Preparation of silver nanoparticles by extract of Yinqiao Jiedu Mixture waste and its antioxidative and antibacterial activity evaluation / 中草药

ABSTRACT

Objective: To develop a novel method to synthesize silver nanoparticles (AgNPs) by using the extract of Yinqiao Jiedu Mixture waste, evaluate the effects of biosynthesis parameters on the formation and polydispersity of AgNPs, and investigate the antioxidative and antibacterial activity. Methods: The formation of AgNPs was confirmed by UV-visible spectroscopy; The size, polydispersity, surface and morphology features of AgNPs were characterized by laser granularity analyzer and transmission electron microscopy; The antioxidative and antibacterial activities of AgNPs were evaluated by calculating the scavenging rate for DPPH and A600 for both Escherichia coli and Staphylococcus aureus, respectively. Results: By using Yinqiao Jiedu Mixture waste, the AgNPs could be prepared at ambient temperature. The size and polydispersity index of the synthesized AgNPs were sensitive to the biosynthesis parameters, such as pH of extract and material proportion with the average size distribution was 14.2-94.8 nm, offering a size-controlled synthetic method for AgNPs. And when the pH was 6.0, the polydispersity could reach the best. The AgNPs could be obtained with high yield and small size at pH 10.0, material proportion 31 after reacting 2 h, which were quasi-spherical in shape with average size of (24.0 ± 0.3) nm and covered by anion [Zeta potential (-23.1 ± 0.2) mV]. The synthesized AgNPs also revealed significant inhibition activities for the growth of E. coli and S. aureus with MIC 50.0 and 25.0 μg/mL, respectively, and potent antioxidative activity with scavenging rate for DPPH 71.1% when adding 100 μg/mL of AgNPs. Conclusion: The extract of Yinqiao Jiedu Mixture waste can be used to synthesize AgNPs with small size at ambient temperature; The biosynthesis parameters have significant effects on the average size and polydispersity index of AgNPs; The synthesized AgNPs have potent antioxidative and antibacterial activity.