Synthesis of silver nanoparticles by solar irradiation of cell-free Bacillus amyloliquefaciens extracts and AgNO₃
2012
Wei, Xuetuan | Luo, Mingfang | Li, Wei | Yang, Liangrong | Liang, Xiangfeng | Xu, Lin | Kong, Peng | Liu, Huizhou
Silver nanoparticles (AgNPs) were obtained by solar irradiation of cell-free extracts of Bacillus amyloliquefaciens and AgNO₃. Light intensity, extract concentration, and NaCl addition influenced the synthesis of AgNPs. Under optimized conditions (solar intensity 70,000lx, extract concentration 3mg/mL, and NaCl content 2mM), 98.23±0.06% of the Ag⁺ (1mM) was reduced to AgNPs within 80min, and the ζ-potential of AgNPs reached −70.84±0.66mV. TEM (Transmission electron microscopy) and XRD (X-ray diffraction) analysis confirmed that circular and triangular crystalline AgNPs with mean diameter of 14.6nm were synthesized. Since heat-inactivated extracts also mediated the formation of AgNPs, enzymatic reactions are likely not involved in AgNPs formation. A high absolute ζ-potential value of the AgNPs, possibly caused by interaction with proteins likely explains the high stability of AgNPs suspensions. AgNPs showed antimicrobial activity against Bacillus subtilis and Escherichia coli in liquid and solid medium.
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