Highly PEGylated silica nanoparticles: “ready to use” stealth functional nanocarriers

The peculiar properties of silica nanoparticles make them well suited to the development of smart nanomaterials for medicine. Here we report a new procedure to prepare doped and PEGylated silicabased nanoparticles. Thus, a complex multifunctional system is obtained simply by a one-pot reaction followed by a straightforward purification procedure. Control of the nanoparticles final size is obtained by carefully choosing reactants and conditions. Moreover, reactive functional groups necessary to allow subsequent bioconjugation are easily introduced in the PEG coating by the same procedure. Unprecedented high-density surface coating is obtained and this successfully stabilizes the nanoparticles against aggregation both in saline solution and in the presence of serum proteins. The absence of cytotoxicity and "stealth" behaviour toward phagocytic capture by human macrophages has been demonstrated and this enables such nanosystems as candidates for the development of drug delivery agents.