Speaker
Description
Silica nanoparticles (SiNPs) have emerged as promising nanoplatforms for both the diagnosis and treatment of diseases. A comprehensive understanding of nanoparticle–cell interactions is essential for advancing nanomedicine, yet most studies rely on static observations and lack volumetric information under near-native conditions. Among the factors influencing cellular uptake, the formation of the protein corona plays a key role in modulating nanoparticle behavior and reducing cytotoxicity. Here, we establish a synchrotron-based correlative X-ray microscopy framework to investigate how nanoparticle concentration and successive cell-division cycles govern the intracellular fate of SiNPs in macrophages. Fluorescent SiNPs internalized by RAW 264.7 macrophages were analyzed using a multimodal imaging workflow combining cryo-soft X-ray tomography (cryo-SXT), cryogenic structured illumination microscopy (cryo-SIM), coherent X-ray ptychography, and confocal fluorescence microscopy. Experiments were conducted at the B24 beamline of Diamond Light Source, the Mistral beamline of ALBA Synchrotron, and the Cateretê beamline of Sirius. Correlative cryo-SXT and cryo-SIM reveal a concentration-dependent redistribution of nanoparticle-containing vesicles from peripheral endosomal regions toward the perinuclear area. Cryo-SIM confirms persistent vesicular confinement. At higher concentrations, nanoparticles approach the nuclear region through vesicles associated with nuclear-envelope invaginations, an event not observed at lower concentrations. Successive cell divisions further redistribute the intracellular nanoparticle load and promote stable perinuclear clustering, indicating a long-term sequestration pathway. Confocal fluorescence microscopy supports these observations at the population level, revealing concentration-dependent increases in ATTO-633 signal intensity and progressive clustering over time. After two doubling times, fluorescence is predominantly localized in the perinuclear region, suggesting accumulation mediated by late endocytic processes or vesicle maturation. Coherent X-ray ptychography further reveals nanoscale deformations of the nuclear envelope associated with perinuclear vesicle accumulation. These results establish correlative synchrotron-based multimodal imaging as a powerful multiscale platform for resolving the dynamic intracellular fate of nanoparticles, with important implications for the design of safer and more effective nanomedicine strategies.