Synergistic Integration of Carbon Quantum Dots and Zeolitic Imidazolate Framework‐8 for Advanced Electrochemical Biosensing of Dopamine

Abstract

Dopamine is a key catecholaminergic neurotransmitter, and its precise determination in biological fluids is essential for studying neurological dysfunction and developing diagnostic approaches. This study reports a thermally optimized carbon quantum dot‐embedded zeolitic imidazolate framework‐8 (CDs@ZIF‐8) nanocomposite as an electrochemical sensing platform for ultrasensitive dopamine detection. Carbon quantum dots were synthesized via a hydrothermal route using L‐proline and o‐phenylenediamine as carbon and nitrogen precursors and subsequently integrated into the ZIF‐8 framework through pH‐regulated electrostatic impregnation. Structural characterization confirmed the successful incorporation of CDs while preserving the sodalite‐type crystalline structure of ZIF‐8. The introduction of CDs significantly improved the electrochemical properties of ZIF‐8 by reducing the charge transfer resistance from approximately 510 to 55 Ω and enhancing dopamine oxidation performance through improved electron transport and increased accessible active sites. Temperature optimization identified 30 °C as the optimal sensing condition, enabling the CDs@ZIF‐8‐modified glassy carbon electrode to achieve a wide linear detection range from 0.05 to 180 μM, a sensitivity of 0.2156 μA μM −1 , and a detection limit of 18 nM ( S / N = 3). The sensor exhibited high selectivity against common interfering substances, excellent storage stability with 93.8% signal retention after 10 days, and reliable analytical performance in fetal bovine serum samples with recoveries of 97.1%–104.8%. The developed CDs@ZIF‐8 platform provides an effective strategy for improving metal–organic framework‐based electrochemical sensing systems and demonstrates potential for dopamine monitoring in complex biological matrices.