Disposable Electrochemical Sensor Using Graphene Oxide–Chitosan Modified Carbon-Based Electrodes for the Detection of Tyrosine

Despite the many recent advances in disposable and wearable sensing technologies for point of care testing (POCT), few affordable, flexible, and disposable sensors are available for the detection of tyrosine (Tyr), a valuable biomarker for metabolic and neurodegenerative diseases. In this regard, the disposable screen-printed electrodes on flexible substrates are attractive. However, current screen-printed approaches for the detection of Tyr use rigid ceramic substrates, expensive metal nanoparticle conductive inks and stiff metal or metal oxide-based sensitive materials, that are not suitable for single-use disposable or wearable POCT devices. To address these challenges, this work presents a flexible and disposable electrochemical sensor using graphene oxide – chitosan (GO-CS) modified carbon-based electrodes for the detection of Tyr. The affordable and easy to fabricate sensor consists of a three-carbon electrode system screen printed on a flexible, low-cost polyvinyl chloride (PVC) substrate. GO and CS were chosen as the sensitive nanocomposite due to their natural abundance and excellent electrochemical sensing properties. Quantitative determination of Tyr using DPV revealed a linear proportional response between 1 and $100~\mu \text{M}$ , with a correlation coefficient of 0.9993. The GO-CS-screen-printed carbon sensor (SPCS) also offers a linear range detection limit of $5.86~\mu \text{M}$ , and excellent sensitivity ( $0.0846\,\,\mu \text{A}\,\,\mu \text{M}^{-1}$ ) and repeatability (RSD =4.02%). The GO-CS-SPCS thereby provides a promising platform for the active sensing elements of single-use, disposable, and wearable POCT devices suitable for early diagnosis and monitoring of metabolic or neurodegenerative diseases or nutritional management.