Delivering nitric oxide into human skin from encapsulated S-nitrosoglutathione under UV light: An in vitro and ex vivo study.  Nitric oxide (NO) is a crucial molecule in the human body. The encapsulation of exogenous NO donors into chitosan nanoparticles (CS NPs) has been widely used to overcome NO drawbacks in pharmacological applications, such as, its short half-life. The NO donor, S-nitrosoglutathione (GSNO), was encapsulated into CS NPs (GSNO-CS NPs) and characterized by AFM and DLS measurements. The nanoparticles presented a hydrodynamic size of 123.3 ± 1.5 nm and a polydispersity of 0.25 ± 0.01. The ability of GSNO-CS NPs, combined with UV irradiation, to deliver NO was evaluated using ex vivo human skin. The human skin was pre-treated with GSNO-CS NPs, in the presence and absence of UV irradiation. The results showed that the combined treatment significantly increased the NO and S-nitrosothiol levels in human skin. This effect can emulate the cardiovascular benefits related to NO without negative side effects of skin exposure to UV light.