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Theranostics With Multifunctional Magnetic Gold Nanoshells: Photothermal Therapy and T2* Magnetic Resonance Imaging

Melancon, Marites P. PhD*†; Elliott, Andrew PhD†; Ji, Xiaojun PhD*; Shetty, Anil MBBS†; Yang, Zhi PhD*; Tian, Mei MD*; Taylor, Brian PhD†; Stafford, R. Jason PhD†; Li, Chun PhD*

doi: 10.1097/RLI.0b013e3181f8e7d8
Original Article

Objectives: To investigate the multifunctional imaging and therapeutic capabilities of core-shell nanoparticles composed of a superparamagnetic iron oxide (SPIO) core and a gold shell (SPIO@AuNS).

Materials and Methods: The magnetic/optical properties of SPIO@AuNS were examined both in an agar gel phantom and in vivo by evaluating contrast-enhanced magnetic resonance imaging (MRI) and by measuring near-infrared (NIR) light-induced temperature changes mediated by SPIO@AuNS. In addition, the biodistribution and pharmacokinetics of 111In-labeled SPIO@AuNS after intravenous injection in mice bearing A431 tumors were evaluated in the presence and absence of an external magnet.

Results: In agar phantoms containing SPIO@AuNS, a significant contrast enhancement in T2-weighted MRI was observed and a linear increase in temperature was observed with increasing concentration and laser output power when irradiated with NIR light centered at an 808 nm. In vivo, T2*-MRI delineated SPIO@AuNS and magnetic resonance temperature imaging of the same tumors revealed significant temperature elevations when intratumorally injected with SPIO@AuNS (1 × 1011 particles/mouse) and irradiated with NIR light (65.70°C ± 0.69°C vs. 44.23°C ± 0.24°C for saline + laser). Biodistribution studies in mice intravenously injected with 111In-labeled-SPIO@AuNS(1 × 1013 particles/mouse) had an approximately 2-fold increase in SPIO@AuNS delivered into tumors in the presence of an external magnet compared with tumors without the magnet.

Conclusions: Owing to its ability to mediate efficient photothermal ablation of cancer cells under MRI guidance, as well as the ability to be directed to solid tumors with an external magnetic field gradient, multifunctional SPIO@AuNS is a promising theranostic nanoplatform.

From the Departments of *Experimental Diagnostic Imaging and †Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, TX. Z.Y. is on leave from the Department of Nuclear Medicine, Peking University School of Oncology and Beijing Cancer Hospital, Beijing, People's Republic of China 100036.

Received August 17, 2009; accepted for publication (after revision) July 31, 2010.

Supported in part by the National Institutes of Health (grant R01 CA119387), the John S. Dunn Foundation, Odyssey Fellowship (to M.P.M.), and SPORE Head and Neck Career Development Award P50CA097007 (to M.P.M.).

Reprints: Chun Li, PhD, Department of Experimental Diagnostic Imaging, The University of Texas M. D. Anderson Cancer Center, Unit 059, 1515 Holcombe Blvd, Houston, TX 77030. E-mail: cli@mdanderson.org.

© 2011 Lippincott Williams & Wilkins, Inc.