Fluorescent chitosan complex nanosphere diazeniumdiolates as donors and sensitive real-time probes of nitric oxide.

A new CuFL (2-{2-chloro-6-hydroxy-5-[(2-methyl-quinolin-8-ylamino)-methyl]-3-oxo-3H-xanthen-9-yl}-benzoic acid)-CS (chitosan) NS diazeniumdiolates system consisting of NO donors and highly-sensitive NO probes is reported. FL-CS NS diazeniumdiolates were synthesized by incorporating the fluorescent molecule FL with chitosan (CS) and reacting the resultant FL-CS complex with pressurized NO and dimethyl sulfate (DMS). Then the FL-CS NS diazeniumdiolates were reacted with copper chloride (CuCl(2)) to generate non-fluorescent CuFL-CS NS diazeniumdiolates. The CuFL-CS NS diazeniumdiolates have a spherical outline with a dimension of ca. 250 nm. They have high selectivity for NO over other related substances. The results of in vitro and in vivo experiments indicate that the CuFL-CS NS diazeniumdiolates can release NO under physiological conditions and meanwhile detect the released NO based on the considerable fluorescence increase of the otherwise non-fluorescent system caused by the NO. The good fluorescence stability of the NO-FL-CS NS provides prospects for the CuFL-CS NS diazeniumdiolates in biomedical applications.