The Octet R8: a fast, sensitive, label-free protein analysis platform for characterising biomolecular interactions

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Interactions between molecules are central to all processes of life. These interactions are diverse in nature and include protein-protein interactions, protein-oligonucleotide interactions, protein-cofactor interactions and interactions involving complex bilayer assemblies. Because of their importance in terms of furthering our biological understanding and accelerating pharmaceutical development, all of these interactions are at the heart of innovative research programs across the globe. Life science research at the University of Leicester has an outstanding track record in conducting groundbreaking research in this important field. To allow the world-leading researchers to drive innovation and address the most important biological questions of our time requires highly sensitive and accurate quantitative analytical tools. The heavily used instrumentation at UoL is ageing and has limitations compared to the currently available techniques. We, therefore, seek to purchase the Sartorius Octet R8.The Octet R8 is a state-of-the-art in bio-layer interferometry (BLI), an optical technique for detecting biomolecular interactions by measuring the interference pattern of white light reflected from the surface of a biosensor. BLI compares the interference pattern of white light reflected from an internal reference layer with that reflected from the immobilised protein layer present on the biosensor tip. The binding of biomolecules (analytes) at the tip surface results in a shift in interference pattern allowing the quantification of binding events in real-time and with high precision. Only interactions of bound biomolecules are measured, making bio-layer interferometry a powerful analytical tool for a wide range of applications. The Octet R8 system measures binding events in small volumes of 200 microliters in a non-destructive manner to determine association rates (kon), dissociation rates (koff), and affinity constants (KD). Arguably one of the most powerful features of the Octet systems is the unique 'dip and read' biosensor format which permits the analysis of complex samples e.g. cell culture supernatants and lysates enabling biomolecular interactions to be studied in biologically relevant environments. Due to the multitude of different biosensors and surface chemistries BLI provides enormous flexibility for a range of multidisciplinary projects.The label-free Octet system negates the need for intrinsic/external chromophores or the addition of fluorescent labels/probes: a prerequisite of solution optical spectroscopies. Although a competing technology like isothermal titration calorimetry (ITC) is a label-free technology that is very useful for providing thermodynamic data, it does not allow for real-time kinetic analyses and is less sensitive than the Octet system. Surface Plasmon Resonance (SPR, a comparable label-free, surface-based technology) generates highly accurate, reproducible data but does not have the high throughput or flexibility offered by the Octet platform and poses significant challenges associated with its microfluidics-based nature.