Your Helpful New Sidekick

ForteBio’s Sidekick Offline Biosensor Immobilization Station

Lynne I. Denny, Research Biochemist,
Marc D. Wenger, Sr. Research Biochemist, and
Pete A. DePhillips, Director, Merck Research Laboratories.

The Sidekick station is an accessory to ForteBio’s Octet family of real-time label-free biomolecular interaction analysis instruments. The instrument enables simultaneous and uniform loading of reagents onto all 96 biosensors in a biosensor tray. Analytes and other reagents that do not require online signal monitoring can be loaded onto biosensors on the Sidekick, freeing the Octet system for other users. The Sidekick can be installed beside an Octet system and used in collaboration with it, or it can be used independently.

The Sidekick station has become an integral part of our Octet assay workflow, significantly decreasing custom biosensor preparation time and assay incubation time while improving assay performance. When preparing custom biosensors, shaking at 400 – 800 rpm during incubation of the biotinylated protein with the streptavidin biosensors decreases the required incubation time by one half, thereby doubling the biosensor preparation productivity (Fig. 1). Further efficiency can be obtained by using the Sidekick station in conjunction with a liquid-handling robotic workstation to automate the custom biosensor preparation.

The Sidekick station can additionally be used to perform multistep sandwich Octet assays in advanced quantitation mode to decrease incubation times during sample capture and drive down assay variability. The sandwich format has a “capture” step during which the target analyte is bound to the custom biosensor, followed by a “rinse” step in which the biosensor is placed in buffer to soak. These steps are performed offline (i.e., on the Sidekick station, outside the Octet instrument). The biosensors with the captured analyte are then transferred to the Octet instrument and the analyte is quantified by dipping the biosensors into a detection antibody solution. The effect of the shaking speed during the capture step is shown in Figure 2 for one such assay. Shaking speeds > 400 rpm increase the sensitivity of the assay as evidenced by the decrease in the midpoint (EC₅₀) of the calibration curve (four-parameter logistic fit). More importantly, the variability of the measurement was significantly decreased with shaking, as shown in Table 1.

In summary, the Sidekick offline immobilization station increases productivity for creating large batches of custom biosensors, enabling widespread distribution of the custom biosensors across multiple research groups. Furthermore, for advanced quantitation assays, it can decrease incubation times and/or increase assay sensitivity at short incubation times while improving assay precision and robustness. For these reasons, the Sidekick station has become an essential component of our custom Octet assays.

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