Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
Analyst. 2016 Nov 28;141(24):6490-6498. doi: 10.1039/c6an01771a.
Linear dichroism (LD) spectroscopy involves measuring the wavelength (or energy) dependence of the difference in absorption of light parallel and perpendicular to an orientation direction. It requires samples to have a net orientation. The aim of this review is to summarise some UV-visible linear dichroism (LD) methods that can be usefully applied to increase our understanding of biomacromolecules and their complexes that have a high aspect ratio. LD shares the advantages of most spectroscopic techniques including the fact that data collection is fairly straightforward and many sample types can be investigated. Conversely, LD shares the disadvantage that the measured signal is an average over all species in the sample on which the light beam is incident. LD mitigates this disadvantage somewhat in that only species which are oriented give a net signal. How the data can be analysed to give structural information about small molecules in stretched films and membrane systems or bound to biomacromolecules and directly about biomacromolecules such as DNA and protein fibres forms part of this review. In the UV-visible region LD often suffers noticeably from light scattering since the samples tend to be large relative to the wavelength of the incident light, so consideration is also given to data analysis challenges including removal of scattering contributions to an observed signal. Brief mention is made of fluorescence detected LD.
线性二色性（LD）光谱学涉及测量光平行和垂直于取向方向的吸收差异的波长（或能量）依赖性。它需要样品具有净取向。本综述的目的是总结一些可用于增加对具有高纵横比的生物大分子及其复合物的理解的紫外可见线性二色性（LD）方法。LD 具有大多数光谱技术的优点，包括数据采集相当简单，可以研究许多样品类型。相反，LD 具有这样的缺点，即测量的信号是入射光束照射的样品中所有物质的平均值。LD 通过仅对取向的物质给出净信号，在某种程度上减轻了这一缺点。如何分析数据以获得拉伸薄膜和膜系统中的小分子或与生物大分子结合的小分子以及直接关于 DNA 和蛋白质纤维等生物大分子的结构信息，是本综述的一部分。在紫外可见区域，LD 通常由于光散射而明显受到影响，因为样品相对于入射光的波长通常较大，因此还考虑了数据分析挑战，包括去除观察到的信号中的散射贡献。简要提及了荧光检测 LD。
