Preparation Of The Cu₂O/Pt Hydrogel And Its Application In Diabetic Wound

Chronic wound healing is one of the common persistent complications in diabetic patients.Compared to the normal wounds,high glucose levels on the diabetic wound provide a nutritional environment for bacterial growth,while pathologically high glucose levels reduce inflammatory cell chemotaxis and phagocytosis,making bacteria less likely to be removed.Wound repair thus stays in the inflammatory phase,and prolonged inflammation will lead to tissue damage and delay wound healing.Therefore,finding effective antimicrobial strategies is the key to treating the diabetic chronic wounds.Hydrogels are widely used in bacterial infection and wound healing due to their unique three-dimensional structure,good biocompatibility and similarity to human soft tissues.In response to the problem that the use of hydrogels containing antibiotics can generate bacterial resistance,it is more advantageous to choose metal nanoparticles with broad-spectrum bactericidal properties and photothermal properties as hydrogel antimicrobial materials.Therefore,the design of a new hydrogel wound dressing with antimicrobial properties,good biocompatibility,and the ability to promote chronic wound healing has good prospects for application.Based on this,Cu₂O/Pt ALG-HA hydrogel（Cu₂O/Pt hydrogel）was prepared and combined with glucose oxidase（GOx）for photothermal and starvation-enhanced chemodynamic antimicrobial therapy in this paper.The main research ideas,contents and results are as follows:1.Cu₂O/Pt hydrogels were synthesized using Cu₂O/Pt nanoparticles（Cu₂O/Pt NPs）as the antimicrobial agent,ALG and HA as the hydrogel matrix.Through a series of characterizations,Cu₂O/Pt was found to have a cubic structure with an average particle size of200 nm,and Cu and Pt existed mainly in the form of Cu⁺and Pt⁰.The Cu₂O/Pt hydrogel was cross-linked by Fe³⁺-COOH and had a porous mesh structure.The rheological tests proved that the Cu₂O/Pt hydrogel has good mechanical properties.2.The antibacterial mechanism and antibacterial activity in vitro of Cu₂O/Pt hydrogels were then investigated.Copper ion release experiments and gel degradation experiments illustrated that Cu₂O/Pt hydrogels can gradually release copper ions with degradation.TMB color development and fluorescent probe method demonstrated that Cu₂O/Pt hydrogels can catalyze H₂O₂to generate reactive oxygen species for photodynamic therapy.The photothermal performance results showed that the Cu₂O/Pt hydrogel exhibited time-dependent,concentration-dependent and laser power density-dependent properties with good stability under 808 nm NIR light irradiation.The antibacterial properties of Cu₂O/Pt hydrogels against E.coli and S.aureus were then evaluated by means of plate coating experiments,SEM characterization and reactive oxygen species detection.The results showed that under 808 nm NIR irradiation,Cu₂O/Pt hydrogels coupled with GOx could exhibit good antibacterial effects through photothermal synergistic chemical dynamics.3.After exploring the antibacterial mechanism and antibacterial activity of Cu₂O/Pt hydrogels,we continued to evaluate the biocompatibility of Cu₂O/Pt hydrogels at the cellular level.Live-dead cell staining assay illustrated that Cu₂O/Pt hydrogels had no significant toxic effects on 3T3-L1 cells.Cell viability assay and migration assay showed that Cu₂O/Pt hydrogel had significant pro-proliferative and migratory effects on HUVECs cells.The hemolysis assay showed that Cu₂O/Pt hydrogel has good hemocompatibility.4.Based on these results,we evaluated the in vivo wound healing effect of Cu₂O/Pt hydrogels by establishing a wound model of bacterial infection in diabetic rats.The results showed that the wound healing speed of Cu₂O/Pt hydrogel+GOx+NIR group was significantly better than that of the control group from day 3,and Cu₂O/Pt hydrogels showed good photothermal and bactericidal effects.Compared with the control group,the rats in the Cu₂O/Pt hydrogel+GOx+NIR group showed significant hair follicle regeneration and collagen deposition,and the levels of CD31,ki67 and VEGF molecules were significantly upregulated.The biosafety of Cu₂O/Pt hydrogel was demonstrated by measuring the body weight,serum biochemical indexes and HE staining of major organs of rats.In summary,the temperature of Cu₂O/Pt hydrogels was rapidly increased under 808 nm NIR laser irradiation,which simultaneously enhanced the catalytic activity of Cu₂O/Pt nanotubes and GOx.GOx catalyzes the production of gluconate and hydrogen peroxide from glucose for starvation therapy,and the subsequently released Cu₂O/Pt nanoparticles react with hydrogen peroxide under acidic conditions to produce cytotoxic hydroxyl radicals（·OH）.In addition,with decreasing p H,Cu₂O/Pt hydrogels gradually release copper ions,which promote endothelial cell proliferation,migration and angiogenesis,and thus promote diabetic wound healing in rats.