No abstract

Medical applications of nanoparticles (NPs) require understanding of their interactions with living systems in order to control their physiological response, such as cellular uptake and cytotoxicity. When NPs are exposed to biological fluids, the adsorption of extracellular proteins on the surface of NPs, creating the so-called protein corona, can critically affect their interactions with cells. Here, the effect of surface coating of silver nanoparticles (AgNPs) on the adsorption of serum proteins (SPs) and its consequence on cellular uptake and cytotoxicity in mouse embryonic fibroblasts are shown. In particular, citrate-capped AgNPs are internalized by cells and show a time- and dose-dependent toxicity, while the passivation of the NP surface with an oligo(ethylene glycol) (OEG)-alkanethiol drastically reduces their uptake and cytotoxicity. The exposure to growth media containing SPs reveals that citrate-capped AgNPs are promptly coated and stabilized by proteins, while the AgNPs resulting from capping with the OEG-alkanethiol are more resistant to adsorption of proteins onto their surface. Using NIH-3T3 cultured in serum-free, the key role of the adsorption of SPs onto surface of NPs is shown as only AgNPs with a preformed protein corona can be internalized by the cells and, consequently, carry out their inherent cytotoxic activity.

Controlling materials on multiple length scales is one of the most compelling issues in nanotechnology research today. Here we demonstrate that arrays of nanometer-sized aggregates, each made of a few hundred single-molecule magnets derived from Mn12 complexes, can be patterned on large areas by self-organization assisted by stamps on a surface in a dewetting regime. The large length scale is imposed by the motif of the stamp protrusions, and the smaller length scales, viz., the size and distance of the molecular aggregates, are controlled by deposition and growth phenomena occurring in a volume confined beneath the protrusions by capillary forces. The method is general to a variety of molecular materials and substrates because repulsive, as opposed to specific, interactions are required. Our result hints at the possibility of sustainable patterning of single-molecule magnets for ultra-high-density magnetic storage and quantum computing.