Quantitative cellular in vitro nanoparticle uptake measurements are possible with a large number of different techniques, however, all have their respective restrictions. Here, we demon-strate the application of synchrotron-based X-ray fluorescence imaging (XFI) on prostate tumor cells, which have internalized differently functionalized gold nanoparticles. Total nanoparticle uptake on the order of a few hundred picograms could be conveniently observed with microsamples consisting of only a few hundreds of cells. A comparison with mass spectroscopy quantification is provided, experimental results are both supported and sensitivity limits of this XFI approach ex-trapolated by Monte-Carlo simulations, yielding a minimum detectable nanoparticle mass of just 5 pg. This study demonstrates the high sensitivity level of XFI, allowing non-destructive uptake measurements with very small microsamples within just seconds of irradiation time.
A study
on the surface chemistry of gold nanoparticles (AuNPs)
utilizing gel electrophoresis is presented. The molecular design of
targeting and stabilizing PEG ligands allows one to combine them in
mixed ligand layers with control of relative composition. For all
tested targeting and control ligands, coadsorption of PEG significantly
reduces protein adsorption and matrix effects of cell media as compared
to conjugates without PEG. Introducing carboxylic acid groups into
the PEG ligand layer does not lead to increased protein adsorption
as shown with carboxylic acid terminated PEG ligands. The controlled
adsorption of PEG ligands with different molecular weights is used
to disentangle the effects of particle charge and hydrodynamic diameter.
Taken together, this study provides directions for the functionalization
of nanoparticles to obtain conjugates which are well-defined in terms
of composition and colloidally stable in complex media. This is in
particular relevant for targeting applications and cell experiments.
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