Department of Chemistry, ‡Department of Materials Science and Engineering, and §Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
J Phys Chem B. 2013 Oct 24;117(42):13069-81. doi: 10.1021/jp402731f. Epub 2013 May 30.
Studies of the interactions between cells and surrounding environment including cell culture surfaces and their responses to distinct chemical and physical cues are essential to understanding the regulation of cell growth, migration, and differentiation. In this work, we demonstrate the capability of a label-free optical imaging technique-surface plasmon resonance (SPR)-to quantitatively investigate the relative thickness of complex biomolecular structures using a nanoimprinted plasmonic crystal and laboratory microscope. Polyelectrolyte films of different thicknesses deposited by layer-by-layer assembly served as the model system to calibrate the reflection contrast response originating from SPRs. The calibrated SPR system allows quantitative analysis of the thicknesses of the interface formed between the cell culture substrate and cellular membrane regions of fixed Aplysia californica pedal ganglion neurons. Bandpass filters were used to isolate spectral regions of reflected light with distinctive image contrast changes. Combining of the data from images acquired using different bandpass filters leads to increase image contrast and sensitivity to topological differences in interface thicknesses. This SPR-based imaging technique is restricted in measurable thickness range (∼100-200 nm) due to the limited plasmonic sensing volume, but we complement this technique with an interferometric analysis method. Described here simple reflection imaging techniques show promise as quantitative methods for analyzing surface thicknesses at nanometer scale over large areas in real-time and in physicochemical diverse environments.
研究细胞与周围环境（包括细胞培养表面）之间的相互作用及其对不同化学和物理线索的反应，对于理解细胞生长、迁移和分化的调控至关重要。在这项工作中，我们展示了一种无标记的光学成像技术——表面等离子体共振（SPR）——利用纳米压印等离子体晶体和实验室显微镜定量研究复杂生物分子结构相对厚度的能力。通过层层组装沉积的不同厚度的聚电解质膜作为模型系统，对源自 SPR 的反射对比度响应进行校准。校准后的 SPR 系统允许对固定加利福尼亚海兔踏板神经节神经元的细胞培养基底和细胞膜区域之间形成的界面的厚度进行定量分析。带通滤波器用于隔离具有独特图像对比度变化的反射光的光谱区域。结合使用不同带通滤波器获取的图像数据，可以提高对界面厚度拓扑差异的图像对比度和灵敏度。由于等离子体传感体积有限，这种基于 SPR 的成像技术在可测量的厚度范围内（约 100-200nm）受到限制，但我们使用干涉分析方法对其进行了补充。这里描述的简单反射成像技术有望成为在实时和物理化学多样化环境中分析纳米级大面积表面厚度的定量方法。
