Kim Geun Wan, Ha Ji Won
Department of Chemistry, University of Ulsan, 93 Daehak-ro, Nam-gu, Ulsan 44610, South Korea.
Energy Harvest-Storage Research Center (EHSRC), University of Ulsan, 93 Daehak-ro, Nam-gu, Ulsan 44610, South Korea.
JACS Au. 2023 Dec 2;3(12):3436-3445. doi: 10.1021/jacsau.3c00594. eCollection 2023 Dec 25.
Breaking the angular degeneracy arising from the 2-fold optical symmetry of plasmonic anisotropic nanoprobes is critical in biological studies. In this study, we propose differential interference contrast (DIC) microscopy-based focused orientation and position imaging (dFOPI) to break the angular degeneracy of single gold nanorods (AuNRs). Single AuNRs (39 nm × 123 nm) within a spherical mesoporous silica shell were characterized with high throughput and produced distinct doughnut-shaped DIC image patterns featuring two lobes in the peripheral region, attributed to the scattering contribution of the AuNRs with large scattering cross sections. Interestingly, rotation of the lobes was observed in the focal plane for a large AuNR (>100 nm) tilted by more than ∼20° from the horizontal plane as the rotational stage was moved by 10° in a rotational study. From the rotation-dependent characteristic patterns, we directly visualized counterclockwise/clockwise rotations without the angular degeneracy at the localized surface plasmon resonance wavelength. Therefore, our dFOPI method can be applied for studies of important biological systems. To validate this claim, we tracked the three-dimensional rotational behavior of transferrin-modified AuNRs during clathrin-mediated endocytosis in real time without sacrificing the temporal and spatial resolution. In the invagination and scission stage, one or two directed twist motions of the AuNR cargos detached the AuNR-containing vesicles from the cell membrane. Furthermore, the dFOPI method directly visualized and revealed the right-handed twisting action along the dynamin helix in dynamin-catalyzed fission in live cells.
打破等离子体各向异性纳米探针的二重光学对称性所产生的角度简并性在生物学研究中至关重要。在本研究中，我们提出基于微分干涉对比（DIC）显微镜的聚焦取向和位置成像（dFOPI）来打破单个金纳米棒（AuNRs）的角度简并性。对球形介孔二氧化硅壳内的单个AuNRs（39 nm×123 nm）进行了高通量表征，并产生了独特的甜甜圈形状的DIC图像模式，其在外围区域有两个叶瓣，这归因于具有大散射截面的AuNRs的散射贡献。有趣的是，在旋转研究中，当旋转台移动10°时，对于一个从水平面倾斜超过约20°的大AuNR（>100 nm），在焦平面上观察到叶瓣的旋转。从依赖于旋转的特征模式中，我们直接可视化了逆时针/顺时针旋转，而在局部表面等离子体共振波长处没有角度简并性。因此，我们的dFOPI方法可应用于重要生物系统的研究。为了验证这一说法，我们实时跟踪了转铁蛋白修饰的AuNRs在网格蛋白介导的内吞作用过程中的三维旋转行为，而不牺牲时间和空间分辨率。在凹陷和切割阶段，AuNR货物的一个或两个定向扭转运动使含有AuNR的囊泡从细胞膜上脱离。此外，dFOPI方法直接可视化并揭示了活细胞中发动蛋白催化裂变过程中沿着发动蛋白螺旋的右手扭转作用。
