Studies on Biosensing Property and Functionalization of In2O3 and Carbon Nanotube Field Effect Transistor
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0915-R02-09
Studies on Biosensing Property and Functionalization of In2O3 and Carbon Nanotube Field Effect Transistor Fumiaki Ishikawa, Chao Li, Marco Curreli, Mark E. Thompson, and Chongwu Zhou University of Southern California, Los Angeles, CA, 90089 ABSTRACT Biosensing property and functionalization of In2O3 nanowire (NW) and carbon nanotube (CNT) field effect transistor (FET) were investigated. Low-density lipoproteins (LDL) adsorbed on their surface were found to give complementary effects on their electrical property, e.g., enhanced conductance in NW and suppressed conductance in CNT. Prostate specific antigen (PSA) was selectively detected by functionalizing the sensors with PSA antibody (AB) via linker molecules. It was found that the exposure to 0.14 nM (5 ng/ml) PSA increases the conductance of In2O3 NW by 1.3 %, while 1.4 nM (50 ng/ml) PSA decreases that of CNT by 2 %. Additionally, selective functionalization of Indium Tin Oxide (ITO) thin film and In2O3 NWs with probe DNA single strand was achieved by selectively converting hydroquinone (HQ) into quinone (Q) using electrochemistry, as confirmed by the fluorescence (FL) study. INTRODUCTION NWs and CNT are attracting a lot of attention as one of the most promising candidates for the next generation biosensors because of their high sensitivities due to their high surface to volume ratio [1-4]. Selectivity can be added to these sensors by utilizing antigen-antibody interaction, e.g., by adopting AB as the recognition elements for the analyte, which enables label free detection. In spite of extensive investigations on this subject, no report has been published so far, where the possibility of combining these sensors is studied and the performances are compared. In this report, we investigated the biosensing properties of In2O3 NWs and CNT FET with LDL and PSA as the model cases. In addition, we demonstrated selective functionalization of ITO and In2O3 NW with single DNA strand and selective immobilization of the complementary DNA strand, as confirmed by FL study. EXPERIMENTAL DETAILS (i) Chemical gating effect of LDL on In2O3 NWs and CNTs NWs (produced by laser ablation) and CNTs (obtained from Carbon Nanotechnology Inc.) on Si/SiO2 substrates, were incubated in the LDL suspension (0.1 mg/1 ml D.I. water) overnight, respectively. All the measurements were conducted in a vacuum chamber.
(ii) PSA detection with NW and CNT FET NW device was submerged in a 0.1 mM aqueous solution of 3-Phosphonopropionic acid for 16 hours at room temperature, followed by submerging into a 0.05 mM solution of DCC in dry DCM for 30 minutes and then in a 0.05 mM solution of N-hydroxysuccinimide in dry acetonitrile for 1 hour. The device was incubated in a PBS solution of anti-PSA monoclonalantibody for 12 hours. CNT device was also submerged in a 5mM solution of 1- pyrenebutanoic acid succinimidyl ester in dry DMF for 1 hour, and then was incubated in a PBS solution of anti-PSA monoclonalantibody for 12 hours. (iii) Selective functionalization of ITO and NWs 2-(1,4-dihydroxybenze
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