We present a force spectroscopic method to quantify the torque exerted by braided DNA molecules. It involved a rotating magnetic field, with torsional stiffness comparable to the torque exerted by braided DNA molecules, to manipulate the macromolecules. During the initial stages of the braiding process, the probe rotated synchronously with the external field. However, when enough torsional free energy was accumulated in the molecules, the probe started oscillating. We exploited this oscillatory behavior for developing a procedure to estimate the torque exerted by the molecules. The procedure entailed modelling the system as a non-linear oscillator, which considered the dynamics of the angular orientation of the magnetic field vector with respect to the magnetic moment of the probe.

我们提出了一种力谱方法来量化编织的DNA分子施加的扭矩。它涉及旋转磁场，其扭转刚度与编织的DNA分子施加的扭矩相当，可操纵大分子。在编织过程的初始阶段，探头与外部磁场同步旋转。但是，当分子中积累了足够的扭转自由能时，探头开始振荡。我们利用这种振荡行为来开发一种程序来估计分子施加的扭矩。该过程需要将系统建模为非线性振荡器，该振荡器考虑了磁场矢量相对于探头磁矩的角度方向的动力学。