Cytosine derivatized diethylenetriaminepentaacetic acid (dtpa) and Eu(III) complexes for selective recognition of 6-Thioguanine

Abstract

Eu III-dtpa-bis(cytosine) complex was designed and synthesized to serve as a fluorescent probe for the 3 determination of 6-Thioguanine (6-TG). With the addition of 6-TG, the fluorescence intensity of the Eu III-dtpa-bis(cytosine) complex was enhanced at 575 nm, meanwhile, a new fluorescence emission peak emerged at 525 nm. The influence of pH value and the interference of 6-mercaptopurine, Guanine, Cytosine, Adenine, Hypoxanthine, Xanthine, Thymine, Uracil and Uric acid on the detection of 6-TG using the Eu III-dtpa-bis(cytosine) complex as a fluorescence probe was examed. It was found that the sensitivity and specificity of the Eu III-dtpa-bis(cytosine) complex in the 6-TG detection could be confirmed. The detection mechanism of 6-TG using the Eu III-dtpa-bis(cytosine) complex in buffer solution was studied by ultraviolet-visible (UV-vis) and fluorescence spectroscopy. A linear response of fluorescence intensity of the Eu III-dtpa-bis(cytosine) complex at 575 nm as a function of 6-TG concentration in the range of 0.00-7.00 × 10-5 mol•L-1 was observed. The detection limit is about 5.11 × 10-8 mol•L-1. The corresponding correlation coefficient of the linear equation was 0.989. Besides, we have also studied the detection of 6-TG in the actual urines. It was found that the fluorescent probe could be reliable and effective for the determination of 6-TG in real urines.