A New and Facile Method To Prepare Uniform Hollow MnO/Functionalized mSiO(2) Core/Shell Nanocomposites

Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
ACS Nano (Impact Factor: 12.88). 05/2011; 5(5):4177-87. DOI: 10.1021/nn200928r
Source: PubMed


Trifunctional uniform nanoparticles comprising a manganese nanocrystal core and a functionalized mesoporous silica shell (MnO@mSiO(2)(Ir)@PEG, where Ir is an emissive iridium complex and PEG is polyethylene glycol) have been strategically designed and synthesized. The T(1) signal can be optimized by forming hollow core (H-MnO@mSiO(2)(Ir)@PEG) via a novel and facile etching process, for which the mechanism has been discussed in detail. Systematic investigation on correlation for longitudinal relaxation (T(1)) versus core shapes and shell silica porosity of the nanocomposites (MnO, H-MnO, MnO@SiO(2), MnO@mSiO(2), H-MnO@mSiO(2)) has been carried out. The results show that the worm-like nanochannels in the mesoporous silica shell not only increase water permeability to the interior hollow manganese oxide core for T(1) signal but also enhance photodynamic therapy (PDT) efficacy by enabling the free diffusion of oxygen. Notably, the H-MnO@mSiO(2)(Ir)@PEG nanocomposite with promising r(1) relaxivity demonstrates its versatility, in which the magnetic core provides the capability for magnetic resonance imaging, while the simultaneous red phosphorescence and singlet oxygen generation from the Ir complex are capable of providing optical imaging and inducing apoptosis, respectively.

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    • "Hollow mesoporous silica particles (H-MSPs) with unique large hollow cavities and mesoporous shells have attracted extensive attention in both fundamental and practical studies because of their unique properties [1], such as low density, large surface area, high cargo-loading capacity, as well as their potential applications in drug/gene delivery [2] [3], biomedical imaging [4] catalysis [5], etc. A recent breakthrough in the field of H-MSP preparation is the so-called 'structural difference-based selective dissolution' strategy which does not need soft/hard templates for templating the hollow cavities [6]. "
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    • "The iridium complexes have been also conjugated to MnO based mesoporous silicate nanoparticles that exhibit T1 weighted contrast enhancement. The photodynamic therapy effect is proved efficacious at in vitro HeLa cell model (Peng et al., 2011). "

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    • "Indeed, MnO nanoparticles with intact silica coatings only have an r1 of 0.07 mM-1s-1. Such a figure was found increased to 0.16 mM-1s-1 for MnO@mSiO2 and 0.2 mM-1s-1 for H-MnO@mSiO2 32. "
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