A graphene field-effect transistor sensor based on Au-S bond self-assembly for highly selective detection of l-cysteine in chicken soup

l -cysteine plays a vital role in both the nutritional value and taste profile of chicken broth, underscoring the necessity for an accurate and sensitive approach to detect and measure l -cysteine at minute concentrations. A reliable method for identifying trace amounts of l -cysteine is imperative for ensuring the quality and authenticity of chicken broth products. Such a technique would enable precise control over the levels of this crucial amino acid, ultimately contributing to the overall consumer satisfaction and product consistency. This research focused on developing an SGGT-based sensor for the rapid detection of l -cysteine by leveraging the self-assembly of l -cysteine molecules on the surface of the Au gate electrode to form covalent Au-S bonds. This process triggers a rearrangement of charge carriers on the surface, leading to a shift in the electric double layer potential. Through field effect amplification, a substantial channel current response is generated. This innovative sensing mechanism effectively addresses the selectivity challenges of SGGT in complex liquid environments, significantly enhancing its ability to detect l -cysteine. Subsequently, the study examined three different gate voltages, with the optimal voltage achieving a detection limit of 10 nM (1.21 ng/mL) and a linear detection range of 30 nM – 3 μM. Moreover, the sensor exhibits highly selective detection of l -cysteine in chicken broth, demonstrating an 85.87 % recovery rate. The innovative technology demonstrates encouraging prospects for real-world usage in the identification of l -cysteine in food items or as a biomarker. Its capabilities offer a reliable method for detecting this amino acid, showcasing its versatility and potential impact on food safety and quality assessment.