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

Lead Research Organisation: University of Leicester
Department Name: Molecular and Cell Biology


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.

Technical Summary

The Sartorius Octet R8 platform we seek here will provide continuity to our biolayer interferometry platform by replacing a 10-year-old Octet QKe, which will no longer be supported by the manufacturer by the end of 2022. The R8 will also constitute a significant step-change in our capabilities to measure biomolecular interactions due to the following improvements: (1) The Octet QKe provides enough sensitivity to measure interactions involving molecules with molecular weight as low as 10 kD, but not below. The R8 is advertised to measure down to 150 Da, and our own research suggests that it can will measure reliably to 300 Da. This corresponds to a more than 10-fold improvement in sensitivity, which provides access to most small molecules involved in biomolecular interactions. (2) The Octet QKe operates at 0.3 and 0.6 Hz using one spectrophotometer for all 8 channels. In contrast, each channel in the R8 has its dedicated spectrometer, which allows it to operate at 2, 5 or 10 Hz, yielding a more than 10-fold higher sampling rate, which is critical for measuring fast on and off rates. This permits the quantification of a wider range of affinities from 1 mM to 10 pM (compared with 0.1 mM-0.1 nM for the Octet QKe). (3) While the QKe is limited to operation above 28C, the Octet R8 features a cooling system that allows controlling the temperature down to 15C. This feature is critical for successfully measuring temperature-sensitive systems. (4) The R8 comes with a microplate evaporation cover that extends the observation time from 2.5 h to 12 h, which is instrumental for accurate measurements of very slow off rates. It also allows for measuring a full 96-well plate with minimal user intervention (6-12h run time). In summary, the Octet R8 will not only serve the current level of need for measuring binding kinetics but expand our capabilities in BLI to small molecules, drugs and more challenging biomolecular interactions.
Description The primary objective of this award was to provide continuity and expand capabilities in Biolayer
Interferometry (BLI) at University of Leicester (UoL) by the purchase of a Sartorius Octet R8 BLI system. The Octet R8 platform, which enables researchers to measure biomolecular interactions in real-time, has replaced our aging Octet QKe system and has been integrated into our suite of complementary biophysical instruments used to detect and quantify molecular interactions.

The impact of the new BLI platform (in place for ca. 12 months at UoL) was immediately apparent with several research groups using the instrument extensively to generate high quality, often pivotal, kinetic data. Key biomolecular affinity data characterising a range of diverse and important biological interactions has been presented at conferences, published in a research journal and contributed to theses chapters (detailed in the' publications outcomes' section).

Major improvements in the detection system of the Octet R8 has also provided our researchers with the opportunity to study a wider range of biomolecular interactions: higher data acquisition rates, coupled with a 10-fold increase in sensitivity, enables small molecule (drugs, inhibitors, peptides) binding to be measured and several groups have taken advantage of this. The Octet R8 is also capable of data collection over extended time periods - a pre-requisite for accurate measurements of very slow off rates that characterise high affinity molecular interactions. These binding parameters were not accessible with our outdated Octet QKe instrument.

As outlined above, the Octet R8 has constituted a significant step-change in our capabilities to quantify the kinetics of binding and, consequently, has become the technique of choice for many research groups that study biomolecular interactions at UoL. A continuation of easy access, 1-to-1 training and regular instrument maintenance should ensure optimal on-going/future use of the BLI platform in supporting the research needs of our users.
Exploitation Route N/A
Sectors Pharmaceuticals and Medical Biotechnology


Description Directed evolution of a highly specific binder to determine the role of histone H3 lysine 14 ubiquitination in genomes and organisms
Amount £100,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 06/2022 
End 03/2023
Description Future 50 PhD studentship
Amount £110,000 (GBP)
Organisation University of Leicester 
Sector Academic/University
Country United Kingdom
Start 08/2023 
End 09/2026
Description Doctoral training program: Biophysical techniques to explore biological systems 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact All first year PhD students within the College of Life Sciences, University of Leicester (UoL) are strongly encouraged to attend a Doctoral Training Program (DTP) which runs throughout the academic year. As part of the DTP training session entitled 'Biophysical techniques to explore biological systems', postgraduate students are given an introduction to BLI theory followed by a practical demonstration of the Octet R8 system. The instrument demo sessions, which cover topics such as experimental set-up, assay design and data analysis, are run in small groups (3-5 students) to maximise student engagement. Students gain a better understanding of Octet R8 capabilities and how they can use the instrument to address their own research project goals. As a result of the training sessions, a number of students have started to use the Octet R8 system or are planning to do so in the near future.
Year(s) Of Engagement Activity 2023
Description Sartorius Octet R8: theoretical and practical training sessions 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Professional Practitioners
Results and Impact A three day workshop led by Gail Calvert, Field Applications Scientist from Sartorius (manufacturers of the Octet R8 instrument) was held at the University of Leicester (UoL). 23 researchers attended a one day theoretical training session (covering instrument basics, Octet (BLI) technology, assay design, optimisation and data analysis) followed by a one day practical training session. During the practical sessions, researchers were shown how to use the instrument, set up assays, analyze data and could bring along their own samples for testing. The purpose of this workshop was to enable (potential) users to gain a greater understanding of the capabilities of Octet R8 instrument and how BLI technology could be best used to address their own research needs.
Gail Calvert is a leading UK expert in BLI detection methodology with specialist knowledge of the Octet R8 platform. During her visit, new and experienced Octet R8 users were given the opportunity to ask Gail questions relating to Octet R8 instrumentation, experimental design and the more challenging aspects of data analysis. This was an invaluable workshop that was highly beneficial to, and praised by, all attendees.
Year(s) Of Engagement Activity 2023