Factorial Experimental Design for Optimization of Zinc Oxide Nanoparticles Production

Background: Biosynthetic nanomaterials have recently received increasing attention because they are non-toxic, clean, environmentally acceptable, safe, and biocompatible. Objective: In the present study, cell-free culture filtrate of Aspergillus sp. was used for extra cellular synthesis of zinc oxide (ZnO) nanoparticles. MethodS: Plackett-Burman and Taguchi designs were implemented to optimize conditions for maximum ZnO nanoparticle production. In the Plackett-Burman design, 15 factors, representing different carbon and nitrogen sources, were studied. For the Taguchi design, an L-27 (3(13)) standard orthogonal array was constructed to examine nine factors. Results: The maximum yield of ZnO nanoparticles of 21.73 g/L was achieved with 1.0 mM ZnSO4 under optimal conditions of peptone extract (20 g/L), yeast extract (10 g/L), meat extract (10 g/L), K2HPO4 (0.25 g/L), FeSO4 center dot 7H(2)O (0.002 g/L), NaCl (2.5 g/L), pH 6, 32 degrees C, and a 200-mL volume. The ZnO nanoparticles' production was confirmed by the formation of white aggregates. The UN/absorption spectrum showed one peak at 376 nm, which also confirmed the formation of nanoparticles. Transmission electron microscopy revealed that the nanoparticles were large rods of 11.6-43.97 nm diameter, and 355.91 nm length. Importantly, the ZnO nanoparticles exhibited broad antimicrobial activity against gram-positive and grant-negative bacteria and a unicellular fungus. Conclusion: The concentrations of ZnSO4 ions, ferrous ions, and peptone and meat extracts, and the interactions between them, were observed to he the main parameters influencing ZnO nanoparticles' yield.