Biosafety, Optimization, and Application of Bioflocculant-Synthesized Zinc Oxide Nanoparticles

• Published in: BioNanoScience 2022-12, Vol.12 (4), p.1289-1304
• Main Authors: Ntombela, Zuzingcebo Goldern, Pullabhotla, Viswanadha Srirama Rajasekhar, Basson, Albertus Kotze
• Format: Article
• Language: English
• Subjects: Antiinfectives and antibacterials; Antimicrobial activity; Antimicrobial agents; Bacteria; Biochemical oxygen demand; Biocompatibility; Biological and Medical Physics; Biomaterials; Biophysics; Biosynthesis; Breast cancer; Chemical oxygen demand; Circuits and Systems; Cytotoxicity; Dyes; Engineering; Flocculants; Flocculation; Gram-negative bacteria; Gram-positive bacteria; Industrial wastes; Lithium chloride; Nanoparticles; Nanotechnology; Natural products; Optimization; Pollutants; Thermal stability; Toxicity; Tumor cell lines; Wastewater; Zinc oxide; Zinc oxides
• ISSN: 2191-1630; 2191-1649
• DOI: 10.1007/s12668-022-01017-6

Biosynthesis of zinc oxide (ZnO) nanoparticles using natural products seems to be an interesting research to study in nanotechnology, as they (ZnO nanoparticles) are biocompatible and stable in nature, owing to their wide applications industrially. In this study, the bioflocculant-synthesized zinc oxide nanoparticles were used in the removal of various pollutants and dyes from wastewater and solutions. ZnO nanoparticles were synthesized using a bioflocculant from two bacteria and assessed for flocculation and antimicrobial activity properties. Cytotoxicity effects of the ZnO nanoparticles were also evaluated using human embryonic kidney (HEK 293) and breast cancer (MFC 7) cell lines. Biosynthesized ZnO nanoparticles were characterized using different spectroscopic and microscopic methods. An optimum flocculating activity (88%) was obtained with 0.2 mg/mL ZnO nanoparticles concentration at pH 3 and LiCl as a stimulating agent. Biosynthesized ZnO nanoparticles are thermally stable with 75% flocculating activity retained at 100 °C and 71% after autoclaved (121 °C for 15 min). The as-synthesized nanoparticles showed significant cytotoxic effects in HEK 293 and MFC 7 cell lines in a concentration-dependent manner. Biosynthesized ZnO nanoparticles revealed strong antimicrobial potential on both Gram-positive and Gram-negative pathogenic bacteria tested. The nanoparticles exhibited dye removal efficiency greater than 89% of all tested dyes. ZnO nanoparticles showed great removal efficiencies of various pollutants in wastewater. Biosynthesized ZnO nanoparticles have great potential to remove both biological oxygen demand (BOD) and chemical oxygen demand (COD) compared to traditional flocculants. Therefore, as-synthesized ZnO nanoparticles have prospective to replace chemical flocculants in the purification of industrial wastewater. Graphical Abstract