New Insights into the Effects of Surface Functionalization on the Peroxidase Activity of Cytochrome c Adsorbed on Silica Nanoparticles

The immobilization of proteins on inorganic supports is attracting increasing interest since the realization of active surfaces finds application in enzyme-assisted catalysis, environmental sciences, and medical fields. In the present study, cytochrome c (cyt c) is adsorbed on silica nanoparticles (SNPs) and amino-functionalized silica nanoparticles (SNPs–APTES), which are prepared for this purpose and having a diameter of about 50 nm. The peroxidase activity of the protein is investigated under different experimental conditions, to evaluate the impact of differently charged surfaces on the catalytic activity of the biomolecule. The peroxidase activity of cyt c increases upon adsorption on SNPs, and it shows a linear behavior with nanoparticles concentration; on the other hand, the contact with increasing amounts of SNPs–APTES does not affect the catalytic activity of the protein. The kinetic profile of the oxidation reaction is altered for cyt c–SNPs sample, suggesting that upon adsorption, changes in th...