Stable gold nanoparticles as a novel peroxidase mimic for colorimetric detection of cysteine

摘要

In this work, a novel method for colorimetric detection of cysteine was proposed based on the inhibition of peroxidase-like behavior of AuNPs. Kiwi juice prepared gold nanoparticles presented strong catalytic activity, which could catalyze H2O2-TMB to generate a blue product, resulting in strong absorption at 650 nm. In HAc-NaAc (pH 4.0) buffer, cysteine induced the aggregation of gold nanoparticles through covalent Au-S bonds and electrostatic as well as hydrogen bonding, leading to the reduction of the catalytic activity of gold nanoparticles with a weakened blue color product and a lower absorbance. Under optimal conditions, the concentrations of cysteine were proportional to the degree of reduced absorbance. This approach offers a new, simple, sensitive and selective assay for cysteine.