Phytosynthesis of silver nanoparticles using aqueous leaf extracts of Lippia citriodora: Antimicrobial, larvicidal and photocatalytic evaluations

作者:Elemike Elias E*; Onwudiwe Damian C; Ekennia Anthony C; Ehiri Richard C; Nnaji Nnaemeka J
来源:Materials Science & Engineering C-Materials for Biological Applications, 2017, 75: 980-989.
DOI:10.1016/j.msec.2017.02.161

摘要

Nanoscience and nanotechnology represent new and enabling platforms that promise to provide broad range of novel and improved technologies for environmental, biological and other scientific applications. This study reports the synthesis of silver nanoparticles mediated by aqueous leaf extract of Lippia citriodora at two different temperatures of 50 degrees C and 90 degrees C. The synthesis of colloidal silver nanoparticles (AgNPs) was monitored by the use of UV-visible spectroscopy at different temperatures and time intervals. The surface plasmon bands (SPBs) showed peaks between 417 and 421 nm at 90 degrees C and around 430 nm at 50 degrees C, indicating a red shift at lower temperature. Fourier transform infrared (FTIR) analysis of the nanoparticles showed the presence of similar peaks found in the spectra of the plant extract. The size of the AgNPs was confirmed by transmission electron microscopy (TEM) which indicated an average size of 23.8 nm (90 degrees C) and 25 nm (50 degrees C). The nanoparticles showed better antimicrobial activities when compared to the crude plant extract against several screened pathogens: Gram negative (Escherichia coli, and Salmonella typhi) and Gram positive (Bacillus subtilis and Staphylococcus aureus) strains and a fungi organism; Candida albicans. In addition, the AgNPs showed good larvicidal efficacy against early 4th instar of Culex quinquefasciatus (a vector of lymphatic filariasis). Finally, the nanoparticles exhibited photocatalytic properties on an industrial waste pollutant, methylene blue.