Switching peroxidase activity of gold nanoparticles to detect proteolytic biomarker

Nanoparticles that mimic the complexity and function of natural enzymes can act as effective peroxidase to catalyse for the oxidization of 3,3,5,5-tetramethylbenzidine (TMB), generating an oxidised blue-coloured product. For the first time scientists found that when the surface of gold nanoparticle (AuNPs) is coated with casein, the intrinsic peroxidase-mimicking activity of AuNPs is suppressed strongly, i.e. by up to 77.1%, due to the surface shielding effects.