The unique characteristics of 2D transition metal carbides/nitrides (MXenes), including their hydrophilicity, metallic conductivity, mechanical robustness, and adaptable structure, position them as promising candidates for integration into hydrogel systems. This study introduces an advanced combination of MXenes and poly(ethylene glycol) diacrylate (PEGDA) to create a composite hydrogel capable of electrochemically detecting neurotransmitters and antioxidants simultaneously, addressing the crucial interplay between oxidative stress and neurodegenerative diseases. The MXene synthesis involves a mild etching route, followed by functionalization with silane molecules to enhance the activity and stability within the PEGDA hydrogel matrix. The resulting composite hydrogel, enriched with modified MXene and fortified with CaCl2 for ionic cross-linking, develops a three-dimensional structure that markedly enhances the electro-oxidation of dopamine (DA), uric acid (UA), and serotonin (5-HT). Furthermore, the composite hydrogel exhibits outstanding stability against oxidation, surpassing that of its thin-film counterparts. The composite-hydrogel-based electrochemical sensor demonstrates a wide linear detection range of 2.5–200 μM for DA, 10–100 μM for UA, and 1–100 μM for 5-HT, with detection limits of 2.55 μM for DA, 25.11 μM for UA, and 0.83 μM for 5-HT. Importantly, this sensor enables the simultaneous detection of these multiple molecules. This study suggests the potential for neurotransmitter and antioxidant detection in human serum, marking a significant advancement in real-world sensing applications. By integrating MXenes into hydrogel systems, we enhanced the robustness and performance of the electrochemical sensors, highlighting their potential for developing this sensor for future in vivo applications.
