Ultrasensitive and Selective Detection of Dopamine Through Substituent-Regulated Evolution of Quantum Defects

Accurate detection and analysis of biomolecules like dopamine (DA) are vital for monitoring human health, particularly given DA's critical roles in a lot of medical disorders such as depression, Parkinson's and Alzheimer's diseases, and myopia. DA is often found at very low concentrations within certain body fluids, making it a challenging yet essential target for detection. This study presents an innovative and ultrasensitive detection methodology based on a quantum system, characterized by its exceptional sensitivity, selectivity, and linearity. By leveraging the unique quantum defect emission from semiconducting single-walled carbon nanotubes (SWCNTs) in the near-infrared II region, our approach effectively detects DA with high sensitivity, within the physiologically relevant range of nanomolar, and a detection limit as low as 1 nM. The sensing system maintains performance in phosphate-buffered saline and human urine environments. The interaction between aryldiazonium salts and DA that generates sp³ defects on the SWCNTs surface, regulated by specific substituents on the benzene ring, dictates the sensor's performance, ensuring superior selectivity against biologically relevant molecules. These advancements hold great potential for early disease detection, prevention, and treatment, marking an important advance in the field of biomedical diagnostics and nanosensor research.