The Octet platform from Pall FortéBio comprises several devices that enable real-time, label-free analysis of biomolecular interactions for the purpose of detection, quantification and kinetic analysis. Octet systems allow for high throughput automated binding analysis in 96- and 384-well microplates. The Octet RED96e system is extremely sensitive, allows for long-term measurements (characterisation of slow interactions) and is very efficient at regeneration and re-usage of biosensors.
Irene Schaffner PhD, Jakob Wallner BSc
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Methods & Expertise for Research Infrastructure
The FortéBio systems use Biolayer Interferometry (BLI), an optical analytical technique that measures patterns between waves of light to determine binding interactions of small molecules, proteins, antibodies, and even cells, determine specificity, calculate titer, characterize affinity, and more. The system utilizes single-use, glass fiber-based biosensors, where the surface chemistry occurs at the very tip of the glass fiber. The biosensor tip is composed of two optical interfaces: an internal reference layer (optical layer) and a biocompatible matrix that minimizes non-specific binding on the surface. This matrix is coated with ligand molecules that bind the target molecules in the samples. During measurement, white light is directed down the biosensor towards the two interfaces at the tip of the biosensor. The reflected beams from each of the two layers interfere constructively or destructively at different wavelengths in the spectrum, creating an interference pattern. When molecules bind to the surface of the biosensor, the thickness of the molecular layer at the tip increases and, thus, the effective distance between the two reflective layers increases, too. This causes a shift in the interference pattern of the reflected light. The interferometric profile therefore changes as a function of the optical thickness of the molecular layer (i.e. the number of molecules bound to the biosensor surface). The change in wavelength (nm shift) is reported as a function of time and a classical association/dissociation curve is obtained. Real-time, label-free analysis provides fast, sensitive and accurate measurement of kinetics, affinity and activity of complex formation without the need of generating labelled biomolecules. BLI also delivers stoichiometric information about binding interactions, allowing the elimination of proteins exhibiting non-optimal binding behaviour. The Octet RED96e system monitors binding events in real-time to calculate on rates (ka), off rates (kd) and affinity constants (KD). It is able to detect small molecules as well as large molecules like mammalian cells down over a temperature range of 15-40°C, allowing for kinetics measurement of unstable proteins at lower temperatures or biologically relevant molecules at physiological temperatures. Additionally, sample cooling allows to rapidly determine binding rate constants at multiple temperatures to extrapolate thermodynamic measurements. The eight channels of the system can be used independently. With its large quantitation dynamic range, the system is able to perform highly sensitive quantitation down to sub-ng/mL levels.