Synthesis, structure, and biological effects of ultrasmall (1-2 nm) bimetallic silver-platinum nanoparticles

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In the preceding project we synthesized bimetallic nanoparticles (around 10 nm) on the basis of silver and different noble metals. We have carried out comparative investigations on their microstructure and their biological activity. In this proposal, we want to focus on ultrasmall bimetallic nanoparticles (about 2 nm) on the basis of silver and platinum (AgPt). These shall be prepared both in monometallic and alloyed form.Such ultrasmall nanoparticles are especially mobile in cells and have a size which is comparable to biological macromolecules like proteins. Their biological pathways and effects are only poorly investigated and understood. We want to address the following questions:Which synthetic routes lead to homogeneous samples of ultrasmall AgPt nanoparticles with respect to size and internal domain structure?By which mechanisms (e.g. endocytosis or passive transport) are ultrasmall AgPt nanoparticles entering cells? How are they transported inside the cells and where are they localized? Here, their ability to penetrate the cell nucleus is especially interesting due to the presence of silver (genotoxicity).Which cell-biological effects are caused by the bimetallic nanoparticles? We want to focus on the mechanistic analysis and the cell activation, up to cell death.Which antimicrobial effects are caused by ultrasmall AgPt nanoparticles? We want to focus on the cell membrane fluidity and the activity against biofilms. In this context we also want to analyse to which degree the nanoparticles are taken up by bacteria.How can we correlate the biological effects with the release of silver ions and the uptake by tissue cells and bacteria?Due the presence of antibacterial silver, the system AgPt has clinical relevance. A central hypothesis is the assumption that alloyed silver-platinum nanoparticles have an enhanced antimicrobial effect.