Optical Fibers Functionalized with Single-Walled Carbon Nanotubes for Flexible Fluorescent Catecholamine Detection

Despite the popularity of drugs that act on catecholamine receptors, our knowledge of catecholamine dynamics in human health and disease remains incomplete. Recent advances in fluorescent sensors have enabled unprecedented access to catecholamine dynamics in preclinical animal models, but the requirements of these technologies to use in model organisms limit their translational value for clinical diagnostics. Here, we introduce proof of principle fluorescent catecholamine detection via optical fibers functionalized with single-walled carbon nanotube (SWNT)-based near-infrared catecholamine sensors (nIRCats), a catecholamine detection form factor that has potential for more convenient and less invasive clinical translation. We show that these near-infrared functionalized (nIRF) fibers respond to dopamine in a biologically relevant concentration range (10 nM through 1 μM), with minimal responsivity loss following 16 h exposure to human blood plasma. We further demonstrate the utility of these fibers in detecting dopamine from as little as 10 μL volumes of clinically relevant biofluids up to 24 weeks after fiber synthesis. We also introduce a compact, mobile dual-near-infrared fiber photometry rig and demonstrate its success detecting dopamine in acute brain slices with nIRF fibers. Together, this fiber-based dopamine detection tool and photometry rig expand the toolset for catecholamine detection.