Direct Observation of Nanoparticles within Cells at Subcellular Levels by Super-Resolution Fluorescence Imaging.

Direct observation of nanoparticles with high spatial resolution at subcellular levels is of great importance to understand the nanotoxicology and promote the biomedical applications of nanoparticles. Super-resolution fluorescence microscopy can break the diffraction resolution limit to achieve spatial resolution of tens of nanometers, making it ideal for highly accurate observation of nanoparticles in the cellular world. In this study, we introduced the employment of super-resolution fluorescence imaging for monitoring nanoparticles within cells. Carbocyanine dyes Alexa Flour 647 labeled mesoporous silica nanoparticles (designated as MSNs-AF647) were constructed as the super-resolution imaging nanoplatform in this work as proof of concept. The MSNs-AF647 were incubated with Hela cells, and the nanoparticles within cells were further monitored by super-resolution fluorescence microscopy. The fluorescence images of MSNs-AF647 within cells captured with the super-resolution fluorescence microscopy showed a much higher spatial resolution than that obtained using conventional fluorescence microscopy, showing that super-resolution fluorescence images can provide more accurate information to locate the nanoparticles at the subcellular levels. Moreover, other functional molecules can be easily loaded into the MSNs-AF647 super-resolution imaging nanoplatform, which suggested that super-resolution fluorescence imaging can further be applied to various bioimaging-related areas, such as imaging-guided therapy, with the aid of the MSNs-AF647 nanoplatform. This study demonstrates that super-resolution fluorescence microscopy offers a highly accurate method to study nanoparticles in the cellular world. We anticipate this strategy may further be applied to research areas such as studying the nanotoxicology and optimization of nanoparticle-based bioprobes or drugs by designing new nanostructured materials with multifunctional properties based on MSNs-AF647.