Iron oxide nanoparticles (IONPs), have been coated with two different polymers, i.e.poly(oligoethylene glycol) methyl ether acrylate (P(OEG-A) and poly(dimethylaminoethyl acrylate) (P(DMAEA)).The polymers were attached to the nanoparticle surface, with the aim of creating an intemal layer of P(DMAEA) and an outer shell of P(OEG-A).These hybrid organic/inorganic particles proved to be stable in both water and 50 v% fetal bovine serum (FBS).Zeta potential measurements confirmed that P(OEG-A) chains effectively mask the positive charge originating from P(DMAEA) thereby limiting protein adsorption on these particles as proven by Bradfords assays.The internal cationic layer, P(DMAEMA), was exploited for the complexation of siRNA, thereby generating IONP siRNA nano-carriers with anti-fouling P(OEG-A) shells.