Regulation of hemin peroxidase catalytic activity by arsenic-binding aptamers for the colorimetric detection of arsenic(iii)

The catalytic activity of higher concentration of hemin can be temporarily inhibited by arsenic-binding aptamers, and it will recover in the presence of As(III) due to the exhaustion of aptamers, so the subsequent TMB molecules can be oxidized thoroughly and cause a remarkable increase of absorbance value at 442 nm, which enables the colorimetric detection of As(III) with high selectivity and a detection limit of 6 ppb.