AFS and single-molecules
The figure shows a typical AFS experimental setup, where multiple molecules, such as DNA molecules are tethered between the surface of the chip and microspheres.
When turning on the acoustic forces, the microspheres experience a force along the vertical (z) direction of the standing wave. This results in the stretching of the DNA molecules towards the acoustic node.
By measuring the z-position of the beads, the extension and mechanical properties of the biomolecules can be determined.
The importance of measuring many biomolecules in parallel lies in the fact that many independent measurements are often needed to distinguish heterogeneous behavior and rare events from intrinsic stochastic behavior caused by thermal fluctuations.
When investigating the mechanical properties of biomolecular structures, such as DNA or proteins, it is essential to be able to apply a wide range of forces, so as to induce conformational changes such as protein unfolding or bond ruptures. AFS features a large force range from 0 to 200 pN, ensuring that these applications can be performed. In combination with the fast loading rates ranging from 10-4 pN/s to 103pN/s, it is possible to conduct these experiments in a massively parallel manner.