A dual-modal optical probe for GST detection: a measure of GST activity in lipid metabolic disorders

This study introduces Hcy-GST, a new dual-modal optical probe for detecting glutathione S-transferase (GST) activity. The probe combines hemicyanine and rhodamine derivatives, which use fluorescence and photoacoustic (PA) signals, controlled by a photoinduced electron transfer (PET) mechanism. In its original form, the nitro groups in Hcy-GST quench fluorescence, producing weak fluorescence and strong PA signals. When GST replaces the nitro groups with glutathione (GSH), the PET effect is interrupted, leading to fluorescence recovery and reduced PA signals. Hcy-GST shows high sensitivity, with fluorescence and PA signals strongly correlating with GST concentration. It has high selectivity and minimal interference from other substances. In cellular tests, Hcy-GST detected GST inhibition by ethacrynic acid. In vivo studies revealed lower GST activity in obese models, with PA signals increasing after probe injection. Hcy-GST demonstrated excellent stability and low toxicity, showing promise for GST detection in research and diagnostics.