一辆堪称世界最小的“电动车”出现在最新一期英国《自然》杂志的封面上，这是一个结构特殊的分子，它也有四个“轮子”，当接收到电流时就向前“行驶”，不过，它行驶的距离要以纳米来计算。
荷兰格罗宁根大学等机构的研究人员报告了这项成果。他们合成的这个分子在中间有一根“主轴”，前后两端各有两个类似轮子的结构。如果用特别小的探针碰一下这个分子，为之提供电流，四个“轮子”就会开始旋转，驱动整个分子前行。在铜板表面对这辆“电动车”进行的测试显示，如果施加10次电流，它可以前进6纳米（1纳米为百万分之一毫米）。
研究人员蒂博尔·库贝纳奇说，这辆“电动车”的原理与许多生物机体组织中天然存在的现象类似，在机体组织中，有些蛋白质在受电流刺激后会变形，从而产生运动，肌肉的收缩就是基于这个原理。本次研究显示，可以在纳米尺度上人工模拟这类现象。
这种分子“电动车”将来可用于许多微观领域，比如把微量药物送达人体所需要的地点。不过研究人员表示，这还有很长路要走，因为本次实验是在零下200多摄氏度的低温和高度真空环境中完成的，如何在常规环境下也能让分子“电动车”工作是首先要解决的问题。(生物谷 Bioon.com)
doi:10.1038/nature10587
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Electrically driven directional motion of a four-wheeled molecule on a metal surface
Tibor Kudernac, Nopporn Ruangsupapichat, Manfred Parschau, Beatriz Maciá, Nathalie Katsonis, Syuzanna R. Harutyunyan, Karl-Heinz Ernst & Ben L. Feringa
Propelling single molecules in a controlled manner along an unmodified surface remains extremely challenging because it requires molecules that can use light, chemical or electrical energy to modulate their interaction with the surface in a way that generates motion. Nature’s motor proteins have mastered the art of converting conformational changes into directed motion, and have inspired the design of artificial systems3 such as DNA walkers and light- and redox-driven molecular motors. But although controlled movement of single molecules along a surface has been reported, the molecules in these examples act as passive elements that either diffuse along a preferential direction with equal probability for forward and backward movement or are dragged by an STM tip. Here we present a molecule with four functional units—our previously reported rotary motors—that undergo continuous and defined conformational changes upon sequential electronic and vibrational excitation. Scanning tunnelling microscopy confirms that activation of the conformational changes of the rotors through inelastic electron tunnelling propels the molecule unidirectionally across a Cu(111) surface. The system can be adapted to follow either linear or random surface trajectories or to remain stationary, by tuning the chirality of the individual motor units. Our design provides a starting point for the exploration of more sophisticated molecular mechanical systems with directionally controlled motion.
