Green Synthesis of Silver and Titanium Oxide Nanoparticles Using Tea and Eggshell Wastes, Their Characterization, and Biocompatibility Evaluation

Using biodegradable wastes represents a viable alternative to creating a sustainable economy that benefits all humans. The present study aimed to use daily used waste products, tea (TE) and eggshell (ES) wastes, to synthesize silver (AgNPs) and titanium oxide (TiO 2 NPs) nanoparticles, respectively. Firstly, the green-synthesized nanoparticles were characterized using an ultraviolet-visible spectrophotometer (UV-VIS), Scanning (SEM), transmission electron microscope (TEM), Dynamic light scattering (DLS), zeta potential analysis, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Then, followed by their cytotoxic assessment against normal human skin fibroblast (HSF) cells using sulforhodamine B (SRB) assay, AgNPs_TE (300 and 470 nm) and TiO 2 NPs_ESE (320 nm) formation was confirmed using UV-vis spectra. SEM and XRD showed their crystalline shape. TEM images determined the nano-size of AgNPs_TE (25 nm) and TiO 2 NPs_ESE (120 nm), which appeared smaller in comparison with DLS analysis (299.8 and 742.9 nm), with zeta potentials of −20.5 mV and −12.6 mV, respectively. There was a great difference in both NPs’ sizes using TEM and DLS measurements because DLS is known to be more sensitive to larger particles due to their light scattering. FTIR detected the functional groups found in TE and ESE that were responsible for the synthesis, capping, and stabilization of the synthesized AgNPs and TiO 2 NPs. The SRB assay reveals the safety of TiO 2 NPs on normal HSF cells with an IC50 > 100, while AgNPs have a high cytotoxic effect with an IC50 = 54.99 μg/mL.