A label-free fluorescence aptasensor based on conformational switching of aptamer induced by Cd2+ was established for the good selective determination of Cd2+. The aptamer could act as a recognition element for Cd2+. SYBR green I (SG), as a signal reporter, can bind to the small groove of double-stranded DNA (dsDNA) constituted the aptamer and the complementary strand, establishing the dsDNA-SG complex and generating high fluorescence intensity. In the presence of Cd2+, the specific recognition and binging of aptamers preferentially with Cd2+ induce free of complementary strands from dsDNA and...
