In-situ gastritis diagnosis by an oral-administration NIR fluorescent probe with a large Stokes shift and high signal-to-noise ratio

Gastritis is one of the most common digestive disorders and affecting millions of people worldwide. Recent in-vestigations discovered that abnormal viscosity changes in organisms are associated with an increasing number of diseases that cannot be cured or managed. However, the relationship between gastritis and viscosity has not been explored so far due to lacking the suitable tools for in situ detecting the variations of viscosity in stomach. Herein, we developed a new oral-administration fluorescent probe (NS-V) for in situ elucidation of gastritis viscosity variations, for the first time. Based on the TICT mechanism, the probe employs naphthalene as the fluorescence platform, the rotatable single bond as the viscosity sensitive site, N, N-dimethyl as the strong electron donating moiety and the pyridine salt as the strong withdrawing group to enlarge the pi-conjugated system to prolong the emission wavelength. Interestingly, NS-V revealed a good fluorescence response for vis-cosity at the NIR region from a silent "off" state to "on" and demonstrated high sensitivity, large Stokes shift (262 nm in MeCN), and high signal-to-noise ratio. In addition, NS-V could elucidate the altered mitochondrial vis-cosity in inflammatory cells. More importantly, utilizing these satisfactory features of NS-V, we discovered a significant increase in viscosity in the gastritis mice. Notably, with the assistance of the oral fluorescence molecule, in vivo and in situ visualizing for the first time revealed the positive correlation between viscosity and gastritis. This work provides an important basis for the diagnosis of gastritis and the robust probe developed in this work possesses a potential application in diagnosis of gastritis without any pain.