Mapar Mokhtar, Sjöberg Mattias, Zhdanov Vladimir P, Agnarsson Björn, Höök Fredrik
Division of Biological Physics, Department of Physics, Chalmers University of Technology, SE-41296 Göteborg, Sweden.
Nanolyze AB, BioVentureHub, Pepparedsleden 1, SE-43183 Göteborg, Sweden.
Biomed Opt Express. 2023 Jul 10;14(8):4003-4016. doi: 10.1364/BOE.490051. eCollection 2023 Aug 1.
Recent innovations in microscopy techniques are paving the way for label-free studies of single nanoscopic biological entities such as viruses, lipid-nanoparticle drug carriers, and even proteins. One such technique is waveguide evanescent-field microscopy, which offers a relatively simple, yet sensitive, way of achieving label-free light scattering-based imaging of nanoparticles on surfaces. Herein, we extend the application of this technique by incorporating microfluidic liquid control and adapting the design for use with inverted microscopes by fabricating a waveguide on a transparent substrate. We furthermore formulate analytical models describing scattering and fluorescence intensities from single spherical and shell-like objects interacting with evanescent fields. The models are then applied to analyze scattering and fluorescence intensities from adsorbed polystyrene beads and to temporally resolve cholera-toxin B (CTB) binding to individual surface-immobilized glycosphingolipid G containing vesicles. We also propose a self-consistent means to quantify the thickness of the CTB layer, revealing that protein-binding to individual vesicles can be characterized with sub-nm precision in a time-resolved manner.
显微镜技术的最新创新为对单个纳米级生物实体(如病毒、脂质纳米颗粒药物载体甚至蛋白质)进行无标记研究铺平了道路。一种这样的技术是波导倏逝场显微镜,它提供了一种相对简单但灵敏的方法,可实现基于无标记光散射的表面纳米颗粒成像。在此,我们通过整合微流体液体控制并通过在透明基板上制造波导来调整设计以用于倒置显微镜,从而扩展了该技术的应用。我们还制定了分析模型,描述与倏逝场相互作用的单个球形和壳状物体的散射和荧光强度。然后将这些模型应用于分析吸附的聚苯乙烯珠的散射和荧光强度,并在时间上解析霍乱毒素B(CTB)与单个表面固定的含神经节苷脂G的囊泡的结合。我们还提出了一种自洽的方法来量化CTB层的厚度,揭示了蛋白质与单个囊泡的结合可以在时间分辨的方式下以亚纳米精度进行表征。