Preparation Of Nitride Nanoenzyme And Its Bactericidal Treatment

Bacterial infections has a serious impact on human health and have become a public health problem plaguing the world.Among the traditional therapeutic options,antibiotics are widely used in the treatment of bacterial infections due to their direct and effective bactericidal properties.There is a widespread reliance on antibiotics in the therapy process for a long time,and the increased doses of antibiotics and prolonged therapeutic periods have led to the emergence of increasingly drug-resistant bacteria.If left unregulated,patients with serious bacterial infections may be at risk of being left without drugs and thus have life-threatening conditions.The development of new antimicrobial means that have excellent antimicrobial properties and won’t cause bacteria to be resistant is crucial.Due to the booming development of nanotechnology,the higher specific surface area of nanomaterials and the controlled regulation of morphological and dimensions,making nanomaterials have powerful antibacterial potential.Due to the drawbacks of natural enzymes such as poor stability,cost effectiveness and environmental sensitivity,nanozymes that possess both the catalytic effect of natural enzymes and the unique properties of nanomaterials are widely used in biomedical therapies.Owing to their excellent stability and catalytic efficiency,nanozymes can rapidly catalyze specific substrates to produce highly reactive oxygen species（ROS）,which can cause significant damage to cellular proteins,lipids,and DNA.Due to the convenience of surface modification and controlled regulation at the nanoscale,multifunctional nanozymes with specific catalytic properties can be constructed and thus have great potential for application in bacterial infection treatment scenarios.This thesis focuses on nitrogenated metalloenzymes as the main research content.By constructing metal-nitrogen bonds,nitrogenated metalloenzymes with enzymatic activity properties were fabricated,and the obtained nanozymes were able to satisfy the demand of clinical antibacterial therapy,providing a new idea for nanozymes in the field of bacterial infection therapy.The research work of this thesis is as follows:Firstly,the nanozymes suffers from weak material-bacteria interaction and insufficient ROS diffusion distance in sterilization.To overcome the above problems,we synthesized WS₂with nanoflower-like structure by a simple hydrothermal method,and further used ammonia high-temperature annealing to construct W-N bonds in situ in WS₂.The morphology and crystal structure changes of the nanozymes before and after nitridation have been further characterized.The results indicated that the introduction of the W-N bond conferred the catalytic activity of WN peroxidase（POD）,which could effectively catalyze the decomposition of H₂O₂ at low concentrations to produce highly cytotoxic hydroxyl radicals（·OH）.WN exhibits favorable catalytic stability over a wide p H and temperature range.The flower-like structure of WN is composed of many two-dimensional nanosheets,which have a superior bacterial trapping ability.Thus,the bacteria can be confined to the effective range of ROS production by the nanozymes,and the antibacterial effect of the nanozymes can be strengthened.This method provides a fresh concept towards novel nanozymes for bactericidal applications.Secondly,WN nanoflowers have issues such as small specific surface area and unsatisfactory catalytic activity in the sterilization process.Mo elements,as human trace elements,have superior biocompatibility,and Mo-based nanomaterials are considered safer and more reliable compared to tungsten elements in the biomedical application process.We annealed Mo Cl₅ under ammonia environment to prepare Mo₅N₆ with ideal specific surface area,which has excellent peroxidase-like activity.And the relative activity of 80%was maintained over a wide temperature range,showing stable catalytic performance.The catalytic ability of Mo₅N₆ was extremely effective in killing bacteria,and after co-incubation with bacteria Mo₅N₆was widely distributed on the bacterial surface,and the bacterial morphology changed significantly,showing crumpling of the biofilm and exposure of the contents.This was attributed to the dispersion and superior catalytic performance of Mo₅N₆,which has a robust potential for biotherapeutic applications.