School of Physics and Astronomy , Cardiff University , The Parade , Cardiff CF24 3AA , U.K.
School of Biosciences , Cardiff University , Museum Avenue , Cardiff CF10 3AX , U.K.
Langmuir. 2019 Oct 29;35(43):13805-13814. doi: 10.1021/acs.langmuir.9b02538. Epub 2019 Oct 14.
Quantitative differential interference contrast microscopy is demonstrated here as a label-free method, which is able to image and measure the thickness of lipid bilayers with 0.1 nm precision. We investigate the influence of the substrate on the thickness of fluid-phase 1,2-dioleoyl--glycero-3-phosphocholine (DOPC)-supported lipid bilayers and find a thinning of up to 10%, depending on substrate hydrophilicity, local bilayer coverage, and ionic strength of the medium. With fluorescently labeled lipid bilayers, we also observe changes in the bilayer thickness depending on the choice of fluorophore. Furthermore, liquid-ordered domains in bilayers, formed from DOPC, cholesterol, and sphingomyelin, are measured, and the corresponding thickness change between the liquid-ordered and liquid-disordered phases is accurately determined. Again, the thickness difference is found to be dependent on the presence of the fluorophore label, highlighting the need for quantitative label-free techniques.
定量微分干涉差显微镜在这里被证明是一种无需标记的方法，它能够以 0.1nm 的精度成像和测量脂质双层的厚度。我们研究了衬底对流体相 1,2-二油酰基-甘油-3-磷酸胆碱（DOPC）支撑脂质双层厚度的影响，发现厚度变薄了 10%，这取决于衬底的亲水性、局部双层覆盖率和介质的离子强度。对于荧光标记的脂质双层，我们还观察到了荧光染料选择对双层厚度的影响。此外，还测量了由 DOPC、胆固醇和鞘磷脂形成的双层中的有序液域，并准确地确定了有序相与无序相之间的厚度变化。同样，发现厚度差取决于荧光标记的存在，这突出了需要定量的无标记技术。
