Functionalized nanoparticles with long-term stability in biological media

A study was conducted to demonstrate a surface engineering approach to produce ultrafine, monodisperse, hydrophilic, and functionalized oxide nanomaterials that displayed long-term colloidal stability in biological media. The approach was demonstrated with iron oxide nanoparticles as the model system. The oleic acid-coated nanoparticles (NP-OA) were synthesized through thermal decomposition of iron oleate complex. The NP-OA were reacted with triethoxysilylpropysuccinic anhydride (SAS) to form SAS-coated nanoparticles (NP-SAS) through a ligand-exchange and condensation process. Amine-functionalized PEG was attached to NP-SAS through N,N'- dicyclohexylcarbodiimide (DCC)-mediated coupling reaction to yield PEGlated nanoparticles (NP-SAS-PEG-NH2). It was also observed that the PEG coating was able to prevent nanoparticles from agglomeration and protein adsorption.