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Applying Indium Oxide Nanowires as Sensitive and Specific Redox Protein Sensors

Mahsa Rouhanizadeh1, Tao Tang2, Chao Li2, Gopikrishnan Soundararajan1, Chongwu Zhou2, and Tzung K. Hsiai*, 1

1Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California,
Los Angeles, CA 90007 USA

2Department of Electrical Engineering, University of Southern California

This is an abstract for a presentation given at the
11th Foresight Conference on Molecular Nanotechnology


Indium Oxide nanowires have been found to demonstrate high sensitivity and specificity for detecting O3, Cl2, NO2, CO, H2. Low-density lipoprotein (LDL) initiates the development of heart disease. LDL particles, which harbor redox properties, can be modified from the reduced state to the oxidized state as one of the fundamental processes to coronary artery disease. Cytochrome C is an important electron transported in intracellular respiration. We hereby demonstrate Indium Oxide nanowire sensors as a potential sensor for detecting oxidatively modified LDL particles and cytochrome C.

We have built field effect transistors (FET) based on individual indium oxide nanowires of 10 nm in diameter. The conductance of such transistors critically depends on their interaction with the environment, as oxidative or reductive species can significantly modulate the carrier concentration inside the nanowires. We have fabricated a PDMS microfluidic channel (2mm in length, 360 µm in width by 100 µm in depth) in which the individual FET Indium Oxide Nanowire was exposed to water, LDL particles in both the reduced and oxidized states at 0.1 mg/mlit and cytochrome-c at 0.1 mg/milt in the reduced state. Precise flow rate at 10 µlit/min was delivered to the channel. The redox proteins were injected through a T-connection upstream. We obtained I vs. Voltage and Id vs. time curves for individual species.

We observed that that oxidized LDL generated higher conductivity than the reduced LDL particles. This differential level of conductivity was reproducible after repeated trials. Cytochrome C in its reduced form also demonstrated a distinct level of conductivity (Figure). Our study demonstrates the possibility of using Indium Oxide Nanowires as the sensitivity and specific sensors for detecting coronary artery disease.


1. Alex Sevanian, L.A., Ouliana Ziozankova, Low Density Lipoprotein (LDL) modification: Basic Concept and Relationship to Atherosclerosis. Blood Purification, 1999. 17: p. 66-68.
2. C. Li, D.Z., X. Liu, S. Han, T. Tang, J. Han and C. Zhou, In2O3 nanowires as chemical sensors. Appl. Phys.Lett, 2003. 82( 1613).
3. David C. Duffy, J.C.M., Olivier J.A.Schueller, George M.Whitesides, Rapid prototyping of Micro Fluidic Systems in Poly (dimethylsiloxane). Analytical Chemistry, 1998. 70(23).
4. Kong, J.F., Nathan R.; Zhou, Chongwu, Chapline, Michael G., Peng Shu; Cho,Kyeongjae; Dai, Hongjie, Nanotube Molecular Wires as Chemical Sensors. Science, 1999. 287(5453): p. 622-625.

Abstract in Microsoft Word® format 55,622 bytes

*Corresponding Address:
Tzung K. Hsiai
Department of Biomedical Engineering and Cardiovascular Medicine
University of Southern California
3650 McClintock Ave, University Park, OHE 500
Los Angeles, CA 90007 USA
Phone: 213-804-8308 Fax: 213-740-0343


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