Label-free SERS detection of small proteins modified to act as bifunctional linkers
Label-free SERS detection of small proteins modified to act as bifunctional linkers
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DOI：
10.1021/jp710261y
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发表时间：
2008-04-03
影响因子：
3.7
通讯作者：
Moskovits, Martin
中科院分区：
文献类型：
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作者：
Pavel, Ioana;McCarney, Evan;Moskovits, Martin
制备了小蛋白的两个双半胱氨酸突变体，其被明智地修饰，使得半胱氨酸出现在天然折叠的轴向相对侧，从而在两个突变体中定义了不同的轴。还原后，二硫键断裂，蛋白质充当银纳米颗粒的双功能配体，促进它们组装成纳米颗粒二聚体和小聚集体，这样，当用激光激发时，蛋白质会自动定位在聚集体内的电磁热点处。由于蛋白质分子很小（类似于 2.3 nm），并且随着颗粒间间隙尺寸的减小，热点处的电磁能趋于增加，因此这种纳米颗粒-蛋白质-纳米颗粒几何形状显着增强了金属表面的拉曼发射。利用这种效应，我们在近单分子水平上记录了蛋白质的表面增强拉曼光谱（SERS）。观察到的 SERS 光谱主要由蛋白质锚定点附近分子基团的振动主导。
Two double-cysteine mutants of a small protein judiciously modified so that the cysteines appear at axially opposite sides of the native fold were prepared such that different axes were defined in the two mutants. Upon reduction, the disulfide bonds are broken, and the proteins act as bifunctional ligands toward Ag nanoparticles, encouraging their assembly into nanoparticle dimers and small aggregates such that, when excited with laser light, the proteins are automatically located at electromagnetic hot spots within the aggregates. Because the protein molecules are small (similar to 2.3 nm) and because the electromagnetic energy at a hot spot tends to increase as the size of the interparticle gap decreases, this nanoparticle-protein- nanoparticle geometry significantly enhances the Raman emission at the metallic surface. Exploiting this effect, we have recorded surface-enhanced Raman spectra (SERS) of the proteins at near-single-molecule level. The observed SERS spectra were dominated,by the vibrations of molecular groups near the anchor points of the proteins.