A tunable fluorescent probe for superoxide anion detection during inflammation caused by Treponema pallidum

Abstract

Syphilis, caused by Treponema pallidum (T. pallidum), is associated with the oxidative stress due to its inflammation-like symptom, and detecting the reactive oxygen species (ROS) is crucial for monitoring the infectious process. Herein, we design and synthesize a perylene-based tunable fluorescent probe, PerqdOH, which can detect endogenous O₂˙⁻ during T. pallidum infection. The fluorescence peak shifted from 540 nm to 750 nm with increasing O₂˙⁻ levels. Besides, both decreased green fluorescence and enhanced red fluorescence could be observed simultaneously during the in vitro infection, providing the real-time monitoring of intracellular O₂˙⁻ caused by T. pallidum. Furthermore, the probe exhibited a remarkable signal in the treponemal lesions on the back of a rabbit model. Taken together, our synthesized PerqdOH holds great potential for application in clarifying the infectious process caused by T. pallidum in real time.