Dahlin Andreas B, Jönsson Peter, Jonsson Magnus P, Schmid Emanuel, Zhou Ye, Höök Fredrik
Division of Solid State Physics, Department of Physics, Lund University, Lund, Sweden.
ACS Nano. 2008 Oct 28;2(10):2174-82. doi: 10.1021/nn800254h.
We present a method providing synchronized measurements using the two techniques: quartz crystal microbalance with dissipation (QCM-D) monitoring and localized surface plasmon resonance (LSPR). This was achieved by letting a thin gold film perforated with short-ranged ordered plasmon-active nanoholes act as one of the electrodes of a QCM-D crystal. This enabled transmission-mode optical spectroscopy to be used to temporally resolve colorimetric changes of the LSPR active substrate induced upon biomolecular binding events. The LSPR response could thus be compared with simultaneously obtained changes in resonance frequency, Deltaf, and energy dissipation, DeltaD, of the QCM-D device. Since the LSPR technique is preferentially sensitive to changes within the voids of the nanoholes, while the QCM-D technique is preferentially sensitive to reactions on the planar region between the holes, a surface chemistry providing the same binding kinetics on both gold and silica was used. This was achieved by coating the substrate with poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), which was shown to bind in the same manner on silica and gold modified with a carboxyl-terminated thiol. In this way, the combined setup provided new information about structural changes upon PLL-g-PEG adsorption. We also demonstrate subsequent binding of NeutrAvidin and an immunoreaction utilizing biotin-modified IgG. The combined information from the synchronized measurements was also used in a new way to estimate the sensing volume of the LSPR sensor.
带耗散监测的石英晶体微天平（QCM-D）和局域表面等离子体共振（LSPR）。这是通过让一个带有短程有序等离子体活性纳米孔的薄金膜充当QCM-D晶体的一个电极来实现的。这使得透射模式光谱能够用于暂时解析生物分子结合事件引起的LSPR活性底物的比色变化。因此，可以将LSPR响应与同时获得的QCM-D设备的共振频率变化（Δf）和能量耗散变化（ΔD）进行比较。由于LSPR技术对纳米孔空隙内的变化优先敏感，而QCM-D技术对孔之间平面区域上的反应优先敏感，因此使用了一种在金和二氧化硅上提供相同结合动力学的表面化学方法。这是通过用聚（L-赖氨酸）-接枝-聚（乙二醇）（PLL-g-PEG）涂覆底物来实现的，已证明其在二氧化硅和用羧基封端的硫醇修饰的金上以相同方式结合。通过这种方式，组合装置提供了关于PLL-g-PEG吸附时结构变化的新信息。我们还展示了中性抗生物素蛋白的后续结合以及利用生物素修饰的IgG的免疫反应。来自同步测量的组合信息还以一种新的方式用于估计LSPR传感器的传感体积。
