Fig. 6. Photocatalytic oxidation of NADH by Os2 under light irradiation.

a Reaction of Os2 (20 μM) and NADH (175 μM) in PBS solution under blue light irradiation monitored by UV–Vis absorption spectra at 298 K. b TON of Os2 under dark or irradiation conditions (n = 3 independent experiments, p = 0.0000016). c Photocatalytic oxidation of NADH (3.5 mM) by Os2 (0.25 mM) under dark or irradiation conditions monitored by ¹H NMR spectroscopy at 298 K. Peaks associated with blue triangles represent NADH, those with red squares represent NAD⁺. d NADH concentrations in the treated HeLa cells. Os2: 20 μM, 310 K, 8 h. All the experiments were performed as duplicates of triplicates (n = 3 biologically independent samples, p = 0.000039). Error bars represent S.D. from the mean. Statistical significance was calculated with two-tailed Student’s t test (*p < 0.05, **p ≤ 0.01 or ***p ≤ 0.001). e Schematic diagram of the photocatalytic oxidation of NADH by Os2 and followed by induced ferroptosis. Light irradiation: 465 nm, 13 mW/cm². TON turnover number, NADH 1,4-dihydro-nicotinamide adenine dinucleotide, GSH glutathione; GSSG oxidized glutathione, GPX4 glutathione peroxidase 4, GR glutathione reductase.