Ratiometric Two-Photon Fluorescent Probe for in Vivo Hydrogen Polysulfides Detection and Imaging during Lipopolysaccharide-Induced Acute Organs Injury.

Acute organ injury observed during sepsis, caused by an uncontrolled release of inflammatory mediators, such as lipopolysaccharide (LPS), is quite fatal. The development of efficient methods for early diagnosis of sepsis and LPS-induced acute organ injury in living systems is of great biomedical importance. In living systems, cystathionine γ-lyase (CSE) can be overexpressed due to LPS, and H2Sn can be formed by CSE-mediated cysteine metabolism. Thus, acute organ injury during sepsis may be correlated with H2Sn levels, making accurate detection of H2Sn in living systems of great physiological and pathological significance. In this work, our previously reported fluorescent platform was employed to design and synthesize a FRET-based ratiometric two-photon (TP) fluorescent probe TPR-S, producing a large emission shift in the presence of H2Sn. In this work, a naphthalene derivative two-photon fluorophore was chosen as the energy donor; a rhodol derivative fluorophore served as the acceptor. The 2-fluoro-5-nitrobenzoate group of probe TPR-S reacted with H2Sn and was selectively removed to release the fluorophore, resulting in a fluorescent signal decrease at 448 nm and enhancement at 541 nm. The ratio value of the fluorescence intensity between 541 and 448 nm (I541 nm/I448 nm) varied from 0.13 to 8.12 (∼62-fold), with the H2Sn concentration changing from 0 to 1 mM. The detection limit of the probe was 0.7 μM. Moreover, the probe was applied for imaging H2Sn in living cells, tissues, and organs of LPS-induced acute organ injury, which demonstrated its practical application in complex biosystems as a potential method to achieve early diagnosis of LPS-induced acute organ injury.