Monitoring the distribution of internalized silica nanoparticles inside cells via direct stochastic optical...

Understanding the exact localization of nanoparticles within cell is of particular importance for rational design of high-effective nanomedicines. In the present study, direct stochastic optical reconstruction microscopy (dSTORM) is employed to elucidate the precise localization of nanoparticles within cells owing to its superiority of nanometric resolution, multicolour ability and minimal invasiveness. The localization of the Cy5 labelled mesoporous silica nanoparticles (MSNs-Cy5) in MCF-7 cells are monitored by dSTORM and conventional fluorescence microscopy, respectively. The dSTORM images demonstrate much higher spatial resolution for locating MSNs-Cy5 within cells compared to that of the conventional fluorescence images. Moreover, the distribution of MSNs-Cy5 within three cell lines over time are obtained. For the MCF-7 and HeLa cells, MSNs-Cy5 nanoparticles distribute nearly all around the cytoplasm after 5 h incubation. In contrast, MSNs-Cy5 nanoparticles within NIH 3T3 cells are quite different that they are found to be either attached to or embedded into cell membranes, without penetrating into the cytoplasm. Overall, we provide a practical method to reveal the in situ precise imaging of nanoparticles in cells with nanometric resolution precision. This method may open up new opportunities for organelle-specific targeting drug delivery to achieve maximum therapeutic benefit.