Tuning the fluorescence response of surface modified CdSe quantum dots between tyrosine and cysteine by addition of p-sulfonatocalix4arene

摘要

A simple identification method of L-tyrosine (Tyr) and x-cysteine (Cys) using gemini surfactant coated CdSe quantum dots by using a fluorescent spectroscopic technique is proposed. The gemini surfactant modified QDs show a selective fluorescence response between Tyr and Cys by addition of p-sulfonatocalix4arene (pSCA). The CdSe QDs coated with gemini surfactant C_(12)H_(25)N~+(CH3)2(CH2)4(CH3)2N~+C_(12)H_(25)·2Br~- (GS) obviously responds to Tyr. While in the presence of pSCA, it shows selectivity to Cys due to the cooperation of gemini surfactant coated QDs (GS-QDs) and pSCA. Under optimal conditions, it is found that the luminescence of the GS-QDs enhanced by Tyr in a concentration-dependent fashion is described by a Langmuir binding isotherm equation in the range 5 x 10~(-8)-10~(-5) M. In the presence of pSCA, the luminescence of the GS-QDs enhanced by Cys in a concentration-dependent fashion can also be described by a Langmuir binding isotherm equation in the range 10~(-8)-10~(-4) M. The possible mechanism is discussed.