Modulating Bioactivity with Gold Nanoparticles

Abstract

Clusters are small ensembles of atoms or molecules. They often show strong quantum effects, depending on the number of particles constituting the cluster. It has been shown that gold clusters made up of exactly eight atoms mimic the electronic structure of noble gases. Au7 and Au9 clusters behave in a similar manner as halogens or alkali metals respectively and are easily ionized. Our working group developed a protocol to efficiently produce and deposit monodisperse clusters without ligand stabilization. To do so, helium is expanded into ultrahigh vacuum, resulting in a beam of superfluid, ultra-cold helium nanodroplets. After ionization the droplets pick up gaseous gold and act as reaction matrix for the formation of gold cluster ions. These ions can be size selected for the exact amount of gold atoms and deposited on various surfaces. Due to their size dependent behavior, this enables us to make directed manipulations to surface properties. Since it has been shown that parameters like surface charge greatly influence cell adhesion behavior, coatings with precisely size selected gold clusters are a promising way to affect bioactivity. In this project, the optimal parameters for depositing, sterilization and coating density as well as the effect of the treated surfaces on a model cell line are investigated by means of transmission electron microscopy, atomic force microscopy, mass spectroscopy and immunofluorescence imaging. We gratefully acknowledge the financial support by funding from EFRE (K-Regio project FAENOMENAL, grant number EFRE 2016-4).