Super-resolution fluorescence microscopy and cryogenic soft X-ray tomography enable intracellular localization of stable nanoparticles

Abstract

Cubosomes have emerged as a powerful platform for cancer treatment due to their biocompatibility and ability to encapsulate hydrophilic/lipophilic drugs, providing controlled drug release. While investigating these nanoparticles' stability and intracellular localization is essential for advancing them as clinically efficient nanomedicine, such studies are still lacking, and those available do not provide a reliable and comprehensive understanding. Here, we analyze cubosomes stability in complex media and conduct a pioneering study on visualizing their intracellular localization using a combination of correlative high-resolution three-dimensional fluorescence microscopy and soft X-ray tomography (synchrotron-based technique) at cryogenic temperatures, leveraging natural cellular contrast. Our studies revealed that cubosomes were stable in complex media, confirming their localization within lysosomes. In addition to being crucial for ensuring the advancement of cubosomes for therapeutic purposes, this study paves the way for defining the intracellular localization of other nanoparticles in greater detail, utilizing synchrotron-based 3D imaging techniques. Finally, we confirm the efficacy of doxorubicin-incorporated cubosomes against breast cancer cells.