Development and application of a fluorescence turn-on probe for the nanomolar cysteine detection in serum and milk samples

Abstract

We designed and synthesized a 1H-benzo[d]imidazole analogue, probe AB-MOE, with an N-substituted acrylate functional group for highly selective and highly sensitive detection of Cys in serum and milk samples. AB-MOE demonstrated superior selectivity for Cys over other bio-relevant analytes studied here. AB-MOE allows for the detection of Cys with fluorescence turn-on effect, a crucial quality of an efficient chemosensor. AB-MOE demonstrated the LOD of 67.5 nM and 39.8 nM by UV–visible and fluorescence spectroscopy, respectively. Compared to other analytes, only Cys can eliminate the acrylate group on the benzimidazole ring of AB-MOE, resulting in a distinct fluorescence turn-on effect. Thus, the high selectivity and high sensitivity in terms of LOD, AB-MOE is an excellent chemosensor for detecting Cys in serum and milk samples. The spiking study indeed revealed the bi-functional applicability of AB-MOE for detecting Cys in clinical settings (serum samples) and the food industry (milk samples) without any interference from the sample matrix components.