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Relaxivity Enhancement of Ditopic Bishydrated Gadolinium(III) Complexes Conjugated to Mesoporous Silica Nanoparticles
Author(s) -
Carniato Fabio,
Tei Lorenzo,
Martinelli Jonathan,
Botta Mauro
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201800041
Subject(s) - chemistry , gadolinium , chelation , nanoparticle , conjugated system , mesoporous silica , ethylene glycol , aqueous solution , mesoporous material , chemical stability , peg ratio , covalent bond , inorganic chemistry , chemical engineering , polymer , organic chemistry , catalysis , engineering , finance , economics
Dinuclear Gd 3+ complexes containing thermodynamically stable and bishydrated GdAAZTA (AAZTA = 6‐amino‐6‐methylperhydro‐1,4‐diazepinetetraacetic acid) chelates were covalently linked to the surfaces of mesoporous silica nanoparticles and decorated with poly(ethylene glycol) (PEG 5000 ) molecules. The surface and textural properties of the samples were analyzed. A detailed 1 H NMR relaxometric characterization as a function of the applied magnetic‐field strength was performed for the conjugated systems in aqueous solutions to evaluate their efficacy as potential magnetic resonance imaging (MRI) diagnostic probes. The samples showed enhanced longitudinal relaxivity values (37.5 m m –1 s –1 per ion at 0.7 T and 310 K) compared with those of the free complex (+270 %) and related nanosystems based on monohydrated Gd 3+ chelates (+42 %). The relaxivity gain is the result of the rational design of the ditopic complex, as it ensures an increased hydration state ( q = 2), improvement of the rotational dynamics and a fast rate of water exchange between the inner coordination sphere and the bulk. These favourable properties are obtained without compromise to the high thermodynamic stability and kinetic inertness of the chelating units.