Monday, June 18, 2007
Golden Eagle Eyrie (Boise Centre on the Grove)

Iridium Oxide Nanowire Monitors for Protein Detection

Vinu L. Venkatraman1, Ravikiran K Reddy1, Fengyan Zhang2, Victor Hsu2, Bruce Ulrich2, and Shalini Prasad1. (1) Portland State University, Portland, OR, (2) Sharp Labs of America, Inc

The overarching research objective is the development of a “point-of-care” device based on iridium oxide nanowires for physiological state identification to monitor human health. This device is based on electrical detection of proteins that are biomarkers for the physiological state. The current scope of work focuses on establishing the feasibility of this technology. The methodology that has been adopted is based on measuring capacitance and calibrating its change in magnitude with concentration of proteins. C reactive protein (CRP) model system is used for the demonstration of this protein identification. We demonstrate the following performance metrics: high selectivity, high sensitivity and linear dynamic range of detection with rapid response time. Iridium oxide has very good conductivity and charge storing capacity, and hence has an ability to detect very small changes to the surface charge. This capability is utilized for demonstrating the performance metrics and forms the basis of the key innovations of the technology. The key innovations are improving the selectivity and sensitivity of detection. We demonstrate these improved performance metrics for the model protein- CRP in purified form as well as from serum samples. High selectivity is achieved by incorporating monoclonal antibodies (protein receptors) on the nanowires, which bind only to specific antigens (proteins). This technique is extremely sensitive to the induced surface charge variations; hence, very small concentrations of proteins (up to femto-molar concentrations) can be detected with an anticipated rapid response time in seconds. This biosensor could be efficiently used for early disease diagnosis or for early toxicity detection in a pharmaceutical industry. Future work entails detection of multiple proteins using a single chip with the same accuracy and reliability.