DNA-coated individual single-walled carbon nanotubes (SWNTs) attract research attention as bio-sensors because they have unique optical properties of discrete near-infrared fluorescence. The optical characteristics of SWNTs are attributed to the one-dimensional quantum confinement which also renders SWNTs extremely sensitive to environmental changes. In this work, we investigated optical modulation of DNA-coated SWNTs upon binding to target molecules, and explored the observed phenomena for biomolecular sensing applications. We used insulin-binding aptamer to recognize a molecular target (insulin) with high specificity and sensitivity, by forming a unique secondary structure of guanine quadruplex. We also examined SWNT interactions with insulin based on optical transduction using a novel single SWNT spectroscopy. Based on the quenching of insuiln-binding aptamer-coated SWNT photoluminescence with insulin, we developed the simple biosensor for detection of insulin.
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