Label-free colorimetric assay for arsenic(III) determination based on a truncated short ssDNA and gold nanoparticles

A short ssDNA (Apt-21) rationally truncated from the parent 100 nt As(III) aptamer was used for colorimetric determination of As(III). Apt-21 serves dual functions, i.e., recognition of trace As(III) and regulation of AuNPs dispersion by surface attachment, while gold nanoparticles (AuNPs) functioned as colorimetric signal reporters. Under the optimal conditions, the ratio of the absorbance at 650 nm to 520 nm (A(650)/A(520)) of AuNPs changed proportionally with increasing concentration of As(III), which showed a linear relationship within the concentration ranges 1-30 ppb and 30-100 ppb with a detection limit of 0.18 ppb. The feasibility of this assay was demonstrated by determining As(III) in spiked water samples with mean recoveries ranging from 96.5-107.1%.

Automated summary

This study utilized a short ssDNA (Apt-21) derived from the parent As(III) aptamer for colorimetric determination of As(III) by regulating the dispersion of gold nanoparticles while serving as a recognition element. The assay showed a linear relationship between the absorbance ratio of AuNPs at 650nm to 520nm and As(III) concentration, with a detection limit of 0.18 ppb, demonstrating its feasibility by achieving mean recoveries of 96.5-107.1% in spiked water samples.