Synthesis and functionalization of magnetite nanoparticles with aminopropylsilane and carboxymethyldextran

Magnetite nanoparticles were functionalized with carboxymethyldextran ( CMDx) covalently attached to the particles to prevent polymer desorption in biomedical applications. Carbodiimide chemistry was used to react carboxylic groups ( - COOH) present in the CMDx molecule with amine end groups ( NH2) previously grafted onto the nanoparticle surface by condensation of aminopropylsilane ( APS) molecules. This method produces highly stable suspensions of magnetite nanoparticles with electrostatic and steric repulsion and no particle precipitation in the presence of electrolytes.