Controllable synthesis and antioxidant activity of gold nanoparticles using chlorogenic acid

In this work, we report a controllable green synthesis of gold nanoparticles (AuNPs) using chlorogenic acid (CGA) as the only reducing and stabilizing agent. The well-dispersed AuNPs are obtained due to the protection of CGA against aggregation. The resulting AuNPs are controllable in size and shape mainly by changing the molar ratio of HAuCl4 to CGA in reductive process. With an increase in CGA concentration, the average size of AuNPs increased, which resulted in different morphologies from spherical to flower-like shapes. The dropping speed of gold precursor is also found to influence the size of AuNPs in different trends. Additionally, the advantages of CGA for synergistic biological activities are demonstrated through the enhanced antioxidant activity of AuNPs with CGA for scavenging of DPPH radicals. The controllable size and shape of nanoparticles are potentially important in nanomedical application.