Sustainable recycling of poultry eggshell waste for the synthesis of calcium oxide nanoparticles and evaluating its antibacterial potency against food-borne pathogens

Abstract

Nanoparticles are considered new antibacterial agents with a potential broad range of applications. Recently, the synthesis of bio-nanoparticles (NPs) from natural sources such as coral, Ostrea shell, and eggshell, has attracted considerable attention. Eggshells are organic waste, rich in calcium carbonate (CaCO₃), and it is an easy method to reduce it into powder of nano size. Utilization of waste materials as a precursor for NPs synthesis makes the entire process cheaper, greener, and more sustainable. Waste chicken eggshells were collected from the Specific Pathogen Free farm in Egypt. Eggshells were rinsed, dried, and finely ground to powder. The sol-gel chemical method was used for the synthesis of CaO-NPs from eggshell powder. The characteristics of eggshell NPs were visualized using a scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, and ultraviolet–visible spectroscopy. Additionally, the minimum inhibitory concentration was applied to test the antibacterial efficacy of CaO-NPs at 1.00, 0.50, 0.25, 0.12, and 0.06% concentrations on Methicillin-resistant Staphylococcus aureus (MRSA), Bacillus cereus, Escherichia coli, and Salmonella enteritidis. The results of the characterization confirmed the conversion of CaCO₃ to CaO-NPs with an average diameter of 27.7 nm. Zones of inhibition started to appear from 0.25% concentration for B. cereus, 0.50% for MRSA and E. coli, and 1.0% for S. enteritidis. The concentration of CaO-NPs solution strongly correlated with the resulting zone of inhibition (r = 0.86 to 0.90). CaO-NPs showed a potent efficacy against gram-positive bacteria. Hence, eggshell wastes from poultry production could be a feasible organic source for the biosynthesis of CaO NPs with promising efficient antibacterial properties.