Fig. 6

(a) Au(III) uncages the fluorogenic probe QF4 in cells. HeLa cells were exposed to QF4 in medium for 1 h followed by a wash. Cells were randomly distributed into two conditions: DMSO or Au(III) for 12 h. Confocal image of cells upon treatment shows that the progress of the reaction in cells (green channel). (b) Au(III)-mediated uncaging of drugs in cells: Substrates (PD1, PD2, and ADC1) were used in the study. (c) Toxicity screening of Na[AuCl4] in HeLa cells. Cells were treated with the depicted concentrations for 72 h, and viability was measured by AlamarBlue. (d) ICP-MS analysis of the cellular extracts revealed the intracellular amount of Au after incubation of Na[AuCl4] following several washing steps and lytic treatment. (e, f) HeLa cells were incubated with different concentrations of PD1 or PD2 for 72 h with or without Na[AuCl4] (20 μM, twice a day). (g) Au(III)-mediated drug decaging from an ADC; cysteine-selective and irreversible modification of an internalizing antibody thiomab an MMAE conjugating linker. Deconvoluted ESI–MS mass spectrum of the light-chain confirms the modification. (h) Cell viability of SKBR3 cells (HER++) after treatment with ADC1 and subsequent uncaging efficiency upon treatment with 20 μM Na[AuCl4], twice daily. Toxicity was determined by the AlamarBlue assay. Error bars represent ± standard deviation (n = 3). The statistical significance of the differences between groups was evaluated with the unpaired t test. Statistical results: ns >0.05, **P ≤ 0.01, ***P ≤ 0.001, and ****P ≤ 0.0001.