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Visualizing Thiol Stress Responses in Cells with a Water-Soluble Raman Sensor
Hiroyuki Yamakoshi1, Meichen Wang1, Keisuke Koga1
1Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
Analytical Chemistry
|November 10, 2025
Summary
Accurate live-cell thiol quantification is now possible with iPrCAA, the smallest ratiometric Raman probe. This novel probe enables sensitive, real-time monitoring of intracellular thiol levels and distribution.
Area of Science:
- Chemical Biology
- Molecular Imaging
- Cell Biology
Background:
- Accurate quantification of intracellular thiols in live cells is difficult due to limitations of fluorescent probes.
- Existing probes suffer from signal saturation, photobleaching, and dye aggregation, hindering reliable measurements.
Purpose of the Study:
- To introduce (E)-2-cyano-3-isopropylacrylamide (iPrCAA) as a novel ratiometric Raman probe for quantifying and visualizing intracellular thiol concentrations.
- To demonstrate iPrCAA's utility for real-time monitoring of thiol dynamics in live cells.
Main Methods:
- Development and characterization of iPrCAA, the smallest thiol-detecting probe for live-cell analysis.
- Utilizing iPrCAA as a ratiometric Raman probe for sensitive thiol detection.
- Monitoring intracellular thiol depletion in a thiol-free medium and visualizing thiol distribution.
Main Results:
- iPrCAA is the smallest available thiol-detecting probe (138 g/mol) with high reactivity and water solubility, enhancing sensitivity.
- Real-time monitoring showed a ~3-fold reduction in thiol levels in a thiol-free medium.
- Visualized thiol distribution closely correlated with protein distribution within cells.
Conclusions:
- iPrCAA offers a practical and sensitive method for quantifying endogenous thiols in live cells.
- This Raman probe enables dynamic tracking of thiol fluctuations, particularly under cellular stress conditions.
- iPrCAA overcomes limitations of fluorescent probes for accurate intracellular thiol measurements.
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