Print Email Facebook Twitter Surface PEG Grafting Density Determines Magnetic Relaxation Properties of Gd-Loaded Porous Nanoparticles for MR Imaging Applications Title Surface PEG Grafting Density Determines Magnetic Relaxation Properties of Gd-Loaded Porous Nanoparticles for MR Imaging Applications Author Zhang, W. (TU Delft BT/Biocatalysis) Martinelli, J. (TU Delft BT/Biocatalysis) Peters, J.A. (TU Delft BT/Biocatalysis) van Hengst, Jacob M.A. Bouwmeester, Hans (RIKILT Wageningen Research; Wageningen University & Research) Kramer, Evelien (RIKILT Wageningen Research) Bonnet, Celia S. (CNRS) Szeremeta, Frederic (CNRS) Toth, Eva (CNRS) Djanashvili, K. (TU Delft BT/Biocatalysis; CNRS; Loire Valley Institute for Advanced Studies) Date 2017 Abstract Surface PEGylation of nanoparticles designed for biomedical applications is a common and straightforward way to stabilize the materials for in vivo administration and to increase their circulation time. This strategy becomes less trivial when MRI active porous nanomaterials are concerned as their function relies on water/proton-exchange between the pores and bulk water. Here we present a comprehensive study on the effects of PEGylation on the relaxometric properties of nanozeolite LTL (dimensions of 20 × 40 nm) ion-exchanged with paramagnetic GdIII ions. We evidence that as long as the surface grafting density of the PEG chains does not exceed the “mushroom” regime (conjugation of up to 6.2 wt % of PEG), Gd-LTL retains a remarkable longitudinal relaxivity (38 s–1 mM–1 at 7 T and 25 °C) as well as the pH-dependence of the longitudinal and transverse relaxation times. At higher PEG content, the more compact PEG layer (brush regime) limits proton/water diffusion and exchange between the interior of LTL and the bulk, with detrimental consequences on relaxivity. Furthermore, PEGylation of Gd-LTL dramatically decreases the leakage of toxic GdIII ions in biological media and in the presence of competing anions, which together with minimal cytotoxicity renders these materials promising probes for MRI applications. Subject MRI contrast agentsPEGylationporous nanoparticlesrelaxivitywater exchangezeolites To reference this document use: http://resolver.tudelft.nl/uuid:9c75b403-76be-4891-ab15-0e41bed999e7 DOI https://doi.org/10.1021/acsami.7b05912 ISSN 1944-8244 Source ACS applied materials & interfaces, 9 (28), 23458-23465 Part of collection Institutional Repository Document type journal article Rights © 2017 W. Zhang, J. Martinelli, J.A. Peters, Jacob M.A. van Hengst, Hans Bouwmeester, Evelien Kramer, Celia S. Bonnet, Frederic Szeremeta, Eva Toth, K. Djanashvili Files PDF acsami.7b05912.pdf 2.32 MB Close viewer /islandora/object/uuid:9c75b403-76be-4891-ab15-0e41bed999e7/datastream/OBJ/view