A colorimetric aptamer-based method for detection of cadmium using the enhanced peroxidase-like activity of Au–MoS2 nanocomposites

In this work, a colorimetric aptamer-based method for detection of cadmium using gold nanoparticles modified MoS 2 nanocomposites as enzyme mimic is established. In short, biotinylated Cd 2+ aptamers are immobilized by biotin-avidin binding on the bottoms of the microplate, the complementary strands of Cd 2+ aptamers are connected to the Au–MoS 2 nanocomposites which have the function of enhanced peroxidase-like activity. The csDNA-Au-MoS 2 signal probe and target Cd 2+ compete for binding Cd 2+ aptamer , the color change can be observed by addition of chromogenic substrate, thereby realizing visual detection of Cd 2+ . The absorbance of the solution at 450 nm has a clear linear relationship with the Cd 2+ concentration. The linear range is 1–500 ng/mL, and the limit of detection is 0.7 ng/mL. The assay was used to test white wine samples, the results are consistent with those of atomic absorption spectrometry ; which prove that this method can be used for detection of Cd 2+ in real samples.