The chemometric analysis of UV–visible spectra as a new approach to the study of the NaCl influence on aggregation of cysteine-capped gold nanoparticles

Gold nanoparticles synthesized using citrate reduction method were modified by cysteine at various concentrations. The cysteine-capped nanoparticles were analyzed by UV–vis absorption spectroscopy in the presence of various concentrations of sodium chloride. At higher concentration of sodium chloride the aggregation occurred. Measured spectra were analyzed by statistical methods, namely two-step cluster analysis and partial least square regression, to obtain quantitative parameters. It was demonstrated that the surface coverage of nanoparticles and the bulk concentration of both cysteine and sodium chloride can be predicted.