Simulation of single-molecule trapping in a nanochannel.
Simulation of single-molecule trapping in a nanochannel.
复制标题
纳米通道中单分子捕获的模拟。
DOI：
10.1117/1.3477320
复制
发表时间：
2010
影响因子：
3.5
通讯作者：
Davis,LloydM
中科院分区：
文献类型：
--
作者：
Robinson,WilliamNeil;Davis,LloydM
采用数值模拟方法研究了纳米通道内溶液中单个荧光分子的检测和捕获。由于光学力不足以捕获比光学波长小得多的分子，因此评估了一种沿纳米通道感知分子位置并调节电动力学运动以补偿扩散的方法。荧光激发是由两个相邻聚焦的激光束提供的，其中包含时间交错的激光脉冲。光子检测是时间门控的，分子从两个焦点中间的位移改变了在两个检测通道中收集的计数率。评估了一种响应光子时间的反馈控制电动力学运动的算法，该算法将分子重新定位回中间以捕获，并在分子光漂白或逃逸后快速重新加载陷阱。在适应有限的电动力学速度和实验硬件施加的有限反馈延迟的同时，该算法被证明可以有效地在微米大小的共聚焦区域内捕获快速扩散的单色团分子。研究表明，存在一个最佳的激光功率，使由于光漂白或光噪声波动引起的分子从阱中损失最小化。
The detection and trapping of single fluorescent molecules in solution within a nanochannel is studied using numerical simulations. As optical forces are insufficient for trapping molecules much smaller than the optical wavelength, a means for sensing a molecule’s position along the nanochannel and adjusting electrokinetic motion to compensate diffusion is assessed. Fluorescence excitation is provided by two adjacently focused laser beams containing temporally interleaved laser pulses. Photon detection is time-gated, and the displacement of the molecule from the middle of the two foci alters the count rates collected in the two detection channels. An algorithm for feedback control of the electrokinetic motion in response to the timing of photons, to reposition the molecule back toward the middle for trapping and to rapidly reload the trap after a molecule photobleaches or escapes, is evaluated. While accommodating the limited electrokinetic speed and the finite latency of feedback imposed by experimental hardware, the algorithm is shown to be effective for trapping fast-diffusing single-chromophore molecules within a micron-sized confocal region. Studies show that there is an optimum laser power for which loss of molecules from the trap due to either photobleaching or shot-noise fluctuations is minimized.