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Exploring the influence of internal surface modification of paramagnetic mesoporous silica nanoparticles on MRI relaxation dynamics
File(s)
d6tb01037g.pdf (1.07 MB)
Published version
Author(s)
Wells, Connor JR
Rizk, Marwa MI
Manning, Joseph RH
Winning, Danielle
Brambila, Carlos
Type
Journal Article
Abstract
Paramagnetic mesoporous silica nanoparticles (MSNs) containing immobilised Gd3+-macrocycles are widely investigated as platforms for enhancing magnetic resonance imaging (MRI) contrast, yet the influence of the local chemical surface environment on relaxation dynamics remains underexplored. In this work, we systematically examine how internal surface functionalisation modulates the relaxometric behaviour of Gd3+-chelate modified MSNs. Monodisperse MSNs were prepared with constant Gd3+ loading and varying either proximal thiol or phenyl groups. Thiol-functionalised particles exhibited a clear enhancement in relaxivity with high thiol grafting densities. Fast field-cycling NMR fitting parameters indicated that thiols progressively restrict local rotational dynamics, likely due to changes in local viscosity inside pores coupled with changes in the hydration layer structure around the Gd3+-chelate, reaching a plateau once the grafting density exceeds the density of Gd3+-chelates. In contrast, phenyl groups produce relaxivity enhancement through steric restrictions and hydrophobic crowding that limit chelate motion. Variable-temperature studies confirm that relaxation is dominated by local rotational dynamics rather than water exchange in both cases. These findings demonstrate that different surface modifiers enhance MRI performance via distinct mechanisms, highlighting internal surface chemistry as a key consideration in the design of nanoparticulate contrast agents.
Date Issued
2026-07-15
Date Acceptance
2026-06-17
Citation
Journal of Materials Chemistry B, 2026, 14 (27), pp.8408-8414
URI
URL
DOI
ISSN
2050-750X
Publisher
Royal Society of Chemistry (RSC)
Start Page
8408
End Page
8414
Journal / Book Title
Journal of Materials Chemistry B
Volume
14
Issue
27
Copyright Statement
© The Royal Society of Chemistry 2026 Open Access Article. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
License URL
Identifier
10.1039/d6tb01037g
Publication Status
Published
Date Publish Online
2026-06-18