Bio-waste eggshell membrane assisted synthesis of NiO/ZnO nanocomposite and its characterization: Evaluation of antibacterial and antifungal activity

Abstract

This paper presents the synthesis of NiO/ZnO nanocomposite using a bio-waste eggshell membrane as a template, which is used to control the particle size. It is a two-step process, soaking followed by the calcination method. The synthesized NiO/ZnO nanocomposite was characterized by the following techniques: Powdered X-ray diffraction analysis (PXRD), Ultra-Violet Visible spectroscopy (UV–Visible), Fourier transformed infra-red spectroscopy (FT-IR), Raman spectroscopy, Dynamic Light Scattering analysis (Zeta potential & particle size), Field Emission Scanning Electron Microscope (FE-SEM) with Energy Dispersive X-ray Analysis (EDX), and Hi-ResolutionTransmission electron microscope (HR-TEM) respectively. The NiO/ZnO nanocomposite exists in both face-centered cubic (NiO) and hexagonal wurtzite (ZnO) structures, according to PXRD results. The crystallite size was equal to 14.12 nm (NiO) and 14.70 nm (ZnO). The UV–Visible spectrum showed the wavelength at 302 nm and 372 nm, which indicates the presence of NiO and ZnO. The peaks at 449 cm−1 and 550 cm−1 are due to the stretching vibration of (Ni-O) NiO2 octohedral in the cubic NiO and the stretching vibration of ZnO. A Raman vibrational mode confirms the formation of the NiO/ZnO nanocomposite. The zeta potential analysis of the NiO/ZnO nanocomposite was equal to −42.7 mV, which indicates good stability, and the particle size distribution was equal to be 205.8 nm with a polydispersity index value of 0.5940. The SEM images of the NiO/ZnO nanocomposite appeared aggregated with small rods. The EDX spectra confirmed the presence of nickel, oxygen, and zinc, respectively. TEM images of the NiO/ZnO nanocomposite showed the particle size is less than 50 nm. The synthesized NiO/ZnO nanocomposite was subjected to antibacterial and antifungal activity by the agar-well diffusion method. The results demonstrated that the zone of inhibition of NiO/ZnO nanocomposite was high in Bacillus subtilis (30 ± 0.88 mm) for bacterial pathogens and Aspergillus terreus (30 ± 0.0 mm) for fungal pathogens, respectively. The minimum inhibition concentration (MIC) of NiO/ZnO nanocomposite was tested for bacterial pathogens. The results showed that the synthesized NiO/ZnO nanocomposite inhibited cell growth even at the lowest concentration (9.37 μg/mL). So it is inferred that the NiO/ZnO nanocomposite could act as an antifungal and antibacterial agent for a wide range of diseases.