Viral membranes are nanomaterials whose fluidity depends on their composition, in particular, the cholesterol (chol) content. As differences in the membrane composition of individual virus particles can lead to different intracellular fates, biophysical tools capable of sensing the membrane fluidity on the single-virus level are required. In this manuscript, we demonstrate that fluctuations in the polarization of light scattered off gold or silver nanoparticle (NP)-labeled virus-like-particles (VLPs) encode information about the membrane fluidity of individual VLPs. We developed plasmonic polarization fluctuation tracking microscopy (PFTM) which facilitated the investigation of the effect of chol content on the membrane fluidity and its dependence on temperature, for the first time on the single-VLP level. Chol extraction studies with different methyl-β-cyclodextrin (MβCD) concentrations yielded a gradual decrease in polarization fluctuations as a function of time. The rate of chol extraction for individual VLPs showed a broad spread, presumably due to differences in the membrane composition for the individual VLPs, and this heterogeneity increased with decreasing MβCD concentration.

中文翻译：

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等离子纳米粒子传感器在单个病毒颗粒水平上的膜流动性传感。

病毒膜是纳米材料，其流动性取决于其组成，尤其取决于胆固醇（chol）的含量。由于单个病毒颗粒的膜成分不同会导致不同的细胞内命运，因此需要能够在单病毒水平上检测膜流动性的生物物理工具。在此手稿中，我们证明了金或银纳米颗粒（NP）标记的病毒样颗粒（VLP）散射的光的偏振波动会编码有关各个VLP的膜流动性的信息。我们开发了等离子极化波动跟踪显微镜（PFTM），这首次促进了单VLP水平上对胆碱含量对膜流动性及其对温度的依赖性的研究。使用不同的甲基-β-环糊精（MβCD）浓度进行乙醇萃取研究，得出极化波动随时间的变化逐渐减小。单个VLP的胆汁提取率显示出广泛的分布，这可能是由于单个VLP的膜组成不同所致，并且这种异质性随着MβCD浓度的降低而增加。