Detection of Lectins using Glyco-Functionalized Nanosensors
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Detection of Lectins using Glyco-Functionalized Nanosensors Yanan Chen, 1 Harindra Vedala,1 Gregg P. Kotchey,1 Aymeric Audfray,2 Samy Cecioni,2,3 Anne Imberty,2 Sébastien Vidal,3 Alexander Star1 1 Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA 15260, USA 2 CERMAV - CNRS, affiliated with Université Joseph Fourier and ICMG, BP 53, 38041, Grenoble, France 3 Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Laboratoire de Chimie Organique 2 – Glycochimie, UMR 5246, CNRS, Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, F-69622, Villeurbanne, France ABSTRACT We 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. INTRODUCTION Lectins are sugar-binding proteins with high specificity for their cognate sugar moieties and they play an important role in biological recognition involving cell-cell communication and pathogen binding [1]. In general, lectins have weak interactions with carbohydrate and their dissociation constants are in the range of Kd = 10−6 - 10−7 M. Understanding and mimicking the specific interactions between carbohydrates and lectins are desirable to improve pathogen detection and inhibition of bacterial or viral infections [2]. Because of their unique physical and chemical properties, single-walled carbon nanotubes (SWNTs) and more recently graphene have attracted considerable interest for development of biosensors [3-5]. They are both extremely sensitive to adsorption of chemical or biological species on their surface and have been successfully configured into field-effect transistor (FET) devices, which can be used for ultrasensitive detection of many chemical and biological molecules including proteins. These carbon nanomaterials can be functionalized with glycoconjugates for specific lectin affinity using both covalent and noncov
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