ATTRACTIVE ATOMIC FORCE MICROSCOPY FOR DNA SEQUENCING

原子力显微镜(AFM)在原子力显微镜下观察非导电表面 通过使用原子锐器测量杠杆的挠度来实现分辨率 小费。小力(10-13到10-8牛顿)和挠度( 埃的量级)是使用隧道尖端来测量的。 测量的原子间作用力既有排斥力，又有吸引力。 区域。传统的AFM布置，隧道尖端在后面 原子力尖端，只能测量斥力分支。观察 具有0.1 nm分辨率的有吸引力的分支隧道尖端必须是 在原子力尖端的样本一侧。这种新奇的重新编排 是这项提议的精髓。 这种操作模式将产生较小的试件尖端力， 更大的样品到尖端的工作距离(大约0.5 nm，而不是 小于约0.3 nm)，且样品移动较少。任何 试件与衬底的粘合将减少试件-尖端的相互作用， 释放小费。(在排斥模式中，相反的情况发生，增加 试件运动)。 在生物成像中，减少对标本的作用力是很重要的 分子。这可能在人类基因组测序中具有重要意义 直接的物理观察-这项任务在0.1 nm的情况下是可能的 可以在DNA上获得分辨率。

Atomic force microscopy (AFM) views non-conducting surfaces at atomic resolution by measuring deflection of a lever with an atomically sharp tip. The small forces (10-13 to 10-8Newtons), and deflections (of the order of Angstroms) are measured using a tunneling tip. The inter-atomic forces measured have a repulsive and an attractive region. The conventional AFM arrangement, with the tunneling tip behind the atomic force tip, can only measure the repulsive branch. To observe the attractive branch with 0.1 nm resolution the tunneling tip must be on the specimen side of the atomic force tip. This novel rearrangement is the essence of this proposal. This mode of operation would produce a smaller specimen tip force, greater specimen-to-tip working distance (approximately 0.5 nm, rather than approximately 0.3 nm) and less movement of the specimen. Any specimen-to-substrate adhesion will decrease specimen-tip interaction, freeing the tip. (In the repulsive mode the opposite occurs, increasing specimen motion). Reduced force on the specimen is important in imaging biological molecules. This could be of relevance in sequencing the human genome by direct, physical observation - a task which will be possible if 0.1 nm resolution can be obtained on DNA.