Laser assisted synthesis of surfactant-free Au-Ag alloy nanoparticles in water

Laser assisted synthesis of mono and bimetallic colloidal solution of nanoparticle (NP) is considered as a green method of synthesis as no harmful chemicals and toxic surfactants are needed [1].  The non toxic and pure laser synthesized NPs are significant and favourable for biomedical applications. The Au-Ag alloy NPs are of higher application potential than monometallic Au and Ag owing to the improved plasmonic features of Ag combined with excellent bio compatibility and colloidal stability of Au NPs in the Au-Ag alloy NPs [2]. The citotoxicity of Ag NPs on tissues were also suppressed when alloyed with Au NPs [2]. In this work impurity-free and surfactant-free Au-Ag alloy NPs were synthesized via re-irradiation of laser generated mono metallic colloidal mixtures with 532 nm radiations from Nd: YAG nanosecond laser. The impact of re-irradiating laser energy in alloy formation was investigated. The alloy formation process was analyzed with UV-Visible absorption spectra at different time intervals of laser irradiation. The generated nanoparticles were characterized with dynamic light scattering size analysis, zeta potential studies and HRTEM imaging.