Optical traps can measure bead motions with Å-scale precision. However, using this level of precision to infer 1-bp motion of molecular motors along DNA is difficult, since a variety of noise sources degrade instrumental stability. In this chapter, we detail how to improve instrumental stability by (1) minimizing laser pointing, mode, polarization, and intensity noise using an acousto-optical-modulator mediated feedback loop and (2) minimizing sample motion relative to the optical trap using a three-axis piezoelectric-stage mediated feedback loop. These active techniques play a critical role in achieving a surface stability of 1Åin 3D over tens of seconds and a 1-bp stability and precision in a surface-coupled optical trap over a broad bandwidth (Δf = 0.03–2 Hz) at low force (6 pN). These active stabilization techniques can also aid other biophysical assays that would benefit from improved laser stability and/or Å-scale sample stability, such as atomic force microscopy and super-resolution imaging.
CITATION STYLE
Okoniewski, S. R., Carter, A. R., & Perkins, T. T. (2017). A surface-coupled optical trap with 1-bp precision via active stabilization. In Methods in Molecular Biology (Vol. 1486, pp. 77–107). Humana Press Inc. https://doi.org/10.1007/978-1-4939-6421-5_4
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