Recent advances in hydrogen peroxide imaging for biological applications

Abstract

Mounting evidence supports the role of hydrogen peroxide (H ₂O ₂) in physiological signaling as well as pathological conditions. However, the subtleties of peroxide-mediated signaling are not well understood, in part because the generation, degradation, and diffusion of H ₂O ₂ are highly volatile within different cellular compartments. Therefore, the direct measurement of H ₂O ₂ in living specimens is critically important. Fluorescent probes that can detect small changes in H ₂O ₂ levels within relevant cellular compartments are important tools to study the spatial dynamics of H ₂O ₂. To achieve temporal resolution, the probes must also be photostable enough to allow multiple readings over time without loss of signal. Traditional fluorescent redox sensitive probes that have been commonly used for the detection of H ₂O ₂ tend to react with a wide variety of reactive oxygen species (ROS) and often suffer from photostablilty issues. Recently, new classes of H ₂O ₂ probes have been designed to detect H ₂O ₂ with high selectivity. Advances in H ₂O ₂ measurement have enabled biomedical scientists to study H ₂O ₂ biology at a level of precision previously unachievable. In addition, new imaging techniques such as two-photon microscopy (TPM) have been employed for H ₂O ₂ detection, which permit real-time measurements of H ₂O ₂ in vivo. This review focuses on recent advances in H ₂O ₂ probe development and optical imaging technologies that have been developed for biomedical applications.