Synthesis Of Non-metal Doped Carbon Dots And Their Interactions With Bacteria

Carbon dots,with unique 0-dimension nanostructure,possess special physical and chemical properties.Doping with non-metal elements can increase the intrinsic functions of carbon dots and make them bio-compatible and low-toxic as well,which guarantees the potential applications in biology.Since bacterial infections and the generation of drug-resistance have become serious world-wide problems currently,related research is of high priority.Herein,based on the facile synthesis and properties exploration of non-metal doped carbon dots,we study the interactions of them with bacteria,which widen the path of non-metal doped carbon dots to be applied in the field of bacteria.In this paper,the main works include the following parts:1.Nitrogen,phosphorus and sulfur co-doped carbon dots(NPSCDs)which were synthesized by one-step hydrothermal carbonization of yeast extract exhibit exhibit favorable photoluminescence(PL),excellent photostability,good biocompatibility and low toxicity,NPSCDs show a precise linear response to temperature from 30℃ to 90℃,with the fluorescence intensity decreasing as the temperature increasing and vice versa.Moreover,NPSCDs can selectively stain dead bacteria rather than live ones,indicating that they can serve as an efficient dye for bacterial viability evaluation.Based on these properties,NPSCDs can be served as a novel fluorescent dye to monitor the bacterial viability in real time in different temperature.2.Nitrogen,phosphorus co-doped carbon dots(NPCDs)with high visible fluorescence and tunable negative charges were synthesized by a feasible hydrothermal reaction.The as-prepared NPCDs possess abundant surface functional groups,excellent photostability and bio-compatibility.Especially,the surface negative charges of NPCDs can be tuned by changing the kind of the precursors.The relation between doped-nitrogen atom ratio and negative surface charges can be explained as a combined result of the change of electron cloud density and the hydrogen bonds.The obtained NPCDs as a fluorescent dye could selectively stain dead bacteria due to electrostatic repulsion since the cell walls of bacteria also possess negative charges.The NPCDs with less negative charges provides a low accurate mortality rate due to a weaker repulsion,while NPCDs with the most negative charges give a comparable mortality rate with traditional plate counting method but consumes shorter time.3.A novel kind of carbon dots(CDs)extracted from cigarette smoke shows low in vivo and in vitro toxicity.These CDs show broad-spectrum antimicrobial activities.including multiple drug resistant bacteria,which originate from the destruction of the double helix structure of DNA.CDs can degrade to smaller particles and organic fragments with the existence of horseradish peroxidase(HRP)and H2O2 in 7 days,during which CDs can function as an effective antibiotic within the early days and then gradually degrade and lose the antimicrobial effects until finally being eliminated through metabolism.