Synthesis of a Fluorescent Sensor by Exploiting Nitrogen-Doped MXene Quantum Dots for the Detection of Dopamine

MXene quantum dots (QDs) are emerging two-dimensional materials from the MXene family that possess unique physicochemical properties and are employed in divergent disciplines, such as energy storage, conversion, catalysis, medicine, and biosensing. In this study, we synthesized MXene QDs using the MAX phase of MXene into its sheets by acidic treatment, followed by doping with ethylenediamine (EDA), and produced nitrogen-doped QDs (NMQDs) via the hydrothermal method. The resulting NMQDs showed excellent fluorescence quenching with a neurotransmitter, i.e., dopamine (DA). These NMQDs showed a strong blue fluorescence with a photoluminescence (PL) emission wavelength maximum of 400 nm under the excitation wavelength maximum of 330 nm. The optical properties of NMQDs were investigated using UV–Vis and PL spectroscopy techniques. The morphological, elemental constitution, and phase composition features were characterized by employing HRTEM, SEM, XPS, XRD, FTIR techniques, etc. The NMQDs delivered high sensitivity towards DA with a limit of detection (LOD) of 18 nM within the linear concentration range between 20 and 100 nM. These results suggest that these NMQDs have the potential to be used as fluorescent sensors for neurotransmitter detection.