Vaezi Mehran, Nejat Pishkenari Hossein
Center for Nanoscience and Nanotechnology, Institute for Convergence Science and Technology, Sharif University of Technology, Tehran, 14588-89694, Iran.
Nano Robotics Laboratory, Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran.
Sci Rep. 2024 Sep 16;14(1):21630. doi: 10.1038/s41598-024-72873-3.
Directed transportation of materials at molecular scale is important due to its crucial role in the development of nanoelectromechanical devices, particularly the directional movements along the carbon nanotubes (CNTs), due to the applications of CNTs as nano-manipulators, confined reactors, and drug or other materials delivery systems. In the present investigation, we evaluate the movements of C60 fullerenes on the surface of the cone-shaped CNTs. The fullerene molecules indicate directed motion toward the narrower end of CNTs, which is due to the potential energy gradient along the nanotube length. A continuum model is proposed to evaluate the mechanism of the directed motion and the results of the theoretical model are compared with numerical simulations. Directed movements have been examined at various opening angles of CNTs, considering the trajectories of motions, variation of potential energy, and diffusion coefficients. At smaller opening angles, the driving force on the C60 increases and the molecule experiences more directed transport along the nanotube. The motion of fullerene has also been simulated inside the cone-shaped CNTs, with similar opening angle, and different average radius. At lower average radius of the cone-like nanotubes, the motion of C60 is comparatively more rectilinear. Directional transport of fullerene has been observed in the opposite direction, when the molecule moves on the external surface of the cone-like CNTs, which is due to the stronger interaction of C60 with the parts of the external surface with larger radius. The effect of temperature has been evaluated by performing the simulations at the temperature range of 100 to 400 K. The direction of the velocity reveals that the thermal fluctuations at higher temperatures hinder the directed motion of molecule along the cone-shaped CNTs. The results of the present study propose a new method to obtain directed transport of molecules which can be helpful in different applications such as drug delivery systems.
在分子尺度上进行物质的定向输运非常重要，因为它在纳米机电装置的发展中起着关键作用，特别是沿着碳纳米管（CNT）的定向运动，这是由于碳纳米管可作为纳米操纵器、受限反应器以及药物或其他物质输送系统。在本研究中，我们评估了C60富勒烯在锥形碳纳米管表面的运动。富勒烯分子表现出朝着碳纳米管较窄端的定向运动，这是由于沿纳米管长度方向的势能梯度所致。我们提出了一个连续介质模型来评估定向运动的机制，并将理论模型的结果与数值模拟进行了比较。考虑到运动轨迹、势能变化和扩散系数，我们研究了在碳纳米管不同开口角度下的定向运动。在较小的开口角度下，C60上的驱动力增加，分子沿纳米管经历更多的定向输运。我们还模拟了富勒烯在具有相似开口角度和不同平均半径的锥形碳纳米管内部的运动。在类锥形纳米管平均半径较低时，C60的运动相对更呈直线状。当分子在类锥形碳纳米管的外表面移动时，观察到富勒烯的定向输运方向相反，这是由于C60与外表面半径较大部分的相互作用更强。通过在100至400 K的温度范围内进行模拟来评估温度的影响。速度方向表明，较高温度下的热涨落阻碍了分子沿锥形碳纳米管的定向运动。本研究结果提出了一种获得分子定向输运的新方法，这在诸如药物输送系统等不同应用中可能会有所帮助。
