Kegler K, Salomo M, Kremer F
University of Leipzig, Institute of Experimental Physics I, Linnéstrasse 5, D-04103 Leipzig, Germany.
Phys Rev Lett. 2007 Feb 2;98(5):058304. doi: 10.1103/PhysRevLett.98.058304.
Optical tweezers are employed to measure the forces of interaction between single DNA-grafted colloids. Parameters to be varied are the length of the DNA, the grafting density, and the ion concentration of the surrounding medium. From the measured force-separation dependence an interaction length at a given force is deduced. It shows in the mushroom regime a scaling with the grafting density which levels off for brushes. For the latter the transition from an osmotic to a salted brush can be traced in detail by varying the ion concentration in accordance with mean field theories.
利用光镊测量单个DNA接枝胶体之间的相互作用力。可改变的参数包括DNA的长度、接枝密度以及周围介质的离子浓度。根据测得的力与间距的依赖关系，推导出给定力下的相互作用长度。结果表明，在蘑菇状区域，其与接枝密度呈标度关系，而对于刷状结构则趋于平稳。对于后者，根据平均场理论，通过改变离子浓度，可以详细追踪从渗透刷到盐刷的转变。
