Microbial cell lysate supernatant (CLS) alteration impact on platinum nanoparticles fabrication, characterization, antioxidant and antibacterial activity

Abstract

Microbial mediated biological synthesis of nanoparticles is of enormous interest to modern nanotechnology due to its simplicity and eco-friendliness. In the present study, a novel green method for the synthesis of platinum nanoparticles (PtNPs) has been developed using bio-derived product-cell lysate supernatant (CLS) from various microorganisms including Gram-negative bacteria: Pseudomonas kunmingensis ADR19, Psychrobacter faecalis FZC6, Vibrio fischeri NRRL B-11177, Gram-positive bacteria: Jeotgalicoccus coquinae ZC15, Sporosarcina psychrophila KC19, Kocuria rosea MN23, genetically engineered bacterium: Pseudomonas putida KT2440 and yeast: Rhodotorula mucilaginosa CCV1. The biogenic PtNPs were characterized by UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM). The UV-visible spectra showed a red shift in the absorbance of H₂PtCl₆.6H₂O from 260 nm to 330 nm for all prepared PtNPs. The XRD patterns of the samples indicated the formation of high purity of the cubic phase. The FTIR spectra and EDS profiles of the samples demonstrated the existence of proteins on fabricated and stabilized PtNPs. The TEM and AFM images analysis showed the synthesis of smallest PtNPs by a bacterium strain (FZC6) and yeast while genetically engineered bacteria produced the largest NPs. Also, the HRTEM analysis showed the high crystallinity of PtNPs and the interplanar spacing of 0.2 nm, corresponds to the (1 1 1) of plane of PtNPs. The results of zeta potential indicated the high stability of PtNPs in neutral pH. Moreover, the suitability of PtNPs antioxidant and antibacterial activity was correlated to the size and zeta potential of microbe used for NPs biosynthesis. In conclusion, it was found that the type of microorganisms can have influences on PtNPs characteristics and properties as Gram-negatives produced smaller PtNPs while more negatively charged NPs were obtained by Gram-positives. These findings could facilitate the selection of appropriate green approaches for more effective biotechnological production of PtNPs.

Keywords: Biofabrication; Biological activity; Cell lysate supernatant; Microbe strains; Platinum nanoparticles.