Magnetic Nanoparticle-Based Imaging of RNA Transcripts in Breast Cancer Cells
Annual rept. 1 Jun 2007-31 May 2008
TRUSTEES OF PENNSYLVANIA UNIV PHILADELPHIA PA
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We have developed a novel approach to detect RNA transcripts via magnetic resonance by taking advantage of the decrease in the spin-spin i.e. T2 relaxation time that results from the self-assembly of superparamagnetic iron oxide nanoparticles NPs. Specifically, two unique NP-oligonucleotide ON conjugates were designed to recognize adjacent sites on nucleic acid targets. Thus, upon hybridization to complementary targets the NP-ON conjugate pairs were brought into close proximity, which resulted in a detectable reduction in the T2 relaxation time. This mechanism of switching from a high T2-relaxation time to a low T2-relaxation time is generally referred to as magnetic relaxation switching MRSw. In the presence of target nucleic acids, we measured as much as a 40 decrease in T2 signal due to aggregate formation, with reliable detection of target at levels as low as 10 pmoles. We have also prepared NPs with sizes ranging from 20 nm to 1 um and identified that positively charged NPs 200 nm are taken up by cells much more effectively than larger NPs. Therefore, we plan to use NPs in this size range when attempting to detect RNA in cells.
- Nuclear Physics and Elementary Particle Physics