Characterization of zinc oxide additive eggshell nanocomposites (ZnO@ES) obtained by green synthesis and investigation of their potential biomaterial

In this thesis study, zinc oxide-eggshell (ZnO@ES) nanocomposites were synthesized by an environmentally friendly method using Althaea officinalis flower extract and their biomaterial potential was investigated. Quercetin content of flower extracts was determined by high performance liquid chromatography (HPLC), nanocomposites containing ZnO nanoparticles (NP) in eggshell were synthesized by mixing certain volumes of different molar zinc nitrate solutions with the highest content of pink flower extract. Structural and morphological characterization of nanocomposites were performed by ultraviolet-visible spectroscopy (UV-Vis), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffractometry (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) and transmission electron microscope (TEM). Hemolysis tests revealed that ZnO@ES nanocomposites showed hemolytic activity below 5% and had hemocompatibility. Antimicrobial activity was evaluated against Escherichia coli ATCC 35218, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 10239; especially ZnO@ES4 sample showed strong activity in minimum inhibitory concentration (MIC) and agar diffusion tests. Biofilm inhibition tests against Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853 revealed that ZnO@ES2 and ZnO@ES4 significantly inhibited biofilm formation. MTT cytotoxicity tests on L929 fibroblast cells showed that the nanocomposites were biocompatible and supported cell proliferation. This study indicates that ZnO@ES nanocomposites can be considered as promising, biocompatible and antimicrobial materials for biomedical applications.