A efficient light-controlled nitric oxide releaser in aqueous solution and its red fluorescence imaging in lysosome

Abstract

In this work, a sensitive light-controlled turn on nitric oxide releaser, chromenylium-aniline-N-nitroso (CA-NO), was developed, which could release nitric oxide in pure water media and be applied for the red fluorescence imaging in lysosome. Upon the irradiation, fluorescence of the nitric oxide releaser enhanced quickly due to the light-controlled CA-NO being decomposed into a free radical nitric oxide and the fluorescent group CA, which destroyed of ICT structure. The mechanism was supported by the capture of nitric oxide by the commercial nitric oxide fluorescent probe DAN and the HRMS spectra peak (HRMS calcd for C30H34N3O4+ [M]+: 526.2700, found: 526.2700.) belonging to CA. The fluorescence quantum yield (ΦF) of CA-NO changed from 0.54% to 3.24%. The nitric oxide releasing yield was calculated to be 91.3%, which proved the superiority of CA-NO. With the irradiation, the color of the solution immediately changed from pink to blue purple in visible light which realized the naked-eyed monitoring of nitric oxide releasing. Obvious fluorescence changes and high cell viability above 80% encouraged us to apply CA-NO into living cells and the CA-NO successfully released nitric oxide in living cells through under irradiation. Nitric oxide could easily diffuse into lysosomes and react with related proteins, which prompts nitric oxide to regulate lysosomal catabolism and autophagy. Therefore, the co-location experiment of CA-NO and Lyso Tracker Green in living cells was carried out and the co-localization coefficient was calculated to be 0.842, which implied that morpholine group promoted the nitric oxide releaser to be aggregate in lysosome successfully. This work achieved the fixed-point and quantitative release of nitric oxide, which was helpful to understand the roles of nitric oxide and provided a good basis for our studying on related interaction between protein and nitric oxide in lysosome and cells.