Reagent-free DOPA-dioxygenase colorimetric biosensor for selective detection of L-DOPA

[Display omitted] •A colorimetric L-DOPA biosensor based on the formation of yellow pigment by DOPA 4,5-dioxygenase was developed.•Variants of fluorescent betaxanthin molecules were produced by condensation of betalamic acid with primary amines.•The accuracy and precision of proposed sensor in biological fluids were validated using spiked fetal bovine serum samples. As the immediate precursor for the biosynthesis of dopamine (DA), L-DOPA remains a potent drug in the treatment of Parkinson's disease. In this study, we developed a novel DOPA-dioxygenase-based biosensor for the quantification of L-DOPA through the formation of yellow betalamic acid derivatives in vitro and in vivo. The proposed system is simple, rapid, sensitive, and selective to L-DOPA while remaining robust to interference from other catecholamines, and is further applicable for the determination of L-DOPA in spiked fetal bovine serum samples.