Microporous Silica Particles Prepared by the Salt-Catalytic Sol-Gel Process with Extremely Low Content of Water

Murakami, Yasushi; Tanaka, Kazuhiko; Takechi, Yusuke; Takahashi, Saki; Nakano, Y.; Matsumoto, Taki; Sugimoto, Wataru; Takasu, Yoshio

doi:10.1023/b:jsst.0000016133.24903.ff

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…We used (NH 4 ) 2 CO 3 to catalyze the condensation of the silane reagents. Although (NH 4 ) 2 CO 3 has been used in some reports for the synthesis of silica aerogels,54 mixed‐oxide silica catalysts,55 and microporous silica particles,56 to the best of our knowledge it has not been used for the preparation of silica nanoparticles using a microemulsion approach. The use of (NH 4 ) 2 CO 3 is advantageous for two reasons: first it provides a mild pH (∼9), which does not affect the fluorescence of the ICG dye under prolonged multistep synthesis, and second it helps catalyze the formation of silica nanoparticles.…”

Section: Resultsmentioning

confidence: 99%

“…The silica nanoparticles were synthesized using 0.001 mol of (NH 4 ) 2 CO 3 which is equivalent to the number of moles of NH 4 OH used for traditional silica synthesis in microemulsions 57. Murakami et al have shown that the salt obtained from the neutralization of a weak acid and weak base, such as ammonium carbonate or ammonium acetate, can act as an acid–base pair catalyst for polycondensation 56, 58, 59. The formation of silica particles and titania sheets has been demonstrated via condensation using salts as catalysts 56, 58, 59.…”

Section: Resultsmentioning

confidence: 99%

“…Murakami et al have shown that the salt obtained from the neutralization of a weak acid and weak base, such as ammonium carbonate or ammonium acetate, can act as an acid–base pair catalyst for polycondensation 56, 58, 59. The formation of silica particles and titania sheets has been demonstrated via condensation using salts as catalysts 56, 58, 59. The salt‐catalyzed, mildly basic pH approach opens up new possibilities in the methods of fabricating silica nanoparticles in microemulsions.…”

Section: Resultsmentioning

confidence: 99%

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Gadolinium‐Doped Silica Nanoparticles Encapsulating Indocyanine Green for Near Infrared and Magnetic Resonance Imaging

Sharma

Bengtsson

Walter

et al. 2012

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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.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Gadolinium‐Doped Silica Nanoparticles Encapsulating Indocyanine Green for Near Infrared and Magnetic Resonance Imaging

Sharma

Bengtsson

Walter

et al. 2012

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“…Under a slight degree of hydrolysis of tetramethoxysilane, the microporous powders are obtained in poor yield. 5 Competitive reactions forming by-products will be accelerated by the ionic catalyst. An alternative catalyst is required for the preparation of the microporous precursor for coating.…”

Section: Introductionmentioning

confidence: 99%

Superhydrophilic Microporous Silica Coatings on Polymer Substrate

Shimizu

Matsumoto

Hosoo

et al. 2007

J. Ceram. Soc. Japan

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A transparent smooth superhydrophilic silica coating has been developed by coating a polyethylene terephthalate PET substrate with microporous silica and immersing the microporous silica coating in water at 80? C. The microporous precursor sol for coating was synthesized from tetramethoxysilane under neutral conditions by accelerating the rate of the condensation with hydroxyacetone. Immersing the coating in water is an important process for removing not only the methoxy group, but also the hydroxyacetone to form the hydrophilic surface.

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