PEGylated gold nanoparticles: Stability, cytotoxicity and antibacterial activity

Designing safe nanomaterials is nowadays a critical issue. A way to prepare PEGylated Au NPs by sputtering of Au into pure (PEG), thiol (PEG-SH) and amine terminated polyethylene glycols (PEG-NH2) was explored. Structural characterizations, aging and thermal stability were performed using transmission electron microscope (TEM/HRTEM) and UV-vis spectroscopy. By TEM we observed that spherical Au NPs were successfully prepared with average diameter of 1.5-5.9 nm. HRTEM revealed that a majority of them is rather of a round or irregular shape with a frequent multiple twinning. Dynamic light scattering as well as TEM confirmed that Au NPs have monodal size distribution. According to atomic absorption spectroscopy, concentration of gold increases with sputtering time and does not change with aging time. PEG-SH exhibited loss of SPR absorption band in UV-vis spectrum because of the small NP size (1.5 nm). PEG and PEG-NH2 showed good thermal and aging stability. No significant antibacterial effect of any type of the studied Au NPs has been discovered. Cytotoxic effect on osteoblasts was determined only with the highest concentration of Au NP with PEG and PEG-NH2 stabilization. Au NPs stabilized by PEG-SH showed the overall optimal physical and biological properties for drug delivery applications.