Detection of Lectins using Glyco-Functionalized Nanosensors

ABSTRACTWe have used single-walled carbon nanotube field-effect transistor (SWNT-FET) and chemically converted graphene field-effect transistor (CCG-FET) devices to probe the interactions between carbohydrates and their recognition lectins. Porphyrin- and pyrene-based glycoconjugates were used as receptor molecules and the target lectins were two bacterial lectins that present different carbohydrate preference, namely PA-IL, PA-IIL from Pseudomonas aeruginosa and a plant lectin Concanavalin A. The specific binding between lectin and carbohydrate can be transduced to the change in FET device conductance. An initial study with SWNT-FET noncovalently functionalized with porphyrin-based glycoconjugates showed both good selectivity and sensitivity. To compare SWNT and CCG performance, pyrene- and porphyrin-based glycoconjugates were functionalized noncovalently on the surface of CCG-FET and SWNT-FET devices, which were then treated with non-specific and specific lectins. The responses were compared and rationalized using computer-aided models of carbon nanostructure/glycoconjugate interactions. Fluorescence microscopy, atomic force microscopy, UV-vis-NIR spectroscopy and Isothermal titration microcalorimetry (ITC) measurements were used to confirm the electrical results.