence, commercialization prospects, emerging innovations like 4D printing, and the challenges and future directions in this promising field.

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.

Recent developments in the design of functional derivatives of edaravone and exploration of their antioxidant activities

Edaravone, a pyrazalone derivative, is an antioxidant and free radical scavenger used to treat oxidative stress-related diseases. It is a proven drug to mitigate conditions prevailing to oxidative stress by inhibiting lipid peroxidation, reducing inflammation, and thereby preventing endothelial cell death. In recent years, considerable interest has been given by researchers in the derivatization of edaravone by adding varieties of substituents of versatile steric and functional properties to improve its antioxidant and pharmacological activity. This review accounts all the important methods developed for the derivatization of edaravone and the impacts of the structural modifications on the antioxidant activity of the motif.

Development and evaluation of chitosan-coated virgin coconut oil-asiatic acid-loaded nanoemulgel for enhanced wound management

Wound management remains a significant challenge due to complications such as delayed healing and microbial infections, particularly in the conditions like diabetes mellitus, vascular disorders, and immunosuppression. This study aimed to develop a chitosan-coated virgin coconut oil-asiatic acid-loaded nanoemulsion gel (CS-ASA-NEG) to enhance wound healing outcomes. A central composite design (CCD) was employed using Design Expert 11 software to optimize the nanoemulsion formulation, with ternary phase diagrams (TPD) evaluating stable regions for Tween 20: Span 80 (T20:S80) ratios. The optimized 4:1 ratio yielded a nanoemulsion with a globule size of 131.80 ± 0.33 nm and an entrapment efficiency (EE%) of 94.86 ± 0.05 %. Stability studies confirmed the formulation's robustness at 5 °C and 25 °C for 28 days. The nanoemulgel was prepared using 1 % carbopol gel, with a pH of 5.50 ± 0.04 and viscosity of 16,481 ± 0.01 cP, making it suitable for topical use. Skin permeation and irritation studies indicated superior efficacy, with a maximum flux (Jmax) of 159.10 ± 0.08 μg/cm2/h, outperforming marketed gels. The formulation achieved a wound contraction rate of 99.86 ± 0.24 % by day 20, highlighting the synergistic benefits of asiatic acid, virgin coconut oil, and chitosan. CS-ASA-NEG offers a promising approach to improve wound healing.

Naturally derived hydrogels for wound healing

Natural hydrogels have garnered increasing attention due to their natural origins and beneficial roles in wound healing. Hydrogel water-retaining capacity and excellent biocompatibility create an ideal moist environment for wound healing, thereby enhancing cell proliferation and tissue regeneration. For this reason, naturally derived hydrogels formulated from biomaterials such as chitosan, alginate, gelatin, and fibroin are highly promising due to their biodegradability and low immunogenic responses. Recent integrated approaches to utilizing new technologies with bioactive agents have significantly improved the mechanical properties of hydrogels and the controlled release and delivery of active compounds, thereby increasing the efficiency of the treatment processes. Herein, this review highlights the advantages and the challenges of natural hydrogels in wound healing, focusing on their mechanical strength, controlled degradation rates, safety and efficiency validation, and the potential for incorporating advanced technologies such as tissue engineering and gene therapy for utilization in personalized medicine.

Selectively oxidized chitin as a degradable and biocompatible hemostat for uncontrolled bleeding and wound healing

Chitin (CT), one of the most abundant biopolymers, is insoluble in both dilute aqueous solutions and common organic solvents. In traditional hemostatic applications, chitin must be either converted into acid-soluble chitosan by removing acetyl groups or dissolved in an alkaline aqueous solution at -20 °C. However, acetyl groups are more advantageous than amino groups in promoting hemostasis, biocompatibility, biodegradability, and wound healing. A significant challenge remains in retaining acetyl groups while directly preparing a hemostatic agent from chitin without requiring its dissociation. In this study, we have successfully applied oxidized chitin (OCT) as a hemostatic material, which is directly derived from chitin through a TEMPO-mediated selective oxidation of C6 primary hydroxyl groups to carboxyl groups. Due to its significantly higher hydrophilicity compared to chitin, OCT rapidly forms a gel upon contact with blood, efficiently sealing broken blood vessels and facilitating wound healing. Among OCTs with varying carboxylate contents and the commercial chitosan hemostat Celox™, OCT-24 demonstrated not only the best hemostatic performance in some injury models but also excellent biocompatibility and biodegradability, effectively preventing tissue adhesion and promoting wound healing. The selective oxidation offers a straightforward method for developing a highly effective hemostatic material from chitin to address uncontrolled massive bleeding.

Hydrogel-Based Biomaterials: A Patent Landscape on Innovation Trends and Patterns

The hydrogel patent landscape is characterized by rapid growth and diverse applications, particularly in the biomedical field. Advances in material science, chemistry, novel manufacturing techniques, and a deeper understanding of biological systems have revolutionized the development of hydrogel-based biomaterials. These innovations have led to enhanced properties and expanded applications, particularly in regenerative medicine, drug delivery, and tissue engineering, positioning hydrogels as a pivotal material in the future of biomedical engineering. In this study, an updated patent landscape for hydrogel-based biomaterials is proposed. By analyzing patent documents, classifications, jurisdictions, and applicants, an overview is provided to characterize key trends and insights. The analysis reveals that hydrogel-related patents are experiencing significant growth, with a strong focus on biomedical applications. Foundational research in hydrogel formation remains dominant, with 96,987 patent documents highlighting advancements in crosslinking techniques, polysaccharide-based materials, and biologically active hydrogels for wound care and tissue regeneration. The United States and China lead in hydrogel-related patent filings, with notable contributions from Europe and a high number of international patents under the Patent Cooperation Treaty (PCT) system, reflecting the global interest in hydrogel technologies. Moreover, emerging innovations include biodegradable hydrogels designed for tissue regeneration, wearable hydrogel-based sensors, and advanced therapeutic applications such as chemoembolization agents and vascular defect treatments. The increasing integration of bioactive elements in hydrogel systems is driving the development of multifunctional biomaterials tailored to specific medical and environmental needs. While this study focuses on patent trends, the alignment between hydrogel research and patenting activities underscores the role of patents in bridging scientific discoveries with industrial applications. Future research could explore patent citation analysis and impact assessments to gain deeper insights into the technological significance of hydrogel-related inventions. Finally, a selection of the top 10 recent active and granted patents in the field of hydrogel-based biomaterials is presented as an illustrative example of innovation in this area and to illustrate cutting-edge innovations.

Chitosan Nanoparticles: A Promising Candidate in Wound Healing

The wound healing process is really interesting, dynamic, and complex, captivating researchers for a long time. With the growing worldwide concern regarding the prevalence of wounds and the associated healthcare challenges, efforts to expedite this natural process have intensified. Fortunately, with a particular focus on improving wound dressings, significant advancements have been made in wound care management including using of nanoparticle-based delivery systems. These nanoparticles, similar to molecular messengers, purchase vast promise for revolutionizing wound treatment. Among them, chitosan nanoparticles stand out as remarkable candidates. Their safety profile, biocompatibility, and bioactivity make them particularly appealing for wound care. In this article, we will delve into the intricacies of wound healing and then discuss the wound-healing properties of chitosan nanoparticles, supported by comprehensive study results. Current evidence highlights the wound-healing effects of chitosan nanoparticles, which can be considered independent agents for wound management. In conclusion, the utilization of chitosan nanoparticles for wound healing presents significant opportunities and potential.Graphical abstract [Formula: see text].

Swelling Behavior, Biocompatibility, and Controlled Delivery of Sodium-Diclofenac in New Temperature-Responsive P(OEGMA/OPGMA) Copolymeric Hydrogels

This study investigates the synthesis and properties of innovative poly(oligo(alkylene glycol)) methacrylate hydrogels synthesized via gamma radiation-induced copolymerization and the crosslinking of oligo(ethylene glycol) methacrylate (OEGMA) and oligo(propylene glycol) methacrylate (OPGMA) at varying mole fractions. Our primary objective is to investigate the impact of copolymerization on the swelling properties of P(OEGMA/OPGMA) hydrogels compared to their homopolymeric counterparts, namely, POEGMA and POPGMA, which exhibit distinct volume phase transition temperatures (VPTTs) of around 70 and 13 °C, respectively, under physiological conditions. To this end, a comprehensive library of smart methacrylate-based hydrogel biomaterials was developed, featuring detailed data on their swelling behavior across different copolymer molar ratios and physiological temperature ranges. To achieve these objectives, we conducted swelling behavior analysis across a wide range of temperatures, assessed the pH sensitivity of hydrogels, utilized scanning electron microscopy for morphological characterization, performed in vitro biocompatibility assessment through cell viability and hemolysis assays, and employed diclofenac sodium as a model drug to control drug delivery testing. Our findings demonstrate that the newly synthesized P(OEGMA40/OPGMA60) copolymeric hydrogel exhibits desirable characteristics, with VPTT close to the physiological temperatures required for controlled drug delivery applications.

In Vivo Inflammatory Soft and Hard Tissue Response to Newly Developed Osteosynthesis Material for Pediatric Maxillofacial Traumatology in a Critical Size Bone Defect Model

Childhood trauma defects in the head and neck area are challenging in many aspects for patients and surgeons. One major issue is the still incomplete growth. Bone defect fixation measures have to consider biomechanical forces due to the bone growth from both sides, the bone growth possibly influencing and working against the fixation itself and vice versa. A solution will be the development of a stable but, at the same time, quickly degradable osteosynthesis system (OSS) specifically for the pediatric sector. Besides the physical demands, biocompatibility and low risk for unphysiological tissue response are exceptionally important. A newly developed PDLLA-derivate/chitosan hybrid material (PDLLA:CC:Mg+Chitosan) with promising features confirmed in vitro experimental set-ups has been tested in a critical size bone defect model in Wistar rats to confirm slow degradation and absence of unphysiological integration of the material, and of bone growth induced by the material itself. mCT and histologic analysis of implanted rat skulls after 1, 3, and 5 months confirmed slow degradation of the PDLLA:CC:Mg+Chitosan material without any unintended bone growth induction or morphologic changes due to the material. The results of this in vivo study confirmed the suitability of the material to serve as OSS in clinical practice.

Polyphenols in wound healing: unlocking prospects with clinical applications

Wound healing is a multifaceted, complex process that factors like aging, metabolic diseases, and infections may influence. The potentiality of polyphenols, natural compounds, has shown anti-inflammatory and antimicrobial properties in promoting wound healing and their potential applications in wound management. The studies reviewed indicate that polyphenols have multiple mechanisms that promote wound healing. This involves enhancing antioxidant defenses, reducing oxidative stress, modulating inflammatory responses, improving healing times, reducing infection rates, and enhancing tissue regeneration in clinical trials and in vivo and in vitro studies. Polyphenols have been proven to be effective in managing hard-to-heal wounds, especially in diabetic and elderly populations. Polyphenols have shown significant benefits in promoting angiogenesis and stimulating collagen synthesis. Polyphenol treatment has been demonstrated to have therapeutic effects in wound healing and chronic wound management. Their ability to regulate key healing processes makes them suitable for new wound care products and treatments. Future research should enhance formulations and delivery methods to optimize polyphenols' bioavailability and therapeutic efficacy in wound management approaches.

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.

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.

Graphene oxide/chitosan hydrogels for removal of antibiotics

Antibiotic contamination in aquatic environments is a growing concern, posing risks to public health and ecosystems. To address this issue, advanced materials like graphene oxide (GO) and chitosan-based hydrogels are being extensively explored for their ability to effectively remove antibiotics from wastewater, owing to their distinct characteristics and synergistic benefits. This review comprehensively examines the synthesis, characterization, and applications of GO/chitosan hydrogels in addressing antibiotic pollution. The synthesis methods, including solution casting, crosslinking, and in situ polymerization, are discussed for their simplicity and scalability. The hydrogels' key properties, such as porosity, surface area, and mechanical strength, are essential for their efficient adsorption capabilities. Adsorption mechanisms, including electrostatic interactions, π-π stacking, hydrogen bonding, and surface functional groups, enable these hydrogels to achieve high adsorption capacities. Notable examples include rGO@ZIF-67@CS hydrogels, which achieved higher adsorption capacities of 1685.26 mg·g-1 for tetracycline at pH 4 and 1890.32 mg·g-1 for norfloxacin at pH 5, while the sulfonated CMC/GO-GCC composite hydrogel achieved 312.28 mg·g-1 for sulfamethoxazole at 298 K. Moreover, high adsorption efficiencies of 90.42% with GO-CTS and 97.06% were achieved using AGO-CTS hydrogel for diclofenac adsorption. The review also highlights the practical applications of these hydrogels in wastewater treatment, comparing their performance with other adsorbents and addressing challenges such as scalability and regeneration. Finally, the review explores future research directions to enhance the effectiveness and sustainability of GO/chitosan hydrogels, emphasizing their potential as scalable, eco-friendly solutions for antibiotic removal from water.

Novel injectable self-healing bifunctionalized chitosan hydrogel with cell proliferation and antibacterial activity for promoting wound healing

Wound healing is a complex and continuous process and there is an urgent need to develop effective, functional wound dressings to accelerate wound healing. In this study, we developed an injectable self-healing dual-modified chitosan composite hydrogel, referred to as CSTA@Gel. This hydrogel exhibits good properties, including effective tissue adhesion, rapid hemostatic ability, and good cytocompatibility and hemocompatibility. Additionally, the incorporation of modified adenine and thymine enhances its cell proliferation-promoting and antimicrobial properties, demonstrating significant antibacterial activity against Staphylococcus aureus and Escherichia coli. Histological and immunohistochemical analyses reveal that treatment with CSTA@Gel significantly promotes wound healing, increases collagen deposition, and accelerates angiogenesis. These findings indicate that this hydrogel design presents a promising strategy for developing of novel wound dressings.

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.

Advanced biomaterials in pressure ulcer prevention and care: from basic research to clinical practice

Pressure ulcers are a common and serious medical condition. Conventional treatment methods often fall short in addressing the complexities of prevention and care. This paper provides a comprehensive review of recent advancements in advanced biomaterials for pressure ulcer management, emphasizing their potential to overcome these limitations. The study highlights the roles of biomaterials in enhancing wound healing, preventing infections, and accelerating recovery. Specific focus is placed on the innovation and application of multi-functional composite materials, intelligent systems, and personalized solutions. Future research should prioritize interdisciplinary collaboration to facilitate the clinical translation of these materials, providing more effective and tailored treatment approaches. These advancements aim to improve the quality of life and health outcomes for patients by offering more reliable, efficient, and patient-specific therapeutic options.

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.

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.

Functional hydrogel empowering 3D printing titanium alloys

Titanium alloys are widely used in the manufacture of orthopedic prosthesis given their excellent mechanical properties and biocompatibility. However, the primary drawbacks of traditional titanium alloy prosthesis are their much higher elastic modulus than cancellous bone and poor interfacial adhesion, which lead to poor osseointegration. 3D-printed porous titanium alloys can partly address these issues, but their bio-inertness still requires modifications to adapt to different physiological and pathological microenvironments. Hydrogels composed of three-dimensional networks of hydrophilic polymers can effectively simulate the extracellular matrix of natural bone and are capable of loading bioactive molecules such as proteins, peptides, growths factors, polysaccharides, or nucleotides for localized release within the human body, by directly participating in biological processes. Combining 3D-printed porous titanium alloys with hydrogels to construct a bioactive composite system that regulates cellular adhesion, proliferation, migration, and differentiation in the local microenvironment is of great significance for enhancing the bioactivity of the prosthesis surface. In this review, we focus on three aspects of the bioactive composite system: (Ⅰ) strategies for constructing bioactive interfaces with hydrogels, and (Ⅱ) how bioactive composite systems regulate the microenvironment under different physiological and pathological conditions to enhance the osteointegration and bone regeneration capability of prostheses. Considering the current research status in this field, innovations in orthopedic prosthesis can be achieved through material optimization, personalized customization, and the development of multifunctional composite systems. These advancements provide essential references for the clinical translation of osseointegration and bone regeneration in various physiological and pathological microenvironments.

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.

In Vivo Assessment of Healing Potential of Ointments Containing Bee Products, Vegetal Extracts, and Polymers on Skin Lesions

Background/Objectives: The present experiment aimed to formulate four ointments that included mixtures of plant extracts (Hippophae rhamnoides, Calendula officinalis, Arctium lappa, and Achillea millefolium), apitherapy products (honey, propolis, and apilarnil) and natural polymers (collagen, chitosan, and the lyophilisate of egg white) in an ointment base. Methods: In order to investigate the therapeutic properties of the ointments, experimental in vivo injury models (linear incision, circular excision, and thermal burns) were performed on laboratory animals, namely Wistar rats. The treatment was applied topically, once a day, for 21 days. Clinical and macroscopic evaluation, determination of lesion shrinkage rate, re-epithelialization period, and histopathological examination were performed. Results: The results demonstrate that the tested ointments have a significant effect in healing skin lesions. On the ninth day of treatment, the wound contraction rate was 98.17 ± 0.15% for the mixed ointment group, compared to the negative control group's rate of 14.85 ± 2.95%. At day 21, dermal collagenization and restoration of histological structure occurred for all treated groups. Conclusions: The tested ointments exerted in vivo wound healing and re-epithelialization effects on incision, excision, and thermal burn injuries.

Investigation of Chitosan-Based Hydrogels and Polycaprolactone-Based Electrospun Fibers as Wound Dressing Materials Based on Mechanical, Physical, and Chemical Characterization

The aim of this project is to fabricate fiber mats and hydrogel materials that constitute the two main components of a wound dressing material. The contributions of boric acid (BA) and zinc oxide (ZnO) to the physical and mechanical properties of polycaprolactone (PCL) is investigated. These materials are chosen for their antimicrobial and antifungal effects. Additionally, since chitosan forms brittle hydrogels, it is reinforced with polyvinyl alcohol (PVA) to improve ductility and water uptake properties. For these purposes, PCL, BA, ZnO, PVA, and chitosan are used in different ratios to fabricate nanofiber mats and hydrogels. Mechanical, physical, and chemical characteristics are examined. The highest elastic modulus and tensile strength are obtained from samples with 6% BA and 10% ZnO concentrations. ZnO-decorated fibers exhibit a higher elastic modulus than those with BA, though BA-containing fibers exhibit greater elongation before breakage. All fibers exhibit hydrophobic properties, which help to prevent biofilm formation. In compression tests, CS12 demonstrates the highest strength. Increasing the PVA content enhances ductility, while a higher concentration of chitosan results in a denser structure. This outcome is confirmed by FTIR and swelling tests. These findings highlight the optimal combinations of nanofibrous mats and hydrogels, offering guidance for future wound dressing designs that balance mechanical strength, water absorption, and antimicrobial properties. By stacking these nanofibrous mats and hydrogels in different orders, it is expected to achieve a wound care material that is suitable for various applications. The authors encourage experimentation with different configurations of these nanofiber and hydrogel stackings to observe their mechanical behavior under real-life conditions in future studies.

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.

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.

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.

Folate-engineered chitosan nanoparticles: next-generation anticancer nanocarriers

Chitosan nanoparticles (NPs) are well-recognized as promising vehicles for delivering anticancer drugs due to their distinctive characteristics. They have the potential to enclose hydrophobic anticancer molecules, thereby enhancing their solubilities, permeabilities, and bioavailabilities; without the use of surfactant, i.e., through surfactant-free solubilization. This allows for higher drug concentrations at the tumor sites, prevents excessive toxicity imparted by surfactants, and could circumvent drug resistance. Moreover, biomedical engineers and formulation scientists can also fabricate chitosan NPs to slowly release anticancer agents. This keeps the drugs at the tumor site longer, makes therapy more effective, and lowers the frequency of dosing. Notably, some types of cancer cells (fallopian tube, epithelial tumors of the ovary, and primary peritoneum; lung, kidney, ependymal brain, uterus, breast, colon, and malignant pleural mesothelioma) have overexpression of folate receptors (FRs) on their outer surface, which lets folate-drug conjugate-incorporated NPs to target and kill them more effectively. Strikingly, there is evidence suggesting that the excessively produced FR&αgr (isoforms of the FR) stays consistent throughout treatment in ovarian and endometrial cancer, indicating resistance to conventional treatment; and in this regard, folate-anchored chitosan NPs can overcome it and improve the therapeutic outcomes. Interestingly, overly expressed FRs are present only in certain tumor types, which makes them a promising biomarker for predicting the effectiveness of FR-targeted therapy. On the other hand, the folate-modified chitosan NPs can also enhance the oral absorption of medicines, especially anticancer drugs, and pave the way for effective and long-term low-dose oral metronomic scheduling of poorly soluble and permeable drugs. In this review, we talked briefly about the techniques used to create, characterize, and tailor chitosan-based NPs; and delved deeper into the potential applications of folate-engineered chitosan NPs in treating various cancer types.

Tissue adhesives based on chitosan for biomedical applications

Chitosan bio-adhesives bond strongly with various biological tissues, such as skin, mucosa, and internal organs. Their adhesive ability arises from amino acid and hydroxyl groups in chitosan, facilitating interactions with tissue surfaces through chemical (ionic, covalent, and hydrogen) and physical (chain entanglement) bonding. As non-toxic, biodegradable, and biocompatible materials, chitosan bio-adhesives are a safe option for medical therapies. They are particularly suitable for drug delivery, wound healing, and tissue regeneration. In this review, we address chitosan-based bio-adhesives and the mechanisms associated with them. We also discuss different chitosan composite-based bio-adhesives and their biomedical applications in wound healing, drug delivery, hemostasis, and tissue regeneration. Finally, challenges and future perspectives for the clinical use of chitosan-based bio-adhesives are discussed.

3D Bilayered Hydrogel and Nanofiber Multifunctional Sponge Dressing: An Efficacious Healing Agent for Chronic Wound Healing

Chronic wound management using biomaterial-based dressings has significantly impacted the standard and efficiency of wound healing. However, various available wound healing aids are ineffective in treating deep open injuries and chronic wounds such as diabetic wounds. Herein, we developed a 3D bilayered multifunctional sponge, which addresses the structural and functional issues faced by biomaterial dressings in treating deep and chronic wounds. The 3D bilayered sponge consists of a hydrogel base functionalized with wound healing peptide (Tylotoin)-carrying nanoparticles and topped with a nanofiber layer functionalized with an antimicrobial peptide (LLKKK18). The 3D bilayered sponge, with its highly porous, elastic, and enhanced fluid absorption ability, makes it a suitable wound treatment aid. The developed multifunctional 3D sponge shows antibacterial action and promotes a microenvironment similar to the extracellular matrix (ECM) in regulating dermal cell survival and migration. Study in a full-thickness skin defect diabetic mouse model has shown that the developed 3D bilayered sponge accelerated wound closure and promoted functional skin regeneration through reduced inflammation, faster granulation tissue formation, re-epithelialization, neovascularization, and skin appendage restoration, which make the developed 3D bilayered multifunctional sponge an efficient and advanced chronic wound management aid with potential for future clinical application.

Recombinant Keratin-Chitosan Cryogel Decorated with Gallic Acid-Reduced Silver Nanoparticles for Wound Healing

Background

Wound healing is a complex physiological process that can be roughly divided into four stages: hemostasis, inflammation, proliferation, and remodeling. Conventional wound dressings often fail to meet the diverse needs of these healing stages due to their limited functionality. Cryogels, however, possess several attractive properties, such as large, interconnected pores, good mechanical strength, and ease of modification, making them suitable for developing advanced dressings with multiple functions. In this study, we developed a multifunctional cryogel dressing, with biocompatible polysaccharides as the main component, designed to provide a breathable, moist, and antibacterial microenvironment for chronic infected wounds, thereby promoting wound healing.

Methods

Recombinant keratin 31 (RK31) was combined with chitosan (CS) to produce a CS/RK31 cryogel, referred to as CK. Gallic acid-reduced silver nanoparticles (GA/Ag NPs) were incorporated as the active antibacterial component to create the CS/K31@GA/Ag cryogel, known as CKGA. The cryogel was characterized using scanning electron microscopy (SEM) and a universal testing machine, and its biocompatibility was assessed in vitro. The dynamic hemostatic performance of the cryogel was evaluated with a rat tail amputation bleeding model. Additionally, the antibacterial effects of the cryogel against Staphylococcus aureus and Escherichia coli were tested using agar diffusion assays and turbidimetry. The antioxidant capacity of the CKGA cryogel was also measured in vitro. Finally, the cryogel's ability to promote wound healing was tested in an SD rat model of infected wounds.

Results

Characterization results showed that the CKGA cryogel features an interpenetrating porous network structure and exhibits excellent mechanical properties, with a swelling rate of up to 1800%. Both in vitro and in vivo experiments confirmed that the cryogel has good biocompatibility, effectively absorbs exudates, and rapidly stops bleeding. The addition of GA/Ag NPs provided significant antibacterial effects, achieving an inhibition rate of over 99.9% against both S. aureus and E. coli. Furthermore, CKGA cryogels demonstrated a strong scavenging capacity for ROS in a dose-dependent manner. Studies using the SD rat infected wound model showed that the cryogel effectively inhibited bacterial proliferation on wound surfaces, reduced local tissue inflammation, and promoted the healing of infected wounds.

Conclusion

The multifunctional cryogel, with its rapid hemostatic, antibacterial, and antioxidant properties, as well as its ability to promote cell proliferation, could be widely used as a wound dressing for the healing of bacterial infections.

A gold nanoparticle-based photothermal hydrogel assisted by an N-halamine polymer for bacteria-infected skin wound healing

Bacteria-infected wounds and antibiotic misuse have become a challenge in the treatment of clinical infections. Therefore, there is an urgent need to design non-antibiotic-dependent multifunctional wound dressings for the treatment of bacterially infected wounds. In this study, an injectable antibacterial hydrogel (pAMPS-Cl/AuNR@HA-DA) based on gold nanorods (AuNR) and N-halamine (pAMPS-Cl) with significant photothermal antibacterial properties was developed. The obtained pAMPS-Cl/AuNR@HA-DA hydrogel showed a sponge-like structure with excellent injectability, self-healing, tissue adhesion, and good hemocompatibility. In addition, the hydrogel exhibited excellent in vitro antibacterial capacity under near-infrared (NIR) laser irradiation through the synergistic action of photothermal therapy (PTT) and chemical release therapy. It also showed an excellent ability to eliminate bacterial infection and promote wound healing, indicating that the pAMPS-Cl/AuNR@HA-DA composite hydrogel could be a promising dressing for the treatment of skin wounds.

Hydrogels as a Potential Biomaterial for Multimodal Therapeutic Applications

Hydrogels, composed of hydrophilic polymer networks, have emerged as versatile materials in biomedical applications due to their high water content, biocompatibility, and tunable properties. They mimic natural tissue environments, enhancing cell viability and function. Hydrogels' tunable physical properties allow for tailored antibacterial biomaterial, wound dressings, cancer treatment, and tissue engineering scaffolds. Their ability to respond to physiological stimuli enables the controlled release of therapeutics, while their porous structure supports nutrient diffusion and waste removal, fostering tissue regeneration and repair. In wound healing, hydrogels provide a moist environment, promote cell migration, and deliver bioactive agents and antibiotics, enhancing the healing process. For cancer therapy, they offer localized drug delivery systems that target tumors, minimizing systemic toxicity and improving therapeutic efficacy. Ocular therapy benefits from hydrogels' capacity to form contact lenses and drug delivery systems that maintain prolonged contact with the eye surface, improving treatment outcomes for various eye diseases. In mucosal delivery, hydrogels facilitate the administration of therapeutics across mucosal barriers, ensuring sustained release and the improved bioavailability of drugs. Tissue regeneration sees hydrogels as scaffolds that mimic the extracellular matrix, supporting cell growth and differentiation for repairing damaged tissues. Similarly, in bone regeneration, hydrogels loaded with growth factors and stem cells promote osteogenesis and accelerate bone healing. This article highlights some of the recent advances in the use of hydrogels for various biomedical applications, driven by their ability to be engineered for specific therapeutic needs and their interactive properties with biological tissues.