It should be noted that NO quantification using DAR-2 may lead to inaccurate results if the absorption spectrum of the photodonor changes significantly at the probe excitation wavelength (540 nm) during photolysis. Another possible error source is the intrinsic fluorescence of the molecules under study, which could also change during photolysis. An alternative method is needed to confirm the NO photorelease. For this purpose and also to account for NO that is not trapped by DAR-2 but undergoes reaction with oxygen, we performed experiments with Griess assay as described in Supplementary materials. The Griess assay allows to measure the concentration of nitrites. The amount of nitrites after 10 minutes of photolysis (12 µM) was ~80% of the initial concentration of BODIPY-NOD-2 (15 µM), which is consistent with the total conversion to 2b visible by the change of absorption spectrum.