Electrical Detection of Deoxyribonucleic Acid Hybridization With AlGaN/GaN High Electron Mobility Transistors
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Electrical Detection of Deoxyribonucleic Acid Hybridization With AlGaN/GaN High Electron Mobility Transistors B. S. Kang1, S. J. Pearton1, J. J. Chen2, F. Ren2, J. W. Johnson3, R. J. Therrien3, P. Rajagopal3, J. C. Roberts3, E. L. Piner3, and K. J. Linthicum3 1 Materials Science and Engineering, University of Florida, Gainesville, FL, 32611 2 Chemical Engineering, University of Florida, Gainesville, FL, 32611 3 Nitronex Corporation, Raleigh, NC, 27606
ABSTRACT Au-gated AlGaN/GaN High Electron Mobility Transistor (HEMT) structures were functionalized in the gate region with label free 3'-thiol modified oligonucleotides. This serves as a binding layer to the AlGaN surface for hybridization of matched target Deoxyribonucleic Acid (DNA). X-ray photoelectron spectroscopy (XPS) shows that immobilization of thiol modified DNA covalently bonded with gold on the gated region. Hybridization between probe DNA and matched or mismatched target DNA on the Au-gated HEMT was detected by electrical measurements. The HEMT drain-source current showed a clear decrease of 115 µA as this matched target DNA was introduced to the probe DNA on the surface, showing the promise of the DNA sequence detection approach for biological sensing. INTRODUCTION Biosensing of deoxyribonucleic acid (DNA) oligomer hybridization to form duplex DNA using one immobilized strand on a surface is crucial in diagnosing genetic diseases as well as sequencing the entire human genome(1-5). Several different methods have been used to detect the DNA hybridization through measuring changes in mass, optical properties or electrochemical characteristics. These approaches require pre-labeling of the DNA target, special isotopes, fluorescence tags, or re-dox indicators. These optical measurement techniques are time consuming, expensive, destructive, and may hinder portable real time detection(6-9). To detect base pairs in DNAs rapidly with high accuracy, electronic measurements using semiconductor based field effect transistors (FETs) have been widely studied(9-12). Especially, GaN/AlGaN high electron mobility transistors (HEMTs) are attractive for these applications, since they include a high electron sheet carrier concentration channel induced by piezoelectric polarization of the strained AlGaN layer(13-17). Baur et al. showed the covalent immobilization of self assembled monolayer chemicals on hydroxylated GaN and AlN surfaces and showed DNA hybridization on the functionalized GaN surface with fluorescence labeled DNA(18). However, obtaining direct chemical modification with hydroxyl groups on GaN surfaces with good yield and reproducibility is generally difficult due to surface roughness and unintentional contaminants (18,19) . The surface band bending of GaN is also highly dependent on the thickness of native oxide on GaN surface, which cannot be precisely controlled(20). The nature of interactions between gold surfaces and DNA are well established and are used to analyze duplex DNA sequences in
biotechnology(21). The use of surface coverage in the A
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