Shroff Hari, Reinhard Björn M, Siu Merek, Agarwal Harish, Spakowitz Andrew, Liphardt Jan
Biophysics Graduate Group, University of California, Berkeley, California 94720, USA.
Nano Lett. 2005 Jul;5(7):1509-14. doi: 10.1021/nl050875h.
We have developed a nanoscopic force sensor with optical readout. The sensor consists of a single-stranded DNA oligomer flanked by two dyes. The DNA acts as a nonlinear spring: when the spring is stretched, the distance between the two dyes increases, resulting in reduced Förster resonance energy transfer. The sensor was calibrated between 0 and 20 pN using a combined magnetic tweezers/single-molecule fluorescence microscope. We show that it is possible to tune the sensor's force response by varying the interdye spacing and that the FRET efficiency of the sensors decreases with increasing force. We demonstrate the usefulness of these sensors by using them to measure the forces internal to a single polymer molecule, a small DNA loop. Partial conversion of the single-stranded DNA loop to a double-stranded form results in the accumulation of strain: a force of approximately 6 pN was measured in the loop upon hybridization. The sensors should allow measurement of forces internal to various materials, including programmable DNA self-assemblies, polymer meshes, and DNA-based machines.
我们开发了一种具有光学读出功能的纳米力传感器。该传感器由一个两侧带有两种染料的单链DNA寡聚物组成。DNA充当非线性弹簧：当弹簧被拉伸时，两种染料之间的距离增加，导致Förster共振能量转移减少。使用组合式磁镊/单分子荧光显微镜在0至20皮牛之间对传感器进行了校准。我们表明，可以通过改变染料间间距来调节传感器的力响应，并且传感器的荧光共振能量转移效率随力的增加而降低。我们通过使用这些传感器测量单个聚合物分子（一个小的DNA环）内部的力来证明这些传感器的实用性。单链DNA环部分转化为双链形式会导致应变积累：杂交时在环中测得约6皮牛的力。这些传感器应能测量各种材料内部的力，包括可编程DNA自组装体、聚合物网和基于DNA的机器。
