A merocyanine dye-based superoxide anion fluorescent probe with second-level response agility enables evaluating interstitial cystitis via two-photon excitation imaging

Abstract

As a species tightly associated with inflammation, superoxide anion radical (O2·-) is generally recognized a biomarker for interstitial cystitis (IC) but the reliable detection of such species has been remaining a challenge owing to its elusive nature. Herein, we developed a merocyanine dye-based fluorescent probe, MC-O-TBS, capable of detecting O2·- species with a limit of detection down to 49.3 nM, recognition specificity against other potential interfering species and two-photon excitation fluorescence (TPEF) property for bioimaging with satisfactory depth. As another particularly salient feature, MC-O-TBS generates O2·--mediated fluorescence contrast with response time less than 10 s, an unexampled response agility of probe in O2·- fluorescence sensing as compared to the counterpart probes developed to date. The superior performance of MC-O-TBS probe in terms of recognition specificity, detection sensitivity, TPEF for bioimaging with satisfactory depth and response rate as well as the preliminary in vitro experiment results regarding mapping O2·- level in bladder organ unequivocally proclaimed its potential for reliably monitoring the highly elusive O2·- species and clinically diagnosing IC featured with abnormal O2·- level.