title: Multimodal biomedical imaging with asymmetric single-walled carbon nanotube/iron oxide nanoparticle complexes.
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.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Medical Scholars Program, College of Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana/Champaign, Urbana, Illinois 61801, USA.
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Choi
authors.forename: Freddy T
authors.initials: FT
authors.lastname: Nguyen
authors.forename: Paul W
authors.initials: PW
authors.lastname: Barone
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Heller
authors.forename: Anthonie E
authors.initials: AE
authors.lastname: Moll
authors.forename: Dhaval
authors.initials: D
authors.lastname: Patel
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Boppart
authors.forename: Michael S
authors.initials: MS
authors.lastname: Strano
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003287:Contrast Media / Q000737:chemistry; D003460:Crystallization / Q000379:methods; D005290:Ferric Compounds / Q000737:chemistry*; D007089:Image Enhancement / Q000379:methods*; D008264:Macrophages / Q000166:cytology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; D037742:Nanotubes, Carbon; C000499:ferric oxide