Nanotoxicology edition:3 location:Edinburgh date:2-4 June 2010
For the investigation of the interaction of nanoparticles with bio-molecules, cells, organs and animal models there is a need for well characterized nanoparticle suspensions. We present the preparation of monodisperse amorphous silica nanoparticles (SNP) suspended in physiological media that are sterile and stable against aggregation. SNP sols with various particle sizes were prepared under sterile conditions using either ammonia (Stöber process: 16, 19, 60, 74, 104, 335 nm) or lysine catalyst (2, 26, 34, 36 nm). The series was complemented with commercial silica sols (Ludox®: 11, 14, 15 nm). A series of Stöber silica was prepared with variation in microporosity (0 to 71 µl/g). Silica nanoparticle suspensions were purified by dialysis and dispersed without using any dispersing agent into cell culture media.
Particle sizes in suspension were determined by dynamic light scattering. The SNP sols in cell culture medium were stable for several days. SNP morphology, surface area and porosity were characterized using electron microscopy and nitrogen adsorption. The surface reactivity SNP was investigated using electron paramagnetic resonance. The catalytic activity per square meter of exposed silica surface area was found to be independent of particle size and preparation method.
Using this unique series of nanoparticle suspensions the relationship between cytotoxicity and particle size was investigated using human endothelial and mouse monocyte-macrophage cells. The cytotoxicity of the SNP was strongly dependent on particle size and cell type. This unique methodology and the collection of well-characterized SNP will be useful for further in vitro and in vivo studies exploring the physicochemical determinants of nanoparticle toxicity.