A new selective fluorescent and colorimetric chemosensor for the detection of GSH was developed. The discrimination of GSH from Cys and Hcy is achieved through two emission channel detection. The detection limit of probe 1 for GSH reached 10 nM (3 ppb). The excellent sensitivity and selectivity of probe 1 allow the selective detection of GSH over Cys and Hcy, which can be visualized colorimetrically and/or fluorescently. The sensitive detection of GSH allowed for convenient measurement of the GSH content in human plasma. The presence of GSH in cells was demonstrated through cell imaging.

A highly selective and sensitive turn-on red fluorescent 1-amino BODIPY-based probe (where BODIPY denotes indole-based boron-dipyrromethene) with high off-to-on contrast ratio has been developed. The probe displayed selective response to thiophenols over aliphatic thiols. Probe 1 is promising for the quantitative detection of thiophenol with a linear response from 6 × 10(-6) M to 1 × 10(-4) M, and the detection limit for thiophenol (PhSH) reaches 4 × 10(-6) M measured in acetonitrile/PBS buffer. The detection limit could be improved to 37 nM (detection limit to 4 ppb) in water when 1% Tween 20 was used to assist the dissolvation of probe 1 in water. Probe 1 is also a useful fluorescent probe for detecting thiophenols in living cells in red emission, which may greatly improve the detectable sensitivity.

A selective and sensitive turn-on fluorescent NIR probe for cysteine has been developed. Cleavage of 2,4-dinitrobenzenesulfonyl (DNBS) with thiols switches the weakly fluorescent aza-BODIPY dye (λ(em) = 734 nm, Φ(f) = 0.03) to a strongly fluorescent species in the NIR region (λ(em) = 755 nm, Φ(f) = 0.14).

A BODIPY-based turn-on NIR fluorescent probe containing a partially exposed aldehyde group at the meso position for the detection of homocysteine over cysteine was developed. Such a probe is potentially useful for the discrimination of Hcy from Cys.