School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK.
Nat Nanotechnol. 2010 Nov;5(11):783-7. doi: 10.1038/nnano.2010.209. Epub 2010 Oct 31.
The spectroscopic analysis of large biomolecules is important in applications such as biomedical diagnostics and pathogen detection, and spectroscopic techniques can detect such molecules at the nanogram level or lower. However, spectroscopic techniques have not been able to probe the structure of large biomolecules with similar levels of sensitivity. Here, we show that superchiral electromagnetic fields, generated by the optical excitation of plasmonic planar chiral metamaterials, are highly sensitive probes of chiral supramolecular structure. The differences in the effective refractive indices of chiral samples exposed to left- and right-handed superchiral fields are found to be up to 10(6) times greater than those observed in optical polarimetry measurements, thus allowing picogram quantities of adsorbed molecules to be characterized. The largest differences are observed for biomolecules that have chiral planar sheets, such as proteins with high β-sheet content, which suggests that this approach could form the basis for assaying technologies capable of detecting amyloid diseases and certain types of viruses.
大生物分子的光谱分析在生物医学诊断和病原体检测等应用中很重要，光谱技术可以在纳克甚至更低的水平检测到这些分子。然而，光谱技术一直无法以类似的灵敏度探测大生物分子的结构。在这里，我们表明，由等离子体手性超材料的光学激发产生的超手征电磁场是手性超分子结构的高灵敏度探针。暴露于左、右手超手征场的手性样品的有效折射率的差异被发现比在光学旋光测量中观察到的差异大 10^6 倍，从而允许对吸附的分子进行皮克数量级的特征分析。在具有手性平面片的生物分子中观察到最大的差异，例如具有高β-折叠含量的蛋白质，这表明这种方法可以为能够检测淀粉样疾病和某些类型病毒的分析技术奠定基础。
