Copper(II)-Quenched Oligonucleotide Probes for Fluorescent DNA Sensing

A copper(II)-quenched molecular beacon was prepared by attaching fluorescein to the 3‘-end and a copper(II) complex to the 5‘-end of DNA. In the presence of complementary DNA, copper(II) and dye are spatially separated in the duplex and fluorescence increases up to 15-fold, with excellent discrimination of single base mismatches.