Label-free fluorescent aptasensor of Cd2+ detection based on the conformational switching of aptamer probe and SYBR green I

A label-free fluorescence aptasensor based on conformational switching of aptamer was established for the selective and sensitive detection of Cd2+. SYBR green I (SG), as a signal reporter. In the presence of Cd2+, specific recognition and binging of aptamers preferentially with Cd2+ induce free of complementary strands from dsDNA and conformational switching of aptamer from dsDNA to a stem-loop structure, fluorescence intensity of system decrease dramatically.139