Screen-Printed Electrode-Based Sensing of <scp>l</scp>-Ascorbic Acid Using Metal–Organic Framework Supported Carbon–Palladium-Doped MXene Quantum Dots in Human Serum and Artificial Sweat
Jose Paul, Jongsung Kim
Abstract
Carbon-doped MXene quantum dots (MNQDs) were synthesized through a hydrothermal reaction involving citric acid and ethylene diamine in the presence of MXene. Palladium nanoparticles were subsequently incorporated into the MNQDs and integrated into an iron-based metal–organic framework, forming MIL-PdMNQDs. The successful synthesis of MIL-PdMNQDs was confirmed by PXRD, SEM, TEM, XPS, and FTIR analyses. Modified glassy carbon and screen-printed electrodes with MIL-PdMNQDs were used to measure l -ascorbic acid concentrations in a phosphate buffer solution, ranging from 10 to 100 nM. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) revealed a linear anodic peak current between 52.05 and 82.44 μA, with a linear regression (R 2 ) value of 0.9885. In human serum diluted with PBS (5 mL of serum in 95 mL of PBS), the MIL-PdMNQDs-SPE 1 detected ascorbic acid concentrations from 10 to 50 μM, illustrating a DPV redox peak current between 124.39 and 152.54 μA, with an R 2 of 0.9901. Additionally, in artificial sweat, the DPV sensor detected ascorbic acid concentrations ranging from 100 to 1000 μM, with current readings between 11.132 and 64.83 μA and an R 2 value of 0.9903, demonstrating its selective sensing capability. The limit of detection (LOD) for ascorbic acid in PBS using MIL-PdMNQDs-GCE was determined to be 4.705 nM. The MIL-PdMNQDs-GCE and SPE sensors exhibited high stability and exceptional selectivity for ascorbic acid detection.