Highly efficient photocatalytic degradation of dyes and anticancer activity of eco-friendly synthesized Ag/Ag ₂ O/γ-Fe ₂ O ₃ nanoparticles using <i>Cistus monspeliensis</i> leaf extract

<i>Cistus monspeliensis</i> L., a Mediterranean plant rich in polyphenolic compounds, was employed as a sustainable reducing and capping agent in the green synthesis of Ag/Ag₂O/γ-Fe₂O₃ nanoparticles. The nanoparticles were characterized using UV-Vis spectroscopy, DRS, FTIR, XRD, FESEM-EDX, TEM, and zeta potential analyses. They were subsequently applied for the photocatalytic degradation of Crystal Violet (CV) under UVA and solar irradiation, as well as for evaluating their cytotoxicity against human colorectal cancer cells (HCT-116). The obtained NPs were polydisperse and nearly spherical with sizes averaging 26.49 ± 6.1 nm. Optical characterization using UV-Vis and DRS revealed an absorption peak at 274 nm and a direct bandgap value of 1.934 eV, enabling sufficient visible-light absorption. FE-SEM demonstrated a rough surface with visible particle aggregation, while EDX confirmed the elemental composition of the material. Ag/Ag₂O/γ-Fe₂O₃ NPs exhibited high colloidal stability with a zeta potential of -46.9 mV. Owing to the synergistic combination between Ag and Fe, the nanomaterial achieved rapid photocatalytic degradation of CV (10 mg L^-1 and a catalyst dosage of 0.5 g L^-1), with removal efficiencies of 97.87% under UVA irradiation and 95.50% under solar irradiation within 60 minutes. Radical scavenger tests indicated that ˙OH and O₂˙^- were the main reactive species involved in CV degradation. In addition, Ag/Ag₂O/γ-Fe₂O₃ NPs presented potent cytotoxicity against HCT-116 cells; the activity was dose-dependent with an IC₅₀ value of 23.34 ± 1.61 µg mL^-1 using the MTT assay, inducing severe alterations indicative of apoptotic cell death and cytoskeletal disruption. These findings highlight the interdisciplinary potential of biosynthesized Ag/Ag₂O/γ-Fe₂O₃ NPs in environmental remediation and biomedical applications.