Multimodal biomedical imaging with asymmetric single-walled carbon nanotube/iron oxide nanoparticle complexes.

TitleMultimodal biomedical imaging with asymmetric single-walled carbon nanotube/iron oxide nanoparticle complexes.
Publication TypeJournal Article
Year of Publication2007
AuthorsChoi, Jong Hyun, Nguyen Freddy T., Barone Paul W., Heller Daniel A., Moll Anthonie E., Patel Dhaval, Boppart Stephen A., and Strano Michael S.
JournalNano Lett
Volume7
Issue4
Pagination861-7
Date Published2007 Apr
ISSN1530-6984
KeywordsAnimals, Cells, Cultured, Contrast Media, Crystallization, Ferric Compounds, Image Enhancement, Macrophages, Magnetic Resonance Imaging, Mice, Molecular Conformation, Nanotechnology, Nanotubes, Carbon, Particle Size, Spectrophotometry, Infrared
Abstract

Magnetic iron oxide nanoparticles and near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWNT) form heterostructured complexes that can be utilized as multimodal bioimaging agents. Fe catalyst-grown SWNT were individually dispersed in aqueous solution via encapsulation by oligonucleotides with the sequence d(GT)15, and enriched using a 0.5 T magnetic array. The resulting nanotube complexes show distinct NIR fluorescence, Raman scattering, and visible/NIR absorbance features, corresponding to the various nanotube species. AFM and cryo-TEM images show DNA-encapsulated complexes composed of a approximately 3 nm particle attached to a carbon nanotube on one end. X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) measurements reveal that the nanoparticles are primarily Fe2O3 and superparamagnetic. The Fe2O3 particle-enriched nanotube solution has a magnetic particle content of approximately 35 wt %, a magnetization saturation of approximately 56 emu/g, and a magnetic relaxation time scale ratio (T1/T2) of approximately 12. These complexes have a longer spin-spin relaxation time (T2 approximately 164 ms) than typical ferromagnetic particles due to the smaller size of their magnetic component while still retaining SWNT optical signatures. Macrophage cells that engulf the DNA-wrapped complexes were imaged using magnetic resonance imaging (MRI) and NIR mapping, demonstrating that these multifunctional nanostructures could potentially be useful in multimodal biomedical imaging.

DOI10.1021/nl062306v
Alternate JournalNano Lett.
PubMed ID17335265
Grant List1 R01 EB001777 / EB / NIBIB NIH HHS / United States
1 R21 EB005321 / EB / NIBIB NIH HHS / United States