Fluorescence-colorimetric dual-mode detection of cysteine in artificial urine with potential relevance to cervical cancer.

As cervical cancer poses a serious threat to the health of women, non-invasive and convenient diagnostic methods are still in urgent need. With cysteine (Cys) in urine as the disease marker, a xanthylium-based colorimetric and fluorescent probe SH-OH-NBD for Cys detection was constructed and its response to Cys was explored in artificial urine rather than common buffer solutions. Upon the action of Cys, the nitrobenzoxadiazole ether in SH-OH-NBD was cleaved, generating a new fluorescence peak at 567 nm. Thus, the concentration of Cys could be accurately determined based on the turn-on fluorescence. On the other hand, a smartphone-assisted visual detection method for Cys was developed based on the distinct color changes after the action of Cys. This RGB-based method features independence from expensive instruments and skilled technicians, enabling facile detection of Cys in urine. Overall, this dual-mode probe could achieve both accurate determination of Cys via the fluorescence method and preliminary assessment of Cys via the smartphone-assisted method, demonstrating its potential for practical cervical cancer screening.