Dual-mode colorimetric determination of As(III) based on negatively-charged aptamer-mediated aggregation of positively-charged AuNPs

The aggregation and redispersion of positively-charged AuNPs ((+)AuNPs) modified with cysteamine (CS) could be regulated by the negatively charged As(III)-specific aptamer (As(III)-apt). In general, (+)AuNPs aggregated with increasing inducer concentration. However, in the present study, it was found that (+)AuNPs re-dispersed after a certain high concentration of As(III)-apt was reached. By optimizing the concentration of As(III)-apt that resulted in the aggregation and redispersion behavior of (+)AuNPs, a dual-mode colorimetric aptasensor for As (III) determination was established. It was not only able to quantify As(III) sensitively over a ranges of As(III) concentrations, but also to selectively differentiate As(III) and eliminate false results from other control ions by dual-mode.

Automated summary

In this study, the aggregation and redispersion behavior of positively-charged AuNPs modified with cysteamine were regulated by the negatively charged As(III)-specific aptamer. By optimizing the concentration of As(III)-apt, a dual-mode colorimetric aptasensor for As (III) determination was established, which could sensitively quantify As(III) and selectively differentiate it from other control ions.