A supersensitive fluorescent probe for biothiols by regulating the click reaction and its application in glutathione detection in food samples

A new fluorescent molecular probe (NAM2) with extending conjugation system between the recognition group and naphthalimide fluorophore group was developed for selective and sensitive detection of biothiols. The conjugation system of a phenyl ring with the naphthalimide group improved the efficiency of photoinduced electron transfer (PET). The molecular probe showed a supersensitive “off-on’’ response to glutathione (GSH) and homocysteine (Hcy), and it allowed detecting GSH and Hcy linearly in a range of 0–3 μ M with detection limits of 0.0011 μ M and 0.0032 μ M, respectively. Significantly, the new sensor was applied in accurate detection of GSH in vegetables and fruits with recoveries of 87.26–96.72% (RSDs<3.5%, n = 3), and it was validated by a phthalaldehyde-derivatisation method. The fluorescence spectrometry based on the sensor NAM2 is a high-quality and promising analytical tool for GSH analysis in food samples. • A fluorescent probe was designed by adjusting the molecular extending conjugation. • The switch for biothiol had highly sensitive response and better selectivity. • The probe can detect GSH and Hcy with a short time and low detection limit. • The probe was successfully applied in detecting vegetables and fruits.