Miniaturized magnetic bead-actuators for force-clamp spectroscopy-based single-molecule measurements

Force-clamp spectroscopy can mimic the physiological conditions for the proteins under investigation. In addition, it is a direct way of observing the relationship between bond lifetime and molecular forces. However, traditional force-clamp methods rely on active feedback controllers that can introduce artefacts. In this work, we introduce a new method to enable force-clamp spectroscopy without a need for an active feedback. The method is based on miniaturized magnetic beads offering improved stability. As a case study, we performed force-clamp experiments using biotin-streptavidin molecule pairs with and without active feedback. Our results demonstrate the feasibility of force-clamp experiments without feedback and illustrate the advantages of our method.