title: Gadolinium-doped silica nanoparticles encapsulating indocyanine green for near infrared and magnetic resonance imaging.
abstract: Clinical applications of the indocyanine green (ICG) dye, the only near infrared (NIR) imaging dye approved by the Food and Drug Administration (FDA) in the USA, are limited due to rapid protein binding, fast clearance, and instability in physiologically relevant conditions. Encapsulating ICG in silica particles can enhance its photostability, minimize photobleaching, increase the signal-to-noise (S/N) ratio and enable in vivo studies. Furthermore, a combined magnetic resonance (MR) and NIR imaging particulate can integrate the advantage of high-resolution 3D anatomical imaging with high-sensitivity deep-tissue in-vivo fluorescent imaging. In this report, a novel synthesis technique that can achieve these goals is presented. A reverse-microemulsion-based synthesis protocol is employed to produce 25 nm ICG-doped silica nanoparticles (NPs). The encapsulation of ICG is achieved by manipulating coulombic attractions with bivalent ions and aminated silanes and carrying out silica synthesis in salt-catalyzed, mildly basic pH conditions using dioctyl sulfosuccinate (AOT)/heptane/water microemulsion system. Furthermore, paramagnetic properties are imparted by chelating paramagnetic Gd to the ICG-doped silica NPs. Aqueous ICG-dye-doped silica NPs show increased photostability (over a week) and minimal photobleaching as compared to the dye alone. The MR and optical imaging capabilities of these particles are demonstrated through phantom, in vitro and in vivo experiments. The described particles have the potential to act as theranostic agents by combining photodynamic therapy through the absorption of NIR irradiated light.
authors: Materials Science and Engineering & Particle Engineering Research Center, University of Florida, Gainesville, FL, 32611, USA. psharma@perc.ufl.edu
authors: Parvesh
authors: P
authors: Sharma
authors: Niclas E
authors: NE
authors: Bengtsson
authors: Glenn A
authors: GA
authors: Walter
authors: Han-Byul
authors: HB
authors: Sohn
authors: Guangyin
authors: G
authors: Zhou
authors: Nobutaka
authors: N
authors: Iwakuma
authors: Huadong
authors: H
authors: Zeng
authors: Stephen R
authors: SR
authors: Grobmyer
authors: Edward W
authors: EW
authors: Scott
authors: Brij M
authors: BM
authors: Moudgil
mesh_terms: D045744:Cell Line, Tumor; D005456:Fluorescent Dyes / Q000737:chemistry; D005682:Gadolinium / Q000737:chemistry*; D006801:Humans; D007208:Indocyanine Green / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D053758:Nanoparticles / Q000737:chemistry*; D061848:Optical Imaging; D012822:Silicon Dioxide / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared
chemical_list: D005456:Fluorescent Dyes; D012822:Silicon Dioxide; D005682:Gadolinium; D007208:Indocyanine Green