A functionalized single-layered titanium carbide MXene based biosensor for selective H₂O₂ detection using covalently...

Hydrogen peroxide (H₂O₂) plays a significant role in biological and environmental systems. Therefore, it is crucial to develop an efficient biosensor for H₂O₂ determination, which is important in environmental monitoring and biomedical diagnostics. In this work, we have synthesized an amine functionalized, single-layered Ti₃C₂T_x MXene (NH₂-S-Ti₃C₂T_x), which was modified over a glassy carbon electrode (GCE) to construct NH₂-S-Ti₃C₂T_x/GCE. Thus obtained NH₂-S-Ti₃C₂T_x/GCE was utilized as a platform for the covalent cross-linking of water-soluble horseradish peroxidase (HRP) enzyme through a glutaraldehyde coupling reaction to form HRP/NH₂-S-Ti₃C₂T_x/GCE. The fabricated HRP/NH₂-S-Ti₃C₂T_x/GCE biosensor demonstrated a well-defined redox peak with a formal potential of -0.45 V, corresponding to the Fe^III/Fe^II redox center of HRP. Additionally, the designed biosensor has been employed towards the electrocatalytic detection of H₂O₂ under both static and dynamic conditions. The HRP/NH₂-S-Ti₃C₂T_x/GCE sensor displayed a broad linear range of 20 µM to 1160 µM with a low limit of detection of 5.3 µM and a high sensitivity of 0.078 µA mM^-1 cm^-2. The reported sensor demonstrated excellent analytical performance due to direct electron transfer through the covalent immobilization of HRP over NH₂-S-Ti₃C₂T_x. Furthermore, the sensor was employed for the real-time detection of H₂O₂, and it portrayed good recovery results.