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.
