Prof. Reginald Penner, University of California, Irvine

Ingredients: Metal Nanowires and Viruses - A Recipe for a Universal Biosensor

In this talk I'll describe a new approach to biosensors that has as its objective the development of ultra-cheap, disposable biosensors that are able to detect virtually any analyte molecule. One concrete target application envisioned for these devices is the detection of biomarkers for urinary tract cancer, bladder cancer, and prostate cancer in urine in a packaged device resembling the home pregnancy test. This is the goal.
The realization of this biosensor is made possible by two very new developments in our laboratory: The first is a nanowire fabrication technique called Lithographically Patterned Nanowire Electrodeposition (LPNE) that permits very long (> 1 cm), very uniform noble metal nanowires as small as 6 nm x 20 nm to be patterned on glass surfaces. Previously, such nanowires could only be obtained using electron beam lithography - a tedious and expensive fabrication method. The second is the demonstration that filamentous bactiophage particles that have been engineered using phage display to selectively recognize and bind a particular analyte molecule can be covalently attached to metal surfaces. The resulting "covalent virus surfaces" retain the ability to recognize and bind molecules from a buffer solution. In fact, these surfaces show kinetic and thermodynamic binding properties for selected analyte molecules that are comparable to immobilized monoclonal antibodies, the gold standard receptors for biosensing.
How can the state of a covalent virus surface - in terms of the quantity of bound target molecule - be transduced? Of course conventional methods such as fluorescence and quartz crystal microbalance gravimetry can be used for this purpose but neither of these methods is suitable for the sort of disposable devices we ultimately seek to develop. Surprisingly, electrochemical impedance spectroscopy provides a simple, cheap, and surprisingly sensitive means for carrying out this measurement and I'll describe the exact methodology in this talk and our first results. Nanowires offer a unique opportunity to carry out this transduction measurement with high sensitivity in a highly miniaturized device.
The integration of these ingredients is occurring now and the biosensor is beginning emerge. I will provide you with our latest data and our most optimistic assessment of our prospects for success :-)

For more information contact Prof. Art Janata (404-894-4828).