title: Selective anchoring of Gd(III) chelates on the external surface of organo-modified mesoporous silica nanoparticles: a new chemical strategy to enhance relaxivity.
abstract: The optimization of the physico-chemical properties of both Gd(III) chelates and nanocarriers is of great importance for the development of effective nanosystems for magnetic resonance imaging (MRI) applications. With this aim, macrocyclic Gd(III) chelates were selectively attached to the pendant amino groups exposed to the external surface of spheroidal mesoporous silica nanoparticles (MSNs). This was achieved by treating the metal complexes with MSNs that contained the templating surfactant molecules confined within the silica channels (hexadecyltrimethylammonium (CTA)/MSN), followed by extraction of the surfactant. The nanoparticles showed greatly improved (1)H relaxometric efficiency relative to corresponding systems that also feature Gd(III) chelates conjugated inside the pores. A further significant relaxivity enhancement was observed after chemical transformation of the free amino groups into amides. The ionic relaxivity of the final nanoparticles (r(1p) =79.1 mM(-1) s(-1); 0.5 T, 310 K) is one of the highest reported so far.
authors.affiliation: Dipartimento di Scienze e Innovazione Tecnologica, Universitá del Piemonte Orientale Amedeo Avogadro, Viale Teresa Michel 11, 15121 Alessandria, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Carniato
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Tei
authors.forename: Aldo
authors.initials: A
authors.lastname: Arrais
authors.forename: Leonardo
authors.initials: L
authors.lastname: Marchese
authors.forename: Mauro
authors.initials: M
authors.lastname: Botta
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D003287:Contrast Media / Q000138:chemical synthesis / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry; D005682:Gadolinium / Q000737:chemistry*; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry; D008279:Magnetic Resonance Imaging; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D003287:Contrast Media; D056831:Coordination Complexes; D006573:Heterocyclic Compounds, 1-Ring; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; D012822:Silicon Dioxide; D005682:Gadolinium