Design And Antibacterial Properities Of Ultrasmall Iron-doped Carbon Dots Nanozyme

Bacterial infection is a major factor hindering wound healing,although antibiotics can be used clinically to deal with bacterial infection.However,the indiscriminate use of antibiotics has led to increasing bacterial resistance and drug resistance,and even superbugs,making bacterial infection a huge public health risk.Therefore,exploring non-antibiotic alternative strategies to combat bacterial infections becomes particularly critical.Nanozymes refer to nanoscale artificial enzymes that can catalyze the conversion of enzyme substrates into products by following enzyme kinetics under relevant physiological conditions.Based on this,we constructed an iron-doped carbon dot nanozyme（Fe-CDs）with good photothermal conversion ability and photo-enhanced peroxidase-like（POD-like）catalytic activity.The mild heat generated by Fe-CDs under near-infrared（NIR）laser irradiation and a large amount of catalytically generated reactive oxygen species（ROS）were used to efficiently and synergistically kill bacteria,and were successfully applied to the antibacterial treatment of skin wound surfaces and to promote wound healing.The research contents are as follows:（1）Nanozymes with ultrasmall size iron-doped carbon dots（Fe-CDs,～3 nm）were constructed by one-pot pyrolysis method.The Fe-doped improved structure and the ultrasmall size exposed active sites.These points enable Fe-CDs to efficiently catalyze the decomposition of hydrogen peroxide（H₂O₂）to generate hydroxyl radicals（·OH）;under NIR laser irradiation,Fe-CDs have the characteristic of absorbing light energy and converting it into thermal energy,and at the same time,the photothermal effect makes Fe-The ability of CDs to catalyze the generation of·OH was enhanced.（2）The antibacterial properties of Fe-CDs in vitro were systematically evaluated by dilution coating plate method and fluorescent staining method,which showed high antibacterial rates against Escherichia coli and Staphylococcus aureus,which were 99.85%and 99.68%,respectively.（3）The cytotoxicity of Fe-CDs was assessed by MTT method.Fe-CDs had no obvious toxicity to NIH-3T3 cells,and could promote the proliferation of NIH-3T3 cells,with good biocompatibility.The antibacterial and wound-promoting effects of Fe-CDs on animal level were explored by immunohistochemistry and immunofluorescence staining experiments,and the efficient wound healing effect was related to the prevention of infection and promotion of fibroblast proliferation brought by Fe-CDs nanozyme-mediated treatment.The dual-function strategy of Fe-CDs provides a good reference for the use of good biocompatible antibiotic-free nanomaterials for antibacterial treatment and wound healing,showing a broad application prospect.