Design,Preparation And Detection Of Fluorescent Carbon Quantum Dots

Carbon dots(CDs)is a new type of carbon based nano materials,which have attracted increasing attention due to its excellent biocompatibility,tunable fluorescence characteristics and good stability,easy synthesis and surface modification.CDs possess great potential applications in fluorescent sensing and imaging.In recent years,the design strategy and sensing mechanism of CDs based fluorescent probes have attracted extensive attention.In this paper,blue fluorescent carbon quantum dots were synthesized by one pot hydrothermal method.The detection of heavy metal ions and explosives by using CDs were investigated according to their luminescent properties,and these CDs based probes exhibit valuable performance on the recognizing heavy metal ions and explosives.Blue fluorescent carbon dots(Met-CDs)were synthesized by using methionine and formamide as precursor by hydrothermal method.The CDs emitted blue fluorescence at442 nm excited at the 360 nm,with the fluorescence quantum efficiency of 35%.The CDs exhibit excellent specificity to Cu²⁺causing the quench of fluorescence,and the fluorescence decreased with the rising of the Cu²⁺gradually.The detection limit of Cu²⁺was 8.6 n M.The nitrogen and sulfur co-doped carbon dots(MSA-CDs)were synthesized by using thiosuccinic acid and formamide as raw materials,the MSA-CDs exhibited bright blue fluorescence with the fluorescence quantum yield of 32%.MSA-CDs can be used as fluorescent probes for sensing 2-nitrophenol(2-NP)and 4-nitrophenol(4-NP)within5 minutes with high sensitivity and good selectivity.The detection limits were calculated to 24.0 n M and 18.3 n M for 2-NP and 4-NP,respectively.Nitrogen Fluorescent carbon dots(PCS-CDs)were prepared by phellodendron chinense powder as nitrogen and carbon sources raw materials by one pot method.The synthesized PCS-CDs exhibited optimal emission at 371 nm with the excitation at 310nm,and the fluorescence quantum efficiency was calculated as 40%.The CDs can be used to detect 2,4-dinitrophenol(DNP)by colorimetry with a detection limit of 20.1n M,and the detection limit of Hg²⁺was 12.8 n M.The CDs sensing system can be successfully applied to the analysis of DNP and Hg²⁺in actual samples with good recovery.