2.2.1 Stability as a function of protein concentration
To study further the mechanism of protein-induced stabilization of GNPs of different shapes, we incubated AuNP50, AuNP70, and AuNS with aqueous BSA solutions of different concentrations (0.1, 2, 9 and 15 mg/mL) without any salts present. Extinction spectra of GNPs samples incubated with BSA without removal of unbound proteins (“unwashed”) are shown inFigure 3 A–C . Extinction spectra of the same samples after one cycle of centrifugation and resuspension in water (“washed”) are shown in Figure 3 D–F . The AuNS show little change as a function of the protein concentration, but spherical particles intriguingly aggregated at intermediate protein concentrations and do not at low or high concentrations.