Gallic- and ω-3-linolenic-acids-mediated MgO nanoplates enable band-edge tuning and ROS-driven anticancer activity

Green nanotechnology seeks earth-abundant, low-toxicity oxides that can deliver biomedical benefits with minimal environmental impact. We report the first magnesium oxide (MgO) nanoparticles (NPs) synthesised exclusively from Pinus patula needle waste via a one-pot, aqueous route that requires no organic solvents or post-calcination. Targeted GC-MS profiling pinpoints gallic acid, ω-3 linolenic-acid bis-TMS ether and three mono-linoleoylglycerol derivatives as the dominant reductive/capping agents (Σ > 35 % TIC), while FT-IR confirms they are in-situ chelation to Mg²⁺. The renewable extract simultaneously reduces Mg²⁺, caps nascent nuclei and templates mesoporosity, affording a 78 % yield of well-crystalized platelets (XRD domain 55 ± 3 nm; BET surface area 54 m² g⁻¹; pore diameter 3.8 nm). Oxygen-vacancy enrichment contracts the bulk 7.8 eV gap to an indirect 3.24 eV; the resulting band edges (-0.29 V and +1.81 V vs NHE, pH 7) favour superoxide but suppress hydroxyl-radical formation, enabling stimulus-dependent redox switching. In vitro, the particles trigger intrinsic apoptosis in MCF-7 cells with an IC₅₀ of 71 ng mL⁻¹ and a 32-fold Bax/Bcl-2 shift, yet exhibit negligible haemolysis toward erythrocytes. Antioxidant assays reveal a DPPH•-scavenging IC₅₀ of 25 µg mL⁻¹ lower than any green-synthesised MgO reported to date. Comprehensive GC-MS, FT-IR and time-resolved XRD tracking link the vacancy stabilization and ripening inhibition to the coordinated gallic-acid/flavolipid corona.