Biosynthesis and Characterization of Silver Nanoparticles

A characterized B. cereus (GenBank accession number KF944447) isolate was inoculated into flasks containing sterile LB broth and incubated for 24 hours at 37°C with agitation (200 rpm). After incubation, the culture was centrifuged at 10,000 rpm for 10 minutes and the supernatant was used for AgNP synthesis. In a typical reaction, culture supernatant was mixed with 1 mM and 5 mM aqueous silver nitrate (AgNO₃) solution and incubated at 60°C for 6 hours to produce AgNPs of two different sizes (10 and 20 nm). The synthesized particles were characterized as previously described.34 (link) X-ray diffraction (XRD) analyses were performed using an X-ray diffractometer (Bruker D8 DISCOVER; Bruker AXS GmBH, Karlsruhe, Germany). The high-resolution XRD measurements were performed at 3 kW with Cu target using a scintillation counter (λ=1.5406 Å) at 40 kV and 40 mA, and were recorded in the range of 2θ=5° to 80°. Further characterization of AgNPs surface changes and composition was performed by Fourier transform infrared spectroscopy (FTIR) (PerkinElmer Spectroscope GX; PerkinElmer, Waltham, MA, USA). Transmission electron microscopy (TEM) (Hitachi H-7500; Seoul National University, Seoul, South Korea) was used to determine AgNPs size and morphology. TEM images of bio-AgNPs were obtained at an accelerating voltage of 300 kV.35 (link)