Peroxide-responsive boronate ester-coupled turn-on fluorogenic probes: Direct linkers supersede self-immolative linkers for sensing peroxides

Abstract

Turn-on fluorogenic probes are commonly utilized for an efficient estimation of reactive oxygen species such as H2O2. In the present study, three different sets of turn-on fluorogenic probes for sensing H2O2 were rationally designed by coupling boronate ester group with three important fluorescent dyes either by linking directly or via self-immolative linkers. Interestingly, our results reveal that directly-linked boronate ester probes are superior and sensitive than the self-immolative linker-containing probes in detecting traces of exogenous and endogenous levels of H2O2. The difference in probe efficiency was also dependent on the nature of fluorophore unit being used. Considering these aspects, our detailed studies reveal that the directly-linked boronate ester-based fluorescein probe 19 is the best probe for efficiently sensing H2O2 both in aqueous as well as cellular medium with very high level of sensitivity. The present observation would be useful while designing the fluorogenic sensors for ROS as well as during their utilization in ROS-associated pathologies.