Preparation Of Heteroatom Carbon Dots And Their Application In Sensing

Dopamine(DA)is an important information conveying substance in the human central nervous system,which plays an important role in maintaining and regulating the nervous system,cardiovascular system and kidney function.Its concentration variation in human body is closely related to many physiological and pathological processes,such as cardiovascular disease,renal metabolic disease,cancer,Alzheimer’s disease and Parkinson’s disease.Amoxicillin(AMO),as a broad spectrum of semi-synthetic penicillin antibiotics,plays an indispensable role in the field of veterinary drugs and feed additives due to its quick action,but the residues in animal-derived food will cause a series of consequences such as bacterial resistance or human allergic reaction.Therefore,it is of great significance to achieve selectivity and sensitivity detection of DA and AMO.As an emerging member of carbon nanoluminescent materials,carbon dots(CDs)have attracted much attention due to their advantages of high sensitivity,good selectivity,and fast response speed,and have broad application prospects in biological imaging,biosensing,drug delivery,photocatalysis,and other fields.Based on this,the main research work of this paper is as follows:(1)Using o-phenylenediamine as carbon source,ethylenediamine as nitrogen source and sodium phosphate as phosphorus source,nitrogen and phosphorus co-doped carbon dots(N,P-CDs)which can emit bright yellow fluorescence were prepared by a simple one-step hydrothermal method.The morphology and structure of N,P-CDs were characterized by transmission electron microscopy(TEM)and X-ray diffraction spectroscopy(XRD).The experimental results showed that the morphology of the prepared N,P-CDs was spherical and there were a large number of organic functional groups on the surface.N,P-CDs showed high selectivity and sensitivity to DA.When there were other interfering ions and biological microfractions,the detection limit of N,P-CDs on DA was 6.28 μM.The hydrogels combined with N,P-CDs were prepared by a simple method to realize the visual sensing of DA.At the same time,N,P-CDs can be used to detect DA in mouse serum and human urine samples with satisfactory results.The results show that the prepared N,P-CDs is a simple and effective fluorescence sensor,which has a broad application prospect in the field of biological analysis.(2)Orange light emitting nitrogen doped carbon dots(N-CDs)were prepared by onestep hydrothermal method and simple centrifugal dialysis using o-phenylenediamine and melamine as precursors.As a new type of fluorescence nanosensor,the quantitative detection of AMO can be realized through the internal filtration effect.The fluorescence quenching intensity of N-CDs has a good linear relationship with the concentration of AMO(10-100 n M).Based on this,a fluorescence sensing system for simple and rapid detection of AMO in milk and environmental water samples was constructed.The fluorescence sensing system has the advantages of fast response speed,excellent selectivity and good recovery rate,which can realize the sensitive detection of trace amoxicillin.The detection limit(LOD)is 50.11 n M,much lower than the maximum residue limit(MRLs)of the European Union.Therefore,the fluorescence sensing system has potential application value in food analysis and environmental monitoring.