Temperature control methods in a laser tweezers system
Temperature control methods in a laser tweezers system
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DOI：
10.1529/biophysj.104.054536
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发表时间：
2005-08-01
影响因子：
3.4
通讯作者：
Bustamante, C
中科院分区：
文献类型：
--
作者：
Mao, HB;Arias-Gonzalez, JR;Bustamante, C
对双光束光镊系统的两种温度控制方法进行了比较。在第一种方法中，我们使用975 nm红外激光器将非加热（830 nm）光阱中的温度提高5.6℃/100mW。温度增量沿加热束外围呈对数递减，在180 mm厚的微腔内产生8 μ m/s的流体对流。在第二种方法中，加热或冷却流体通过放置在微室两侧的水浸物镜上的铜套泵送，将微室的温度控制在4.5℃到68℃之间。第二种方法控制的温度既稳定又均匀，很少产生影响单分子应用的流体对流。对被困球上的热力功率谱的分析表明，由于液体循环，没有检测到振动。在这两种方法中，力都是由光动量通量传感器直接测量的，不受环境干扰，包括随温度变化的折射率变化。第二种方法的实用性在单分子实验中得到了证明，在8.4℃至45.6℃的温度范围内测量了41 kbp lambda双链DNA的机械拉伸。
Two methods of temperature control of a dual-beam optical-tweezers system are compared. In the first method, we used a 975 nm infrared laser to raise the temperature 5.6 degrees C/100mW in a nonheating ( 830 nm) optical trap. The temperature increment logarithmically decreases toward the periphery of the heating beam, causing a fluid convection of 8 mu m/s inside a 180 mm thick microchamber. In the second method, heating or cooling fluid was pumped through copper jackets that were placed on the water immersion objectives on both sides of the microchamber to control its temperature from 4.5 degrees C to 68 degrees C. The temperature controlled by the second method was both stable and homogeneous, inducing little fluid convection that would disturb single-molecule applications. An analysis of the power spectrum of the thermal force on a trapped bead showed no detectable vibration due to the liquid circulation. In both methods, force was measured directly by sensors of the momentum flux of light, independent of environmental disturbances including refractive index changes that vary with temperature. The utility of the second method was demonstrated in single-molecule experiments by measuring the mechanical stretch of a 41 kbp lambda double-stranded DNA at temperatures ranging from 8.4 degrees C to 45.6 degrees C.