Controlled hydrolysis of tetraethoxysilane in a nonionic water-in-oil microemulsion: a statistical model of silica nucleation

Arriagada, Francisco; Osseo‐Asare, K.

doi:10.1016/s0927-7757(98)00870-x

Cited by 95 publications

(84 citation statements)

References 24 publications

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“…In principle, the nucleate and growth rate of inorganic nanoparticles were strongly dependent on the environment such as reaction temperature, time, pH, surfactants, concentration of solutions, etc., so does the formed capsules. 18,[37][38][39][40] To better control the capsule morphologies, the influence of some key parameters were investigated, as shown in Table 1, and SEM images of the resulting capsule were given in Figure 2. By fixing the volume ratio of the ammonia to TEOS solution at 25:1, the effects of temperature, solution adding order and holding time on the morphology of the composite microcapsules were studied.…”

Section: Influence Of Reaction Conditions On Composite Capsule Morphomentioning

confidence: 99%

“…In this case, TEOS was hydrolyzed very fast according to the hydrolysis reaction equations (1) 43,44 and the partially hydrolysed species were expected to be located on the capsule surfaces. 40 The synthesis would produce the smallest particles due to the initial nucleation of a larger number of particles. 44 Moreover, the presence of ammonia would render the new formed silica particles with a negative surface charge so that those silica particles would be attached to the positive charged PE capsule shells ( Figure S1, Supporting Information).…”

Section: Influence Of Reaction Conditions On Composite Capsule Morphomentioning

confidence: 99%

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Composite silica nanoparticle/polyelectrolyte microcapsules with reduced permeability and enhanced ultrasound sensitivity

2015

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Many chemical and biomedical systems require delivery and controlled release of small molecules, which cannot be achieved by conventional polyelectrolyte-based layer-by-layer capsules. This work proposes an innovative hybrid microcapsule by incorporating in situ formed silica nanoparticles within or on the shell. The influence of various experimental conditions on the stability, mechanical strength and morphology of capsules w as investigated, and characterised by SEM, TEM, XRD, EDX and FTIR. The multifunctional capabilities of formed capsules were examined by encapsulating a small molecule Rhodamine B (Rh-B), which could be further released by an ultrasonic trigger. The results show that in situ formed SiO2 nanoparticles through hydrolysis greatly reduced the permeability of the shell yet with increased mechanical strength and ultrasound response. SiO 2 nanoparticles were shown to be distributed on the surface or inside polyelectrolyte shell, acting as supports for free -standing capsules in both liquid and dry environment. Rapid Rh-B molecules release and the fragmentation of the capsule shells were observed under 50W ultrasound irradiation for a few seconds. Such innovative capsules with capability of small molecule encapsulation and high ultrasound sensitivity could be promising for many applications where pulse release of small molecules is required.

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Section: Influence Of Reaction Conditions On Composite Capsule Morphomentioning

confidence: 99%

Section: Influence Of Reaction Conditions On Composite Capsule Morphomentioning

confidence: 99%

Composite silica nanoparticle/polyelectrolyte microcapsules with reduced permeability and enhanced ultrasound sensitivity

2015

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“…W/o microemulsions consist of an oil (continuous phase) and water (as surfactant coated nanosize droplets). These water droplets ser ve as nano-reactors and their collision, coalescence and de-coalescence causes nucleation and growth of silica particles inside the confined volume of nanoreactor [13][14][15] (Fig. 1).…”

Section: Dye Doped Silica Nanoparticlesmentioning

confidence: 99%

“…1). This elegant synthesis approach facilitates the size-tuning of silica particles by varying the water to surfactant molar ratio and the dynamic properties of the microemulsion system [14][15][16] . W/o emulsion mediated sol gel synthesis is currently used for the synthesis of organic as well as inorganic dye-doped silica nanoparticles 3,12) .…”

Section: Dye Doped Silica Nanoparticlesmentioning

confidence: 99%

Luminescent and Magnetic Nanoparticulates as Biomarkers

Singh

Sharma

Brown

et al. 2010

KONA

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“…By changing the charge and packing properties of the surfactant in the micelles, water to surfactant ratio or the amount of free water and ammonium hydroxide concentration, the diameter of spherical and monodispersed SiNPs can be adjusted from 20 to 500 nm. 206,207 The monnodispersity of SiNPs with diameters of 30-60 nm obtained by reverse microemulsion method is superior compared to Stöber approach. However, the use of large amount of surfactants requires an extensive washing time, which limits the potential of microemulsion method for industrial/mass production.…”

Section: Synthesis Of Fluorescent Sinpsmentioning

confidence: 99%

Designed synthesis of mono-dispersed silica-based nanostructures and their applications in drug/gene delivery

Yu¹

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Over the last two decades, silica based nanoparticles (SiNPs) have been extensively investigated as promising nano-carriers to deliver various therapeutic/diagnostic agents into living systems, due to their unique properties of tunable pore structure and particle size, easy surface modification and low cost. In particular, SiNPs with small sizes ( 100 nm) and high monodispersity, SiNPs possess great advantages in cell endocytosis process, which is vital to achieve high efficiency in biomedical applications. Although there have been tremendous studies in the synthesis of monodisperse nanometer-sized SiNPs, more efforts are still needed to develop facile, economic and environmentally friendly synthesis approaches for fabricating novel monodisperse SiNPs with desired particle size, nano-structure and functionality. The as-designed novel SiNPs are expected to expand their capacity in various biomedical applications, such as enhanced bio-imaging performance in three dimensional spheroid models, improved cellular drug/gene delivery efficiency.The aim of this project is to develop novel and facile approaches to prepare highly monodispersed SiNPs with finely controlled structures for drug/gene delivery and gain insight into the roles of particle size, surface functionality on cell penetration performance and drug/gene delivery efficiency. The main achievements obtained in this thesis are listed below.In the first part, a new and facile approach has been developed to prepare monodisperse mesoporous silica nanospheres (MMSNs) with controlled particle sizes (50-100 nm) and pore diameters (2.8-4.0 nm). In this approach, MMSNs were synthesized simply in a sodium acetate solution without adding any other alkali or alcohol additives. By further investigations on formation process, we proposed a spherical micelle templating mechanism to explain the formation of MMSNs in our system, which is different from that of traditional highly ordered mesoporous silica nanoparticles (MCM-41). MMSNs developed in this part are expected to have potential applications in drug/gene delivery and cell imaging.In the second part, even smaller mono-dispersed SiNPs (ultra-small hybrid silica spheres, UHSS) with a diameter of only  10 nm were developed by a facile strategy under phosphate-citrate buffer solution (pH = 4.6) at room temperature without addition of toxic additives. Compared to traditional MCM-41 nanomaterials, the designed novel UHSS showed enhanced penetration ability in three dimensional glioma spheroids.Following the second part, epoxysilane functionalized UHSS (Epoxy-UHSS) with a diameter of 10 nm were designed under similar synthesis conditions, which can be easily covalently conjugated with cationic polyethyleneimine (PEI) (PEI-UHSS). This designed positively charged PEI-UHSS demonstrated excellent delivery efficiency of a functional siRNA against polo-like kinase 1 (PLK1-siRNA) in osteosarcoma cancer cells (KHOS) and survivin-siRNA in human colon cancer cells (HCT-116) inducing a significant cell inhibition, which is c...

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Controlled hydrolysis of tetraethoxysilane in a nonionic water-in-oil microemulsion: a statistical model of silica nucleation

Cited by 95 publications

References 24 publications

Composite silica nanoparticle/polyelectrolyte microcapsules with reduced permeability and enhanced ultrasound sensitivity

Composite silica nanoparticle/polyelectrolyte microcapsules with reduced permeability and enhanced ultrasound sensitivity

Luminescent and Magnetic Nanoparticulates as Biomarkers

Designed synthesis of mono-dispersed silica-based nanostructures and their applications in drug/gene delivery

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