Gold Nanoparticle-Based Surface-Enhanced Raman Scattering for Noninvasive Molecular Probing of Embryonic Stem Cell Differentiation

This study reports the use of gold nanoparticle-based surface-enhanced Raman scattering (SERS) for probing the differentiation of mouse embryonic stem (mES) cells, including undifferentiated single cells, embryoid bodies (EBs), and terminally differentiated cardiomyocytes. Gold nanoparticles (GNPs) were successfully delivered into all 3 mES cell differentiation stages without affecting cell viability or proliferation. Transmission electron microscopy (TEM) confirmed the localization of GNPs inside the following cell organelles: mitochondria, secondary lysosome, and endoplasmic reticulum. Using bright- and dark-field imaging, the bright scattering of GNPs and nanoaggregates in all 3 ES cell differentiation stages could be visualized. EB (an early differentiation stage) and terminally differentiated cardiomyocytes both showed SERS peaks specific to metabolic activity in the mitochondria and to protein translation (amide I, amide II, and amide III peaks). These peaks have been rarely identified in undifferentiated single ES cells. Spatiotemporal changes observed in the SERS spectra from terminally differentiated cardiomyocyte tissues revealed local and dynamic molecular interactions as well as transformations during ES cell differentiation.本研究报道了基于金纳米粒子的表面增强拉曼散射（surface-enhanced Raman scattering, SERS）技术，用于探测小鼠胚胎干细胞（mouse embryonic stem, mES）的分化进程，涵盖未分化单细胞、拟胚体（embryoid bodies, EBs）以及终末分化心肌细胞三类样本。研究团队成功将金纳米粒子（gold nanoparticles, GNPs）递送至全部三个小鼠胚胎干细胞分化阶段的细胞中，且未对细胞活力与增殖能力产生负面影响。透射电子显微镜（transmission electron microscopy, TEM）证实，金纳米粒子定位于下述细胞器内：线粒体、次级溶酶体与内质网。通过明场与暗场成像，可观测到全部三个胚胎干细胞分化阶段中金纳米粒子及其纳米聚集体的明亮散射信号。作为分化早期阶段的拟胚体与终末分化心肌细胞，均呈现出与线粒体代谢活性及蛋白质翻译相关的特异性SERS峰，包括酰胺I、酰胺II及酰胺III峰。此类特征峰在未分化的单胚胎干细胞中鲜有被观测到。对终末分化心肌组织的SERS光谱进行时空变化分析，揭示了小鼠胚胎干细胞分化过程中局部且动态的分子相互作用与分子转化过程。