Ultrasensitive dopamine detection using CsPbBr(3)-PQD-COF nanocomposites: a synergistic fluorescence and EIS approach.

This study presents a novel dual-mode sensing platform for ultrasensitive dopamine (DA) detection using CsPbBr(3) perovskite quantum dot (PQD)-integrated covalent organic framework (COF) (CsPbBr(3)-PQD-COF) nanocomposites. Leveraging the synergistic effects of fluorescence quenching and electrochemical impedance spectroscopy (EIS), the CsPbBr(3)-PQD-COF nanocomposites achieve exceptional sensitivity with limits of detection of 0.3 fM (fluorescence) and 2.5 fM (EIS), spanning a wide linear range from 1 fM to 500 μM. The platform exploits the optoelectronic properties of CsPbBr(3) PQDs and the π-conjugated COF scaffold, enabling selective DA recognition via electron transfer and π-π stacking interactions. Incorporation of rhodamine B provides a visual green-to-pink shift at DA concentrations above 100 pM, enhancing practical utility. Specificity is demonstrated against common interferents (e.g., ascorbic acid, uric acid), with minimal cross-reactivity (<6%). In real-sample validation, the sensor exhibits excellent recovery (97.5-103.8% in human serum; 97.9-99.7% in PC12 supernatant) and stability over 30 days. This multimodal approach, combining femtosecond sensitivity, broad dynamic range, and visual indication, positions the CsPbBr(3)-PQD-COF nanocomposite as a promising tool for neurotransmitter monitoring in biomedical and clinical applications.