Detection Of Tetracyclic Antibiotics And Ascorbic Acid Based On Fluorescence Carbon Dots

Carbon dots?CDs?have lots of advantages,including excellent optical performance,good biocompatibility,adjustable-luminous color,simple synthetic methods and so on.As a new fluorescent carbon nanomaterial,it has been widely used in analysis,biological imaging,fingerprint recognition,photoelectrocatalysis,etc.CDs can provide good fluorescence signal,and its surface have rich active groups,which interacts easily with other substances to achieve the purpose of analysis.Fluorescence analysis is a modern analytical technique with high sensitivity and selectivity.CDs provides a new idea and direction for fluorescence analysis sensing,and various fluorescent probes based on CDs have been designed to meet the analysis needs.The introduction of this paper mainly gives a basic overview of CDs and the description of common synthesis methods and application fields in detail.The main purpose of this topic is to use the special properties of CDs to construct special fluorescence sensors to improve the specificity and selectivity of fluorescence analysis for some substances.On the one hand,the blue and green fluorescent CDs were synthesized through the screening of CDs,and the fluorescence sensor array was constructed to identify and determine a variety of drugs with similar structure and efficacy.On the other hand,carbon dots and molybdenum oxide nanosheet composite materials are used to construct an AND-NAND logic pair based on ratio fluorescence to realize the specific detection of ascorbic acid.The main contents of the experimental investigation are as follows:1.A quadruple-channel fluorescent sensor array based on label-free carbon dots for sensitive detection of tetracyclinesA quadruple-channel fluorescent sensor array based on label-free carbon dots?CDs?was fabricated to detect and discriminate a series of tetracyclines?TCs?,including chlortetracycline?CTC?,oxytetracycline?OTC?,tetracycline?TC?and doxycycline?DOX?.Blue-emitting carbon dots?B-CDs?,green-emitting carbon dots?G-CDs?and mixture of they were prepared to serve as four sensing elements.When the TCs were directly mixed with CDs,the fluorescence quenching phenomenon appeared.Since different TCs exhibited different affinities for sensing elements,the sensor array displays a distinct fluorescence pattern of the fluorescence intensity variation?F₀-F?/F₀ for each of these TCs,which is further analyzed by principal component analysis?PCA?.The present fluorescent sensor array has the capacity to differentiate TCs at a low concentration of 1 ?M.Meanwhile,quantitative detection with a lower limit?0.30?M?for TCs could be achieved by applying a single element.Moreover,a high accuracy?100%?examination of unknown samples is acquired.Finally,the fluorescent sensor array performs well in distinguishing binary mixtures and could also recognize TCs in milk2.A ratio fluorescent sensor for ascorbic acid detection based on AND-NAND logic pairAn AND-NAND logic pair based on CDs and molybdenum oxide nanosheets?MoO₃NSs?was developed,and a ratio fluorescence sensor was designed to detect ascorbic acid?AA?.In the NAD-NAND logic operation,MoO₃ NSs and AA were employed as two input signals,CDs as the signal converter of AND-NAND logic pair,and two fluorescence emission peaks?347 nm and 500 nm?as the output signals of AND and NAND logic gate respectively.In the presence of AA,MoO₃ NSs are reduced to plasmonic molybdenum oxide,which the fluorescence intensity of CDs decreases due to internal filtration effect.Meanwhile,AA is oxidized to dehydroascorbic acid and form fluorescent 3-?dihydroxyethyl?furo[3,4-b]quinoxaline-1-one with o-phenylenediamine from non-purified CDs.On this basis,a AND-NAND logic pair was successfully constructed and used as a ratio fluorescent sensor for highly sensitive detection of AA.The method has a wide detection range from 0.05 to 300?M,and the detection limit is low to 34 nM.In addition,it has been successfully applied to the detection of AA in fruits.We believe it has some additional potential applications in chemical computing,optoelectronic devices,biomedical science,environmental monitoring and so forth.