Protein Corona Formation on Magnetic Nanoparticles Conjugated with Luminescent Europium Complexes

The evaluation of the nanoparticles interactions with blood plasma enables a first and important insight on the organization of the adsorbed protein layer. In this context, we studied the formation of protein corona on magneto-luminescent Fe3O4@calix-Eu(TTA) nanoparticles in human plasma. The difference in the surface chemistry of F3O4 functionalized with calixarene (+30 mV zeta-potential) and europium (III) thenoyltrifluoroacetonate (Eu3+-TTA) complex (+7.4 mV zeta-potential) affected the colloidal stability and hard corona composition of the nanoparticles, which were monitored by SDS-PAGE gel electrophoresis, differential centrifugal sedimentation analyses and luminescence spectroscopy. Strikingly, after conjugation with Eu3+ TTA complex, the magnetic nanoparticles show lower adsorption affinity to proteins at higher blood plasma concentration. Moreover, the Eu3+ compound is featured with the narrow emission lines of D-5(0)-> F-7(J) (J=0-4) transitions, imparting additional characteristics to bifunctional nanoparticles that were used as probes to evaluate the protein corona formation.