MXene Supported Molecularly Imprinted Polymer‐Based Disposable Screen‐Printed Electrodes for Sensitive Quantification of Sweat‐Associated Stress Biomarker

ABSTRACT

A novel disposable point‐of‐care testing (POCT) sensor was developed for the physiological quantification of L‐tryptophan, an essential amino acid, using electro‐polymerized molecularly imprinted polymer (MIP) on screen‐printed carbon electrodes (SPCEs). To enhance the SPCE conductivity and active area, a highly conducting MXene layers was initially drop‐casted on the electrode surface. The MXene supported MIP sensor's electrochemical performance was evaluated using various electrochemical impedimetric and Voltammetric techniques. The detection of L‐tryptophan is assessed by measuring the change in the electrochemical response of K ₃ [Fe(CN) ₆ ] redox probe using MIP sensor. Electrochemical analysis revealed a linear decrease in oxidation peak current and an increase in charge transfer resistance (R _ct ) of the MIP electrode for test redox probe solution with increasing L‐tryptophan concentration. It is due to the rebinding of L‐tryptophan with MIP binding site, which hinders the electrochemical reaction of redox probe. The sensor demonstrated high sensitivity by achieving a detection limit about 30 nM and showed the remarkable selectivity toward L‐tryptophan, even in the presence of potential interferents. Additionally, the proposed sensor showed superior sensitivity and selectivity for L‐tryptophan compared to many previously reported electrochemical sensors. Furthermore, the real‐world usability of developed sensor was demonstrated successfully with the artificial human sweat samples.