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

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 mu g/mL). So it is inferred that the NiO/ZnO nanocomposite could act as an antifungal and antibacterial agent for a wide range of diseases.