title: Magnetic resonance imaging studies on gadonanotube-reinforced biodegradable polymer nanocomposites.
abstract: We report about the in vitro cytotoxicity and MRI studies of Gd(3+)ions-doped ultra-short single-walled carbon nanotube (gadonanotubes), gadonanotubes- reinforced poly(lactic-co-glycolic acid) (PLGA) polymer nanocomposites and in vivo small animal MRI studies using the gadonanotubes. These studies were performed to explore the suitability of gadonanotubes-reinforced PLGA polymer nanocomposite as a model scaffold for noninvasive magnetic resonance imaging (MRI) to evaluate nanotube release during the degradation process of the scaffold and their biodistribution upon release from the polymer matrix in vivo. The gadonanotubes at 1-100 ppm and the gadonanotubes/PLGA nanocomposites (2 wt % gadonanotubes) did not show any cytotoxicity in vitro as demonstrated using the LIVE/DEAD viability assay. For the first time, r(2) relaxivity measurements were obtained for the superparamagnetic gadonanotubes. In vitro 7T MRI of the superparamagnetic gadonanotubes ([Gd] = 0.15 mM) suspended in a biocompatible 1% Pluronic F127 solution, gave a r(2) value of 578 mM(-1) s(-1). Upon subcutaneous injection of the gadonanotubes suspension into the dorsal region of rats, the high r(2) value translated into excellent and prolonged negative contrast enhancement of in vivo T(2)weighted proton MRI images. The in vitro characterization of the nanocomposite discs and their degradation process by MRI, showed strong influence of the gadonanotube on water proton relaxations. These results indicate that the gadonanotubes/PLGA nanocomposites are suitable for further in vivo studies to track by MRI the biodegradation release and biodistribution of gadonanotubes.
authors.affiliation: Department of Bioengineering, Rice University, P.O. Box 1892, MS-142, Houston, Texas 77251-1892, USA.
authors.forename: Balaji
authors.initials: B
authors.lastname: Sitharaman
authors.forename: Meike
authors.initials: M
authors.lastname: Van Der Zande
authors.forename: Jeyarama S
authors.initials: JS
authors.lastname: Ananta
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Shi
authors.forename: Andor
authors.initials: A
authors.lastname: Veltien
authors.forename: X Frank
authors.initials: XF
authors.lastname: Walboomers
authors.forename: Lon J
authors.initials: LJ
authors.lastname: Wilson
authors.forename: Antonios G
authors.initials: AG
authors.lastname: Mikos
authors.forename: Arend
authors.initials: A
authors.lastname: Heerschap
authors.forename: John A
authors.initials: JA
authors.lastname: Jansen
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D001673:Biodegradation, Environmental; D002470:Cell Survival; D003287:Contrast Media / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology; D005682:Gadolinium / Q000737:chemistry*; D007477:Ions; D019344:Lactic Acid / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D053761:Nanocomposites / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods; D037742:Nanotubes, Carbon / Q000737:chemistry*; D020442:Poloxamer / Q000737:chemistry; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D051381:Rats
chemical_list: D001672:Biocompatible Materials; D003287:Contrast Media; D007477:Ions; D037742:Nanotubes, Carbon; D020442:Poloxamer; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D005682:Gadolinium