SWNT Network for Biomolecule Detection
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SWNT NETWORK for BIOMOLECULE DETECTION Massood Z. Atashbar1, Bruce Bejcek2, and Srikanth Singamaneni1 Electrical and Computer Engineering, 2 Department of Biological Sciences Western Michigan University, Kalamazoo, MI-49008, USA
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ABSTRACT In this paper we describe a single wall carbon nanotube (SWNT) based biological sensor for the detection of biomolecules using streptavidin and IgG. Two types of sensing mechanisms have been used to demonstrate the ability of carbon nanotubes to form nanoscale biosensors. The first sensing mechanism involves a CNT based conduction sensor in which the decrease in the current was observed when the specific biomolecule was bound. In the second mechanism Quartz Crystal Microbalance (QCM) was used to quantify the mass of the biomolecule bound on the sidewalls of the carbon nanotube. Both sensing mechanisms proved to be efficient and consistent. Immobilization of the biomolecules on the carbon nanotube surface was confirmed by Atomic Force Microscopy. INTRODUCTION Nanotechnology and Biotechnology are two emerging fields of science at the same size scale. Biological systems and structures such as found in DNA have served as new paradigms for the creation of many novel nanostructured materials. Carbon nanotube is an interesting material at the intersection of these two technologies. Although carbon nanotubes have many applications, one of the most important and promising applications which might find a significant place in the technologies related to these buckytubes is its biosensing ability [1]. The unique electronic properties of CNT in conjunction with the specific recognition properties of the incubated biomolecules would make CNTs as an ideal nanoscale biosensors. A close observation reveals that carbon nanotubes have a large surface area with all the carbon atoms on the surface. Hence, by a careful alteration of the surface chemistry of the carbon nanotube, they can be exploited for biosensing applications [2]. It has been recently demonstrated that individual semiconducting single wall carbon nanotubes can be used for the detection of glucose oxidase [3]. Controlled attachment of the glucose oxidase enzyme (GOx) to the SWNT sidewall was achieved through a linking molecule which resulted in a clear change of the conductance of the sensing device. In the present work the electrical conductivity changes and the mass uptake of SWNT matrices on biomolecule incubation is reported. EXPERIMENTAL DETAILS Streptavidin from Streptomyces avidinii was purchased as a lyophilized powder from the SigmaAldrich Company. The Protein was dissolved in phosphate buffered saline (PBS, Sigma-Aldrich) and stored as aliquots at -20°C. Mouse monoclonal IgG was purchased from Bio Design International Inc. The antibody solution was diluted in PBS and stored frozen at -20°C until use. Single wall carbon nanotubes (Corbolex Inc.) were synthesized with nickel and yttrium as catalyst with 70% purity. The SWNTs have been dissolved in chloroform and then filtered through a 0.02 µm pore size Anatop filte
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