Paper Abstract

Quantifying intracellular trafficking of silica-coated magnetic nanoparticle in live single cells by site-specific direct stochastic optical reconstruction microscopy
Background: Nanoparticles have been used for biomedical applications, including drug delivery, diagnosis, and imaging based on their unique properties derived from small size and large surface-to-volume ratio. However, concerns regarding unexpected toxicity due to the localization of nanoparticles in the cells are growing. Herein, we quantifed the number of cell-internalized nanoparticles and monitored their cellular localization, which are critical factors for biomedical applications of nanoparticles. Methods: This study investigates the intracellular trafcking of silica-coated magnetic nanoparticles containing rho?damine B isothiocyanate dye [MNPs@SiO2(RITC)] in various live single cells, such as HEK293, NIH3T3, and RAW 264.7 cells, using site-specifc direct stochastic optical reconstruction microscopy (dSTORM). The time-dependent subdif?fraction-limit spatial resolution of the dSTORM method allowed intracellular site-specifc quantifcation and tracking of MNPs@SiO2(RITC). Results: The MNPs@SiO2(RITC) were observed to be highly internalized in RAW 264.7 cells, compared to the HEK293 and NIH3T3 cells undergoing single-particle analysis. In addition, MNPs@SiO2(RITC) were internalized within the nuclei of RAW 264.7 and HEK293 cells but were not detected in the nuclei of NIH3T3 cells. Moreover, because of the treatment of the MNPs@SiO2(RITC), more micronuclei were detected in RAW 264.7 cells than in other cells. Conclusion: The sensitive and quantitative evaluations of MNPs@SiO2(RITC) at specifc sites in three diferent cells using a combination of dSTORM, transcriptomics, and molecular biology were performed. These fndings highlight the quantitative diferences in the uptake efciency of MNPs@SiO2(RITC) and ultra-sensitivity, varying according to the cell types as ascertained by subdifraction-limit super-resolution microscopy.