Specific detection and determination of cysteine by a luminescent samarium macrocycle-based fluorescent probe platform

Samarium macrocycle-based complex Sm-2n, a luminescent matrix bearing two dynamic imine bonds as recognition sites and a Sm(III) emitter as the fluorescence indicator, can selectively probe cysteine over other analogous amino acids and show remarkable turn-off fluorescent character. Moreover, using Sm-2n-impregnated paper-based test strips and RGB outputs, we develop a smartphone-based analysis method to give a convenient approach with satisfactory results for cysteine detection and determination.