Magnetic, optical and relaxometric properties of organically coated gold-magnetite (Au-Fe3O4) hybrid nanoparticles for potential use in biomedical applications

We presentthemagnetic,opticalandrelaxometricpropertiesofmultifunctionalAu–Fe3O4 hybrid
nanoparticles(HNPs),aspossiblenovelcontrastagents(CAs)formagneticresonanceimaging(MRI).
The HNPshavebeensynthesizedbywetchemicalmethodsinheterodimerandcore–shellgeometries
and cappedwitholeylamine.StructuralcharacterizationofthesampleshavebeenmadebyX-ray
diffractionandtransmissionelectronmicroscopy,whilemagneticpropertieshavebeeninvestigated
by meansofSuperconductingQuantumInterferenceDevice-SQUIDmagnetometryexperiments.
As requiredforMRIapplicationsusingnegativeCAs,thesamplesresultedsuperparamagneticatroom
temperatureandwellabovetheirblockingtemperatures.Opticalpropertieshavebeeninvestigatedby
analyzingtheopticalabsorbtionspectracollectedinUV–visibleregion.Relaxometricmeasurements
have beenperformedonorganicsuspensionsofHNPsandNuclearMagneticResonance(NMR)
dispersioncurveshavebeenobtainedbymeasuringthelongitudinal1/T1 and transverse1/T2 relaxation
ratesofsolventprotonsintherange10kHz/300MHzatroomtemperature.NMRrelaxivities r1 and r2
have beencomparedwithENDOREMs, oneofthecommercialsuperparamagneticironoxidebased
MRI contrastagents.MRIcontrastenhancementefficiencieshavebeeninvestigatedalsobyexamining
T2-weightedMRimagesofsuspensions.Theexperimentalresultssuggestthatthenanoparticles’
suspensionsaregoodcandidatesasnegativeCAs.