Preparation And Analytical Application Of Carbon Quantum Dots/Organic Dye Complex Ratio Fluorescent Probes

As a sensor signal,the fluorescent probe becomes an effective and rapid sensor system for the detection of analysis in the biomechanics,biosensing,drug diagnosis,metal cation,non-metallic anion and biological small molecule detection.Although the ordinary fluorescent probe of fluorescent "turn-off" and "turn-on" type have many advantages,the accuracy of the results vulnerable to the external environment,detection of substrate and light bleaching,probe load and retention and other factors.The presence of the ratio fluorescence technique overcomes the shortcomings of ordinary fluorescence analysis.In recent years,carbon quantum dots have been shown an important role in biological imaging,biosensing,metal cations and biological small molecule detection with their excellent optical,electrical,biological low toxicity and biocompatibility properties.In this paper,an environmental-friendly and low-cost hydrothermal method was developed for preparation of high fluorescent CDs with the plant of kelp and sodium citrate as a carbon source.Then we exploded the fluorescent probe for electivity and sensitivity detection of p H?Cu2+ and quercetin.The main contents of this article are as follows:(1)An environmental-friendly,low-cost and high fluorescent hydrothermal method was developed for preparation of water-soluble fluorescent CDs with the plant of kelp as a carbon source.The fluorescence probes based on CDs and Fluorescein isothiocyanate(FITC)were designed for pH and Cu2+ detection.Studies have shown that modified CDs can be used as internal constant output signal.FITC is a fluorescent organic dye with good p H sensitivity and have a broad fluorescence spectrum in the visible region.By data processing the ratio relationship between the fluorescence intensity of CDs and FITC in the CDs/FITC complex,it is possible to achieve specificity detection both pH and dual signal detection of Cu2+.And the method of quantitative detection of pH and Cu2+ with broad linear ranges of 4.6~7.7 for pH and 1?12.5 ?M for Cu2+,as well as low detection limits of 7 nM and 9 nM under S/N=3.The ratio fluorescent probe of CDs/FITC is simple,novel and easy to operate,with the analysis of pH in the actual sample,and to detection of Cu2+ based on CDs/FITC composites shows promising and promising applications in latent fingerprint and leaf fluorescence imaging.(2)High fluorescent and will-dispersed CDs synthesized by hydrothermal method with sodium citrate and ammonium carbonate as carbon source.We designed a dual signal fluorescent probe based on CDs and Rhodamine 6G(Rhodamine 6G,R6G)for QCT detection.R6 G is a fluorescent organic dye with high fluorescence quantum yield.The ratio fluorescent probe of CDs/R6 G can be prepared by electrostatic adsorption.Experiments show that QCT can quench the fluorescence signals of CDs and R6 G.The fluorescence color of the fluorescent probe gradually changes from purple to green,so QCT can be visualized by visual inspection.The double-signal fluorescence probe of CDs/R6 G complexes have become more sensitive and specific for QCT detection.And the method of quantitative detection of QCT with broad linear ranges of 9~120 ?M,as well as low detection limits of 5 nM under S/N=3.Therefore,a new method for quantitative detection of QCT with fast,efficient and low cost is established.More importantly,the dual-signal fluorescent probe of CDs/R6 G can be applied to filter paper imaging,opening up the path for its development.