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Single-wall carbon nanotubes (SWNT) have a strong and stable near-infrared (nIR) signal and can interact with target analytes selectively, even at the single molecule level, to alter fluorescence intensity and/or emission peak wavelength. SWNT have been employed as nIR optical sensors for detecting a variety of analytes. However, high cost, long fabrication time, and poor fluorescence yield limit the current methods for immobilizing SWNT sensors on solid substrates. Recently, our group reported a protocol for SWNT immobilization resulting in high fluorescence yield, signal longevity, fluorescence distribution, and quick sensing response time. However, it takes 5 days to fabricate these sensor arrays. We have improved our previously reported protocol to immobilize SWNT sensors with a method that takes only 2 days, results in a platform with similar surface morphology, and has a higher fluorescence intensity than the previous platforms without sacrificing the sensing capabilities. 

Cell communication via chemical signaling depends on spatial and temporal concentration changes. Nitric oxide (NO), a gaseous signaling molecule, is critical in physiological and pathological processes. However, current NO sensing methods lack the spatiotemporal resolution necessary to study subcellular NO efflux. This study introduces an innovative sensory platform utilizing single‐walled carbon nanotubes (SWNT) as an optical transducer for the spatial and temporal detection of extracellular NO. The platform quantifies NO diffusion gradients produced by human (THP‐1) and murine (RAW 264.7) macrophage cells. The uniform fluorescence distribution of the nanoarray enables precise analysis of NO efflux directionality, both under and surrounding the cell. It is demonstrated that cellular adhesion to the surface of the sensory platform does not affect its fluorescence functionality or sensing response rate. By combining the platform's high spatiotemporal resolution with the advanced analysis methods, the SWNT sensor platform offers a robust tool for studying extracellular NO dynamics within the cellular microenvironment. This work lays the foundation for advanced diagnostic and therapeutic tools elucidating NO cellular communication analysis.