Plant-based synthesis of Ag-doped ZnO/MgO nanocomposites using Caccinia macranthera extract and evaluation of their photocatalytic activity, cytotoxicity, and potential application as a novel sensor for detection of Pb2+ ions

For the first time, this study presented an eco-friendly procedure for the production of Ag-doped ZnO/MgO nanocomposites (NCPs) through a green chemistry method that involves the application of Caccinia macranthera extract, salts solution of zinc nitrate, Mg nitrate, and silver nitrate. The functionality of synthesized NCPs was investigated by FT-IR analysis. The results of morphological and structural examinations obtained from FESEM and XRD techniques displayed a spherical and crystallite product with an Fm3m group space. Next to evaluating the optical properties through PL and UV–Vis spectrophotometry, their ability to sensor heavy metal ions was also investigated as well. Considering their notable reply toward Pb²⁺ions, NCPs exerted a selective absorbance probe for the detection of Pb²⁺ ions throughout various metal ions such as Mg²⁺, Cr³⁺, Ce³⁺, Fe³⁺, Ni²⁺, Ag⁺, Zn²⁺, Ca²⁺, Pb²⁺, and Cu²⁺. The sensor exhibited high selectivity for the detection of Pb²⁺ ion in the range of 10–100 µM, while the limit of detection (LOD) was about LOD = 2.7 µM. We examined the cytotoxicity effect of synthesized NCPs on Huh-7 cancer cell lines by MTT assay, which resulted in concentration-dependent cytotoxicity with the IC₅₀ value at a concentration of 62.5 ppm. Additionally, we assessed the photocatalytic activity of our product toward the dye degradation of methylene blue (MB) from aqueous solutions, leading to the degradation percentage of about 90% after 120 min. The outcomes suggested the potential of synthesized nanocomposites in acting as a catalyst for organic dye degradation of wastewater.