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Enhancing T1 magnetic resonance imaging contrast with internalized gadolinium(III) in a multilayer nanoparticle.

Abstract：

:Multifunctional nanoparticles for biomedical applications have shown extraordinary potential as contrast agents in various bioimaging modalities, near-IR photothermal therapy, and for light-triggered therapeutic release processes. Over the past several years, numerous studies have been performed to synthesize and enhance MRI contrast with nanoparticles. However, understanding the MRI enhancement mechanism in a multishell nanoparticle geometry, and controlling its properties, remains a challenge. To systematically examine MRI enhancement in a nanoparticle geometry, we have synthesized MRI-active Au nanomatryoshkas. These are Au core-silica layer-Au shell nanoparticles, where Gd(III) ions are encapsulated within the silica layer between the inner core and outer Au layer of the nanoparticle (Gd-NM). This multifunctional nanoparticle retains its strong near-IR Fano-resonant optical absorption properties essential for photothermal or other near-IR light-triggered therapy, while simultaneously providing increased T1 contrast in MR imaging by concentrating Gd(III) within the nanoparticle. Measurements of Gd-NM revealed a strongly enhanced T1 relaxivity (r1 ∼ 24 mM-1⋅s-1) even at 4.7 T, substantially surpassing conventional Gd(III) chelating agents (r1 ∼ 3 mM-1⋅s-1 at 4.7 T) currently in clinical use. By varying the thickness of the outer gold layer of the nanoparticle, we show that the observed relaxivities are consistent with Solomon-Bloembergen-Morgan (SBM) theory, which takes into account the longer-range interactions between the encapsulated Gd(III) and the protons of the H2O molecules outside the nanoparticle. This nanoparticle complex and its MRI T1-enhancing properties open the door for future studies on quantitative tracking of therapeutic nanoparticles in vivo, an essential step for optimizing light-induced, nanoparticle-based therapies.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Marangoni VS,Neumann O,Henderson L,Kaffes CC,Zhang H,Zhang R,Bishnoi S,Ayala-Orozco C,Zucolotto V,Bankson JA,Nordlander P,Halas NJ

doi

10.1073/pnas.1701944114

subject

Has Abstract

pub_date

2017-07-03 00:00:00

pages

6960-6965

issue

eissn

0027-8424

issn

1091-6490

pii

1701944114

journal_volume

114

pub_type

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Enhancing T1 magnetic resonance imaging contrast with internalized gadolinium(III) in a multilayer nanoparticle.