Fukuba Shin-Ya, Tsuboi Kazuma, Abe Shinya, Kajikawa Kotaro
Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8502, Japan.
Langmuir. 2008 Aug 5;24(15):8367-72. doi: 10.1021/la800643e. Epub 2008 Jun 21.
A new nonlinear optical method is presented to detect proteins binding to a gold surface without using fluorescent-dye labeling. After exposure of the protein-binding surface to a gold nanosphere solution, the nanospheres are immobilized above a gold surface with a nanogap supported by the protein. The gold nanospheres immobilized on the gold surface show strong localized surface plasmon (LSP) resonance, and the formation of this structure results in a marked increase in the optical second harmonic (SH) activity of the gold surface arising from a large enhancement of the electric field localized adjacent to the nanospheres on the LSP resonance. The SH image, therefore, gives a high contrast ratio, 7.0:1, of protein-binding spots to control spots. The contrast ratio is much greater than those obtained by linear reflectivity imaging.
提出了一种新的非线性光学方法，用于在不使用荧光染料标记的情况下检测与金表面结合的蛋白质。将蛋白质结合表面暴露于金纳米球溶液后，纳米球通过蛋白质支撑的纳米间隙固定在金表面上方。固定在金表面的金纳米球表现出强烈的局域表面等离子体（LSP）共振，这种结构的形成导致金表面的光学二次谐波（SH）活性显著增加，这是由于在LSP共振时纳米球附近的电场大幅增强所致。因此，SH图像给出了蛋白质结合斑点与对照斑点的高对比度，为7.0:1。该对比度远高于通过线性反射率成像获得的对比度。
