A new fluorescence turn-on probe for biothiols based on photoinduced electron transfer and its application in living cells

• A new fluorescence turn-on probe for biothiols was developed.
• The probe could selectively detect cysteine at pH 3.5.
• The probe responded well to cysteine, glutathione and homocysteine at pH 5.5.
• The probe was successfully applied for imaging of thiols in living cells.

A new biothiol-selective fluorescent probe 1 based on photoinduced electron transfer (PET) mechanism was designed and synthesized. The UV–Vis absorption and fluorescent emission properties of probe 1 towards various analytes were studied in detail. The probe exhibited a large stokes shift (~ 200 nm) after reacted with biothiols and could selectively detect cysteine (Cys) in dimethyl sulfoxide (DMSO)/H2O solution (9:1, v/v, 10 mM phosphate buffer saline, pH 3.5) over glutathione (GSH), homocysteine (Hcy) and other analytes with a detection limit of 0.117 μM. In addition, probe 1 responded well to GSH, Hcy and Cys in the same above solution with pH 5.5 and got the detection limits of 0.151 μM, 0.128 μM and 0.037 μM, respectively. Probe 1 was of very low cytotoxicity and successfully applied for imaging of thiols in living cells.

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