is a label-free technology for measuring biomolecular interactions within the interactome
Interactome is defined as the whole set of molecular interactions in cells. It is usually displayed as a directed graph. Molecular interactions can occur between molecules belonging to different biochemical families and also within a given family...
. It is an optical analytical technique that analyzes the interference pattern of white light reflected from two surfaces: a layer of immobilized protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
on the biosensor tip, and an internal reference layer (Figure 1). Any change in the number of molecules bound to the biosensor tip causes a shift in the interference pattern that can be measured in real-time (Figures 1 and 2).
The binding between a ligand immobilized on the biosensor tip surface and an analyte in solution produces an increase in optical thickness at the biosensor tip, which results in a wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
shift, Δλ (Figure 3), which is a direct measure of the change in thickness of the biological layer. Interactions are measured in real time, providing the ability to monitor binding specificity, rates of association and dissociation, or concentration, with precision and accuracy.
Only molecules binding to or dissociating from the biosensor can shift the interference pattern and generate a response profile. Unbound molecules, changes in the refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
of the surrounding medium, or changes in flow rate do not affect the interference pattern. This is a unique characteristic of bio-layer interferometry and extends its capability to perform in crude samples used in applications for protein-protein interactions, quantitation, affinity, and kinetics.
Bio-layer interferometry was pioneered by the founders of ForteBio
, an instrument manufacturer with headquarters in Menlo Park California.