Choline and acetylcholine detection based on peroxidase-like activity and protein antifouling property of platinum nanoparticles in bovine serum albumin scaffold

Platinum nanoparticles (PtNPs) in the scaffold of bovine serum albumin (BSA) through biomineralization are found to possess excellent peroxidase-like activity that can catalyze N-ethyl-N-(3-sulfopropyl)-3-methylaniline sodium salt (TOPS) coupled with 4-amino-antipyrine (4-AAP) by the action of hydrogen peroxide to give an obvious purple product. Based on this phenomenon, acetylcholinesterase (AChE) and choline oxidase (ChOx) are used to catalyze ACh and choline to form the active product H2O2 and the as-produced H2O2 is detected optically. Owning to the protection effect of the protein shell, BSA-PtNPs turn out to be very stable and preserve the catalytic activity in the presence of protein and even in the real plasma samples. This protein antifouling property makes the BSA-PtNPs suitable for a wide range of applications in sensors for biological samples. Choline in infant formula and ACh in plasma have been successfully detected.