Correlation between physicochemical properties of superparamagnetic iron oxide nanoparticles and their reactivity with hydrogen peroxide

The present study focuses on the effects of the physicochemical properties of superparamagnetic PEG-modified, positively charged, and negatively charged iron oxide nanoparticles (SPIONs) on their reactivity with hydrogen peroxide. Our hypothesis was that the reactivity of SPIONs in this reaction would depend on their surface properties. The comparative study of the nanoparticles with DLS and TEM revealed the average sizes of PEG-modified, positively charged, and negatively charged SPIONs. We observed that the reactivity of negatively charged SPIONs with hydrogen peroxide was less than that of positively charged SPIONs and that of these second nanoparticles was less than that of PEG-modified SPIONs. This difference in the reactivity of these SPIONs with hydrogen peroxide was attributed to the presence of carboxyl or amine groups on their surface. However, the values of the rate constants of the reactions of PEG-modified, positively charged, and negatively charged SPIONs with hydrogen peroxide showed that the reaction of negatively charged SPIONs with hydrogen peroxide was more rapid than that of PEG-modified SPIONs and the reaction of these second SPIONs with hydrogen peroxide was more rapid than that of positively charged SPIONs. The surface study of the SPIONs using XPS showed that the high-resolution spectra of these nanoparticles changed after reaction with hydrogen peroxide, which indicates their surface modifications. These investigations can help develop more appropriate nanoparticles with controlled physicochemical properties. Key words: superparamagnetic iron oxide nanoparticles, FTIR, DLS, SEM, XPS, oxygen uptake. La presente etude porte sur les effets des proprietes physicochimiques de nanoparticules d'oxyde de fer superparamagetique (SPION, acronyme anglais pour superparamagnetic iron oxide nanoparticles) soit modifiees par le polyethylèneglycol (PEG), chargees positivement ou chargees negativement sur leur reactivite face au peroxyde d'hydrogène. Nous avions pose l'hypothèse que la reactivite des SPIONs dans cette reaction devrait dependre de leurs proprietes de surface. L'etude comparative de ces nanoparticules par diffusion dynamique de la lumière (DDL) et microscopie electronique en transmission (MET) a permis de determiner la taille moyenne des SPIONs modifiees par le PEG, chargees positivement et chargees negativement. Nous avons observe que la reactivite des SPIONs chargees negativement à l'egard du peroxyde d'hydrogène etait moindre que celle des SPIONs chargees positivement, et que celle de ces dernières nanoparticules etait moindre que celle des SPIONs modifiees par le PEG. Nous avons attribue cette difference de reactivite entre ces SPION à l'egard du peroxyde d'hydrogène à la presence de groupes carboxyle et amine à leur surface. Cependant, les valeurs de la constante de vitesse des reactions des SPION-PEGs, des SPIONs chargees positivement et des SPIONs chargees negativement avec le peroxyde d'hydrogène ont montre que la reaction des SPIONs chargees negativement avec le peroxyde d'hydrogène etait plus rapide que celle des SPION-PEGs et que la reaction de ces dernières avec le peroxyde d'hydrogène etait plus rapide que celle des SPIONs chargees positivement. L'etude de surface des SPIONs à l'aide de la spectroscopie de photoelectrons X (XPS) a montre que les spectres à haute resolution de ces nanoparticules avaient change après la reaction avec le peroxyde d'hydrogène, ce qui est revelateur de modifications de la surface. Ces recherches pourront permettre la mise au point de nanoparticules plus appropriees aux proprietes physicochimiques modulables. [Traduit par la Redaction] Mots-cles : nanoparticules d'oxyde de fer superparamagnetique, FTIR, DDL, MEB, XPS, consommation d'oxygène.
Introduction The surface modification of nanoparticles (NPs) has attracted significant interest over the last decades. NPs consist of a core and shell with dimensions of 1-100 nm that result in [...]