Bovine serum albumin driven interfacial growth of selenium-gold/silver hybrid nanomaterials

Selenium (Se) nanorods (NRs) capped with BSA were used as precursor to synthesize Se-Au/Ag hybrid nanocrystals (NCs). Aqueous Au/Ag ions in the presence of fixed amount of purified dried Se NRs were reduced by ascorbic acid at 80 degrees C to generate respective nucleating centres which subsequently grew on the capped BSA hot spots. The hybrid NCs thus obtained were characterized by SEM, TEM, and EDS analysis while their synthesis was monitored simultaneously by UV-visible absorbance due to the surface plasmon resonance of Au and Ag nanoparticles (NPs). In both cases, a gradual decrease in the absorbance of Au/Ag NPs with respect to reaction time was observed which indicated a diminishing number density of such particles in colloidal aqueous phase. SEM and TEM analyses then explained the presence of Au NPs in self assembled ball shaped aggregates and their selective adsorption on Se NRs, whereas no self aggregated balls of Ag NPs were observed and they always grew on the Se NRs. The results were discussed on the basis of different routes followed by the Au and Ag nucleating centres to produced hybrid nanomaterials.