Graphene oxide nanoribbon-based sensors for the simultaneous bio-electrochemical enantiomeric resolution and analysis of amino acid biomarkers.

In this work, a straightforward in-situ measurement of L and D-amino acids (AAs) has been developed using disposable graphene oxide nanoribbon (GON) screen printed electrodes. For that, we took advantage of the electroactivity of certain clinically relevant AAs, such as tyrosine (Tyr) and methionine (Met), which are involved in important bacterial diseases (Bacillus subtilis and Vibrio cholera, respectively). The strategy is based on a dual electrochemical and enzymatic approach. The D-AA with the class enzyme D amino acid oxidase (DAAO) generates H2O2. This H2O2 is simultaneously detected with the L-AA, electroactive molecule by differential pulse voltammetry (DPV). These GON disposable platforms use just 50 μL of sample and a total analysis time of 360 s. Both L and D enantiomers calibration and quantitative analysis were explored and were simultaneously detected with accuracy and precision in urine samples. Any interference of uric acid and other electroactive AAs was noticed. This proposed electrochemical GON-based enantiomeric bio-sensor becomes a highly promising tool as future point of care for fast and reliable early diagnosis of diseases related to the presence of D-AAs.