Highly sensitive detection of Hg2+ using molybdenum disulfide-DNA sensors

Mercury ion (Hg2+) is one of the heavy metal ions that cause significant physiological damage to an organism even in trace amount. To facilitate Hg2+ detection, a thiol-modified DNA was used as helper sequence to hybridize with a DNA modified with FAM (Carboxyfluorescein) and containing phosphorothioate (PS)-modified RNA linkages that can be cleaved by Hg2+, because thiol group can covalently bond with gold particles. The hybridized DNA sequence was immobilized onto the surface of MoS2@AuNPs (Molybdenum disulfide-gold particle) to form a MoS2-DNA sensors for detecting Hg2+. The results showed that the detection limit in this method was 9.41 nM. Moreover, when the immobilization process was conducted under freezing conditions, the detection limit was further increased to 4.58 nM, lower than the recommended maximum contaminant level in drinking water (9.9 nM).