Aptamer-based colorimetric detection of various targets based on catalytic Au NPs/Graphene nanohybrids

In this paper, a label-free aptamer-based colorimetric assay was developed by incorporating catalytic Au nanoparticles/Graphene (Au NPs/Gr) nanohybrids. As an efficient peroxidase mimic, Au NPs/Gr can oxidize ABTS1 in the presence of H2O2, generating visible color change that can be recorded by a simple UV–vis spectrophotometer. The ssDNA aptamer can absorb on Au NPs/Gr interface through non-covalent interaction, thereby reducing the catalytic activity of Au NPs/Gr. In the presence of target molecule, the combination of aptamer with target caused the aptamer to assume a folded state and lose its ability to bind with Au NPs/Gr, leading to recovery of the catalytic activity of Au NPs/Gr. Base on this tunable strategy, calibration curves obtained for Hg2+ and MC-LR have detection limits of 3.63 nM and 7.14 ng/L with the linear range of 0.01–0.5 μM and 0.01–1.0 μg/L, respectively. These results indicated that various targets could be detected by this simple, rapid and universal colorimetric assay based on catalytic nanomaterials.