title: Cellular uptake and imaging studies of gadolinium-loaded single-walled carbon nanotubes as MRI contrast agents.
abstract: We quantify here, for the first time, the intracellular uptake (J774A.1 murine macrophage cells) of gadolinium-loaded ultra-short single-walled carbon nanotubes (gadonanotubes or GNTs) in a 3 T MRI scanner using R(2) and R(2)* mapping in vitro. GNT-labeled cells exhibited high and linear changes in net transverse relaxations (ΔR(2) and ΔR 2*) with increasing cell concentration. The measured ΔR(2)* were about three to four times greater than the respective ΔR(2) for each cell concentration. The intracellular uptake of GNTs was validated with inductively coupled plasma optical emission spectrometry (ICP-OES), indicating an average cellular uptake of 0.44 ± 0.09 pg Gd per cell or 1.69 × 10(9) Gd(3+) ions per cell. Cell proliferation MTS assays demonstrated that the cells were effectively labeled, without cytotoxicity, for GNTs concentrations ≤28 µM Gd. In vivo relaxometry of a subcutaneously-injected GNT-labeled cell pellet in a mouse was also demonstrated at 3 T. Finally, the pronounced R(2)* effect of GNT-labeled cells enabled successful in vitro visualization of labeled cells at 9.4 T.
authors.affiliation: Bioengineering and Bioinformatics Program, The Methodist Hospital Research Institute & Weill Cornell Medical College Houston, TX 77030, USA.
authors.forename: Annie M
authors.initials: AM
authors.lastname: Tang
authors.forename: Jeyarama S
authors.initials: JS
authors.lastname: Ananta
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.forename: Brandon T
authors.initials: BT
authors.lastname: Cisneros
authors.forename: Edmund Y
authors.initials: EY
authors.lastname: Lam
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Wong
authors.forename: Lon J
authors.initials: LJ
authors.lastname: Wilson
authors.forename: Kelvin K
authors.initials: KK
authors.lastname: Wong
mesh_terms: D000818:Animals; D002460:Cell Line; D003287:Contrast Media / Q000737:chemistry* / Q000378:metabolism; D005682:Gadolinium / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008856:Microscopy, Fluorescence; D037742:Nanotubes, Carbon / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D037742:Nanotubes, Carbon; D005682:Gadolinium