title: Determination of nanoparticle vehicle unpackaging by MR imaging of a T(2) magnetic relaxation switch.
abstract: Non-invasive imaging of gene and drug delivery is an important tool in understanding the biodistribution and pharmacokinetics of vectors after in vivo administration. In this work, we demonstrate the utility of a multifunctional delivery vector comprised of polyethylenimine conjugated to ultrasmall, superparamagnetic iron oxide (USPIO). The conjugate (USPIO-PEI) is capable of complexing plasmid DNA into nanoparticles (SPIO-polyplex) with diameters approximately 100 nm and protecting the DNA from nuclease degradation. SPIO-polyplexes transfect cells with high efficiency and low toxicity. In addition, the T2 relaxation time of water enhanced by USPIO is shown to be a function of the packaging state of the vector. Thus, this material integrates capabilities of gene delivery with magnetic resonance (MR) contrast and also provides an MR-based read-out for vector unpackaging.
authors.affiliation: Department of Bioengineering, University of Washington. W.H. Foege Building, Room N530P, Box 355061, 1705 NE Pacific Street, Seattle, WA 98195, USA.
authors.forename: In-Kyu
authors.initials: IK
authors.lastname: Park
authors.forename: Chee-Ping
authors.initials: CP
authors.lastname: Ng
authors.forename: Jinnan
authors.initials: J
authors.lastname: Wang
authors.forename: Baocheng
authors.initials: B
authors.lastname: Chu
authors.forename: Chun
authors.initials: C
authors.lastname: Yuan
authors.forename: Shanrong
authors.initials: S
authors.lastname: Zhang
authors.forename: Suzie H
authors.initials: SH
authors.lastname: Pun
mesh_terms: D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D006367:HeLa Cells; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles