The role of protein binding in the poisoning of gold nanoparticle catalysts

Seed mediated catalytic growth of gold nanoparticles is used in the design of biosensors for the products of peroxidase proteins, though the role of in situ proteins and the enzymes themselves on the sensitivity of these biosensors is yet to be addressed. This work specifically focuses on whether the presence of proteins with a strong attraction to the gold nanoparticle seeds, such as albumin proteins, inhibits the nanoparticle's catalytic properties. We have determined that the sensitivity of the biosensor design, defined as its response to the reducing agent hydrogen peroxide, is highly dependent on the presence of bovine serum albumin (BSA) and less dependent on the presence of the enzyme glucose oxidase. We suggest that the strong interaction between BSA and the gold surface leads to poisoning of the catalytic sites on the particle surface, which reduces the uniform growth of the nanoparticles and increases asymmetric growth of small gold nanoparticles onto the seed surface. The overall effect of the protein interaction is to lower the sensitivity of the model biosensor.