Enantioselective recognition of d- and l-tryptophan by imprinted polymer-carbon composite fiber sensor

Electrochemical sensors demonstrating enantioselectivity to tryptophan enantiomers, with high selectivity and sensitivity, were fabricated by the use of a monolithic fiber of molecularly imprinted polymer-carbon composite. The recognition mechanism and performance of these sensors were evaluated by differential pulse anodic stripping voltammetry. The sensor imprinted for l-tryptophan not only discriminated the target from its analogues and other amino acids but also responded specifically in racemic mixture in aqueous, biological, and pharmaceutical samples. The binding kinetics of l-tryptophan was also established with the help of anodic stripping cyclic voltammetry and chronocoulometry. The detection limit for l-tryptophan was as low as 0.24 ng mL−1 (signal/noise = 3) which is appropriate for biomarking diseases, caused by an acute tryptophan-depletion, in clinical setting.