title: Manganese-enhanced MRI of rat brain based on slow cerebral delivery of manganese(II) with silica-encapsulated Mn x Fe(1-x) O nanoparticles.
abstract: In this work, we report a monodisperse bifunctional nanoparticle system, MIO@SiO2 -RITC, as an MRI contrast agent [core, manganese iron oxide (MIO); shell, amorphous silica conjugated with rhodamine B isothiocyanate (RITC)]. It was prepared by thermal decomposition and modified microemulsion methods. The nanoparticles with varying iron to manganese ratios displayed different saturated magnetizations and relaxivities. In vivo MRI of rats injected intravenously with MIO@SiO2-RITC nanoparticles exhibited enhancement of the T1 contrast in brain tissue, in particular a time-delayed enhancement in the hippocampus, pituitary gland, striatum and cerebellum. This is attributable to the gradual degradation of MIO@SiO2-RITC nanoparticles in the liver, resulting in the slow release of manganese(II) [Mn(II)] into the blood pool and, subsequently, accumulation in the brain tissue. Thus, T1-weighted contrast enhancement was clearly detected in the anatomic structure of the brain as time progressed. In addition, T2*-weighted images of the liver showed a gradual darkening effect. Here, we demonstrate the concept of the slow release of Mn(II) for neuroimaging. This new nanoparticle-based manganese contrast agent allows one simple intravenous injection (rather than multiple infusions) of Mn(II) precursor, and results in delineation of the detailed anatomic neuroarchitecture in MRI; hence, this provides the advantage of the long-term study of neural function.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Fang
authors.initials: F
authors.lastname: Lu
authors.forename: Chiao-Chi V
authors.initials: CC
authors.lastname: Chen
authors.forename: Kuan-Chi
authors.initials: KC
authors.lastname: Mo
authors.forename: Yann
authors.initials: Y
authors.lastname: Hung
authors.forename: Zhi-Xuan
authors.initials: ZX
authors.lastname: Guo
authors.forename: Chia-Hui
authors.initials: CH
authors.lastname: Lin
authors.forename: Ming-Huang
authors.initials: MH
authors.lastname: Lin
authors.forename: Yu-Hsuan
authors.initials: YH
authors.lastname: Lin
authors.forename: Chen
authors.initials: C
authors.lastname: Chang
authors.forename: Chung-Yuan
authors.initials: CY
authors.lastname: Mou
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D016923:Cell Death; D003198:Computer Simulation; D005290:Ferric Compounds; D008099:Liver / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008345:Manganese / Q000097:blood; D051379:Mice; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D053758:Nanoparticles / Q000648:ultrastructure; D051381:Rats; D012235:Rhodamines / Q000378:metabolism; D012822:Silicon Dioxide; D013997:Time Factors
chemical_list: D005290:Ferric Compounds; D012235:Rhodamines; C000499:ferric oxide; D008345:Manganese; D012822:Silicon Dioxide; C027755:rhodamine isothiocyanate
keywords: MEMRI; brain image; imaging agent; magnetic nanoparticle; manganese; neuroarchitecture; silica sphere; slow release