CONICET | Buscador de Institutos y Recursos Humanos

Gold nanoparticles (AuNPs) are one of the most studied nanomaterial. Plasmonic properties in the visible spectra are one of the most important and straightforward characterization methods. Naked AuNPs are very sensitive to the changes of the environment caused by the addition of different organic solvents, pH, ionic strength and temperature which can influence in the plasmonic signal. In a previous work, a novel protein-multilayer coating process has been recently developed. This process involves the use of radiation-induced crosslinking to stabilize the protein coating onto AuNPs1. The protein layer induced a shift in the maximum plasmonic signal to longer wavelength and changes in the peak shape. The extinction spectra corresponding to protein-coated AuNPs suspensions in different conditions have been fitted using a model of core/shell metal/dielectric spherical nanoparticle and Mie theory for a log-normal distribution of the NPs population. Protein layer has been characterized by two parameters, thickness and refraction index with the only assumption that the NP has a spherical shape.Two different coating models have been proposed: (a) coating thickness proportional to AuNPs radii and (b) one where it will be considered that all NPs will have a same coating thickness for a particular experimental condition. The theoretical results reached from the fitting process have an excellent correlation with TEM, DLS data of the samples, in addition to other data from literature.The fitting process was able to discriminate between different coating models and explain different experimental conditions. Therefore, UV-visible spectroscopy can be very useful technique as a quality control of the coating process. 1Flores CY, Achilli E, Grasselli M. Radiation-induced preparation of core/shell gold/albumin nanoparticles. Radiation Physics and Chemistry. 2017 Feb 14.