PURPOSE: To develop cross-linked nanoassemblies (CNAs) as carriers for superparamagnetic iron oxide nanoparticles (IONPs).

METHODS: Ferric and ferrous ions were co-precipitated inside core-shell type nanoparticles prepared by cross-linking poly(ethylene glycol)-poly(aspartate) block copolymers to prepare CNAs entrapping Fe(3)O(4) IONPs (CNA-IONPs). Particle stability and biocompatibility of CNA-IONPs were characterized in comparison to citrate-coated Fe(3)O(4) IONPs (Citrate-IONPs).

RESULTS: CNA-IONPs, approximately 30 nm in diameter, showed no precipitation in water, PBS, or a cell culture medium after 3 or 30 h, at 22, 37, and 43°C, and 1, 2.5, and 5 mg/mL, whereas Citrate-IONPs agglomerated rapidly (> 400 nm) in all aqueous media tested. No cytotoxicity was observed in a mouse brain endothelial-derived cell line (bEnd.3) exposed to CNA-IONPs up to 10 mg/mL for 30 h. Citrate-IONPs (> 0.05 mg/mL) reduced cell viability after 3 h. CNA-IONPs retained the superparamagnetic properties of entrapped IONPs, enhancing T2-weighted magnetic resonance images (MRI) at 0.02 mg/mL, and generating heat at a mild hyperthermic level (40 ~ 42°C) with an alternating magnetic field (AMF).

CONCLUSION: Compared to citric acid coating, CNAs with a cross-linked anionic core improved particle stability and biocompatibility of IONPs, which would be beneficial for future MRI and AMF-induced remote hyperthermia applications.

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Notes/Citation Information

Published in Pharmaceutical Research, v. 30, no. 2, p. 552-561.

© Springer Science+Business Media New York 2012

The copyright holders have granted the permission for posting the article here.

The document available for download is the authors' post-peer-review final draft of the article. The final publication is available at Springer via http://dx.doi.org/10.1007/s11095-012-0900-8

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Funding Information

MD and DS acknowledge the financial support from a NCI-CNTC (National Cancer Institute Cancer Nanotechnology Training Center) predoctoral and postdoctoral traineeship (NCI 5R25CA153954).