Supramolecular Hydrogels for Precisely Controlled Antimicrobial Peptide Delivery for Diabetic Wound Healing

Self-healing hydrogel based on polyvinyl alcohol/dextran with hyperglycemia-triggered cascade enzyme catalytic activity promotes diabetic wound healing

Bacterial infection, hypoxia and oxidative stress caused by high blood glucose are the main problems in diabetic wound healing. The glucose-activated cascade reaction could fundamentally solve these problems in diabetic wounds by consuming glucose and eliminating bacteria. In this paper, glucose oxidase (GOx) was immobilized on polyethylenimine (PEI) adsorbed molybdenum disulfide (MoS2) to prepare MoS2-PEI-GOx (MPG) composite particles, which were doped into the self-healing hydrogel of polyvinyl alcohol (PVA) and dextran (Dex) for preparing PD@MPG hydrogel. GOx can decompose excessive glucose into H2O2 and gluconic acid, thereby reducing the pH value and improving the microenvironment of the wound. Low pH value enables MoS2 exert a similar role as peroxidase, catalyzing H2O2 to produce hydroxyl radicals (OH) to kill bacteria. After reducing the blood glucose of the wound, MoS2 can play a similar role as catalase, catalyzing the excess H2O2 at the wound converted to O2, thereby alleviating hypoxia and oxidative stress. In addition, the wound healing ability of PD@MPG has been evaluated by in vivo study. The self-healing hydrogels developed in this study hold promise as an innovative dressing for diabetic wound healing.

Exploring the Antimicrobial Potential of LL-37 Derivatives: Recent Developments and Challenges

The human antimicrobial peptide LL-37 exhibits broad antimicrobial efficacy. However, it has several limitations including high production costs, reduced efficacy under physiological conditions, susceptibility to proteolytic degradation and significant toxicity to human cells. Recent research has improved the clinical potential of peptide LL-37 through multiple systematic modifications. Therefore, we review the various modification techniques for LL-37 and explore the structure-activity relationships that underpin its antimicrobial properties. We also highlight the benefits of LL-37 derivatives and investigate their mechanisms of action against bacterial infections, particularly their effects on biofilms and cell membranes. Furthermore, we review the antimicrobial applications of LL-37 derivatives, examine nanocarrier systems for their delivery, and highlight the potential synergy between these derivatives and traditional antibiotics. Finally, it assesses the status of LL-37 derivatives in clinical applications, identifies ongoing challenges, and provides insights into future modifications and potential applications. This review aims to offer valuable strategies for enhancing LL-37 derivatives and facilitating their transition from laboratory research to clinical practice.

Polysaccharides as submucosal injection materials (SIMs) in endoscopic resection: A comprehensive review

Submucosal injection materials (SIMs) play a vital role in the endoscopic treatment of benign and early malignant gastrointestinal lesions by effectively elevating lesions while significantly reducing the risks of thermal injury and bleeding. However, the traditional use of normal saline (NS) presents challenges due to its rapid absorption, which necessitates frequent reapplications and complicates procedural efficiency. Therefore, there is a pressing need for ideal SIMs that are cost-effective, readily available, and suitable for personalized therapy, while also demonstrating excellent biocompatibility and physicochemical stability. Recent advancements have highlighted the potential of polysaccharide-based natural polymers, such as sodium hyaluronate, cellulose, starch derivatives, chitosan, and sodium alginate, due to their superior biocompatibility and biodegradability. These polysaccharides have exhibited enhanced operational characteristics and therapeutic efficacy in animal and clinical studies. Nevertheless, ongoing research must address several challenges, including optimizing cost-effectiveness, improving mechanical strength and bioactivity, and mitigating intraoperative and postoperative complications. This review systematically examines the progress of polysaccharide-based natural polymers in SIMs, evaluates their current status and challenges in both research and clinical applications, and proposes future directions to enhance their utilization in gastrointestinal endoscopic therapy.

Potent antimicrobial activity of hydrogel loaded with the antimicrobial peptide, D-Bac8c2,5 Leu, against monospecies and polymicrobial biofilms of Staphylococcus aureus and Pseudomonas aeruginosa

Introduction

Acute and chronic wound infections involving biofilms and caused by antimicrobial resistant (AMR) pathogens present significant challenges in healthcare, leading to substantial patient morbidity, increased hospital stays, and rising healthcare costs. Novel antimicrobial therapies are urgently needed to address these infections.

Methods

A screening of multiple antimicrobial peptides (AMPs) was performed and the most potent candidate, D-Bac8c2,5 Leu, was tested against monospecies and polymicrobial biofilms of Staphylococcus aureus and Pseudomonas aeruginosa using static and dynamic in vitro models. Cytotoxicity was evaluated on human cell lines, and the peptide was incorporated into a methylcellulose hydrogel to assess sustained release and antimicrobial efficacy as a hydrogel dressing.

Results

D-Bac8c2,5 Leu significantly reduced biofilm viability in both monospecies and polymicrobial biofilms. In static biofilm assays, treatment led to a 2-3 log reduction in bacterial load compared to untreated controls. In Duckworth biofilm flow device, a similar reduction was observed, demonstrating efficacy in conditions mimicking wound environments. Furthermore, D-Bac8c2,5 Leu exhibited low cytotoxicity against human cell lines, and its incorporation into a methylcellulose hydrogel facilitated sustained release and enhanced antimicrobial activity. Furthermore, the peptide-loaded hydrogel showed considerable efficacy in disrupting pre-formed biofilms, underscoring its potential as a novel treatment for acute and chronic wound infections.

Discussion

These findings highlight the potential of D-Bac8c2,5 Leu to help address the urgent need for effective therapies against AMR pathogens and biofilm-associated wound infections. Further studies should focus on in vivo efficacy to optimize its therapeutic application in wound care.

Progress in the classification, optimization, activity, and application of antimicrobial peptides

Antimicrobial peptides (AMPs) come from various sources and exhibit unique antimicrobial properties. Their rapid action, effectiveness, and resistance to resistance development make them promising alternatives to combat antibiotic resistance. In addition to its excellent antibacterial properties, AMPs have superior immunomodulatory, antitumor, and antiviral activities. In recent years, the demand for AMPs has continued to increase in many fields, especially in the medical field, and the prospects are extensive. However, AMPs have the disadvantages of expensive development cost, higher hemolysis, short half-life, susceptibility to degradation by protein hydrolases, low bioavailability, toxic side effects, and other disadvantages, which seriously limit the wide application of AMPs. Therefore, fewer AMPs have been approved for marketing or are undergoing clinical trials. The review covers the period from 2001 to 2025 and provides a detailed discussion by searching databases such as Google Scholar and Web of Science. This paper reviews the progress of research on AMPs sources, structures, optimization strategies, biological activities, mechanisms of action, and applications. In general, the development approaches and the number of new AMPs have increased significantly. The improvement technologies for AMPs high hemolysis, poor stability, low bioavailability and high cost have increased significantly. The development cost of AMPs is still high, but many AMPs have been widely used in clinical, food, livestock, poultry, cosmetics and other fields. This article focuses on the commonly used optimization strategies and main activities of AMPs, aiming to effectively respond to challenges and provide a theoretical basis for expanding their application range.

Hyaluronic acid as a versatile building block for the development of biofunctional hydrogels: In vitro models and preclinical innovations

Hyaluronic acid (HyA) is a non-sulphated linear polysaccharide found abundantly in the extracellular matrix, known for its biocompatibility and versatility in tissue engineering. Chemical modifications of HyA, including methacrylate, acrylate, click chemistry, norbornene, or host-guest chemistry, are necessary for the formation of stable hydrogels with tuneable biophysical characteristics. These modifications enable precise control over stiffness, swelling, degradation, and advanced functionalities such as shear-thinning, self-healing, and injectability. Functionalisation further enhances hydrogel bioactivity, enabling controlled cell adhesion, modulation of cell behaviour, hydrogel degradation, and release profiles, as well as inflammation modulation or bacterial growth inhibition. These are achieved by conjugating proteins, peptides, antibodies, or reactive chemical groups. HyA hydrogels find broad applications both in vitro and in vivo. In vitro, HyA-based hydrogels can support the development of models to understand fundamental processes in health and mechanisms behind disease progression, serving as highly tuneable extracellular matrix mimetics. As therapeutic interventions, injectable or implantable HyA-based hydrogels have been developed to repair a range of tissues, including cartilage, bone, muscle, and skin defects. However, issues remain to be addressed before widespread adoption of HyA-based hydrogels as clinical options. Future innovations for HyA hydrogels include its establishment as an enabling technology for the delivery of novel therapeutics, with a particular focus on immunomodulatory molecules, and the development of more dynamic, tissue-mimetic HyA-based hydrogels.

Multiple-Layer Chitosan-Based Patches Medicated With LTX-109 Antimicrobial Peptide for Modulated Local Therapy in the Management of Chronic Wounds

In response to the critical issue of chronic wound management, this research explores the development of a multiple-layer biomaterial loaded with LTX-109 a novel broad-spectrum topical antimicrobial peptide currently investigated for the treatment of bacterial skin infections. The novel patch is conceived to load and preserve the function of LTX-109, release it on site in a progressive manner, and therefore make available a device for simultaneous wounds disinfection and tissues healing. Chitosan, tannic acid and glycerol along with the solvent casting process are selected for the development of a multilayer structure in which each single layer is designed by choosing a specific composition and stability to tune its behavior and function. On the top, a protective layer to protect the wound from external contaminations, in the middle a medicated layer loaded with LTX-109 and at the bottom a multifunctional layer to modulate the release of LTX-109. Extensive characterizations show that the patch meets the essential requirements for creating an effective wound healing environment, such as absorption of exudate, maintenance of good oxygen and moisture permeability, biodegradability, biocompatibility, and sustained release of LTX-109 with fully retained antibacterial activity as demonstrated by MIC values obtained against reference bacteria.

Bioactive Deep Eutectic Solvent-Involved Sprayable Versatile Hydrogel for Monkeypox Virus Lesions Treatment

To address the issues of infectious virus, bacterial secondary infections, skin pigmentation, and scarring caused by monkeypox virus (MPXV), a sprayable hydrogel with versatile functions was developed with comprehensive properties. Based on current research, the bioactive deep eutectic solvent (DES) of rosmarinic acid-proanthocyanidin-glycol (RPG) was designed and synthesized as active agent, and molecular docking was applied to discover its binding to MPXV proteins through H-bonds and van der Waals interactions, and the docking results show the binding energies between RA, PC, Gly and MPXV proteins are -58.7188, -50.2311, and -18.4755 kcal/mol, respectively. Additionally, poly(vinyl alcohol) (PVA), borate, and xylitol (Xyl) were integrated with RPG to prepare the PB-RPG-Xyl hydrogel, which was characterized by popular ways. The pH-responsive properties of the hydrogel accelerated the release of RPG under acidic conditions, resulting in an increased cumulative release percentage of 84.83% at pH 5.5 at 210 min. Besides that, it was proved to have the expected sprayability, self-healing, adhesion, and shape-adaptability. The results of molecular dynamic simulation were meaningful to understanding its formation and self-healing mechanisms. Furthermore, the hydrogel shows ideal degradability, removability, and biocompatibility. Lastly, its multiple functions were systematically explored, including UV-blocking, blood clotting, cooling, antioxidant, antibacterial, and virus inhibition properties. The developed sprayable PB-RPG-Xyl hydrogel represents the first promising dressing based on natural bioactive DES for MPXV lesions management, which not only expands the application of green solvents in health care but also provides a convenient and effective treatment process for MPXV infection in the face of difficult skin lesions and complex treatment needs.

Hyaluronan Scaffold Decorated with Bifunctional Peptide Promotes Wound Healing via Antibacterial and Anti-Inflammatory

The invasion of bacteria and inflammation impeded infected wounds heal. Here, a hyaluronan-based scaffold (HAG-g-C) was designed by cross-linking with gallic acid-modified gelatin to provide a protein microenvironment and decorated with cathelicidin-BF (CBF), a natural antimicrobial peptide, to remove bacterial infections and reverse the inflammatory environment. In vitro, HAG-g-C presented an antibacterial effect on Staphylococcus aureus and Escherichia coli. Meanwhile, it could drive the phenotypic switch of macrophage from M1 to M2 to accelerate tissue remodeling. In a mouse model of S. aureus-infected total skin defects, HAG-g-C inhibited the process of infection at the beginning of the wound and then regulated the M1 macrophage transformed to M2 phenotype on day 12. In addition, HAG-g-C induced collagen deposition, and reduced the expression of TNF-α, thereby significantly accelerating the reconstruction of infected wounds.

Antimicrobial Peptide Delivery Systems as Promising Tools Against Resistant Bacterial Infections

The extensive use of antibiotics during recent years has led to antimicrobial resistance development, a significant threat to global public health. It is estimated that around 1.27 million people died worldwide in 2019 due to infectious diseases caused by antibiotic-resistant microorganisms, according to the WHO. It is estimated that 700,000 people die each year worldwide, which is expected to rise to 10 million by 2050. Therefore, new and efficient antimicrobials against resistant pathogenic bacteria are urgently needed. Antimicrobial peptides (AMPs) present a broad spectrum of antibacterial effects and are considered potential tools for developing novel therapies to combat resistant infections. However, their clinical application is currently limited due to instability, low selectivity, toxicity, and limited bioavailability, resulting in a narrow therapeutic window. Here we describe an overview of the clinical application of AMPs against resistant bacterial infections through nanoformulation. It evaluates metal, polymeric, and lipid AMP delivery systems as promising for the treatment of resistant bacterial infections, offering a potential solution to the aforementioned limitations.

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.

Construction and Performance Study of an Injectable Dual-Network Hydrogel Dressing with Inherent Drainage Function

With the widespread utilization of moist wound dressings, the extended healing time and increased risk of wound infection caused by excessively moist environments have garnered significant attention. The development of hydrogel dressings that can effectively control the wound moisture level and promote healing is very important. Inspired by the pore-opening perspiration effect of the skin, this study constructed an injectable dual-network hydrogel, CMCS-OSA/AG/MXene, by the composition of a dynamic covalent network of carboxymethyl chitosan and oxidized sodium alginate based on the Schiff base and hydrogen bond network of the thermosensitive low-melting-point agar with the advantage of the upper critical solution temperature (UCST) effect. Under near-infrared (NIR) light stimulation, the CMCS-OSA/AG/MXene hydrogel shows characteristics conducive to rapid removal of wound exudate while maintaining an appropriate moist environment for the wound and excellent antibacterial effects with its photothermal responses. The excellent conductivity of the hydrogel can also promote cell proliferation under external electrical stimulation (ES). Further validation through animal experiments on a full-thickness skin defect model demonstrates the excellent capability of CMCS-OSA/AG/MXene in accelerating wound healing. This work provides an innovative approach to the development of injectable hydrogel dressing materials with inherent drainage functionality and shows a new avenue to wound moisture control and wound healing promotion.

Advancing diabetic wound care: The role of copper-containing hydrogels

Diabetic wounds pose a significant challenge in healthcare due to their complex nature and the difficulties they present in treatment and healing. Impaired healing processes in individuals with diabetes can lead to complications and prolonged recovery times. However, recent advancements in wound healing provide reasons for optimism. Researchers are actively developing innovative strategies and therapies specifically tailored to address the unique challenges of diabetic wounds. One focus area is biomimetic hydrogel scaffolds that mimic the natural extracellular matrix, promoting angiogenesis, collagen deposition, and the healing process while also reducing infection risk. Copper nanoparticles and copper compounds incorporated into hydrogels release copper ions with antimicrobial, anti-inflammatory, and angiogenic properties. Copper reduces infection risk, modulates inflammatory response, and promotes tissue regeneration through cell adhesion, proliferation, and differentiation. Utilizing copper nanoparticles has transformative potential for expediting diabetic wound healing and improving patient outcomes while enhancing overall well-being by preventing severe complications associated with untreated wounds. It is crucial to write a review highlighting the importance of investigating the use of copper nanoparticles and compounds in diabetic wound healing and tissue engineering. These groundbreaking strategies hold the potential to transform the treatment of diabetic wounds, accelerating the healing process and enhancing patient outcomes.

Green and recyclable catalyst based on chitosan/CuFe2O4 nanocomposite hydrogel for one-step synthesis of 1,2,3-triazoles

The scope of the heterogeneous catalysts has been greatly expanded in last few decades by the development of various catalysts. In this work a new chitosan-based nanocomposite hydrogel (CS/CuFe2O4 NCH) was synthesized as a high-performance heterogeneous catalyst and then, it was utilized for the green synthesis of substituted 1,2,3-triazoles by a multi-component (azide-alkyne-epoxide) cycloaddition reaction. The synthesized nanocomposite hydrogel was investigated by using various instrumental analyses, including FT-IR, XRD, SEM, EDS, HRTEM, DLS, and TGA. The structure of one of the substituted 1,2,3-triazoles was studied by using single-crystal X-ray diffraction analysis. The nanocomposite hydrogel can be easily regenerate after the catalytic reaction. It can be reused frequently without considerable loss of activity. The high catalytic activity, straightforward reaction, easy recyclability, short reaction time, use of a green solvent, and the simple separation of catalyst are the main advantage of the current method, which offers both financial and environmental benefits.

Multifunctional nanofibrous scaffolds for enhancing full-thickness wound healing loaded with Bletilla striata polysaccharides

The considerable challenge of wound healing remains. In this study, we fabricated a novel multifunctional core-shell nanofibrous scaffold named EGF@BSP-CeO2/PLGA (EBCP), which is composed of Bletilla striata polysaccharide (BSP), Ceria nanozyme (CeO2) and epidermal growth factor (EGF) as the core and poly(lactic-co-glycolic acid) (PLGA) as the shell via an emulsion electrospinning technique. An increase in the BSP content within the scaffolds corresponded to improved wound healing performance. These scaffolds exhibited increased hydrophilicity and porosity and improved mechanical properties and anti-UV properties. EBCP exhibited sustained release, and the degradation rate was <4 % in PBS for 30 days. The superior biocompatibility was confirmed by the MTT assay, hemolysis, and H&E staining. In addition, the in vitro results revealed that, compared with the other groups, the EBCP group presented excellent antioxidant and antibacterial effects. More importantly, the in vivo results indicated that the wound closure rate of the EBCP group reached 94.0 % on day 10 in the presence of H2O2. The results demonstrated that EBCP could comprehensively regulate the wound microenvironment, possess hemostatic abilities, and significantly promote wound healing. In conclusion, the EBCP is promising for facilitating the treatment of infected wounds and represents a potential material for clinical applications.

Chemical Modifications in Hyaluronic Acid-Based Electrospun Scaffolds

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

Recent advances in antimicrobial peptide-based therapy

Antimicrobial peptides (AMPs) are a group of polypeptide chains that have the property to target and kill a myriad of microbial organisms including viruses, bacteria, protists, etc. The first discovered AMP was named gramicidin, an extract of aerobic soil bacteria. Further studies discovered that these peptides are present not only in prokaryotes but in eukaryotes as well. They play a vital role in human innate immunity and wound repair. Consequently, they have maintained a high level of intrigue among scientists in the field of immunology, especially so with the rise of antibiotic-resistant pathogens decreasing the reliability of antibiotics in healthcare. While AMPs have promising potential to substitute for common antibiotics, their use as effective replacements is barred by certain limitations. First, they have the potential to be cytotoxic to human cells. Second, they are unstable in the blood due to action by various proteolytic agents and ions that cause their degradation. This review provides an overview of the mechanism of AMPs, their limitations, and developments in recent years that provide techniques to overcome those limitations. We also discuss the advantages and drawbacks of AMPs as a replacement for antibiotics as compared to other alternatives such as synthetically modified bacteriophages, traditional medicine, and probiotics.

β-Glucans obtained from fungus for wound healing: A review

The cell surface of fungus contains a large number of β-glucans, which exhibit various biological activities such as immunomodulatory, anti-inflammatory, and antioxidation. Fungal β-glucans with highly branched structure show great potential as wound healing reagents, because they can stimulate the expression of many immune- and inflammatory-related factors beneficial to wound healing. Recently, the wound healing ability of many fungal β-glucans have been investigated in animals and clinical trials. Studies have proved that fungal β-glucans can promote fibroblasts proliferation, collagen deposition, angiogenesis, and macrophage infiltration during the wound healing process. However, the development of fungal β-glucans as wound healing reagents is not systematically reviewed till now. This review discusses the wound healing studies of β-glucans obtained from different fungal species. The structure characteristics, extraction methods, and biological functions of fungal β-glucans with wound healing ability are summarized. Researches about fungal β-glucan-containing biomaterials and structurally modified β-glucans for wound healing are also involved.

Stimuli-responsive peptide hydrogels for biomedical applications

Stimuli-responsive hydrogels can respond to external stimuli with a change in the network structure and thus have potential application in drug release, intelligent sensing, and scaffold construction. Peptides possess robust supramolecular self-assembly ability, enabling spontaneous formation of nanostructures through supramolecular interactions and subsequently hydrogels. Therefore, peptide-based stimuli-responsive hydrogels have been widely explored as smart soft materials for biomedical applications in the last decade. Herein, we present a review article on design strategies and research progress of peptide hydrogels as stimuli-responsive materials in the field of biomedicine. The latest design and development of peptide hydrogels with responsive behaviors to stimuli are first presented. The following part provides a systematic overview of the functions and applications of stimuli-responsive peptide hydrogels in tissue engineering, drug delivery, wound healing, antimicrobial treatment, 3D cell culture, biosensors, etc. Finally, the remaining challenges and future prospects of stimuli-responsive peptide hydrogels are proposed. It is believed that this review will contribute to the rational design and development of stimuli-responsive peptide hydrogels toward biomedical applications.

Antimicrobial Hydrogels: Potential Materials for Medical Application

Microbial infections based on drug-resistant pathogenic organisms following surgery or trauma and uncontrolled bleeding are the main causes of increased mortality from trauma worldwide. The prevalence of drug-resistant pathogens has led to a significant increase in medical costs and poses a great threat to the normal life of people. This is an important issue in the field of biomedicine, and the emergence of new antimicrobial materials hydrogels holds great promise for solving this problem. Hydrogel is an important material with good biocompatibility, water absorption, oxygen permeability, adhesion, degradation, self-healing, corrosion resistance, and controlled release of drugs as well as structural diversity. Bacteria-disturbing hydrogels have important applications in the direction of surgical treatment, wound dressing, medical device coating, and tissue engineering. This paper reviews the classification of antimicrobial hydrogels, the current status of research, and the potential of antimicrobial hydrogels for one application in biomedicine, and analyzes the current research of hydrogels in biomedical applications from five aspects: metal-loaded hydrogels, drug-loaded hydrogels, carbon-material-loaded hydrogels, hydrogels with fixed antimicrobial activity and biological antimicrobial hydrogels, and provides an outlook on the high antimicrobial activity, biodegradability, biocompatibility, injectability, clinical applicability and future development prospects of hydrogels in this field.

Recent advances of hydrogels as smart dressings for diabetic wounds

Chronic diabetic wounds have been an urgent clinical problem, and wound dressings play an important role in their management. Due to the design of traditional dressings, it is difficult to achieve adaptive adhesion and on-demand removal of complex diabetic wounds, real-time monitoring of wound status, and dynamic adjustment of drug release behavior according to the wound microenvironment. Smart hydrogels, as smart dressings, can respond to environmental stimuli and achieve more precise local treatment. Here, we review the latest progress of smart hydrogels in wound bandaging, dynamic monitoring, and drug delivery for treatment of diabetic wounds. It is worth noting that we have summarized the most important properties of smart hydrogels for diabetic wound healing. In addition, we discuss the unresolved challenges and future prospects in this field. We hope that this review will contribute to furthering progress on smart hydrogels as improved dressing for diabetic wound healing and practical clinical application.

Microenvironmental dynamics of diabetic wounds and insights for hydrogel-based therapeutics

The rising prevalence of diabetes has underscored concerns surrounding diabetic wounds and their potential to induce disability. The intricate healing mechanisms of diabetic wounds are multifaceted, influenced by ambient microenvironment, including prolonged hyperglycemia, severe infection, inflammation, elevated levels of reactive oxygen species (ROS), ischemia, impaired vascularization, and altered wound physicochemical properties. In recent years, hydrogels have emerged as promising candidates for diabetic wound treatment owing to their exceptional biocompatibility and resemblance to the extracellular matrix (ECM) through a three-dimensional (3D) porous network. This review will first summarize the microenvironment alterations occurring in the diabetic wounds, aiming to provide a comprehensive understanding of its pathogenesis, then a comprehensive classification of recently developed hydrogels will be presented, encompassing properties such as hypoglycemic effects, anti-inflammatory capabilities, antibacterial attributes, ROS scavenging abilities, promotion of angiogenesis, pH responsiveness, and more. The primary objective is to offer a valuable reference for repairing diabetic wounds based on their unique microenvironment. Moreover, this paper outlines potential avenues for future advancements in hydrogel dressings to facilitate and expedite the healing process of diabetic wounds.

Injectable smart stimuli-responsive hydrogels: pioneering advancements in biomedical applications

Hydrogels have established their significance as prominent biomaterials within the realm of biomedical research. However, injectable hydrogels have garnered greater attention compared with their conventional counterparts due to their excellent minimally invasive nature and adaptive behavior post-injection. With the rapid advancement of emerging chemistry and deepened understanding of biological processes, contemporary injectable hydrogels have been endowed with an "intelligent" capacity to respond to various endogenous/exogenous stimuli (such as temperature, pH, light and magnetic field). This innovation has spearheaded revolutionary transformations across fields such as tissue engineering repair, controlled drug delivery, disease-responsive therapies, and beyond. In this review, we comprehensively expound upon the raw materials (including natural and synthetic materials) and injectable principles of these advanced hydrogels, concurrently providing a detailed discussion of the prevalent strategies for conferring stimulus responsiveness. Finally, we elucidate the latest applications of these injectable "smart" stimuli-responsive hydrogels in the biomedical domain, offering insights into their prospects.

Keratin- and VEGF-Incorporated Honey-Based Sponge-Nanofiber Dressing: An Ideal Construct for Wound Healing

To overcome the drawbacks of single-layered wound dressings, bilayer dressings are now introduced as an alternative to achieve effective and long-term treatment. Here, a bilayer dressing composed of electrospun nanofibers in the bottom layer (BL) and a sponge structure as the top layer (TL) is presented. Hydrophilic poly(acrylic acid) (PAAc)-honey (Hny) with interconnected pores of 76.04 μm was prepared as the TL and keratin (Kr), Hny, and vascular endothelial growth factor (VEGF) were prepared as the BL. VEGF indicates a gradual release over 7 days, promoting angiogenesis, as proven by the chick chorioallantoic membrane assay and in vivo tissue histomorphology observation. Additionally, the fabricated dressing material indicated a satisfactory tensile profile, cytocompatibility for human keratinocyte cells, and the ability to promote cell attachment and migration. The in vivo animal model demonstrated that the full-thickness wound healed faster when it was covered with PAAc-Hny/Hny-Kr-VEGF than in other groups. Additionally, faster blood vessel formation, collagen synthetization, and epidermal layer generation were also confirmed, which have proven efficient healing acceleration in wounds treated with synthesized bilayer dressings. Our findings indicated that the fabricated material can be promising as a functional wound dressing.

Tailoring Hyaluronic Acid Hydrogels for Biomedical Applications

Hyaluronic acid (HA) is an attractive anionic polysaccharide polymer with inherent pharmacological properties and versatile chemical groups for modification. Due to their water retention ability, biocompatibility, biodegradation, cluster of differentiation‐44 targeting, and highly designable capacity, HA hydrogels have been an emerging biomaterial, showing tailoring performance in terms of chemical modifications and hydrogel forms. Various preparation technologies have been developed for the fabrication of the tailoring HA hydrogels with unique structures and functions. They have been utilized in diverse biomedical applications like drug delivery and tissue engineering scaffolds. Herein, this review comprehensively summarizes the HA derivatives with different molecule weights and functional modifications. Then the various fabrication methods to obtain tailoring hydrogels in the forms of nanogel, nanofiber, microparticle, microneedle patch, injectable hydrogel, and scaffold are reviewed as well. The emphasis is focused on the shining biomedical applications of these tailoring HA hydrogels in anti‐bacteria, anti‐inflammation, wound healing, cancer treatment, regenerative medicine, psoriasis treatment, diagnosis, etc. The potentials and prospects are subsequently given to inspire further investigation, aiming at accelerating product translation from research to clinic.

Multifunctional and theranostic hydrogels for wound healing acceleration: An emphasis on diabetic-related chronic wounds

Hydrogels represent intricate three-dimensional polymeric structures, renowned for their compatibility with living systems and their ability to naturally degrade. These networks stand as promising and viable foundations for a range of biomedical uses. The practical feasibility of employing hydrogels in clinical trials has been well-demonstrated. Among the prevalent biomedical uses of hydrogels, a significant application arises in the context of wound healing. This intricate progression involves distinct phases of inflammation, proliferation, and remodeling, often triggered by trauma, skin injuries, and various diseases. Metabolic conditions like diabetes have the potential to give rise to persistent wounds, leading to delayed healing processes. This current review consolidates a collection of experiments focused on the utilization of hydrogels to expedite the recovery of wounds. Hydrogels have the capacity to improve the inflammatory conditions at the wound site, and they achieve this by diminishing levels of reactive oxygen species (ROS), thereby exhibiting antioxidant effects. Hydrogels have the potential to enhance the growth of fibroblasts and keratinocytes at the wound site. They also possess the capability to inhibit both Gram-positive and Gram-negative bacteria, effectively managing wounds infected by drug-resistant bacteria. Hydrogels can trigger angiogenesis and neovascularization processes, while also promoting the M2 polarization of macrophages, which in turn mitigates inflammation at the wound site. Intelligent and versatile hydrogels, encompassing features such as pH sensitivity, reactivity to reactive oxygen species (ROS), and responsiveness to light and temperature, have proven advantageous in expediting wound healing. Furthermore, hydrogels synthesized using environmentally friendly methods, characterized by high levels of biocompatibility and biodegradability, hold the potential for enhancing the wound healing process. Hydrogels can facilitate the controlled discharge of bioactive substances. More recently, there has been progress in the creation of conductive hydrogels, which, when subjected to electrical stimulation, contribute to the enhancement of wound healing. Diabetes mellitus, a metabolic disorder, leads to a slowdown in the wound healing process, often resulting in the formation of persistent wounds. Hydrogels have the capability to expedite the healing of diabetic wounds, facilitating the transition from the inflammatory phase to the proliferative stage. The current review sheds light on the biological functionalities of hydrogels, encompassing their role in modulating diverse mechanisms and cell types, including inflammation, oxidative stress, macrophages, and bacteriology. Additionally, this review emphasizes the significance of smart hydrogels with responsiveness to external stimuli, as well as conductive hydrogels for promoting wound healing. Lastly, the discussion delves into the advancement of environmentally friendly hydrogels with high biocompatibility, aimed at accelerating the wound healing process.

Multiple Bio-Actives Loaded Gellan Gum Microfibers from Microfluidics for Wound Healing

Wound healing, known as a fundamental healthcare issue worldwide, has been attracting great attention from researchers. Here, novel bioactive gellan gum microfibers loaded with antibacterial peptides (ABPs) and vascular endothelial growth factor (VEGF) are proposed for wound healing by using microfluidic spinning. Benefitting from the high controllability of microfluidics, bioactive microfibers with uniform morphologies are obtained. The loaded ABPs are demonstrated to effectively act on bacteria at the wound site, reducing the risk of bacterial infection. Besides, sustained release of VEGF from microfibers helps to accelerate angiogenesis and further promote wound healing. The practical value of woven bioactive microfibers is demonstrated via animal experiments, where the wound healing process is greatly facilitated because of the excellent circulation of air and nutritious substances. Featured with the above properties, it is believed that the novel bioactive gellan gum microfibers would have a remarkable effect in the field of biomedical application, especially in promoting wound healing.

In-vitro immunomodulatory responses and antiviral activities of antimicrobial peptide octominin against fish pathogenic viruses

Antimicrobial peptides (AMPs) are considered a novel approach to stimulate fish antiviral mechanisms for defense against a broad range of viral infections by enhancing immunomodulatory activities. Octominin is an AMP derived from the defense proteins of Octopus minor. In this study, preliminary screening of octominin against viral hemorrhagic septicemia virus (VHSV), infectious hematopoietic necrosis virus (IHNV), and infectious pancreatic necrosis virus (IPNV) was carried out. Moreover, immune responses upon octominin treatment and IHNV challenge were investigated using fathead minnow (FHM) cells. The CC50s of octominin for FHM and Chinook salmon embryo-214 (CHSE-214) cells were 2146.2 and 1865.2 μg/mL, respectively. With octominin treatment, EC50 resulted in 732.8, 435.1, and 925.9 μg/mL for VHSV, IHNV, and IPNV, respectively. The selectivity indices were 2.9, 4.9, and 2.0, respectively. The transcriptional analysis results demonstrated the induced transcription factors (Irf3; 143-fold, Irf7; 105-fold, and NF-κB; 8-fold), stress response gene (HspB8; 2-fold), and apoptosis functional gene (p53; 3-fold) in octominin treated (500 μg/mL) FHM cells for 48 h. Moreover, IHNV viral copy number was slightly decreased with the octominin treatment (500 μg/mL) in FHM cells. Overall results suggest that octominin could be a potential antiviral agent, although further studies are necessary to understand its mode of action and the mechanism of its antiviral activity.

"AMP plus": Immunostimulant-Inspired Design Based on Chemotactic Motif-(PhHAhPH)n

Ability to stimulate antimicrobial immunity has proven to be a useful therapeutic strategy in treating infections, especially in the face of increasing antibiotic resistance. Natural antimicrobial peptides (AMPs) exhibiting immunomodulatory functions normally encompass complex activities, which make it difficult to optimize their therapeutic benefits. Here, a chemotactic motif was harnessed as a template to design a series of AMPs with immunostimulatory activities plus bacteria-killing activities ("AMP plus"). An amphipathic peptide ((PhHAhPH)n) was employed to improve the antimicrobial impact and expand the therapeutic potential of the chemotactic motif that lacked obvious bacteria-killing properties. A total of 18 peptides were designed and evaluated for their structure-activity relationships. Among the designed, KWH2 (1) potently killed bacteria and exhibited a narrow antimicrobial spectrum against Gram-negative bacteria and (2) activated macrophages (i.e., inducing Ca2+ influx, cell migration, and reactive oxygen species production) as a macrophage chemoattractant. Membrane permeabilization is the major antimicrobial mechanism of KWH2. Furthermore, the mouse subcutaneous abscess model supported the dual immunomodulatory and antimicrobial potential of KWH2 in vivo. The above results confirmed the efficiency of KWH2 in treating bacterial infection and provided a viable approach to develop immunomodulatory antimicrobial materials with desired properties.

Recent Advances in Antimicrobial Peptide Hydrogels

Advances in the number and type of available biomaterials have improved medical devices such as catheters, stents, pacemakers, prosthetic joints, and orthopedic devices. The introduction of a foreign material into the body comes with a risk of microbial colonization and subsequent infection. Infections of surgically implanted devices often lead to device failure, which leads to increased patient morbidity and mortality. The overuse and improper use of antimicrobials has led to an alarming rise and spread of drug-resistant infections. To overcome the problem of drug-resistant infections, novel antimicrobial biomaterials are increasingly being researched and developed. Hydrogels are a class of 3D biomaterials consisting of a hydrated polymer network with tunable functionality. As hydrogels are customizable, many different antimicrobial agents, such as inorganic molecules, metals, and antibiotics have been incorporated or tethered to them. Due to the increased prevalence of antibiotic resistance, antimicrobial peptides (AMPs) are being increasingly explored as alternative agents. AMP-tethered hydrogels are being increasingly examined for antimicrobial properties and practical applications, such as wound-healing. Here, we provide a recent update, from the last 5 years of innovations and discoveries made in the development of photopolymerizable, self-assembling, and AMP-releasing hydrogels.