Carbon Quantum Dot Embedding Silica–Molecularly Imprinted Polymer Coated Optical Fiber as Ratiometric Biosensors Toward Dopamine Detection

We have developed a ratiometric fluorescence sensor for detecting dopamine (DA) using a silica-based molecular imprinting polymer (MIP) coated on cabbage-derived blue emissive carbon quantum dot (CQD) and deposited on optical fiber. Physicochemical characterization confirmed the successful integration of MIP and CQD, which created the selective lossy mode resonance (LMR) for DA monitoring. The experimental factors were optimized to obtain the maximum responses, and the sensing probe displays a dynamic response range of 0.3– $100 \mu \text {m}$ and detection limit $0.027 \mu \text {m}$ . This strategy was successfully applied to detect DA in red wine, coffee, apple, orange, and broad bean juices samples, with negligible cross-reactivity toward other potential interfering species (e.g., epinephrine, ascorbic acid, and uric acid). This novel rotational optical fiber-based sensor has promising potential and versatility for point-of-care, portable, and on-site sensing of environmental and biological samples.