Sensitive electrochemical detection of l-cysteine based on a highly stable Pd@Ti₃C₂T_:X(MXene) nanocomposite modified glassy carbon electrode

Rapid and real-time detection of l-cysteine (l-Cys) is important for early diagnostics of several diseases and biological disorders. We report here a stable and highly sensitive electrochemical sensor for the detection of l-Cys based on a Pd@Ti₃C₂T_x (MXene)-modified glassy carbon electrode (GCE). The Pd@Ti₃C₂T_x nanocomposite was prepared by in situ reduction of Pd(ii) salt on the surface of delaminated (DL) Ti₃C₂T_x nanosheets to form pseudo-spherical palladium nanoparticles (PdNPs) with 2-6 nm size distributions. The MXene acts as the conductive matrix and a reducing agent at the electrode surface, while PdNPs are there to improve the stability of Ti₃C₂T_x and to enhance the electrocatalytic activity towards l-Cys detection. The Pd@Ti₃C₂T_x/GCE sensor exhibited a detection limit of 0.14 μM and a linear electro-oxidative response to l-Cys within the concentration range from 0.5 to 10 μM. The sensor also demonstrated excellent selectivity over common interfering ions such as ascorbic acid, uric acid, dopamine and glucose.