Department of Chemistry, The State University of New York, Geneseo College, One College Circle, Geneseo, New York 14454, USA.
J Phys Chem A. 2010 Jan 28;114(3):1521-8. doi: 10.1021/jp907880f.
The absorption spectrum of the amyloid beta 1-40 peptide (Abeta(1-40)) conjugated to gold colloidal suspension of 15, 20, 30, and 40 nm size were examined under temperature ranging from 5 to 50 degrees C. As the pH was externally altered repetitively between pH 4 and 10, Abeta(1-40)-coated 20 nm gold colloid nanoparticles exhibited a reversible color change at the entire temperature range tested in this study except for 5 +/- 0.2 degrees C. This reversible change may be due to the fact that hydrophilic Abeta(1-40) evolves between a three-dimensional network containing mainly beta-sheet and alpha-helices, and an intermediate of this process implies a reversible step reported as initiation of the fibrillogenesis in Alzheimer's disease. When other nanosize particles were investigated, Abeta(1-40)-coated 30 and 40 nm colloids exhibited the reversible color change when temperature was lowered to 18 +/- 0.2 and 6 +/- 0.2 degrees C, respectively. This specific and unique size and temperature dependence in reversible color change strongly suggests that the noncovalent intrinsic intermolecular potential formed between the nanocolloidal surface and each Abeta(1-40) monomer conjugated at the surface drives the process.
将 15、20、30 和 40nm 大小的金胶体悬浮液中的淀粉样蛋白β 1-40 肽（Abeta(1-40)）与金胶体悬浮液偶联，在 5 至 50°C 的温度范围内检查其吸收光谱。当 pH 值在 4 至 10 之间反复外部改变时，Abeta(1-40)-涂覆的 20nm 金胶体纳米颗粒在本研究测试的整个温度范围内表现出可逆的颜色变化，除了 5 +/- 0.2°C 以外。这种可逆变化可能是由于亲水 Abeta(1-40)在主要包含β-折叠和α-螺旋的三维网络之间演变，并且该过程的中间产物暗示了阿尔茨海默病中纤维形成的起始的可逆步骤。当研究其他纳米颗粒时，当温度降至 18 +/- 0.2°C 和 6 +/- 0.2°C 时，Abeta(1-40)-涂覆的 30nm 和 40nm 胶体分别表现出可逆的颜色变化。这种在可逆颜色变化中特定且独特的尺寸和温度依赖性强烈表明，纳米胶体表面与表面上偶联的每个 Abeta(1-40)单体之间形成的非共价内在分子间势能驱动该过程。
