Specord 200 spectrometer

All NMR spectra were recorded on a Varian MR-400 spectrometer (Varian, Inc., Walnut Creek, CA, USA) with standard pulse sequences operating at 400 MHz for 1H-NMR and 100 MHz for 13C-NMR. For all NMR spectra, DMSO-d6 was used as a solvent. Chemical shift values are referenced to residual protons (δ 2.49 ppm) and carbons (δ 39.6 ppm) of the solvent as an internal standard. Elemental analysis was performed on a EuroEA-3000 CHNS-O analyzer (Euro Vector, Milan, Italy). Melting points were measured with a Buchi B-520 melting point apparatus (Buchi AG, Flawil, Switzerland). LC/MS spectra were recorded with ELSD Alltech 3300 liquid chromatograph (Buchi AG, Flawil, Switzerland) equipped with a UV detector (λ_max 254 nm), API-150EX mass-spectrometer and using a Zorbax SB-C18 column, Phenomenex (100 × 4 mm) Rapid Resolution HT Cartridge 4.6 × 30 mm, 1.8-Micron. Elution started with 0.1 M solution of HCOOH in water and ended with 0.1 M solution of HCOOH in acetonitrile used a linear gradient at a flow rate of 0.15 mL/min and an analysis cycle time of 25 min. UV/Vis spectra of solutions in CH₃CN were recorded on a Specord 200 spectrometer (Analytik Jena AG, Jena, Germany). IR spectra in KBr pellets were recorded on a Bruker Vertex 70 FTIR spectrometer (Bruker Optik GmbH, Ettlingen, Germany).

UV-Vis spectra (see Fig. S2) have been recorded in Hellma QS-110 10 mm quartz cuvettes on an Analytic jena Specord 200 spectrometer using WinASPEC 2.2 software.
Raw absorbance data have been smoothed (Adjacent-Averaging, Points of Window: 5), corrected by subtraction of smoothed values of a solvent blank (PBS or EtOH, respectively) and plotted against the wavelength. Local absorption maxima λ_max have been determined to be very similar between the three samples with values of 284 and 286 nm, respectively. Molar extinction coefficients ε (listed in Table S2) have been determined according to the Lambert-Beer law by linear regression of the absorbance values at λ_max and at 365 nm (the wavelength applied for BAPO activation in in vitro experiments), respectively. R² values from the regression analysis are given. Please note that especially the values ε(365 nm) for NaBAPO in PBS and DoBAPO in EtOH must be regarded as inaccurate due to low absorbances at this wavelength. Furthermore, the extinction coefficients ε of the liposomal formulation of DoBAPO must be regarded with care as the Lambert-Beer law is not applicable to colloidal solutions due to light scattering.

Stock solutions with concentrations of c = 0.175 mM were prepared of both ProSQ-C16 enantiomers by dissolving 1.65 mg of the respective enantiomer in chloroform in 10 mL graduated flasks. For each measurement 0.1 mL of the respective stock solution were transferred into a 10 mm Hellma quartz cuvette and subsequently diluted with 3 mL of a chloroform-acetonitrile mixture to give a concentration of ~5.7 μM. For the solvent mixture the acetonitrile volume percentage is indicated ranging from 70% to 100% in steps of three. Cuvettes were gently shaken three times for equilibration and immediately measured. CD spectra were recorded with a Jasco J-810 spectro-polarimeter with 0.1 nm step size, 500 nm/min scan speeds, and 1 nm bandwidth. The instrument was calibrated with a reference sample in advance. UV–vis spectra were recorded on an Analytik Jena AG Specord 200 spectrometer with 0.2 nm step size.