Calibration of Optical Tweezers for In Vivo Force Measurements: How do Different Approaches Compare?
Calibration of Optical Tweezers for In Vivo Force Measurements: How do Different Approaches Compare?
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DOI：
10.1016/j.bpj.2014.07.033
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发表时间：
2014-09-16
影响因子：
3.4
通讯作者：
Gross, Steven P.
中科院分区：
文献类型：
--
作者：
Jun, Yonggun;Tripathy, Suvranta K.;Gross, Steven P.
人们对量化细胞内部的力产生有着极大的兴趣，但由于体内条件不如体外条件控制得好，因此体内测量具有挑战性。特别是，在体内环境可能会局部变化，只要其光学特性，和光阱操纵的细胞器经常在大小和形状上变化。已经提出了几种方法来克服这些困难。我们评估这些方法的相对优点，并直接比较其中两个，折射率匹配方法，和光动量变化的方法。由于体内力通常相对较高（例如，对于脂滴可以超过15pN），采用高功率激光。我们发现，这种高功率的陷阱诱导局部温度的变化，我们开发了一种方法来补偿由于这种温度变化所施加的力的大小的不确定性。
There is significant interest in quantifying force production inside cells, but since conditions in vivo are less well controlled than those in vitro, in vivo measurements are challenging. In particular, the in vivo environment may vary locally as far as its optical properties, and the organelles manipulated by the optical trap frequently vary in size and shape. Several methods have been proposed to overcome these difficulties. We evaluate the relative merits of these methods and directly compare two of them, a refractive index matching method, and a light-momentum-change method. Since in vivo forces are frequently relatively high (e.g., can exceed 15 pN for lipid droplets), a high-power laser is employed. We discover that this high-powered trap induces local temperature changes, and we develop an approach to compensate for uncertainties in the magnitude of applied force due to such temperature variations.