Quantifying Intracellular Nanoparticle Distributions with Three-Dimensional Super-Resolution Microscopy

Abstract

Super-resolution microscopy can transform our understanding of nanoparticle−cell interactions. Here, we established a super-resolution imaging technology to visualize nanoparticle distributions inside mammalian cells. The cells were exposed to metallic nanoparticles and then embedded within different swellable hydrogels to enable quantitative three-dimensional (3D) imaging approaching electron-microscopy-like resolution using a standard light microscope. By exploiting the nanoparticles' light scattering properties, we demonstrated quantitative label-free imaging of intracellular nanoparticles with ultrastructural context. We confirmed the compatibility of two expansion microscopy protocols, protein retention and pan-expansion microscopy, with nanoparticle uptake studies. We validated relative differences between nanoparticle cellular accumulation for various surface modifications using mass spectrometry and determined the intracellular nanoparticle spatial distribution in 3D for entire single cells. This super-resolution imaging platform technology may be broadly used to understand the nanoparticle intracellular fate in fundamental and applied studies to potentially inform the engineering of safer and more effective nanomedicines.

PExM: polyplex expansion microscopy for cell trafficking studies

“…One interesting possibility is expansion microscopy (ExM), a powerful and accessible high-resolution imaging strategy where biomolecules are anchored to a swellable hydrogel that enables samples to be expanded by a factor of four to twenty, 12 providing high resolutions with a conventional microscope. 13,14 ExM was first proposed in 2015, by Chen, Tillberg, and Boyden, devoted to the expansion of biological molecules. 15 Further work in 2022, by White and coworkers described the adaptation of this tech-nique for the study of lipid molecules.…”

DNAzymes-Embedded Framework Nucleic Acids (FNAzymes) for Metal Ions Imaging in Living Cells

“…These methods are commonly cumbersome and cell-destructive, and thus, they are not suitable for live-cell detection. In recent years, fluorescent sensors have turned out to be powerful tools for intracellular and super-resolution imaging [10][11][12]. Great efforts have been focused on the development of fluorescent probes for the imaging of intracellular metal ions such as Ca 2+ , Cu 2+ , Zn 2+ , and Mg 2+ [13][14][15].…”