Title

Gadolinium-Encapsulating Iron Oxide Nanoprobe As Activatable Nmr/Mri Contrast Agent

Keywords

activatable MRI imaging; Gd-DTPA complex; iron oxide nanoprobe; magnetic relaxation; theranostic application

Abstract

Herein we report a novel gadolinium-encapsulating iron oxide nanoparticle-based activatable NMR/MRI nanoprobe. In our design, Gd-DTPA is encapsulated within the poly(acrylic acid) (PAA) polymer coating of a superparamagnetic iron oxide nanoparticle (IO-PAA), yielding a composite magnetic nanoprobe (IO-PAA-Gd-DTPA) with quenched longitudinal spin-lattice magnetic relaxation (T 1). Upon release of the Gd-DTPA complex from the nanoprobe's polymeric coating in acidic media, an increase in the T 1 relaxation rate (1/T 1) of the composite magnetic nanoprobe was observed, indicating a dequenching of the nanoprobe with a corresponding increase in the T 1-weighted MRI signal. When a folate-conjugated nanoprobe was incubated in HeLa cells, a cancer cell line overexpressing folate receptors, an increase in the 1/T 1 signal was observed. This result suggests that, upon receptor-mediated internalization, the composite magnetic nanoprobe degraded within the cell's lysosome acidic (pH 5.0) environment, resulting in an intracellular release of Gd-DTPA complex with subsequent T 1 activation. In addition, when an anticancer drug (Taxol) was coencapsulated with the Gd-DTPA within the folate receptor targeting composite magnetic nanoprobe, the T 1 activation of the probe coincided with the rate of drug release and corresponding cytotoxic effect in cell culture studies. Taken together, these results suggest that our activatable T 1 nanoagent could be of great importance for the detection of acidic tumors and assessment of drug targeting and release by MRI. © 2012 American Chemical Society.

Publication Date

8-28-2012

Publication Title

ACS Nano

Volume

6

Issue

8

Number of Pages

7281-7294

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/nn302393e

Socpus ID

84865592337 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84865592337

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