Dextran and peptide-based pH-sensitive hydrogel boosts healing process in multidrug-resistant bacteria-infected wounds

Sprayable and self-healing chitosan-based hydrogels for promoting healing of infected wound via anti-bacteria, anti-inflammation and angiogenesis

Treatment of infected wound by simultaneously eliminating bacteria and inducing angiogenesis to promote wound tissue regeneration remains a clinical challenge. Dynamic and reversable hydrogels can adapt to irregular wound beds, which have raised great attention as wound dressings. Herein, a sprayable chitosan-based hydrogel (HPC/CCS/ODex-IGF1) was developed using hydroxypropyl chitosan (HPC), caffeic acid functionalized chitosan (CCS), oxidized dextran (ODex) to crosslink through the dynamic imine bond, which was pH-responsive to the acidic microenvironment and could controllably release insulin growth factor-1 (IGF1). The HPC/CCS/ODex-IGF1 hydrogels not only showed self-healing, self-adaptable and sprayable properties, but also exhibited excellent antibacterial ability, antioxidant property, low-cytotoxicity and angiogenetic activity. In vivo experiments demonstrated that hydrogels promoted tissue regeneration and healing of bacteria-infected wound with a rate of approximately 98.4 % on day 11 by eliminating bacteria, reducing inflammatory and facilitating angiogenesis, demonstrating its great potential for wound dressing.

A structure-functionality insight into the bioactivity of microbial polysaccharides toward biomedical applications: A review

Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

Exosome/antimicrobial peptide laden hydrogel wound dressings promote scarless wound healing through miR-21-5p-mediated multiple functions

Mesenchymal stem cell (MSC)-based therapy is an effective strategy for regenerative therapy. However, safety and ease of use are still issues to be overcome in clinical applications. Exosomes are naturally derived nanoparticles containing bioactive molecules, which serve as ideal cell-free therapeutic modalities. However, issues such as delivery, long-term preservation and activity maintenance of exosomes are other problems that limit their application. In this study, we proposed the use of rapid freeze-dry-thaw macroporous hydrogels for the encapsulation of HucMSC-derived exosomes (HucMSC-Exos) combined with an antimicrobial peptide coating. This exosome-encapsulated hyaluronic acid macroporous hydrogel HD-DP7/Exo can achieve long-term storage and transport by lyophilization and can be rapidly redissolved for treatment. After comprehensively comparing the therapeutic effects of HucMSC-Exos and HucMSC-loaded hydrogels, we found that HucMSC-Exos could also effectively regulate fibroblasts, vascular endothelial cells, and macrophages and inhibit myofibroblast-mediated fibrosis, thus promoting tissue regeneration and inhibiting scar formation in a mouse model of deep second-degree burn infection healing. These properties of lyophilized storage and whole-process-repair make HD-DP7/Exo have potential application value and application prospects.

Emerging trends and challenges in polysaccharide derived materials for wound care applications: A review

Polysaccharides are favourable and promising biopolymers for wound care applications due to their abundant natural availability, low cost and excellent biocompatibility. They possess different functional groups, such as carboxylic, hydroxyl and amino, and can easily be modified to obtain the desirable properties and various forms. This review systematically analyses the recent progress in polysaccharides derived materials for wound care applications, emphasizing the most commonly used cellulose, chitosan, alginate, starch, dextran and hyaluronic acid derived materials. The distinctive attributes of each polysaccharide derived wound care material are discussed in detail, along with their different forms, i.e., films, membranes, sponges, nanoemulsions, nanofibers, scaffolds, nanocomposites and hydrogels. The processing methods to develop polysaccharides derived wound care materials are also summarized. In the end, challenges related to polysaccharides derived materials in wound care management are listed, and suggestions are given to expand their utilization in the future to compete with conventional wound healing materials.

Micro-environment triple-responsive hyaluronic acid hydrogel dressings to promote antibacterial activity, collagen deposition, and angiogenesis for diabetic wound healing

The clinical treatment of chronic diabetic wounds is a long-standing thorny issue. Strategies targeting the diabetic micro-environment have been developed to promote wound healing. However, it remains challenging to reverse the adverse conditions and re-activate tissue regeneration and angiogenesis. In this work, we develop injectable hydrogels that are responsive to acidic conditions, reactive oxygen species (ROS), and high glucose levels in a diabetic wound micro-environment to sustainably deliver tannic acid (TA) to augment antibacterial, anti-inflammatory, and anti-oxidative activities. This triple-responsive mechanism is designed by introducing dynamic acylhydrazone and phenylboronic ester bonds to crosslink modified hyaluronic acid (HA) chains. At a diabetic wound, the acylhydrazone bonds may be hydrolyzed at low pH. Meanwhile, glucose may compete with TA, and ROS may oxidize the C-B bond to release TA. Thus, sustained release of TA is triggered by the diabetic micro-environment. The released TA effectively scavenges ROS and kills bacteria. In vivo experiments on diabetic mice demonstrate that the hydrogel dressing highly promotes angiogenesis and extracellular matrix (ECM) deposition, leading to eventual full healing of diabetic skin wounds. This micro-environment-triggered triple-responsive drug release provides a promising method for chronic diabetic wound healing.

Recent Advances in the Degradability and Applications of Tissue Adhesives Based on Biodegradable Polymers

In clinical practice, tissue adhesives have emerged as an alternative tool for wound treatments due to their advantages in ease of use, rapid application, less pain, and minimal tissue damage. Since most tissue adhesives are designed for internal use or wound treatments, the biodegradation of adhesives is important. To endow tissue adhesives with biodegradability, in the past few decades, various biodegradable polymers, either natural polymers (such as chitosan, hyaluronic acid, gelatin, chondroitin sulfate, starch, sodium alginate, glucans, pectin, functional proteins, and peptides) or synthetic polymers (such as poly(lactic acid), polyurethanes, polycaprolactone, and poly(lactic-co-glycolic acid)), have been utilized to develop novel biodegradable tissue adhesives. Incorporated biodegradable polymers are degraded in vivo with time under specific conditions, leading to the destruction of the structure and the further degradation of tissue adhesives. In this review, we first summarize the strategies of utilizing biodegradable polymers to develop tissue adhesives. Furthermore, we provide a symmetric overview of the biodegradable polymers used for tissue adhesives, with a specific focus on the degradability and applications of these tissue adhesives. Additionally, the challenges and perspectives of biodegradable polymer-based tissue adhesives are discussed. We expect that this review can provide new inspirations for the design of novel biodegradable tissue adhesives for biomedical applications.

Hyaluronidase-Responsive Bactericidal Cryogel for Promoting Healing of Infected Wounds: Inflammatory Attenuation, ROS Scavenging, and Immune Regulation

Wounds infected with multidrug-resistant (MDR) bacteria are increasingly threatening public health and challenging clinical treatments because of intensive bacterial colonization, excessive inflammatory responses, and superabundant oxidative stress. To overcome this malignant burden and promote wound healing, a multifunctional cryogel (HA/TA2/KR2) composed of hyaluronic acid (HA), tannic acid (TA), and KR-12 peptides is designed. The cryogel exhibited excellent shape-memory properties, strong absorption performance, and hemostatic capacity. In vitro experiments demonstrated that KR-12 in the cryogel can be responsively released by stimulation with hyaluronidase produced by bacteria, reaching robust antibacterial activity against Escherichia coli (E. coli), MDR Pseudomonas aeruginosa (MDR-PA), and methicillin-resistant Staphylococcus aureus (MRSA) by disrupting bacterial cell membranes. Furthermore, the synergetic effect of KR-12 and TA can efficiently scavenge ROS and decrease expression of pro-inflammatory cytokines (tumor necrosis factor (TNF)-α & interleukin (IL)-6), as well as modulate the macrophage phenotype toward the M2 type. In vivo animal tests indicated that the cryogel can effectively destroy bacteria in the wound and promote healing process via accelerating angiogenesis and re-epithelialization. Proteomic analysis revealed the underlying mechanism by which the cryogel mainly reshaped the infected wound microenvironment by inhibiting the Nuclear factor kappa B (NF-κB) signaling pathway and activating the Janus kinase-Signal transducer and activator of transcription (JAK-STAT6) signaling pathway. Therefore, the HA/TA2/KR2 cryogel is a promising dressing candidate for MDR bacteria-infected wound healing.

Dextran-based antibacterial hydrogel-derived fluorescent sensors for the visual monitoring of AgNPs

The unpredictable release behavior of metal nanoparticles/metal ions from metal nanoparticle-loaded hydrogels, without a suitable in situ detection method, is resulting in serious cytotoxicity. To optimize the preparation and design of antibacterial hydrogels for in situ detection of metal nanoparticles, an in-situ detection platform based on the fluorescence signal change caused by the potential surface energy transfer of silver nanoparticles (AgNPs) and carbon dots (CD) through silver mirror reaction and Schiff base reaction was established. The antimicrobial test results show that the composite antimicrobial hydrogel, with lower dosages of AgNPs and CD, exhibited a higher inhibition rate of 99.1 % against E. coli and 99.8 % against S. aureus compared to the single antimicrobial component. This suggests a potential synergistic antimicrobial activity. Furthermore, the fluorescence detection platform was established with a difference of <3 μg between detected values and actual values over a period of 72 h. This demonstrates the excellent in situ detection capability of the hydrogel in antimicrobial-related applications.

KGRT peptide incorporated hydrogel with antibacterial activity for wound healing by optimizing cellular functions via ERK/eNOS signaling

Bacterial infected wounds, which is characterized by easy infection, multiple inflammation and slow healing, is a complex symptom, resulting from metabolic disorder of the wound microenvironment. In this study, a series of self-healing double-network hydrogels based on KGRT peptide (Lys-Gly-Arg-Thr) with antibacterial, anti-inflammatory and optimizing cellular functions were designed to promote the healing of infected wounds with full-thickness skin defects. Moreover, the dextran hydrogelintroduces a large number of side chains, which are entangled with each other in the Schiff base network to form an interpenetrating structure. The hydrogel might regulate cell metabolism, differentiation and vascular endothelial growth factor (VEGF) function. Importantly, both in vitro and in vivo data showed that hydrogel not only has good antibacterial properties (99.8 %), but also can eradicate bacterial biofilm, effectively reduce inflammation (down-regulated IL-1β, TNF-α and ROS) and accelerate chronic wound healing process by speeding-up wound closure, increasing granulation tissue thickness, collagen deposition, angiogenesis (up-regulated CD31). The hydrogel could up-regulate mRNA expression of PI3K, AKT, ERK, eNOS, HIF-1α and VEGF, which were correlated with wound healing. Consistently, the hydrogel could promote infected wounds healing and inhibit inflammation through ERK/eNOS signaling pathway. Collectively, hydrogel has excellent clinical application potential for promoting infected wound healing.

A tough, antibacterial and antioxidant hydrogel dressing accelerates wound healing and suppresses hypertrophic scar formation in infected wounds

Wound management is an important issue that places enormous pressure on the physical and mental health of patients, especially in cases of infection, where the increased inflammatory response could lead to severe hypertrophic scars (HSs). In this study, a hydrogel dressing was developed by combining the high strength and toughness, swelling resistance, antibacterial and antioxidant capabilities. The hydrogel matrix was composed of a double network of polyvinyl alcohol (PVA) and agarose with excellent mechanical properties. Hyperbranched polylysine (HBPL), a highly effective antibacterial cationic polymer, and tannic acid (TA), a strong antioxidant molecule, were added to the hydrogel as functional components. Examination of antibacterial and antioxidant properties of the hydrogel confirmed the full play of the efficacy of HBPL and TA. In the in vivo studies of methicillin-resistant Staphylococcus aureus (MRSA) infection, the hydrogel had shown obvious promotion of wound healing, and more profoundly, significant suppression of scar formation. Due to the common raw materials and simple preparation methods, this hydrogel can be mass produced and used for accelerating wound healing while preventing HSs in infected wounds.

DP7-C/mir-26a system promotes bone regeneration by remodeling the osteogenic immune microenvironment

OBJECTIVE

This study investigates the DP7-C/miR-26a complex as a stable entity resulting from the combination of miR-26a with the immunomodulatory peptide DP7-C. Our focus is on utilizing DP7-C loaded with miR-26a to modulate the immune microenvironment in bone and facilitate osteogenesis.

METHODS

The DP7-C/miR-26a complex was characterized through transmission electron microscopy, agarose electrophoresis, and nanoparticle size potentiometer analysis. Transfection efficiency and cytotoxicity of DP7-C were assessed using flow cytometry and the CCK-8 assay. We validated the effects of DP7-C/miR-26a on bone marrow mesenchymal stem cells (BMSCs) and macrophages RAW 264.7 through gene expression and protein synthesis assays. A comprehensive evaluation of appositional bone formation involved micro-CT imaging, histologic analysis, and immunohistochemical staining.

RESULTS

DP7-C/miR-26a, a nanoscale, and low-toxic cationic complex, demonstrated the ability to enter BMSCs and RAW 264.7 via distinct pathways. The treatment with DP7-C/miR-26a significantly increased the synthesis of multiple osteogenesis-related factors in BMSCs, facilitating calcium nodule formation in vitro. Furthermore, DP7-C/miR-26a promoted M1 macrophage polarization toward M2 while suppressing the release of inflammatory factors. Coculture studies corroborated these findings, indicating significant repair of rat skull defects following treatment with DP7-C/miR-26a.

CONCLUSION

The DP7-C/miR-26a system offers a safer, more efficient, and feasible technical means for treating bone defects.

Current status of development and biomedical applications of peptide-based antimicrobial hydrogels

Microbial contamination poses a serious threat to human life and health. Through the intersection of material science and modern medicine, advanced bionic hydrogels have shown great potential for biomedical applications due to their unique bioactivity and ability to mimic the extracellular matrix environment. In particular, as a promising antimicrobial material, the synthesis and practical biomedical applications of peptide-based antimicrobial hydrogels have drawn increasing research interest. The synergistic effect of peptides and hydrogels facilitate the controlled release of antimicrobial agents and mitigation of their biotoxicity while achieving antimicrobial effects and protecting the active agents from degradation. This review reports on the progress and trends of researches in the last five years and provides a brief outlook, aiming to provide theoretical background on peptide-based antimicrobial hydrogels and make suggestions for future related work.

Antibiofilm activity of polyethylene glycol-quercetin nanoparticles-loaded gelatin-N,O-carboxymethyl chitosan composite nanogels against Staphylococcus epidermidis

BACKGROUND

Biofilms, such as those from Staphylococcus epidermidis, are generally insensitive to traditional antimicrobial agents, making it difficult to inhibit their formation. Although quercetin has excellent antibiofilm effects, its clinical applications are limited by the lack of sustained and targeted release at the site of S. epidermidis infection.

OBJECTIVES

Polyethylene glycol-quercetin nanoparticles (PQ-NPs)-loaded gelatin-N,O-carboxymethyl chitosan (N,O-CMCS) composite nanogels were prepared and assessed for the on-demand release potential for reducing S. epidermidis biofilm formation.

METHODS

The formation mechanism, physicochemical characterization, and antibiofilm activity of PQ-nanogels against S. epidermidis were studied.

RESULTS

Physicochemical characterization confirmed that PQ-nanogels had been prepared by the electrostatic interactions between gelatin and N,O-CMCS with sodium tripolyphosphate. The PQ-nanogels exhibited obvious pH and gelatinase-responsive to achieve on-demand release in the micro-environment (pH 5.5 and gelatinase) of S. epidermidis. In addition, PQ-nanogels had excellent antibiofilm activity, and the potential antibiofilm mechanism may enhance its antibiofilm activity by reducing its relative biofilm formation, surface hydrophobicity, exopolysaccharides production, and eDNA production.

CONCLUSIONS

This study will guide the development of the dual responsiveness (pH and gelatinase) of nanogels to achieve on-demand release for reducing S. epidermidis biofilm formation.

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.

Development of a Novel Covalently Bonded Conjugate of Caprylic Acid Tripeptide (Isoleucine-Leucine-Aspartic Acid) for Wound-Compatible and Injectable Hydrogel to Accelerate Healing

Third-degree burn injuries pose a significant health threat. Safer, easier-to-use, and more effective techniques are urgently needed for their treatment. We hypothesized that covalently bonded conjugates of fatty acids and tripeptides can form wound-compatible hydrogels that can accelerate healing. We first designed conjugated structures as fatty acid-aminoacid1-amonoacid2-aspartate amphiphiles (Cn acid-AA1-AA2-D), which were potentially capable of self-assembling into hydrogels according to the structure and properties of each moiety. We then generated 14 novel conjugates based on this design by using two Fmoc/tBu solid-phase peptide synthesis techniques; we verified their structures and purities through liquid chromatography with tandem mass spectrometry and nuclear magnetic resonance spectroscopy. Of them, 13 conjugates formed hydrogels at low concentrations (≥0.25% w/v), but C8 acid-ILD-NH2 showed the best hydrogelation and was investigated further. Scanning electron microscopy revealed that C8 acid-ILD-NH2 formed fibrous network structures and rapidly formed hydrogels that were stable in phosphate-buffered saline (pH 2-8, 37 °C), a typical pathophysiological condition. Injection and rheological studies revealed that the hydrogels manifested important wound treatment properties, including injectability, shear thinning, rapid re-gelation, and wound-compatible mechanics (e.g., moduli G″ and G', ~0.5-15 kPa). The C8 acid-ILD-NH2(2) hydrogel markedly accelerated the healing of third-degree burn wounds on C57BL/6J mice. Taken together, our findings demonstrated the potential of the Cn fatty acid-AA1-AA2-D molecular template to form hydrogels capable of promoting the wound healing of third-degree burns.

Designing Composite Stimuli-Responsive Hydrogels for Wound Healing Applications: The State-of-the-Art and Recent Discoveries

Effective wound treatment has become one of the most important challenges for healthcare as it continues to be one of the leading causes of death worldwide. Therefore, wound care technologies significantly evolved in order to provide a holistic approach based on various designs of functional wound dressings. Among them, hydrogels have been widely used for wound treatment due to their biocompatibility and similarity to the extracellular matrix. The hydrogel formula offers the control of an optimal wound moisture level due to its ability to absorb excess fluid from the wound or release moisture as needed. Additionally, hydrogels can be successfully integrated with a plethora of biologically active components (e.g., nanoparticles, pharmaceuticals, natural extracts, peptides), thus enhancing the performance of resulting composite hydrogels in wound healing applications. In this review, the-state-of-the-art discoveries related to stimuli-responsive hydrogel-based dressings have been summarized, taking into account their antimicrobial, anti-inflammatory, antioxidant, and hemostatic properties, as well as other effects (e.g., re-epithelialization, vascularization, and restoration of the tissue) resulting from their use.

Sprayable chitosan nanogel with nitric oxide to accelerate diabetic wound healing through bacteria inhibition, biofilm eradication and macrophage polarization

Bacterial infection and chronic inflammation are two major risks in diabetic wound healing, which increase patient mortality. In this study, a multifunctional sprayable nanogel (Ag-G@CS) based on chitosan has been developed to synergistically inhibit bacterial infection, eradicate biofilm, and relieve inflammation of diabetic wounds. The nanogel is successfully crafted by encapsulating with a nitric oxide (NO) donor and performing in-situ reduction of silver nanoparticles (Ag). The released NO enhances the antibacterial efficacy of Ag, nearly achieving complete eradication of biofilms in vitro. Upon application on both normal or diabetic chronic wounds, the combination effects of released NO and Ag offer a notable antibacterial effect. Furthermore, after bacteria inhibition and biofilm eradication, the NO released by the nanogel orchestrates a transformation of M1 macrophages into M2 macrophages, significantly reducing tumor necrosis factor α (TNF-α) release and relieving inflammation. Remarkably, the released NO also promotes M2a to M2c macrophages, thereby facilitating tissue remodeling in chronic wounds. More importantly, it upregulates the expression of vascular endothelial growth factor (VEGF), further accelerating the wound healing process. Collectively, the formed sprayable nanogel exhibits excellent inhibition of bacterial infections and biofilms, and promotes chronic wound healing via inflammation resolution, which has excellent potential for clinical use in the future.

Stimulus-Responsive Hydrogels as Drug Delivery Systems for Inflammation Targeted Therapy

Deregulated inflammations induced by various factors are one of the most common diseases in people's daily life, while severe inflammation can even lead to death. Thus, the efficient treatment of inflammation has always been the hot topic in the research of medicine. In the past decades, as a potential biomaterial, stimuli-responsive hydrogels have been a focus of attention for the inflammation treatment due to their excellent biocompatibility and design flexibility. Recently, thanks to the rapid development of nanotechnology and material science, more and more efforts have been made to develop safer, more personal and more effective hydrogels for the therapy of some frequent but tough inflammations such as sepsis, rheumatoid arthritis, osteoarthritis, periodontitis, and ulcerative colitis. Herein, from recent studies and articles, the conventional and emerging hydrogels in the delivery of anti-inflammatory drugs and the therapy for various inflammations are summarized. And their prospects of clinical translation and future development are also discussed in further detail.

Recent advances in biopolymer-based hydrogels and their potential biomedical applications

Hydrogels are three-dimensional networks of polymer chains containing large amounts of water in their structure. Hydrogels have received significant attention in biomedical applications owing to their attractive physicochemical properties, including flexibility, softness, biodegradability, and biocompatibility. Different natural and synthetic polymers have been intensely explored in developing hydrogels for the desired applications. Biopolymers-based hydrogels have advantages over synthetic polymers regarding improved cellular activity and weak immune response. These properties can be further improved by grafting with other polymers or adding nanomaterials, and they structurally mimic the living tissue environments, which opens their broad applicability. The hydrogels can be physically or chemically cross-linked depending on the structure. The use of different biopolymers-based hydrogels in biomedical applications has been reviewed and discussed earlier. However, no report is still available to comprehensively introduce the synthesis, advantages, disadvantages, and biomedical applications of biopolymers-based hydrogels from the material point of view. Herein, we systematically overview different synthesis methods of hydrogels and provide a holistic approach to biopolymers-based hydrogels for biomedical applications, especially in bone regeneration, wound healing, drug delivery, bioimaging, and therapy. The current challenges and prospects of biopolymers-based hydrogels are highlighted rationally, giving an insight into the progress of these hydrogels and their practical applications.

Dialdehyde carbohydrates - Advanced functional materials for biomedical applications

Dialdehyde carbohydrates (DCs) have found applications in a wide range of biomedical field due to their great versatility, biocompatibility/biodegradability, biological properties, and controllable chemical/physical characteristics. The presence of dialdehyde groups in carbohydrate structure allows cross-linking of DCs to form versatile architectures serving as interesting matrices for biomedical applications (e.g., drug delivery, tissue engineering, and regenerative medicine). Recently, DCs have noticeably contributed to the development of diverse physical forms of advanced functional biomaterials i.e., bulk architectures (hydrogels, films/coatings, or scaffolds) and nano/-micro formulations. We underline here the current scientific knowledge on DCs, and demonstrate their potential and newly developed biomedical applications. Specifically, an update on the synthesis approach and functional/bioactive attributes is provided, and the selected in vitro/in vivo studies are reviewed comprehensively as examples of the latest progress in the field. Moreover, safety concerns, challenges, and perspectives towards the application of DCs are deliberated.

Versatile Hydrogel Dressings That Dynamically Regulate the Healing of Infected Deep Burn Wounds

Severe burns threaten patient lives due to pain, inflammation, bacterial infection, and scarring. Most burn dressings that are commonly used perform a single function and are not well suited for the management of deep burns. Therefore, a multifunctional antimicrobial peptide- and stem cell-loaded macroporous hydrogel that can fight bacterial infection and regulate wound healing progression by temporally regulating cytokine production by internal stem cells is developed. The macroporous skeletal hydrogel is manufactured via the cryogenic gelation of hyaluronic acid (cryogel). Based on the oxidative polymerization reaction of dopamine, the antimicrobial peptide DP7 is immobilized on the surface of the cryogel (DA7CG). Placental mesenchymal stem cells (PMSCs) are then packaged inside the macroporous hydrogel (DA7CG@C). According to the results of in vitro and in vivo experiments, during the inflammatory phase, DP7 inhibits infection and modulates inflammation; during the proliferative phase, DA7CG@C accelerates the regeneration of skin, blood vessels, and hair follicles via internal stem cells; and during the remodeling phase, DA7CG@C contributes to extracellular matrix remodeling due to the ability of DP7 to regulate the paracrine secretion of PMSCs, synergistically promoting scar-free healing. DA7CG@C can participate in all phases of wound healing; therefore, it is a promising dressing for burn treatment.

Multifunctional Oxidized Dextran-Metformin as a Tissue-Adhesive Hydrogel to Prevent Postoperative Peritoneal Adhesions in Patients with Metabolic Syndrome

Patients with metabolic syndrome (MetS) undergoing surgery are at high risk of developing peritoneal adhesions and other severe postoperative complications. However, the single shielding function and absence of physiological activity render conventional methods less useful in preventing adhesions in patients with MetS. To address this challenge, a convenient method is introduced for developing a novel tissue-adhesive hydrogel called oxidized dextran-metformin (ODE-ME) via Schiff base linkages. This injectable ODE-ME hydrogel exhibits excellent tissue-adhesive properties and various physiological functions, particularly enhanced antibacterial effects. Furthermore, in vivo experiments demonstrate that the hydrogel can effectively alleviate hyperglycemia, reduce excessive inflammation, and improve fibrinolytic activity in MetS mice, thereby preventing adhesions and promoting incisional healing. The hydrogel concurrently isolates injured tissues and lowers the blood glucose levels immediately after surgery in mice. Therefore, the ODE-ME hydrogel functions as a multifunctional barrier material and has potential for preventing postoperative peritoneal adhesions in patients with MetS in clinical settings.

An additive-free multifunctional β-glucan-peptide hydrogel participates in the whole process of bacterial-infected wound healing

Bacterial infections and excessive inflammation can impede the healing of wounds. Hydrogels have emerged as a promising approach for dressing bacterial-infected injuries. However, some antibacterial hydrogels are complex, costly, and even require assistance with other instruments such as light, making them unsuitable for routine outdoor injuries. Here, we developed an in-situ generating hydrogel via hybridizing oxidized β-D-glucan with antimicrobial peptide C8G2 through the Schiff base reaction. This hydrogel is easily accessible and actively contributes to the whole healing process of bacterial-infected wounds, demonstrating remarkable antibacterial activity and biological compatibility. The pH-sensitive reversible imine bond enables the hydrogel to self-heal and sustainably release the antibacterial peptide, thereby improving its bioavailability and reducing toxicity. Meanwhile, the immunoregulating β-D-glucan inhibits the release of inflammatory factors while promoting the release of anti-inflammatory factors. In methicillin-resistant Staphylococcus aureus (MRSA)-infected full-thickness skin wound models, the hybrid hydrogel showed superior antibacterial and anti-inflammatory activity, enhanced the M2 macrophage polarization, expedited wound closure, and regenerated epidermis tissue. These features make this hydrogel an appealing wound dressing for treating multi-drug-resistant bacteria-infected wounds.

Development of a Stretchable and Water-Resistant Hydrogel with Antibacterial and Antioxidant Dual Functions for Wound Healing in Movable Parts

The treatment of wounds that develop on moving parts of the body, such as joints, is considered a challenge due to poor mechanical matching and secondary injury caused by continuous motion and inflammation. Herein, a stretchable, multifunctional hydrogel dressing utilizing the dual cross-linking of chitosan (CS) and acrylic acid (AA) and modified with caffeic acid (CA) and aloin (Alo) was developed. Mechanical testing demonstrated that the hydrogel possessed excellent stretching capability (of approximately 869%) combined with outstanding adhesion (about 56 kPa), contributing to its compatibility with moving parts and allowing complete coverage of wound sites without limiting joint and organ motion. Bioinformatics analysis confirmed that use of the hydrogel resulted in upregulated expression of multiple genes related to angiogenesis and cell proliferation. Furthermore, antibacterial testing indicated that the dressing suppressed the growth of Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA), providing a better microenvironment for wound healing. An in vivo wound defect model on movable skin verified that the wound healing observed with the hydrogel dressing was superior to that observed with a commercially available dressing. Taken together, the results suggest that a stretchable multifunctional hydrogel dressing represents a promising alternative wound dressing with therapeutic potential for superior healing, especially for moving parts of the body.

Composite Hydrogel Dressings with Enhanced Mechanical Properties and Anti-Inflammatory Ability for Effectively Promoting Wound Repair

Background

Hydrogel dressings have been used as a crucial method to keep the wound wet and hasten the healing process. Due to safety concerns regarding the gel components, low mechanical adhesiveness, and unsatisfactory anti-inflammatory capacity qualities for practical uses in vivo, leading to the clinical translation of wound dressings is still difficult.

Methods

A type of composite hydrogel (acrylamide/polyethylene glycol diacrylate/tannic acid, ie, AM/PEGDA/TA) by double bond crosslinking, Schiff base, and hydrogen bond interaction is proposed. The mechanical characteristics, adhesiveness, and biocompatibility of the hydrogel system were all thoroughly examined. Additionally, a full-thickness cutaneous wound model was employed to assess the in vivo wound healing capacity of resulting hydrogel dressings.

Results

Benefiting the mechanism of multiple crosslinking, the designed composite hydrogels showed significant mechanical strength, outstanding adhesive capability, and good cytocompatibility. Moreover, the hydrogel system also had excellent shape adaptability, and they can be perfectly integrated into the irregularly shaped wounds through a fast in situ forming approach. Additional in vivo tests supported the findings that the full-thickness wound treated with the composite hydrogels showed quicker epithelial tissue regeneration, fewer inflammatory cells, more collagen deposition, and greater levels of platelet endothelial cell adhesion molecule (CD31) expression.

Conclusion

These above results might offer a practical and affordable product or method of skin wound therapy in a medical context.

Modern Approaches in Wounds Management

Wound management represents a well-known continuous challenge and concern of the global healthcare systems worldwide. The challenge is on the one hand related to the accurate diagnosis, and on the other hand to establishing an effective treatment plan and choosing appropriate wound care products in order to maximize the healing outcome and minimize the financial cost. The market of wound dressings is a dynamic field which grows and evolves continuously as a result of extensive research on developing versatile formulations with innovative properties. Hydrogels are one of the most attractive wound care products which, in many aspects, are considered ideal for wound treatment and are widely exploited for extension of their advantages in healing process. Smart hydrogels (SHs) offer the opportunities of the modulation physico-chemical properties of hydrogels in response to external stimuli (light, pressure, pH variations, magnetic/electric field, etc.) in order to achieve innovative behavior of their three-dimensional matrix (gel-sol transitions, self-healing and self-adapting abilities, controlled release of drugs). The SHs response to different triggers depends on their composition, cross-linking method, and manufacturing process approach. Both native or functionalized natural and synthetic polymers may be used to develop stimuli-responsive matrices, while the mandatory characteristics of hydrogels (biocompatibility, water permeability, bioadhesion) are preserved. In this review, we briefly present the physiopathology and healing mechanisms of chronic wounds, as well as current therapeutic approaches. The rational of using traditional hydrogels and SHs in wound healing, as well as the current research directions for developing SHs with innovative features, are addressed and discussed along with their limitations and perspectives in industrial-scale manufacturing.

Advancements in dextran-based nanocarriers for treatment and imaging of breast cancer

Breast cancer is the most prevalent type of cancer worldwide,particularly among women, with substantial side effects after therapy. Despite the availability of numerous therapeutic approaches, particularly chemotherapy, the survival rates for breast cancer have declined over time. The therapies currently utilized for breast cancer treatment do not specifically target cancerous cells, resulting in significant adverse effects and potential harm to healthy cells alongside the cancer cells. As a result, nanoparticle-based drug delivery systems have emerged. Among various types of nanoparticles, natural polysaccharide-based nanoparticles have gained significant attention due to their ability to precisely control the drug release and achieve targeted drug delivery. Moreover, polysaccharides are biocompatible, biodegradable, easily modifiable, and renewable, which makes them a unique material for nanoformulation. In recent years, dextran and its derivatives have gained much interest in the field of breast cancer therapy. Dextran is a hydrophilic polysaccharide composed of a main chain formed by α-1,6 linked glucopyranoside residues and a side chain composed of residues linked in α-1,2/3/4 positions. Different dextran-antitumor medication conjugates enhancethe efficacy of anticancer agents. With this context, the present review provides brief insights into dextran and its modification. Further, it meticulously discusses the role of dextran-based nanoparticles in breast cancer therapy and imaging, followed by snippets on their toxicity. Lastly, it presents clinical trials and future perspectives of dextran-based nanoparticles in breast cancer treatment.

Research advances in smart responsive-hydrogel dressings with potential clinical diabetic wound healing properties

The treatment of chronic and non-healing wounds in diabetic patients remains a major medical problem. Recent reports have shown that hydrogel wound dressings might be an effective strategy for treating diabetic wounds due to their excellent hydrophilicity, good drug-loading ability and sustained drug release properties. As a typical example, hyaluronic acid dressing (Healoderm) has been demonstrated in clinical trials to improve wound-healing efficiency and healing rates for diabetic foot ulcers. However, the drug release and degradation behavior of clinically-used hydrogel wound dressings cannot be adjusted according to the wound microenvironment. Due to the intricacy of diabetic wounds, antibiotics and other medications are frequently combined with hydrogel dressings in clinical practice, although these medications are easily hindered by the hostile environment. In this case, scientists have created responsive-hydrogel dressings based on the microenvironment features of diabetic wounds (such as high glucose and low pH) or combined with external stimuli (such as light or magnetic field) to achieve controllable drug release, gel degradation, and microenvironment improvements in order to overcome these clinical issues. These responsive-hydrogel dressings are anticipated to play a significant role in diabetic therapeutic wound dressings. Here, we review recent advances on responsive-hydrogel dressings towards diabetic wound healing, with focus on hydrogel structure design, the principle of responsiveness, and the behavior of degradation. Last but not least, the advantages and limitations of these responsive-hydrogels in clinical applications will also be discussed. We hope that this review will contribute to furthering progress on hydrogels as an improved dressing for diabetic wound healing and practical clinical application.

Recent Advances of Natural-Polymer-Based Hydrogels for Wound Antibacterial Therapeutics

Hydrogels have a three-dimensional network structure and high-water content, are similar in structure to the extracellular matrix, and are often used as wound dressings. Natural polymers have excellent biocompatibility and biodegradability and are commonly utilized to prepare hydrogels. Natural-polymer-based hydrogels can have excellent antibacterial and bioactive properties by loading antibacterial agents or being combined with therapeutics such as phototherapy, which has great advantages in the field of treatment of microbial infections. In the published reviews of hydrogels used in the treatment of infectious wounds, the common classification criteria of hydrogels include function, source of antibacterial properties, type of antibacterial agent, etc. However, there are few reviews on the classification of hydrogels based on raw materials, and the description of natural-polymer-based hydrogels is not comprehensive and detailed. In this paper, based on the principle of material classification, the characteristics of seven types of natural polymers that can be used to prepare hydrogels are discussed, respectively, and the application of natural-polymer-based hydrogels in the treatment of infectious wounds is described in detail. Finally, the research status, limitations, and prospects of natural-polymer-based hydrogels are briefly discussed.

Functional carbohydrate-based hydrogels for diabetic wound therapy

Diabetes wound are grave and universal complications of diabetes. Owing to poor treatment course, high amputation rate and mortality, diabetes wound treatment and care have become a global challenge. Wound dressings have received much attention due to their ease of use, good therapeutic effect, and low costs. Among them, carbohydrate-based hydrogels with excellent biocompatibility are considered to be the best candidates for wound dressings. Based on this, we first systematically summarized the problems and healing mechanism of diabetes wounds. Next, common treatment methods and wound dressings were discussed, and the application of various carbohydrate-based hydrogels and their corresponding functionalization (antibacterial, antioxidant, autoxidation and bioactive substance delivery) in the treatment of diabetes wounds were emphatically introduced. Ultimately, the future development of carbohydrate-based hydrogel dressings was proposed. This review aims to provide a deeper understanding of wound treatment and theoretical support for the design of hydrogel dressings.

Natural biomarocmolecule-based antimicrobial hydrogel for rapid wound healing: A review

Antibacterial hydrogels are a type of hydrogel that is designed to inhibit the growth of bacteria and prevent infections. These hydrogels typically contain antibacterial agents that are either integrated into the polymer network or coated onto the surface of the hydrogel. The antibacterial agents in these hydrogels can work through a variety of mechanisms, such as disrupting bacterial cell walls or inhibiting bacterial enzyme activity. Some examples of antibacterial agents that are commonly used in hydrogels include silver nanoparticles, chitosan, and quaternary ammonium compounds. Antibacterial hydrogels have a wide range of applications, including wound dressings, catheters, and medical implants. They can help to prevent infections, reduce inflammation, and promote tissue healing. In addition, they can be designed with specific properties to suit different applications, such as high mechanical strength or controlled release of antibacterial agents over time. Hydrogel wound dressings have come a long way in recent years, and the future looks very promising for these innovative wound care products. Overall, the future of hydrogel wound dressings is very promising, and we can expect to see continued innovation and advancement in this field in the years to come.

Innovative Functional Biomaterials as Therapeutic Wound Dressings for Chronic Diabetic Foot Ulcers

The imbalance of local and systemic factors in individuals with diabetes mellitus (DM) delays, or even interrupts, the highly complex and dynamic process of wound healing, leading to diabetic foot ulceration (DFU) in 15 to 25% of cases. DFU is the leading cause of non-traumatic amputations worldwide, posing a huge threat to the well-being of individuals with DM and the healthcare system. Moreover, despite all the latest efforts, the efficient management of DFUs still remains a clinical challenge, with limited success rates in treating severe infections. Biomaterial-based wound dressings have emerged as a therapeutic strategy with rising potential to handle the tricky macro and micro wound environments of individuals with DM. Indeed, biomaterials have long been related to unique versatility, biocompatibility, biodegradability, hydrophilicity, and wound healing properties, features that make them ideal candidates for therapeutic applications. Furthermore, biomaterials may be used as a local depot of biomolecules with anti-inflammatory, pro-angiogenic, and antimicrobial properties, further promoting adequate wound healing. Accordingly, this review aims to unravel the multiple functional properties of biomaterials as promising wound dressings for chronic wound healing, and to examine how these are currently being evaluated in research and clinical settings as cutting-edge wound dressings for DFU management.

A multi-crosslinking strategy of organic and inorganic compound bio-adhesive polysaccharide-based hydrogel for wound hemostasis

Polysaccharides are naturally occurring polymers with exceptional biodegradable and biocompatible qualities that are used as hemostatic agents. In this study, photoinduced CC bond network and dynamic bond network binding was used to give polysaccharide-based hydrogels the requisite mechanical strength and tissue adhesion. The designed hydrogel was composed of modified carboxymethyl chitosan (CMCS-MA) and oxidized dextran (OD), and introduced hydrogen bond network through tannic acid (TA) doping. Halloysite nanotubes (HNTs) were also added, and the effects of various doping amount on the performance of the hydrogel were examined, in order to enhance the hemostatic property of hydrogel. Experiments on vitro degradation and swelling demonstrated the strong structural stability of hydrogels. The hydrogel has improved tissue adhesion strength, with a maximum adhesion strength of 157.9 kPa, and demonstrated improved compressive strength, with a maximum compressive strength of 80.9 kPa. Meanwhile, the hydrogel had a low hemolysis rate and had no inhibition on cell proliferation. The created hydrogel exhibited a significant aggregation effect on platelets and a reduced blood clotting index (BCI). Importantly, the hydrogel can quickly adhere to seal the wound and has good hemostatic effect in vivo. Our work successfully prepared a polysaccharide-based bio-adhesive hydrogel dressing with stable structure, appropriate mechanical strength, and good hemostatic properties.

Peptide Supramolecular Hydrogels with Sustained Release Ability for Combating Multidrug-Resistant Bacteria

Chronic wound infection caused by multidrug-resistant bacteria is a major threat globally, leading to high mortality rates and a considerable economic burden. To address it, an innovative supramolecular nanofiber hydrogel (Hydrogel-RL) harboring antimicrobial peptides was developed based on the novel arginine end-tagging peptide (Pep 6) from our recent study, triggering cross-linking. In vitro results demonstrated that Hydrogel-RL can sustain the release of Pep 6 up to 120 h profiles, which is biocompatible and exhibits superior activity for methicillin-resistant Staphylococcus aureus (MRSA) biofilm inhibition and elimination. A single treatment of supramolecular Hydrogel-RL on an MRSA skin infection model revealed formidable antimicrobial activity and therapeutic effects in vivo. In the chronic wound infection model, Hydrogel-RL promoted mouse skin cell proliferation, reduced inflammation, accelerated re-epithelialization, and regulated muscle and collagen fiber formation, rapidly healing full-thickness skin wounds. To show its vehicle property for wound infection combined therapy, etamsylate, an antihemorrhagic drug, was loaded into the porous network of Hydrogel-RL, which demonstrated improved hemostatic activity. Collectively, Hydrogel-RL is a promising clinical candidate agent for functional supramolecular biomaterials designed for combating multidrug-resistant bacteria and rescuing stalled healing in chronic wound infections.

Ultrasonic interfacial crosslinking of TiO2-based nanocomposite hydrogels through thiol-norbornene reactions for sonodynamic antibacterial treatment

Nanocomposite (NC) hydrogels used for sonodynamic therapy (SDT) face challenges such as lacking interfacial interactions between the polymers and nanomaterials as well as presenting uneven dispersion of nanomaterials in the hydrogel network, reducing their mechanical properties and treatment efficiency. Here, we demonstrate a promising approach of co-engineering nanomaterials and interfacial crosslinking to expand the materials construction and biomedical applications of NC hydrogels in SDT. In this work, mesoporous silica-coated titanium dioxide nanoparticles with thiolated surface functionalization (TiO₂@MS-SH) are utilized as crosslinkers to react with norbornene-functionalized dextran (Nor-Dex) through ultrasound-triggered thiol-norbornene reactions, forming TiO₂@MS-SH/Nor-Dex NC hydrogels. The TiO₂@MS-SH nanoparticles act not only as multivalent crosslinkers to improve the mechanical properties of hydrogels under ultrasound irradiation but also as reactive oxygen species (ROS) generators to allow the use of TiO₂@MS-SH/Nor-Dex NC hydrogels in SDT applications. Particularly, the TiO₂@MS-SH/Nor-Dex NC hydrogels present tailorable microstructures, properties, and sonodynamic killing of bacteria through the modulation of the ultrasound frequency. Taken together, a versatile TiO₂-based NC hydrogel platform prepared under ultrasonic interfacial crosslinking reactions is developed for advancing the applications in SDT.

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.

Recent progress of antibacterial hydrogels in wound dressings

Hydrogels are essential biomaterials due to their favorable biocompatibility, mechanical properties similar to human soft tissue extracellular matrix, and tissue repair properties. In skin wound repair, hydrogels with antibacterial functions are especially suitable for dressing applications, so novel antibacterial hydrogel wound dressings have attracted widespread attention, including the design of components, optimization of preparation methods, strategies to reduce bacterial resistance, etc. In this review, we discuss the fabrication of antibacterial hydrogel wound dressings and the challenges associated with the crosslinking methods and chemistry of the materials. We have investigated the advantages and limitations (antibacterial effects and antibacterial mechanisms) of different antibacterial components in the hydrogels to achieve good antibacterial properties, and the response of hydrogels to stimuli such as light, sound, and electricity to reduce bacterial resistance. Conclusively, we provide a systematic summary of antibacterial hydrogel wound dressings findings (crosslinking methods, antibacterial components, antibacterial methods) and an outlook on long-lasting antibacterial effects, a broader antibacterial spectrum, diversified hydrogel forms, and the future development prospects of the field.

Honokiol@PF127 crosslinked hyaluronate-based hydrogel for promoting wound healing by regulating macrophage polarization

Bacterial infection, oxidative stress and inflammation are the main obstacles in wound healing. Hydrogels with moist and inherent properties are beneficial to wound healing. Here, we fabricated a honokiol-laden micelle-crosslinked hyaluronate-based hydrogel by simply mixing honokiol-laden PF127-CHO micelles, 3,3'-dithiobis(propionohydrazide) grafted hyaluronic acid and silver ions. PF127 could not only effectively load hydrophobic small molecules but also be macromolecular crosslinker for preparing hydrogels. Hyaluronic acid plays an essential role in wound healing processes including regulating macrophage polarization towards M2 phenotype. The chemical dynamic acylhydrazone crosslinking and physical crosslinking among PF127-CHO micelles constructed hydrogel's networks, which endowed hydrogel with excellent self-healing properties. PF-HA-3 hydrogel also exhibited outstanding antioxidant and antibacterial capabilities. In a full-thickness skin defect model, this degradable and biocompatible hydrogel could promote wound healing by remodeling wound tissues, regulating M2 polarization and angiogenesis. In summary, this inherent multifunctional hydrogel will provide a promising strategy for designing bioactive compounds-based wound dressings.

Past, present and future of biomedical applications of dextran-based hydrogels: A review

This review extensively surveys the biomedical applications of hydrogels containing dextran. Dextran has gained much attention as a biomaterial due to its distinctive properties such as biocompatibility, non-toxicity, water solubility and biodegradability. It has emerged as a critical constituent of hydrogels for biomedical applications including drug delivery devices, tissue engineering scaffolds and biosensor materials. The benefits, challenges and potential prospects of dextran-based hydrogels as biomaterials are highlighted in this review.

Facile preparation of polyphenol-crosslinked chitosan-based hydrogels for cutaneous wound repair

The design and facile preparation of the smart hydrogel wound dressings with inherent excellent antioxidant and antibacterial capacity to effectively promote wound healing processes is highly desirable in clinical applications. Herein, a series of multifunctional hydrogels were prepared by the dynamic Schiff base and boronate ester crosslinking among phenylboronic acid (PBA) grafted carboxymethyl chitosan (CMCS), polyphenols and Cu²⁺-crosslinked polyphenol nanoparticles (CuNPs). The dynamic crosslinking bonds endowed hydrogels with excellent self-healing and degradable properties. Three polyphenols including tannic acid (TA), oligomeric proanthocyanidins (OPC) and (-)-epigallocatechin-3-O-gallate (EGCG) contributed to the outstanding antibacterial and antioxidant abilities of these hydrogels. The tissue adhesive capacity of hydrogels gave them good hemostatic effect. Through a full-thickness skin defect model of mice, these biocompatible hydrogels could accelerate wound healing processes by promoting granulation tissue formation, collagen deposition, M2 macrophage polarization and cytokine secretion, demonstrating that these natural-derived hydrogels with inherent physiological properties and low-cost preparation approaches could be promising dressing materials.

Multifunctional Nano-Realgar Hydrogel for Enhanced Glioblastoma Synergistic Chemotherapy and Radiotherapy: A New Paradigm of an Old Drug

Purpose

Realgar, as a kind of traditional mineral Chinese medicine, can inhibit multiple solid tumor growth and serve as an adjuvant drug in cancer therapy. However, the extremely low solubility and poor body absorptive capacity limit its application in clinical medicine. To overcome this therapeutic hurdle, realgar can here be fabricated into a nano-realgar hydrogel with enhanced chemotherapy and radiotherapy (RT) ability. Our objective is to evaluate the superior biocompatibility and anti-tumor activity of nano-realgar hydrogel.

Methods

We have successfully synthesized nano-realgar quantum dots (QDs) coupling with 6-AN molecules (NRA QDs) and further encapsulated with a pH-sensitive dextran hydrogel carrier with hyaluronic acid coating (DEX-HA gel) to promote bioavailability, eventually forming a multifunctional nano-realgar hydrogel (NRA@DH Gel). To better investigate the tumor therapy efficiency of the NRA@DH Gel, we have established the mice in situ bearing GL261 brain glioblastoma as animal models assigned to receive intratumor injection of NRA@DH Gel.

Results

The designed NRA@DH Gel as an antitumor drug can not only exert the prominent chemotherapy effect but also as a "sustainable reactive oxygen species (ROS) generator" can inhibit in the pentose phosphate pathway (PPP) metabolism and reduce the production of nicotinamide adenine dinucleotide phosphate (NADPH), thereby inhibiting the conversion of glutathione disulfide (GSSG) to glutathione (GSH), reducing GSH concentrations in tumor cells, triggering the accumulation of ROS, and finally enhancing the effectiveness of RT.

Conclusion

Through the synergistic effect of chemotherapy and RT, NRA@DH Gel effectively inhibited the proliferation and migration of tumor cells, suppressed tumor growth, improved motor coordination, and prolonged survival in tumor-bearing mice. Our work aims to improve the NRA@DH Gel-mediated synergistic chemotherapy and RT will endow a "promising future" for the old drug in clinically comprehensive applications.

Current and future outlook of loaded components in hydrogel composites for the treatment of chronic diabetic ulcers

Due to recalcitrant microangiopathy and chronic infection, traditional treatments do not easily produce satisfactory results for chronic diabetic ulcers. In recent years, due to the advantages of high biocompatibility and modifiability, an increasing number of hydrogel materials have been applied to the treatment of chronic wounds in diabetic patients. Research on composite hydrogels has received increasing attention since loading different components can greatly increase the ability of composite hydrogels to treat chronic diabetic wounds. This review summarizes and details a variety of newly loaded components currently used in hydrogel composites for the treatment of chronic diabetic ulcers, such as polymer/polysaccharides/organic chemicals, stem cells/exosomes/progenitor cells, chelating agents/metal ions, plant extracts, proteins (cytokines/peptides/enzymes) and nucleoside products, and medicines/drugs, to help researchers understand the characteristics of these components in the treatment of diabetic chronic wounds. This review also discusses a number of components that have not yet been applied but have the potential to be loaded into hydrogels, all of which play roles in the biomedical field and may become important loading components in the future. This review provides a "loading component shelf" for researchers of composite hydrogels and a theoretical basis for the future construction of "all-in-one" hydrogels.

Polysaccharide-Based Multifunctional Hydrogel Bio-Adhesives for Wound Healing: A Review

Wound healing is a long-term and complex biological process that involves multiple hemostasis, inflammation, proliferation, and remodeling stages. In order to realize comprehensive and systematic wound management, appropriate wound treatment bio-adhesives are urgently needed. Hydrogel bio-adhesives have excellent properties and show unique and remarkable advantages in the field of wound management. This review begins with a detailed description of the design criteria and functionalities of ideal hydrogel bio-adhesives for wound healing. Then, recent advances in polysaccharide-based multifunctional hydrogel bio-adhesives, which involve chitosan, hyaluronic acid, alginate, cellulose, dextran, konjac glucomannan, chondroitin sulfate, and other polysaccharides, are comprehensively discussed. Finally, the current challenges and future research directions of polysaccharide-based hydrogel bio-adhesives for wound healing are proposed to stimulate further exploration by researchers.

Construction of Smart Biomaterials for Promoting Diabetic Wound Healing

Diabetes mellitus is a complicated metabolic disease that has become one of the fastest-growing health crises in modern society. Diabetic patients may suffer from various complications, and diabetic foot is one of them. It can lead to increased rates of lower-extremity amputation and mortality, even seriously threatening the life and health of patients. Because its healing process is affected by various factors, its management and treatment are very challenging. To address these problems, smart biomaterials have been developed to expedite diabetic wound closure and improve treatment outcomes. This review begins with a discussion of the basic mechanisms of wound recovery and the limitations of current dressings used for diabetic wound healing. Then, the categories and characteristics of the smart biomaterial scaffolds, which can be utilized as a delivery system for drugs with anti-inflammatory activity, bioactive agency, and antibacterial nanoparticles for diabetic wound treatment were described. In addition, it can act as a responsive system to the stimulus of the pH, reactive oxygen species, and glucose concentration from the wound microenvironment. These results show that smart biomaterials have an enormous perspective for the treatment of diabetic wounds in all stages of healing. Finally, the advantages of the construction of smart biomaterials are summarized, and possible new strategies for the clinical management of diabetic wounds are proposed.

Dextran Formulations as Effective Delivery Systems of Therapeutic Agents

Dextran is by far one of the most interesting non-toxic, bio-compatible macromolecules, an exopolysaccharide biosynthesized by lactic acid bacteria. It has been extensively used as a major component in many types of drug-delivery systems (DDS), which can be submitted to the next in-vivo testing stages, and may be proposed for clinical trials or pharmaceutical use approval. An important aspect to consider in order to maintain high DDS' biocompatibility is the use of dextran obtained by fermentation processes and with a minimum chemical modification degree. By performing chemical modifications, artefacts can appear in the dextran spatial structure that can lead to decreased biocompatibility or even cytotoxicity. The present review aims to systematize DDS depending on the dextran type used and the biologically active compounds transported, in order to obtain desired therapeutic effects. So far, pure dextran and modified dextran such as acetalated, oxidised, carboxymethyl, diethylaminoethyl-dextran and dextran sulphate sodium, were used to develop several DDSs: microspheres, microparticles, nanoparticles, nanodroplets, liposomes, micelles and nanomicelles, hydrogels, films, nanowires, bio-conjugates, medical adhesives and others. The DDS are critically presented by structures, biocompatibility, drugs loaded and therapeutic points of view in order to highlight future therapeutic perspectives.

Functional insights to the development of bioactive material for combating bacterial infections

The emergence of antibiotic-resistant "superbugs" poses a serious threat to human health. Nanomaterials and cationic polymers have shown unprecedented advantages as effective antimicrobial therapies due to their flexibility and ability to interact with biological macromolecules. They can incorporate a variety of antimicrobial substances, achieving multifunctional effects without easily developing drug resistance. Herein, this article discusses recent advances in cationic polymers and nano-antibacterial materials, including material options, fabrication techniques, structural characteristics, and activity performance, with a focus on their fundamental active elements.

Effect of composite biodegradable biomaterials on wound healing in diabetes

The repair of diabetic wounds has always been a job that doctors could not tackle quickly in plastic surgery. To solve this problem, it has become an important direction to use biocompatible biodegradable biomaterials as scaffolds or dressing loaded with a variety of active substances or cells, to construct a wound repair system integrating materials, cells, and growth factors. In terms of wound healing, composite biodegradable biomaterials show strong biocompatibility and the ability to promote wound healing. This review describes the multifaceted integration of biomaterials with drugs, stem cells, and active agents. In wounds, stem cells and their secreted exosomes regulate immune responses and inflammation. They promote angiogenesis, accelerate skin cell proliferation and re-epithelialization, and regulate collagen remodeling that inhibits scar hyperplasia. In the process of continuous combination with new materials, a series of materials that can be well matched with active ingredients such as cells or drugs are derived for precise delivery and controlled release of drugs. The ultimate goal of material development is clinical transformation. At present, the types of materials for clinical application are still relatively single, and the bottleneck is that the functions of emerging materials have not yet reached a stable and effective degree. The development of biomaterials that can be further translated into clinical practice will become the focus of research.

Supramolecular Hydrogel Dressing: Effect of Lignin on the Self-Healing, Antibacterial, Antioxidant, and Biological Activity Improvement

The functionalization and performance improvement of supramolecular hydrogels are very important for their application in the wound dressing field. Inspired by the role of lignin in plant cell walls, sulfonated lignin is introduced into the supramolecular hydrogel to improve functionality, mechanical strength, and biological activity. According to the chemical structure characteristics of the sulfonated lignin and the requirements for wound dressing, a novel polymer system is designed and successfully synthesized to cooperate with the sulfonated lignin to form the supramolecular hydrogel dressings. The introduction of the sulfonated lignin can effectively improve the mechanical strength, self-healing property, antioxidant activity, and biological activity of the obtained supramolecular hydrogel dressings. In the rat wound healing model experiment, the supramolecular hydrogel dressings can maintain the moist environment on the wound surface, clean up the excretion of wound tissue, promote wound healing, and reduce the occurrence of inflammation. This supramolecular hydrogel dressing shows obvious potential for wound management and treatment by a facile and effective approach and has great promise for long-term application of wound dressings. This strategy for designing polymers according to the chemical structure characteristics of the sulfonated lignin and the application requirements has reference value for further development of biomass-based compound materials.

Peptide-Based Hydrogels: New Materials for Biosensing and Biomedical Applications

Peptide-based hydrogels have attracted increasing attention for biological applications and diagnostic research due to their impressive features including biocompatibility and biodegradability, injectability, mechanical stability, high water absorption capacity, and tissue-like elasticity. The aim of this review will be to present an updated report on the advancement of peptide-based hydrogels research activity in recent years in the field of anticancer drug delivery, antimicrobial and wound healing materials, 3D bioprinting and tissue engineering, and vaccines. Additionally, the biosensing applications of this key group of hydrogels will be discussed mainly focusing the attention on cancer detection.