Abstract
Gold nanoparticles (AuNPs) are modified immediately by the adsorption of β-lactoglobulin (βlg) when designed as colorimetric probe in raw milk, leading to the formation of a protein corona. This adsorption results mainly from a fast electrostatic force and a slow formation of Au-S covalent bonds, which is a precondition for the use of AuNPs in biodetection. The proteins corona influences the structure and bioactivity of adsorbed protein, such as the allergy. In this study, the mechanism of βlg adsorbed on AuNPs was investigated in terms of stoichiometry, binding affinity (Ka), time evolution of Au-S bond, and general secondary structure changes to address the desensitization of AuNPs. The results show that about 3,600 βlg are adsorbed on a single AuNPs, and the Ka is 2.9 ± 0.7 × 10 6 M -1 . The formation of Au-S bonds takes about 9 h, which is the time needed for complete changes in secondary structure and the IgE combining capacity. The structure of allergenic epitopes assigned to β-sheet was destroyed by the formation of Au-S bond, then induced to the decrease allergy. Furthermore, Fourier transform infrared spectroscopy confirmed a decrease in β-sheet contents after conjugated with AuNPs.
A hard-sphere model of protein corona formation on spherical and cylindrical nanoparticles