Kim S R, Shah R R, Abbott N L
Department of Chemical Engineering, University of Wisconsin, Madison 53705, USA.
Anal Chem. 2000 Oct 1;72(19):4646-53. doi: 10.1021/ac000256n.
We report the uniform planar anchoring of thermotropic liquid crystals on films of bovine serum albumin (BSA) covalently immobilized on the surface of glass microscope slides and mechanically rubbed using a cloth. The azimuthal orientations of the liquid crystals were measured to be parallel to the direction of rubbing. Following immersion and removal of these rubbed films of BSA from aqueous solutions containing either BSA, fibrinogen, lysozyme, anti-FITC immunoglobulin G (IgG), or antistreptavidin IgG, we measured liquid crystals placed onto these surfaces to largely retain their uniform alignment. In contrast, following immersion of a rubbed film of BSA into an aqueous solution of anti-BSA IgG, we observed liquid crystals on these surfaces to assume nonuniform orientations. We conclude that specific binding of anti-BSA IgG to the film of rubbed BSA erased anisotropy induced within the film of BSA by rubbing. This result suggests that the spatial scale of anisotropy within the rubbed film of BSA is comparable to or smaller than the size of the IgG molecule. Because the anisotropy within a rubbed film of a protein can be erased by specific binding of a second protein, we believe these types of substrates (rubbed films of proteins) have the potential to be useful in a variety of label-free biomolecular assays where specific binding of a target species to its ligand can be imaged through observation of the optical appearance of liquid crystal placed onto the surface.
我们报道了热致液晶在共价固定于玻璃显微镜载玻片表面并使用布进行机械摩擦的牛血清白蛋白（BSA）薄膜上的均匀平面锚定。测量发现液晶的方位取向与摩擦方向平行。将这些摩擦过的BSA薄膜从含有BSA、纤维蛋白原、溶菌酶、抗异硫氰酸荧光素免疫球蛋白G（IgG）或抗链霉亲和素IgG的水溶液中浸泡并取出后，我们测量放置在这些表面上的液晶在很大程度上保持其均匀排列。相比之下，将摩擦过的BSA薄膜浸泡在抗BSA IgG水溶液中后，我们观察到这些表面上的液晶呈现出非均匀取向。我们得出结论，抗BSA IgG与摩擦过的BSA薄膜的特异性结合消除了摩擦在BSA薄膜内诱导的各向异性。这一结果表明，摩擦过的BSA薄膜内各向异性的空间尺度与IgG分子的大小相当或更小。由于蛋白质摩擦薄膜内的各向异性可通过第二种蛋白质的特异性结合而消除，我们认为这类底物（蛋白质摩擦薄膜）有潜力用于各种无标记生物分子检测，在这些检测中，通过观察放置在表面的液晶的光学外观，可以对目标物种与其配体的特异性结合进行成像。
