Magnetic Resonance Imaging for Monitoring of Magnetic Polyelectrolyte Capsule In Vivo Delivery
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Layer-by-layer (LbL) assembled polyelectrolyte capsules have been widely studied as promising delivery systems due to their well-controlled architectures. Although their potential applications in vitro have been widely investigated, at present, it is still a challenging task to track their real-time delivery in vivo, where and how they would be located following their administration. In this work, the noninvasive magnetic resonance imaging (MRI) technique was applied to monitor the delivery of polyelectrolyte capsules in vivo, incorporating magnetite nanoparticles as imaging components. First, MRI scan was performed over 6 h after sample administration at the magnetic field of 3.0 T; magnetic capsules, both poly(allylamine hydrochloride)/poly(styrenesulfonate sodium salt)-based and poly-l-arginine hydrochloride/dextran sulfate (Parg/DS)-based, were detected mostly in the liver region, where the transverse relaxation time (T2) was shortened and hypointense images were visualized, demonstrating a contrast-enhanced MRI effect between liver and adjacent tissue. A continuous MRI scan found that the contrast-enhanced MRI effect can last up to 30 h; in the mean time, the Parg/DS-based capsules with smaller diameter were found to have a pronounced clearance effect, which resulted in a weakened MRI effect in the liver. No obvious toxicity was found in animal studies, and all mice survived after MRI scans. Histology study provided evidences to support the MRI results, and also revealed the destination of these magnetic capsules over 30 h after administration.
KeywordsMagnetite Capsule MRI Liver Spleen
The authors thank the Radiology Department of West China Hospital (Sichuan University, China) for the support on the MRI measurement. The authors also acknowledge the National Natural Science Foundation of China (NSFC 51173117) and National Key Basic Research Program of China (2013CB933903) for the financial support. This research was supported by an EPSRC “Global Engagement” grant to establish research links between Queen Mary University of London, and Sichuan University.
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