A novel fluorescent probe RO610 was applied for the in vivo detection of endogenous ClO− using living mice.

To enhance the efficiency of firefly luciferase/luciferin bioluminescence imaging, a series of N-cycloalkylaminoluciferins (cyaLucs) were developed by introducing lipophilic N-cycloalkylated substitutions. The experimental results demonstrate that these cyaLucs are effective substrates for native firefly luciferase (Fluc) and can produce elevated bioluminescent signals in vitro, in cellulo, and in vivo. It should be noted that, in animal studies, N-cyclobutylaminoluciferin (cybLuc) at 10 μM (0.1 mL), which is 0.01% of the standard dose of d-luciferin (dLuc) used in mouse imaging, can radiate 20-fold more bioluminescent light than d-luciferin (dLuc) or aminoluciferin (aLuc) at the same concentration. Longer in vivo emission imaging using cybLuc suggests that it can be used for long-time observation. Regarding the mechanism of cybLuc, our cocrystal structure data from firefly luciferase with oxidized cybLuc suggested that oxidized cybLuc fits into the same pocket as oxyluciferin. Most interestingly, our results demonstrate that the sensitivity of cybLuc in brain tumor imaging contributes to its extended application in deep tissues.

Pantetheinase, a glycosylphosphatidylinositol (GPI) anchored enzyme, overexpresses in intestine, liver, and kidney with various biological functions such as its linkage to the inflammation and some metabolic diseases. It can hydrolyze pantetheine to cysteamine, an antioxidant, and pantothenic acid (Vitamin B5) that is an essential component of coenzyme A (CoA). Until now, very few analytic methods were developed for this enzyme, hampering the further investigation of its biological functions. In this work, we report the design, synthesis, and biological examination of a highly sensitive bioluminogenic probe for pantetheinase with a limit of detection of 1.14 ng/mL. Furthermore, animal experiments validated that our probe can be applied to detect the endogenous pantetheinase activity. To the best of our knowledge, this is the first bioluminogenic probe achieving the detection of pantetheinase level in vivo.

As a kind of biologically important reactive oxygen species (ROS), hypochlorite (ClO) plays a crucial role in many physiological processes. As such, endogenous ClO is a powerful antibacterial agent during pathogen invasion. Nonetheless, excessive endogenous ClO could pose a health threat to mammalian animals including humans. However, the detection of endogenous ClO by bioluminescence probes in vivo remains a considerable challenge. Herein, based on a caged strategy, we developed a turn-on bioluminescent probe 1 for the highly selective detection of ClOin vitro and imaging endogenous ClO in a mouse inflammation model. We anticipate that such a probe could help us understand the role of endogenous ClO in a variety of physiological and pathological processes.