Conjugating S-Nitrosothiols with Glutathiose Stabilized Silver Sulfide Quantum Dots for Controlled Nitric Oxide Release and Near-Infrared Fluorescence Imaging

Light-controllable nitric oxide (NO) delivery nanoparticles with the capability of near-infrared (NIR) fluorescence imaging were reported. Water-dispersible Ag2S quantum dots (QDs) were synthesized via a one-pot procedure using reduced glutathiose (GSH) as both sulfur source and stabilizer. S-nitrosothiols (RSNOs) were conjugated with the GSH stabilized Ag2S QDs at the amino groups of the GSH, leading to Ag2S-GSH-SNO nanoparticles with dimension of ~5.5 nm. The biocompatible Ag2S-GSH-SNO nanoparticles could release NO under UV or visible irradiation and emit NIR fluorescence under NIR excitation for bioimaging at physiological pH and temperature, yet could hardly release NO when NIR irradiation was applied. In vitro cell imaging and mice imaging experiments demonstrated that the Ag2S-GSH-SNO nanoparticles could emit readily observable NIR fluorescence and release NO in living cells and small animals. The NIR fluorescence imaging of the Ag2S-GSH-SNO nanoparticles would not interfere with the light-triggered NO release from them, as the excitation lights needed for these two functions were in different wavelength regions. This work provides new perspectives for the application of multifunctional nanostructured materials in diagnostics and imaging.