Visualizing endoplasmic reticulum carboxylesterase activity during heat shock by a near-infrared fluorescent probe

In heat shock, various enzyme activities are clearly altered due to high body temperature. Evidence accumulated in the last few years indicates that endogenous carboxylesterase (CE) can be regarded as a biomarker of heat shock due to its close relationship to heat shock. To monitor CE activity, this study aims to develop excellent fluorescent probe for CE detection. Fluorescent probe DCM-Br-CE with a NIR turn-on signal at 660 nm and a large Stokes shift of 160 nm, as well as high sensitivity (0.117 × 10−4 U/mL) and good detection capability (30 min) for CE. DCM-Br-CE also has excellent subcellular localization for endoplasmic reticulum (ER). Furthermore, DCM-Br-CE has been shown to effectively visualize endogenous CE in PC12 or HT22 cells, can also monitor changes in CE activity during heat shock in cells and in living mice. This suggests that the probe has potential to be used for CE studies across a variety of pathological conditions, making it a promising tool for heat shock research.