A triple-channel optical signal probe for Hg2+ detection based on acridine orange and aptamer-wrapped gold nanoparticles

A triple-channel optical signal probe has been designed for the detection of Hg2+ ions. In the absence of Hg2+, the thymine-rich ssDNA wrapped AuNPs were well dispersed. Thus, the colour of the solution is pink-red; the resonance light scattering (RLS) signal is low; the fluorescence of acridine orange (AO) is powerfully quenched. In the presence of Hg2+, the ssDNA formed a T–Hg2+–T configuration, which produces a colour change, RLS signal enhancement, and fluorescence of AO restoration. Under the optimum conditions, the system exhibits a dynamic response range for Hg2+ from 50 nM to 5 μM with a detection limit of 30 nM.