Proceedings Article | 17 April 2008
KEYWORDS: Interferometry, Transducers, Sensors, Resonance enhancement, Biological research, Chemical analysis, Surface plasmons, Bacteria, Phase shifts, Refractive index
Small non-coding RNA sequences have recently been discovered as unique identifiers of certain bacterial species,
raising the possibility that they can be used as highly specific Biowarfare Agent detection markers in automated field
deployable integrated detection systems. Because they are present in high abundance they could allow genomic based
bacterial species identification without the need for pre-assay amplification. Further, a direct detection method would
obviate the need for chemical labeling, enabling a rapid, efficient, high sensitivity mechanism for bacterial detection.
Surface Plasmon Resonance enhanced Common Path Interferometry
(SPR-CPI) is a potentially market disruptive, high
sensitivity dual technology that allows real-time direct multiplex measurement of biomolecule interactions, including
small molecules, nucleic acids, proteins, and microbes. SPR-CPI measures differences in phase shift of reflected S and P
polarized light under Total Internal Reflection (TIR) conditions at a surface, caused by changes in refractive index
induced by biomolecular interactions within the evanescent field at the TIR interface. The measurement is performed on
a microarray of discrete 2-dimensional areas functionalized with biomolecule capture reagents, allowing simultaneous
measurement of up to 100 separate analytes. The optical beam encompasses the entire microarray, allowing a solid state
detector system with no scanning requirement. Output consists of simultaneous voltage measurements proportional to
the phase differences resulting from the refractive index changes from each microarray feature, and is automatically
processed and displayed graphically or delivered to a decision making algorithm, enabling a fully automatic detection
system capable of rapid detection and quantification of small nucleic acids at extremely sensitive levels. Proof-of-concept
experiments on model systems and cell culture samples have demonstrated utility of the system, and efforts are
in progress for full development and deployment of the device. The technology has broad applicability as a universal
detection platform for BWA detection, medical diagnostics, and drug discovery research, and represents a new class of
instrumentation as a rapid, high sensitivity, label-free methodology.
