Short-Chain Alkanethiol Coating for Small-Size Gold Nanoparticles Supporting Protein Stability

• Main Authors: Cristina Cantarutti, Paolo Bertoncin, Alessandra Corazza, Sofia Giorgetti, P. Patrizia Mangione, Vittorio Bellotti, Federico Fogolari, Gennaro Esposito
• Format: Article
• Language: English
• Published: MDPI AG 2017-11-01
• Series: Magnetochemistry
• Subjects: amyloidogenic protein-nanoparticle systems; nanoparticle stability; protein unfolding
• Online Access: https://www.mdpi.com/2312-7481/3/4/40

The application of gold nanoparticles (AuNPs) is emerging in many fields, raising the need for a systematic investigation on their safety. In particular, for biomedical purposes, a relevant issue are certainly AuNP interactions with biomolecules, among which proteins are the most abundant ones. Elucidating the effects of those interactions on protein structure and on nanoparticle stability is a major task towards understanding their mechanisms at a molecular level. We investigated the interaction of the 3-mercaptopropionic acid coating of AuNPs (MPA-AuNPs) with β2-microglobulin (β2m), which is a paradigmatic amyloidogenic protein. To this aim, we prepared and characterized MPA-AuNPs with an average diameter of 3.6 nm and we employed NMR spectroscopy and fluorescence spectroscopy to probe protein structure perturbations. We found that β2m interacts with MPA-AuNPs through a highly localized patch maintaining its overall native structure with minor conformational changes. The interaction causes the reversible precipitation of clusters that can be easily re-dispersed through brief sonication.