Quantitative analysis of nanoparticle internalization in mammalian cells by high resolution X-ray microscopy

Abstract

BackgroundQuantitative analysis of nanoparticle uptake at the cellular level is critical to nanomedicine procedures. In particular, it is required for a realistic evaluation of their effects. Unfortunately, quantitative measurements of nanoparticle uptake still pose a formidable technical challenge. We present here a method to tackle this problem and analyze the number of metal nanoparticles present in different types of cells. The method relies on high-lateral-resolution (better than 30 nm) transmission x-ray microimages with both absorption contrast and phase contrast -- including two-dimensional (2D) projection images and three-dimensional (3D) tomographic reconstructions that directly show the nanoparticles.ResultsPractical tests were successfully conducted on bare and polyethylene glycol (PEG) coated gold nanoparticles obtained by x-ray irradiation. Using two different cell lines, EMT and HeLa, we obtained the number of nanoparticle clusters uptaken by each cell and the cluster size. Furthermore, the analysis revealed interesting differences between 2D and 3D cultured cells as well as between 2D and 3D data for the same 3D specimen.ConclusionsWe demonstrated the feasibility and effectiveness of our method, proving that it is accurate enough to measure the nanoparticle uptake differences between cells as well as the sizes of the formed nanoparticle clusters. The differences between 2D and 3D cultures and 2D and 3D images stress the importance of the 3D analysis which is made possible by our approach.

X-ray imaging of tumor growth in live mice by detecting gold-nanoparticle-loaded cells

“…The one-pot, reducing agent free synthesis produced clean and monodisperse AuNPs with high colloidal stability. Optical microscopy and TEM tests on cell specimens in vitro confirmed that the AuNPs were internalized by endocytosis303132 and did not penetrate into the cell nuclei. The nanoparticles were biocompatible with the cell lines we tested up to a concentration of 2.0 mM in the culture media.…”

“…Our own research indicated that different cancer cell lines can internalize large amounts AuNPs without affecting viability303132.…”

Gold nanoparticle enhanced proton therapy: A Monte Carlo simulation of the effects of proton energy, nanoparticle size, coating material, and coating thickness on dose and radiolysis yield

“…A 5 MeV proton energy was chosen as lower proton energies are common in the Bragg peak which is colocated with the tumor in proton therapy and 5 MeV was the lowest energy for which a large self‐absorption loss was not observed. The nanoparticle sizes simulated cover the range of typical single nanoparticle sizes as well as the size of nanoparticle aggregations observed in in vitro experiments …”

X-ray computed tomography of wood-adhesive bondlines: attenuation and phase-contrast effects

“…Achievable XCT image resolution ranges from the millimeter to nanometer scale depending on equipment, experimental parameters, and the size and volume of the imaged specimen (Chen et al 2011;Graafsma and Martin 2008;Ketcham and Carlson 2001;Kinney and Nichols 1992). Although a well-established technique, micro-XCT has only recently been applied to study the structure and behavior of wood and wood-based composites (Hass et al 2010(Hass et al , 2012Kamke et al 2014;Mannes et al 2009aMannes et al , b, 2010Mayo et al 2010;Modzel 2009;Modzel et al 2011;Muszyński 2009;Paris et al 2014;Standfest et al 2012;Steppe et al 2004;Trtik et al 2007), this is the theme of the present work.…”