Effectiveness evaluation of Escherichia coli as a reducing agent in synthesized zinc oxide nanoparticles

This study is conducted to evaluate the effectiveness of using Escherichia coli as a reducing agent in the synthesis of ZnO nanoparticles. E. coli isolated from stool samples as a reducing agent for zinc sulfate to ZnO nanoparticles during the preparation process, a color change from a clear color to a white color is observed, which is preliminary evidence of the reduction process. The results of the biosynthesis of nanoparticles are then confirmed by UV/vis spectrophotometer, where an absorption peak appeared with a wavelength of 273 nm, and this length is within the specified range for nanoparticles (200-800 nm). The results of the examination of the crystal shape and crystal size by X-ray diffraction showed the appearance of 9 clear diffraction peaks at 2θ values, namely 31.65, 34.38, 36.19, 47.50, 56.53, 62.81, 69.01, 72.49, and 76.89, which corresponded to peaks 100, 002, 101, 102, 110, 103, 201, and 202, respectively, in the standard diagram under JCPDS card no. 36-1451. The XRD pattern also shows strong, narrow diffraction peaks, indicating that the biosynthesized ZnO nanoparticles are crystalline in nature, and the nanoparticle size of the crystal is 11.8 nm. Field-emission Scanning Electron Microscope results have revealed that the ZnO nanoparticles have an elongated oval to spherical and cluster-shaped shape with a nanosized ranging from 37.93 to 61.82 nm and an average size of 45.15 nm.