Department of Chemistry, Northwestern University, 2145 North Sheridan Road, Evanston, Illinois 60208, United States.
Nano Lett. 2011 Mar 9;11(3):1098-105. doi: 10.1021/nl103994w. Epub 2011 Jan 31.
The versatile optical and biological properties of a localized surface plasmon resonance (LSPR) sensor that responds to protein conformational changes are illustrated. The sensor detects conformational changes in a surface-bound construct of the calcium-sensitive protein calmodulin. Increases in calcium concentration induce a 0.96 nm red shift in the spectral position of the LSPR extinction maximum (λ(max)). Addition of a calcium chelating agent forces the protein to return to its original conformation and is detected as a reversal of the λ(max) shift. As opposed to previous work, this work demonstrates that these conformational changes produce a detectable shift in λ(max) even in the absence of a protein label, with a signal:noise ratio near 500. In addition, the protein conformational changes reversibly switch both the wavelength and intensity of the resonance peak, representing an example of a bimodal plasmonic component that simultaneously relays two distinct forms of optical information. This highly versatile plasmonic device acts as a biological sensor, enabling the detection of calcium ions with a biologically relevant limit of detection of 23 μM, as well as the detection of calmodulin-specific protein ligands.
局部表面等离子体共振（LSPR）传感器具有多功能的光学和生物学特性，能够响应蛋白质构象变化。该传感器检测与钙敏感蛋白钙调蛋白结合的表面结构的构象变化。钙浓度的增加会导致 LSPR 消光最大值（λ（max））的光谱位置发生 0.96nm 的红移。加入钙螯合剂会迫使蛋白质恢复到原来的构象，并可检测到 λ（max）位移的反转。与之前的工作相比，这项工作表明，即使在没有蛋白质标记的情况下，这些构象变化也会产生可检测到的 λ（max）位移，其信号与噪声比接近 500。此外，蛋白质构象变化可逆地切换共振峰的波长和强度，代表双模态等离子体组件的一个例子，同时传递两种不同形式的光学信息。这种高度通用的等离子体装置充当生物传感器，能够以 23μM 的生物学相关检测限检测钙离子，以及检测钙调蛋白特异性蛋白配体。
