Electrochemical determination of dopamine using a flower-derived carbon quantum dots/polydopamine composite film modified electrode

a hydrothermal method utilizing the rose extract as a sustainable carbon source, subsequently incorporating PDA to improve interfacial electron transport. Thorough analysis validated the successful fabrication of the composite. The UV-visible spectra exhibited distinct π-π* and n-π* transitions, and the FTIR analysis confirmed the existence of oxygen functional groups derived from both CQDs and PDA. The CQDs demonstrated a zeta potential of -19 mV, indicating favorable colloidal stability, along with a DLS-estimated particle size of approximately 3.3 nm. The analysis of photoluminescence (PL) demonstrated significant emission characteristics affected by the modification of the PDA surface. Electrochemical investigations utilizing CQDs/PDA-modified glassy carbon electrodes revealed a marked enhancement in redox activity, superior electron-transfer kinetics, and high conductivity in comparison to unmodified electrodes. The as-prepared sensor demonstrated remarkable stability, high selectivity towards typical interferents, and a wide linear detection range for dopamine. The achieved lowest limit of detection (LOD) was 0.069 µM, while the limit of quantification (LOQ) was 0.233 µM. The analysis of human blood serum validated the practical applicability of the CQDs/PDA-nanocomposite based sensor with high recovery values.