Selective fluorescent activation for bioimaging the expression of nitric oxide in cellular and in vivo systems

Nitric oxide serves as a messenger for cellular signaling and physiological reactions such as inflammatory responses in vivo. Fluorescent bioimaging can be a useful tool in nitric oxide functional research. However, current nitric oxide in vivo imaging protocols often result in suboptimal image quality. Selective fluorescent activation of probes after their reaction with nitric oxide is an appropriate way for imaging nitric oxide. Fluorescent naphtho[2,3-d]imidazol derivatives can react with copper II to form nonfluorescent compounds, which can then enable direct imaging of nitric oxide in vitro or in vivo, based on the redox action of copper II. These probes can be applied to image nitric oxide produced by inducible nitric oxide synthase in cellular systems such as lipopolysaccharide-activated murine macrophages. More importantly, the probes can be utilized for in vivo imaging of nitric oxide production, for example, in acute severe hepatic injury. This chapter describes the methods required to apply such probes as nitric oxide bioimaging agents with potential use for diagnostic and pathological studies of nitric oxide-related diseases.