The understanding of the interaction between nanoparticles and cells is of crucial importance for many applications. Gold nanoparticles have gained popularity as model nanoparticle and as therapeutic nanocarriers. Recent observations in biological systems suggest that changing size, shape and surface coating of gold nanoparticles can affect their nonspecific uptake in cells. However, little has been reported on how cellular uptake of gold nanoparticles can be influenced by hydrophobicity. In our work, we investigate the effect of hydrophobic/hydrophilic balance on the uptake of polymer coated gold nanoparticles by dendritic cells (DCs). DCs are the most important class of antigen presenting cells of our immune system. Polymers with varying hydrophilic-to-hydrophobic ratio were synthesized via Reversible Addition Fragmentation Chain Transfer (RAFT) polymerization, using different monomer ratios of 2-hydroxyethylacrylate to methoxyethylacrylate. Surface modification of citrate-stabilized gold nanoparticles with polymers was achieved by spontaneous ligand exchange in aqueous medium. After separation of free polymers from gold nanoparticles by centrifugation, 4 types of polymers coated gold nanoparticles with increasing hydrophobicity were obtained. Transmission electron microscopy (TEM) revealed monodisperse nanoparticles with a core size of 13 nm, and a distinct corona surrounding the gold nanoparticles, thereby indicating the successful modification with polymers. Mouse dendritic cells (i.e. DC2.4) were used to investigate the difference in cellular uptake of the 4 types of polymer-coated gold nanoparticles. After overnight incubation with the gold nanoparticles, cellular uptake of nanoparticles was analyzed via flow cytometry by measuring the shift in side scatter that is caused by internalized or cell surface bound gold nanoparticles. Focused ion beam scanning electron microscopy was further used to confirm the intracellular localization of the nanoparticles. A strong influence of the polymer coating on the cellular uptake was observed, with higher percentages of nanoparticles positive cells with increasing content of the hydrophobic methoxyethylacrylate comonomer in the polymer coating.

Cellular uptake of polymer coated gold nanoparticles with tailored hydrophilic-to-hydrophobic ratio

248th National Meeting (2014)

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