Conductimetric Detection of Protein and Cancer Cells with Oxide Nanosensors
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1010-V06-09
Conductimetric Detection of Protein and Cancer Cells with Oxide Nanosensors Janagama Goud, P. Markondeya Raj, Jin Liu, Mahadevan Iyer, Z. L. Wang, and Rao Tummala Packaging Research Center, Georgia Institute of Technology, Atlanta, GA, 30332-0560 ABSTRACT Semiconducting oxides are widely known and commercially applied for their gas sensing properties. However, biochemical sensing has mostly depended on optical and electrochemical techniques that are more cumbersome. This work investigates the biosensing characteristics of ZnO nanobelts and ZnO thin films. Zinc oxide thin film sensors showed changes in conductivity after protein functionalization with rabbit IgG and hybridization with anti-rabbit IgG. Conductivity changes were also measured after coating the oxides with anti-bodies to breast cancer cells (MCF-7) and hybridized with MCF-7 cells. In another set of experiments, ZnO nanobelts showed systematic conductivity changes with rabbit IgG protein hybridization. The experimental results in this paper indicate that the conductimetric properties of nano and thin film oxides can be sensitized to protein and cancer cell hybridization reactions. This technique can also be applied to certain other pathogen proteins or toxic proteins from the environment leading to low-cost miniaturized wireless biosensors. INTRODUCTION Large scale integration of multiplexed, ultra sensitive sensor arrays is critical for several applications such as early detection of diseases and real-time health diagnosis. For diseases such as breast cancer and prostate cancer, conventional detection methods are not viable as they fail to detect small quantities of disease causing biomolecules. Nanotechnology based sensor devices, when biofuctionalized with the corresponding biomolecules, can lead to the next-generation embedded bio-sensor systems for early detection. Current ultra sensitive nanoscale sensor integration research is mostly confined to silicon platform with limited choice of sensing materials. Integrating on a packaging platform (System-On-Package) can easily couple the sensing with wireless and digital functions leading to multifunctional bioelectronic systems. Sensor devices based on semiconducting thin films are known to respond to a variety of gases. Single oxides such as ZnO, SnO2, WO3, TiO2 and FeO3, as well as multi-component oxides such as BiFeO3, MgAl2O4, and SrTiO3 are reported to be sensitive to CO, Ethanol and NO2[1-2]. The mechanism for gas detection is known to result from a change in the concentration of absorbed oxygen on the metallic oxide device surface, causing conductivity changes. Chemical and biological sensors based on quasi one-dimensional (1-D) structures, such as silicon nanowires (NW) [3] and nano tubes (NT) have drawn considerable attention lately in the scientific community. Charles Lieber and co-workers [3] have demonstrated real-time, high sensitivity and multiplexed virus detection by silicon NW based sensors. Any depletion or accumulation of charge carriers caused by binding event would impos
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