Controlled green synthesis of Au-Pt bimetallic nanoparticles using chlorogenic acid

Well-dispersed Au-Pt alloyed bimetallic nanoparticles are synthesized using chlorogenic acid as the only reducing agent and stabilizer to reduce Au/Pt precursors successively has been presented here. The shapes of Au-Pt bimetallic nanoparticles are controlled by changing the sequence of successive reduction: the spherical shape in the sequence of Pt precursor reduced prior to Au precursor, and the flower shape by reversing the sequence. The sizes of Au-Pt bimetallic nanoparticles can be tuned by changing the molar ratios of the precursors to chlorogenic acid, and the average size of Au-Pt bimetallic nanoparticles decreased or increased with an increase in chlorogenic acid concentration in different sequence of successive reduction. Additionally, the high antioxidant activity of Au-Pt bimetallic nanoparticles was verified by in vitro radical scavenging assays. Our results show that chlorogenic acid is an excellent reducing and capping agent for the controlled synthesis and stabilization of Au-Pt bimetallic nanoparticles, which could be extended to reduce other metal precursors for synthesizing bimetallic and trimetallic nanoparticles. These shape-controlled and size-tunable Au-Pt bimetallic nanoparticles by chlorogenic acid will expand their biomedical applications in future.