Persea Americana Fruit Peel Extract Mediated Synthesis of Zinc Oxide Nanoparticles and Silver Doped Zinc Oxide Nano composites For Their Antibacterial, Antioxidant And Photo catalytic Degradation Applications

Abstract

Oxidative stress is a condition produced by the imbalance between oxidants and antioxidants in a biological system. Free radicals can damage parts of cells such as proteins, DNA, and cell membranes. On the other hand, the emergence of infectious diseases poses a serious threat to public health worldwide. Most of them are resistant to conventional methods of treatment using antibiotics. The contamination of water by dyes is another very serious environmental problem. In this regard, green synthesized ZnO NPs and Ag-ZnO NCs which is one of the most basic functional materials, have emerged as effective antibacterial, antioxidant activity and photocatalyst materials. The aim of this research is to synthesize ZnO NPs and Ag-ZnO NCs using the Persea americana fruit peel extract for antibacterial, antioxidant activity and photocatalytic degradation. Meanwhile, Highly stable Ag-ZnO NCs have been synthesized by co-precipitation method using Zn(NO3)2.6H2O as host, AgNO3 as dopant and phytochemicals of Persea americana fruit peel extract was used as reducing and capping/stabilizing agent. The synthesized ZnO NPs and Ag-ZnO NCs were characterized for average crystallite size of the samples, functional group identification, spectroscopic measurements(energy band gap), and morphological examination using XRD, FT-IR, UV-Vis and SEM techniques respectively. The peak observed at 365 nm and 375 nm with band gap of 3.20 and 2.85 ev showed formation of ZnO NPs and Ag-ZnO NCs respectively. The decrease in the band-gap from 3.20 to 2.85 ev on doping makes the Ag-ZnO NCs more efficient for antioxidant, antibacterial and photocatalytic applications. The FT-IR spectroscopy confirms formation of NPs and NCs. The XRD data showed the crystalline structures of ZnO NPs and Ag- ZnO NCs with crystallite sizes of 14.70 and 21.38 nm, respectively. The SEM data showed that ZnO NPs has a mixture of spherical and star and Ag-ZnO NCs have a mixture of spherical and sponge-like agglomerates shapes. The Ag ZnO NCs displayed a significant antibacterial activity with a maximum zone of inhibition of 21, 21 and 20 mm at 200 mg/mL in B. Cereus, S. Typhea and S. Aureus respectively. On the other hand, DPPH scavenging activities of 82.01% were obtained using 200 μg/mL of Ag-ZnO NCs. Additionally 94.9% of the MB dye was degraded by using Ag-ZnO NCs on exposure to solar light radiation. Finally, the synthesized Ag-ZnO NCs showed higher activity as compared with ZnO NPs.