Magnetic Nanoparticle-Based Imaging of RNA Transcripts in Breast Cancer Cells
Annual rept. 1 Jun 2008-31 May 2009
PENNSYLVANIA UNIV PHILADELPHIA
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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 Figure 1. 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. We tested the ability of NP-ON conjugates with sizes ranging from 20 nm to 1 um to detect nucleic acid targets. It was found that aminated NPs 100 nm in diameter performed the best, exhibiting as much as a 61 decrease in T2 signal upon the addition of nucleic acid targets, with a lower detection limit of 10 pmoles. It was also found that the 100 nm particles were rapidly internalized into cells, opening up the possibility of detecting endogenous RNA.
- Medicine and Medical Research