Styryl-bodipy fluorescent sensors for reactive oxygen species detection in cells

Abstract

Fluorescent probes are great tools for visualization and imaging of reactive oxygen species (ROS) in living cells. Although several probes perform well with green emission, however, to maximize light penetration for tissue imaging and minimize interference from auto-fluorescence, a probe with longer wavelength is desirable. In this study, three new boron dipyrromethene (BODIPY)-based fluorescent probes SB1, SB2 and SB4 have been developed for detection of ROS. Each probe has two styryl groups anchored to the BODIPY pyrrole rings to extend the emission wavelength into the red region (634–662 nm). Among them, we found that SB2 containing electron-rich p-hydroxyl styryl groups was the best probe for ROS detection. In aqueous media, the probe SB2 demonstrated colorimetric change from blue to purple and gave orange fluorescence turn-on at 590 nm selectively to hypochlorite (NaOCl) over other ROS. SB2 provided the detection limit for NaOCl sensing of 0.26 μM. Several oxidative intermediates were observed from mass spectrometry, suggesting the NaOCl oxidative sensing mechanism of SB2. In RAW264.7 macrophages, SB2 was able to penetrate and detect both exogenous NaOCl and endogenous ROS, induced by lipopolysaccharide (LPS), in the orange field (570–620 nm). Our finding offers long-wavelength probe for ROS detection in live cells.