Ghosh Siddharth, Karedla Narain, Gregor Ingo
III. Institute of Physics - Biophysics and Complex Systems, University of Göttingen, Göttingen, Germany.
Lab Chip. 2020 Sep 7;20(17):3249-3257. doi: 10.1039/d0lc00398k. Epub 2020 Aug 6.
To date, we could not engineer Nature's ability to dynamically handle diffusing single molecules in the liquid-phase as it takes place in pore-forming proteins and tunnelling nanotubes. Consistent handling of individual single molecules in a liquid is of paramount importance to fundamental molecular studies and technological benefits, like single-molecule level separation and sorting for early biomedical diagnostics, microscopic studies of molecular interactions and electron/optical microscopy of molecules and nanomaterials. We can consistently resolve the dynamics of diffusing single molecules if they are confined within a uniform dielectric environment at nanometre length-scales. A uniform dielectric environment is the key characteristic since intrinsic electronic properties of molecules were modified while interacting with any surfaces, and the effect is not the same from one dielectric surface to another. We present dynamic nanofluidic detection of optically active single molecules in a liquid. An all-silica nanofluidic environment was used to electrokinetically handle individual single-molecules where molecular shot noise was resolved. We recorded the single-molecule motion of small fragments of DNA, carbon-nanodots, and organic fluorophores in water. The electrokinetic 1D molecular mass transport under two-focus fluorescence correlation spectroscopy (2fFCS) showed confinement-induced modified molecular interactions (due to various inter-molecular repulsive and attractive forces), which have been theoretically interpreted as molecular shot noise. Our demonstration of high-throughput nanochannel fabrication, 2fFCS-based 1D confined detection of fast-moving single molecules and fundamental understanding of molecular shot noise may open an avenue for single-molecule experiments where physical manipulation of dynamics is necessary.
迄今为止，我们还无法模拟自然界在形成孔道的蛋白质和隧道纳米管中动态处理液相中单个扩散分子的能力。在液体中持续处理单个分子对于基础分子研究和技术应用至关重要，例如用于早期生物医学诊断的单分子水平分离和分选、分子相互作用的微观研究以及分子和纳米材料的电子/光学显微镜观察。如果扩散的单个分子被限制在纳米尺度的均匀介电环境中，我们就能持续解析它们的动力学。均匀介电环境是关键特性，因为分子与任何表面相互作用时其固有电子特性都会改变，而且不同介电表面的这种效应不尽相同。我们展示了在液体中对光学活性单分子进行动态纳米流体检测。利用全硅纳米流体环境通过电动方式处理单个单分子，在此过程中分辨出了分子散粒噪声。我们记录了水中DNA小片段、碳纳米点和有机荧光团的单分子运动。双聚焦荧光相关光谱法（2fFCS）下的电动一维分子质量传输显示了受限诱导的分子相互作用改变（由于各种分子间排斥力和吸引力），这在理论上被解释为分子散粒噪声。我们在高通量纳米通道制造、基于2fFCS的快速移动单分子一维受限检测以及对分子散粒噪声的基本理解方面的展示，可能为需要对动力学进行物理操纵的单分子实验开辟一条道路。
