Electro-optic deflectors deliver advantages over acousto-optical deflectors in a high resolution, ultra-fast force-clamp optical trap.
Electro-optic deflectors deliver advantages over acousto-optical deflectors in a high resolution, ultra-fast force-clamp optical trap.
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DOI：
10.1364/oe.26.011181
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发表时间：
2018-04
期刊：
影响因子：
3.8
通讯作者：
Michael S. Woody;M. Capitanio;E. Ostap;Yale E. Goldman
中科院分区：
文献类型：
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作者：
Michael S. Woody;M. Capitanio;E. Ostap;Yale E. Goldman
我们对超快力钳光镊中声光偏转器（AOD）的非线性响应所产生的实验假象进行了表征，并表明使用电光偏转器（EOD）可消除这些假象。我们给出了在我们对肌球蛋白与肌动蛋白丝相互作用的超快力钳研究中这些假象影响的一个例子。该实验装置基于卡皮塔尼奥等人[《自然方法》9, 1013 - 1019 (2012)]的概念，利用一个由两个力钳光镊固定的珠 - 肌动蛋白 - 珠哑铃结构，光镊对哑铃施加负载以使其以恒定速度移动。当肌球蛋白与肌动蛋白结合时，由于来自光镊的总力转移到肌动球蛋白连接点，丝的运动迅速停止。我们发现，在我们的装置中，由于光束强度和偏转角作为驱动频率的函数存在非线性变化（可能是由偏转器中的低振幅驻声波引起的），AOD不适合用于光束转向。这些像差导致力反馈回路不稳定，从而引起光镊位置出现假象性跳跃。我们证明，使用EOD进行光束转向可提高我们仪器的性能。结合EOD卓越的光束转向能力、通过后焦平面干涉测量获取力以及基于双高速现场可编程门阵列（FPGA）的反馈回路，我们施加精确且恒定的负载来研究肌动蛋白与肌球蛋白之间相互作用的动力学。同样的概念也适用于其他生物分子相互作用的研究。
We characterized experimental artifacts arising from the non-linear response of acousto-optical deflectors (AODs) in an ultra-fast force-clamp optical trap and have shown that using electro-optical deflectors (EODs) instead eliminates these artifacts. We give an example of the effects of these artifacts in our ultra-fast force clamp studies of the interaction of myosin with actin filaments. The experimental setup, based on the concept of Capitanio et al. [Nat. Methods 9, 1013-1019 (2012)] utilizes a bead-actin-bead dumbbell held in two force-clamped optical traps which apply a load to the dumbbell to move it at a constant velocity. When myosin binds to actin, the filament motion stops quickly as the total force from the optical traps is transferred to the actomyosin attachment. We found that in our setup, AODs were unsuitable for beam steering due to non-linear variations in beam intensity and deflection angle as a function of driving frequency, likely caused by low-amplitude standing acoustic waves in the deflectors. These aberrations caused instability in the force feedback loops leading to artifactual jumps in the trap position. We demonstrate that beam steering with EODs improves the performance of our instrument. Combining the superior beam-steering capability of the EODs, force acquisition via back-focal-plane interferometry, and dual high-speed FPGA-based feedback loops, we apply precise and constant loads to study the dynamics of interactions between actin and myosin. The same concept applies to studies of other biomolecular interactions.