Antibacterial Effects Of MoS₂QDs Under Sunlight Irradiation

Research purposes: The emergence of new nanomaterials has made it possible to solve the problem of bacterial resistance.Some types of nanomaterials,such as metal nanomaterials and carbon nanomaterials,have received extensive attention and research due to their good antibacterial properties.However,the biotoxicity of metal-based and carbon-based nanomaterials has seriously hampered its further application.Therefore,the development of new nanomaterials with high antibacterial activity and good biocompatibility has attracted much attention.Molybdenum disulfide?MoS₂?nanomaterials have received extensive attention due to their superior physical and chemical properties.With the decrease of lateral size and layer thickness,the catalytic properties of the formed MoS₂ quantum dots?QDs?under sunlight irradiation are significantly improved,indicating potential antibacterial application prospects.However,research on antibacterial photodynamic therapy of MoS₂QDs has rarely been reported.Therefore,this paper will focus on the photochemical and antibacterial properties of MoS₂QDs under sunlight irradiation.Research methods: MoS₂ nanosheets?NSs?and MoS₂QDs were synthesized by ultrasonic extraction of organic solvents.Different forms of MoS₂ were characterized by transmission electron microscope?TEM?,atomic force microscope?AFM?,Raman spectroscopy,and powder diffractometer.The photochemical properties of photoexcited MoS₂QDs were detected by electron spin resonance?ESR?.Staphylococcus aureus?S.aureus?and Escherichia coli?E.coli?were used as research objects to study the antibacterial properties of MoS₂ nanomaterials with different morphologies under sunlight irradiation and effects of promoting wound healing.Results and conclusions:?1?AFM and TEM results show that the thickness of the synthesized MoS₂NSs is?2.0±0.5?nm,the size of MoS₂QDs is less than 10 nm,and the thickness is?0.75±0.25?nm.The photochemical properties of photoexcited MoS₂QDs were investigated by ESR spectroscopy,which indicated that photoexcited MoS₂QDs can generate hydroxyl radicals,superoxide and singlet oxygen,and the production is related to the concentration of materials;?2?Under light irradiation,the antibacterial effect of MoS₂ with different morphologies showed MoS₂QDs> MoS₂NSs> MoS₂,and the antibacterial effect against Staphylococcus aureus was stronger than that of E.coli.The bacteriostatic mechanism is that MoS₂QDs promote the generation and separation of electron-hole pairs more effectively than MoS₂NSs.MoS₂QDs under photoexcitation conditions produce reactive oxygen species?ROS?mediated oxidative stress to kill bacteria.?3?In the mouse wound infection treatment model,the group of a combination of sunlight irradation and MoS₂QDs was found to significantly shorten the period of wound healing compared with the control group and the sunlight group by photographing and statistical analysis of wound area data.?4?The in vitro safety evaluation of MoS₂QDs was carried out by cell experiments,and a bacterial cell co-culture model was established.The results show that MoS₂QDs did not damage peripheral cells while killing bacteria,showing good bioselectivity.Our findings provide a complete description of the photochemical behavior of MoS₂QDs and the resulting antibacterial activity,which may drive the development of MoS₂ nanomaterials as a photodynamic antibacterial agent in the biological field.