Injectable chitosan hydrogels loaded with antioxidant agent as first-aid dressings for second-degree burn wounds

Burn wounds are destructive skin traumas typically of irregular shape and large area. Prone to infection, they require frequent dressing replacement, and painless removal of dressings from burn wounds remains a major challenge. This study focuses on the dynamic characteristics and treatment difficulty of burn wounds. Hydrogel dressings based on glycol chitosan and propionaldehyde-or benzaldehyde-terminated 4-arm poly(ethylene glycol) were designed on the basis of Schiff base cross-linking networks. The hydrogels exhibited shape-adaptability, self-healing and fast-degradation properties, which makes these hydrogels suitable for burn wounds. Salvianolic acid B(SaB)-loaded hydrogel exhibited good antioxidant properties in vitro. In a rat model of deep second-degree burn wounds, the SaB-loaded hydrogel could quickly reduce wound temperature, regulate wound oxidant microenvironment, promote angiogenesis, and accelerate wound healing. Thus, the drug-loaded hydrogel shows significant potential as a first-aid dressing for treatment of burn wounds.

Designing of tragacanth gum-poly(2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide) and poly(acrylamide) based hydrogels for drug delivery and wound dressing applications

Bioactive tragacanth gum(TG)was functionalized by covalent crosslinking of poly[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide(PMEDSAH)to design network structure in form of hydrogel wound dressings(HWD).These copolymers were encapsulated with antibiotic drug vancomycin to enhance wound healing potential of the dressings.The copolymers were characterized by SEM,AFM,FTIR,13C NMR,XRD,and TGA-DSC analysis.SEM demonstrated uneven heterogeneous morphology and AFM revealed rough surface of copolymer.Inclusion of synthetic component into HD was confirmed by FTIR and 13C NMR.Hydrogel dressings absorbed 8.491.03 g/g simulated wound fluid and exhibited non-hemolytic(3.70.02%hemolytic potential)and antioxidant(37.421.54%free radical scavenging in DPPH assay)properties.Polymers required 35.05.0 mN detachment force to get it detach from the mucosal surface during mucoadhesive test.Tensile strength was found to be 1.880.13 N/mm2 during mechanical stability test.Hydrogel dressings were permeable to O2/H2O and impermeable to microbes.Release of drug vancomycin occurred through non-Fickian diffusion mechanism and release profile was best described by Korsmeyer-Peppas kinetic model.Overall,these results revealed that these hydrogels could be explored as materials for hydrogel wound dressings.

Breathable,antifreezing,mechanically skin-like hydrogel textile wound dressings with dual antibacterial mechanisms

Hydrogels are emerging as the most promising dressings due to their excellent biocompatibility,extracellular matrix mimicking structure,and drug loading ability.However,existing hydrogel dressings exhibit limited breathability,poor environmental adaptability,potential drug resistance,and limited drug options,which extremely restrict their therapeutic effect and working scenarios.Here,the current research introduces the first paradigm of hydrogel textile dressings based on novel gelatin glycerin hydrogel(glyhydrogel)fibers fabricated by the Hofmeister effect based wet spinning.Benefiting from the unique knitted structure,the textile dressing features excellent breathability(1800 times that of the commercially available 3 M dressing)and stretchability(535.51±38.66%).Furthermore,the glyhydrogel textile dressing can also withstand the extreme temperature of-80℃,showing the potential for application in subzero environments.Moreover,the introduction of glycerin endows the textile dressing with remarkable antibacterial property and expands the selection of loaded drugs(e.g.,clindamycin).The prepared glyhydrogel textile dressing shows an excellent infected wound healing effect with a complete rat skin closure within 14 days.All these functions have not been achievable by traditional hydrogel dressings and provide a new approach for the development of hydrogel dressings.

Design of polysaccharide gum based network copolymeric hydrogels for drug delivery and wound dressing applications

This article deals with the exploration of the design of network crosslinked structure by covalent bonding for use as wound dressing materials keeping in view inherent therapeutic role of neem gum in wound healing.These copolymeric hydrogels were prepared by graft-copolymerization reaction of carbopol and poly(N-vinylpyrrolidone)(poly(NVP).Antibiotic drug levofloxacin was encapsulated in dressings for better wound healing.The scanning electron microscopy(SEM),atomic force microscopy(AFM),Fourier transform infrared(FTIR)spectroscopy,^(13)C nuclear magnetic resonance(NMR)spectroscopy,X-ray diffraction(XRD),thermogravimetric analysis(TGA),differential thermal gravimetry(DTG),and differential scanning calorimetry(DSC)techniques were applied for characterization.NMR and FTIR demonstrated incorporation of carbapol and poly(NVP)in dressings.XRD indicated amorphous state in copolymeric dressings.Interactions of copolymers with drug,blood and bio membrane were studied to evaluate biomedical properties which revealed controlled release of drug from hydrogel dressings which were possessing blood-compatible(haemolytic value=2.4±0.82)and mucoadhesive(detachment force=124±41 mN)properties.Dressings were permeable to O2 and H2O vapour and absorbed 6.68±±0.62 g/g wound fluid which is ideal dressing characteristic.Diffusion mechanism type of drug levofloxacin was Fickian with kinetic model First order.These properties suggested use of hydrogel material for wound dressing and drug delivery applications for better wound care management.This article deals with the exploration of the design of network crosslinked structure by covalent bonding for use as wound dressing materials keeping in view inherent therapeutic role of neem gum in wound healing.These copolymeric hydrogels were prepared by graft-copolymerization reaction of carbopol and poly(N-vinylpyrrolidone)(poly(NVP).Antibiotic drug levofloxacin was encapsulated in dressings for better wound healing.The scanning electron microscopy(SEM),atomic force microscopy(AFM),Fourier transform infrared(FTIR)spectroscopy,13C nuclear magnetic resonance(NMR)spectroscopy,X-ray diffraction(XRD),thermogravimetric analysis(TGA),differential thermal gravimetry(DTG),and differential scanning calorimetry(DSC)techniques were applied for characterization.NMR and FTIR demonstrated incorporation of carbapol and poly(NVP)in dressings.XRD indicated amorphous state in copolymeric dressings.Interactions of copolymers with drug,blood and bio membrane were studied to evaluate biomedical properties which revealed controlled release of drug from hydrogel dressings which were possessing blood-compatible(haemolytic value=2.45±.82)and mucoadhesive(detachment force=124±41 mN)properties.Dressings were permeable to O2 and H_(2)O vapour and absorbed 6.68±0.62 g/g wound fluid which is ideal dressing characteristic.Diffusion mechanism type of drug levofloxacin was Fickian with kinetic model First order.These properties suggested use of hydrogel material for wound dressing and drug delivery applications for better wound care management.

Microenvironment responsive nanocomposite hydrogel with NIR photothermal therapy,vascularization and anti-inflammation for diabetic infected wound healing

Bacterial infection,excessive inflammation and damaging blood vessels network are the major factors to delay the healing of diabetic ulcer.At present,most of wound repair materials are passive and can’t response to the wound microenvironment,resulting in a low utilization of bioactive substances and hence a poor therapeutic effect.Therefore,it’s essential to design an intelligent wound dressing responsive to the wound microenvironment to achieve the release of drugs on-demand on the basis of multifunctionality.In this work,metformin-laden CuPDA NPs composite hydrogel(Met@CuPDA NPs/HG)was fabricated by dynamic phenylborate bonding of gelatin modified by dopamine(Gel-DA),Cu-loaded polydopamine nanoparticles(CuPDA NPs)with hyaluronic acid modified by phenyl boronate acid(HA-PBA),which possessed good injectability,self-healing,adhesive and DPPH scavenging performance.The slow release of metformin was achieved by the interaction with CuPDA NPs,boric groups(B-N coordination)and the constraint of hydrogel network.Metformin had a pH and glucose responsive release behavior to treat different wound microenvironment intelligently.Moreover,CuPDA NPs endowed the hydrogel excellent photothermal responsiveness to kill bacteria of>95%within 10 min and also the slow release of Cu^(2+)to protect wound from infection for a long time.Met@CuPDA NPs/HG also recruited cells to a certain direction and promoted vascularization by releasing Cu^(2+).More importantly,Met@CuPDA NPs/HG effectively decreased the inflammation by eliminating ROS and inhibiting the activation of NF-κB pathway.Animal experiments demonstrated that Met@CuPDA NPs/HG significantly promoted wound healing of diabetic SD rats by killing bacteria,inhibiting inflammation,improving angiogenesis and accelerating the deposition of ECM and collagen.Therefore,Met@CuPDA NPs/HG had a great application potential for diabetic wound healing.

Antimicrobial hydrogel with multiple pH-responsiveness for infected burn wound healing

Burns are a common medical problem globally,and wound infection is one of the major causes of inducing related complications.Although antibiotics effectively prevent wound infections,the misuse of antibiotics has created a new problem of superbugs.Herein,we propose a new strategy to obtain pH-responsive antimicrobial P-ZIF(ZIF:zeolitic imidazolate framework)by loading polyhexamethylenebiguanide(PHMB)into the framework of ZIF-8 nanoparticles.This will enable PHMB to be released in the weak acid environment of an infected wound.To address burn infections,P-ZIF nanoparticles were loaded into a hydrogel system made of sodium alginate(SA)and 3-aminophenylboronic acid modified human-like collagen(H-A)through borate ester bonds.The resulting H-A/SA/P-ZIF(HASPZ)hydrogel dressing not only possesses antibacterial and wound healing properties but also has dual pH responsiveness to prevent the overuse of medication while effectively treat deep second-degree burns.Therefore,P-ZIF nanoparticles and the corresponding HASPZ hydrogel dressing are considered of significant importance in antimicrobial,drug delivery,and wound repair.

Macrophage metabolism reprogramming EGCG-Cu coordination capsules delivered in polyzwitterionic hydrogel for burn wound healing and regeneration

Excessive reactive oxygen species(ROS)at severe burn injury sites may promote metabolic reprogramming of macrophages to induce a deteriorative and uncontrolled inflammation cycle,leading to delayed wound healing and regeneration.Here,a novel bioactive,anti-fouling,flexible polyzwitterionic hydrogel encapsulated with epigallocatechin gallate(EGCG)-copper(Cu)capsules(termed as EGCG-Cu@CBgel)is engineered for burn wound management,which is dedicated to synergistically exerting ROS-scavenging,immune metabolic regulation and pro-angiogenic effects.EGCG-Cu@CBgel can scavenge ROS to normalize intracellular redox homeostasis,effectively relieving oxidative damages and blocking proinflammatory signal transduction.Importantly,EGCG-Cu can inhibit the activity of hexokinase and phosphofructokinase,alleviate accumulation of pyruvate and convert it to acetyl coenzyme A(CoA),whereby inhibits glycolysis and normalizes tricarboxylic acid(TCA)cycle.Additionally,metabolic reprogramming of macrophages by EGCG-Cu downregulates M1-type polarization and the expression of proinflammatory cytokines both in vitro and in vivo.Meanwhile,copper ions(Cu^(2+))released from the hydrogel facilitate angiogenesis.EGCG-Cu@CBgel significantly accelerates the healing of severe burn wound via promoting wound closure,weakening tissue-damaging inflammatory responses and enhancing the remodeling of pathological structure.Overall,this study demonstrates the great potential of bioactive hydrogel dressing in treating burn wounds without unnecessary secondary damage to newly formed skin,and highlights the importance of immunometabolism modulation in tissue repair and regeneration.

PREFACE

Hydrogels are classical soft and wet materials that have been extensively studied over the past several decades. Recently, with the development of supramolecular science, nanotechnology and precisely synthetic chemistry, various novel hydrogels have been designed and fabricated, which show emerging applications in tissue engineering, drug delivery, anti-fouling coatings, flexible electronics and soft robotics. Through tailoring their two-dimensional surface structures and three- dimensional networks, unique properties such as ultra-high mechanical strength, responsiveness to various kinds of stimuli, biocompatibility, special wettability and adhesion can be achieved.