In situ Characterization of SiO₂ Nanoparticle Biointeractions Using BrightSilica

Abstract

By adding a gold core to silica nanoparticles (BrightSilica), silica‐like nanoparticles are generated that, unlike unmodified silica nanoparticles, provide three types of complementary information to investigate the silica nano‐biointeraction inside eukaryotic cells in situ. Firstly, organic molecules in proximity of and penetrating into the silica shell in live cells are monitored by surface‐enhanced Raman scattering (SERS). The SERS data show interaction of the hybrid silica particles with tyrosine, cysteine and phenylalanine side chains of adsorbed proteins. Composition of the biomolecular corona of BrightSilica nanoparticles differs in fibroblast and macrophage cells. Secondly, quantification of the BrightSilica nanoparticles using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) micromapping indicates a different interaction of silica nanoparticles compared to gold nanoparticles under the same experimental conditions. Thirdly, the metal cores allow the investigation of particle distribution and interaction in the cellular ultrastructure by cryo nanoscale X‐ray tomography (cryo‐XT). In 3D reconstructions the assumption is confirmed that BrightSilica nanoparticles enter cells by an endocytotic mechanism. The high SERS intensities are explained by the beneficial plasmonic properties due to agglomeration of BrightSilica. The results have implications for the development of multi‐modal qualitative and quantitative characterization in comparative nanotoxicology and bionanotechnology.

X-ray tomography shows the varying three-dimensional morphology of gold nanoaggregates in the cellular ultrastructure

“…The three incubation conditions were chosen based on results of other microscopic methods that we have used to characterize nanoparticles and their interaction in the cell lines used here. 16,28,45 For vitrication, SXT grids were washed three times with PBS buffer, blotted with lter paper and snap-frozen on a plunge freezer using liquid ethane. The cell monolayer with a thickness of up to about 10 mm was examined in the X-ray microscope equipped with a cryostage, allowing for the investigation of cells in their native state.…”

“…25 In cryo-XM images, many different cellular organelles and membranes can be resolved, 17,26,27 enabling the localization of nanoparticles in the cellular ultrastructure with a resolution of a few tens of nanometers. 16,[28][29][30] Here, the cellular uptake and 3D distribution of gold nanoparticles in the cell under different conditions are observed by synchrotron so X-ray tomography (SXT) using a photon energy of 510 eV. As will be discussed, nanoscale SXT can, in addition to the characterization of the nanoparticle-incubated cells, be applied for the quantitative analysis of the average particle properties, the statistical distributions for the level of uptake and the size of nanoparticle aggregates inside the cells.…”

Surface-enhanced hyper Raman hyperspectral imaging and probing in animal cells

“…From nanotomography experiments conducted with the same macrophage cell line under very similar incubation conditions for 3 h (ref. 33) and for longer times 40 we know that the morphology of silver nanoaggregates changes inside the phagosomes over time. It is very likely, that the longer processing time of the 2-NAT SEHRS labels leads to nanoaggregate geometries that support stronger SEHRS enhancement, yielding higher signals from the 2-NAT labels than from the pMBA labels.…”

Inductively coupled plasma mass spectrometry based platforms for studies involving nanoparticle effects in biological samples

“…Plants, such as tobacco and wheat, rice, radish, and sweet basil, have been analyzed using LA‐ICP‐MS. This technique has also been used to analyze other biological samples such as Danio rerio and Daphnia , Manduca sexta , cells, and tissues . Despite the advantages of LA‐ICP‐MS, matrix‐matching, quantitative analysis, particularly in terms of imaging, and the number of analytical/biological replicates pose a challenge in providing reliable analytical results.…”