Research On The Preparation And Application Of Fluorescent Probes Based On Functionalized Carbon Dots

Fluorescent carbon dots,as a new type of carbon nanomaterial,have good chemical stability,excellent biocompatibility and low cytotoxicity,making them the best choice for replacing quantum dots.It has been successfully used in the field of detection of analytes,cell imaging and drug delivery.In this paper,carbon dots were prepared by hydrothermal method and solvothermal method respectively,and their luminescent properties were studied by different functional modification,and applied to analytical detection and bioimaging.The main contents of the paper include the following parts:1.Nitrogen-doped carbon dots(CDs)with quantum yield up to 62%and up-and-down conversion fluorescence properties were prepared from tris(hydroxymethyl)aminomethane and citric acid.The experimental results show that CDs can achieve dual channel detection of Hg2+ and GSH by down-and up-conversion emission.The Hg2+detection limits were estimated to be 0.23 and 0.25 ?M,and the GSH were obtained to be 0.28 and 0.29?M,respectively.The CDs was used to determine Hg2+ and GSH in environmental water samples,and the recoveries were 96.2?110.4%and 93.4?96.9%,respectively.2.Yellow-emissive carbon dots(Y-CDs)were prepared by a solvothermal method using citric acid and 2,3-phenazinediamine as the starting materials.The Y-CDs display a 24%fluorescence quantum yield and a 188-nm Stokes' shift.Y-CDs can be used as a multifunctional probe for the determination of Ag+ and glutathione(GSH).The detection limits for Ag+and GSH were estimated to be 31 nM and 76 nM,respectively.Y-CDs were used to detect Ag+in environmental water samples,and the recovery rate was 93?107%.Y-CDs+Ag+ was used to determine GSH in vegetable samples,showing satisfactory recovery.Y-CDs show low cytotoxicity,which can achieve imaging of Ag+and GSH in living cells.3.CMH-GA-CDs was prepared by covalent modification of 7-diethylaminocoumarin-3-carbohydrazide(CMH)to the surface of glyoxylate modified CDs(GA-CDs)by amidation reaction.CMH-GA-CDs can be used as a novel FRET ratio fluorescent probe for the detection of Cu2+ in aqueous solution.In the range of 0-10?M,the ratio of I458/L400 has a good linear relationship with the concentration of Cu2+,and the detection limit is 0.21 ?M.In addition,CMH-GA-CDs is used for the detection of Cu2+ in environmental water samples with a recovery rate of 91%to 104%.4.Covalent modification of fluorescein hydrazide(FH)via carbodiimide-activated coupling reaction to glyoxylate-modified CDs(GA-CDs)to prepare dual-emitting nanoprobes for FH-GA-CDs ratiometric fluorescence detection of ClO-.FH-GA-CDs exhibit high sensitivity and selectivity to ClO-,and has a good linearity in the range of 0?100?M with detection limit is 0.09 ?M.The potency of the FH-GA-CQDs in the detection of CIO-in actual water samples was verified by the 94?106%recovery and semi-quantification determination of CIO-on fluorescent test strips.Finally,FH-GA-CDs show low cytotoxicity,which was successfully detection of CIO-in living cells and the imaging of ClO~-in nude mice.