Overview
LFIRE™ allows for the precise, real-time measurements of specific interactions between molecular entities in a microarray or well-plate format. These molecular entities can be proteins, nucleic acids, lipids, small molecules such as drugs or steroids, or even whole cells. As a "label-free" detection system it avoids alterations of the molecules from the labeling procedures used in fluorescent systems and directly reduces labor and materials costs associated with tagging. As a "real-time" system, it monitors reactions as they happen, providing information about a sample before and after equilibrium. This additional information is necessary for increasing the dynamic range of concentration measurements, optimizing biological assays and analyzing kinetic activity critical to drug research.
The instrument operates at a large incidence angle (~63°) allowing the light to be totally internally reflected from the glass/liquid interface, creating an evanescent wave, represented schematically in row 1 of the figure below. This localized field interacts with refractive index changes within the first 200 nm of the liquid as analytes (patient antibodies) approach and are bound by the printed antigens (RNP, etc). An image of the reflected beam is projected onto a CCD camera while the polarization state of the light is changed via a temperature controlled liquid crystal retarder. The signal obtained is proportional to both the thickness and density of the surface protein layer as seen over a 15 minute period in rows 2 and 3.
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