The high-power ultrasonic irradiation of preformed magnetite (Fe(3)O(4)) nanoparticles in the presence of monoelectronic Ce-containing ceric ammonium nitrate [Ce(IV)(NH(4))(2)(NO(3))(6)] oxidant in MeCOMe afforded hydrophilic 50 nm-sized colloidal, highly stable maghemite (gamma-Fe(2)O(3)) nanoparticles. An "inorganic" Ce atom doping of the NP surface has been proposed in order to rationalize the observed nanoparticle antiaggregation phenomenon. Quite importantly, this method did not require the use of any organic ligand and/or polymer for the passivation of the nanoparticle surface.

Nanocomposites (NCs) that are made magnetically responsive in controlled conditions attract continuing interest for their added magnetic properties. In this study, we report on the preparation and full characterization of a multifunctional NC composed of magnetic γ-Fe(2)O(3) nanoparticles (NPs) covalently attached to the surface of polyaminated (polyNH(2)) poly(2,6-di-pyrrol-1-yl-hexanoic acid) (pDPL) nanotubes (NTs). Such a hybrid conducting polymer iron oxide maghemite γ-Fe(2)O(3)@pDPL NC built specifically on covalent bonding has never been reported. The maghemite γ-Fe(2)O(3) NPs were prepared using an innovative ultrasound-assisted Ce(3+) doping process, resulting in polycarboxylation of the NP surface useful for control of aggregation and derivatization of functionality. The second component of the NC, i.e. polyNH(2)-modified pDPL NTs, was prepared from an acid functional pyrrole species followed by amine modification. The resulting innovative γ-Fe(2)O(3)@pDPL NC can be viewed as a multifunctional nanomaterial since it possesses both types of derivatization, i.e. polyCOOH (NPs) and polyNH(2) (NTs) combined with magnetic responsivity.