Development of mercury (II) ion biosensors based on mercury-specific oligonucleotide probes

Mercury (II) ion (Hg2+) contamination can be accumulated along the food chain and cause serious threat to the public health. Plenty of research effort thus has been devoted to the development of fast, sensitive and selective biosensors for monitoring Hg2+. Thymine was demonstrated to specifically combine with Hg2+ and form a thymine-Hg2+-thymine (T-Hg2+-T) structure, with binding constant even higher than T-A Watson-Crick pair in DNA duplex. Recently, various novel Hg2+ biosensors have been developed based on T-rich Mercury-Specific Oligonucleotide (MSO) probes, and exhibited advanced selectivity and excellent sensitivity for Hg2+ detection. In this review, we explained recent development of MSO-based Hg2+ biosensors mainly in 3 groups: fluorescent biosensors, colorimetric biosensors and electrochemical biosensors.