Green Synthesis of Multifunctional Ag/ZnO Nanoparticles Using Vitis labrusca L. Extract: Bioactivity, Malachite Green Adsorption, and HMF Removal

In this study, Ag/ZnO nanoparticles (Ag/ZnO NPs) were synthesized via a green route using Vitis labrusca L. extract and evaluated for their bioactive, environmental performance. BM-1 and BM-2 were prepared under different precursor/extract ratios and pH conditions to assess the influence of synthesis parameters. UV–Vis, FT-IR, XRD, HRTEM, DSC, and EDX analyses indicated the successful formation of Ag/ZnO nanostructures with distinct physicochemical features. HRTEM analysis determined that BM-1 exhibited an average particle diameter of 23.18 ± 11.84 nm, while BM-2 demonstrated a mean size of 6.14 ± 1.30 nm. The corresponding relative size-dispersion values were 0.261 for BM-1 and 0.045 for BM-2, indicating a more uniform particle size distribution for BM-2. Antioxidant assays showed that BM-2 exhibited the strongest overall antioxidant performance in DPPH, ABTS•⁺, Fe3+, and Cu2+ assays. Both NPs exhibited antibacterial activity against Gram-positive and Gram-negative bacteria and showed stronger effects than the grape extract alone. Cytotoxicity assays revealed dose-dependent inhibition in A549 and HeLa cancer cells, while lower toxicity was observed in normal ARPE-19 cells, suggesting cell-type-dependent biological response. In adsorption experiments, the NPs effectively removed malachite green, with isotherm analysis providing stronger support for the Langmuir model for BM-1 and comparable Langmuir and Freundlich fits for BM-2, while the pseudo-second-order model provided the best description of the adsorption kinetics. The maximum dye adsorption capacities were 85.5 mg/g for BM-1 and 101.3 mg/g for BM-2. Under optimum conditions (5.0 g/L NPs, 240 min), the highest HMF removal efficiencies reached 44.49% for BM-2 in standard aqueous solutions, whereas competitive matrix interactions in apple juice limited the maximum efficiency to 29.27%. Overall, this study highlights the value of integrating green synthesis, bioactivity, dye adsorption, and food-related contaminant removal within a single Ag/ZnO nanoplatform.