Synthesis of Nanosize Silica in a Nonionic Water-in-Oil Microemulsion: Effects of the Water/Surfactant Molar Ratio and Ammonia Concentration

Arriagada, Francisco; Osseo‐Asare, K.

doi:10.1006/jcis.1998.5985

Cited by 397 publications

(299 citation statements)

References 47 publications

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“…To address the mechanism of cellular uptake and the physiological consequence of NP accumulation in mammalian cells we prepared SiNPs covalently labeled with FITC by modified microemulsion synthesis (20). The resulting dye-labeled spheres were used as cores for the subsequent seeded growth of a silica shell of 3-nm thickness based on the Stöber method (21).…”

Section: Resultsmentioning

confidence: 99%

Lysosomal Dysfunction Caused by Cellular Accumulation of Silica Nanoparticles

Schütz

López-Hernández

Gao

et al. 2016

Journal of Biological Chemistry

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Nanoparticles (NPs) are widely used as components of drugs or cosmetics and hold great promise for biomedicine, yet their effects on cell physiology remain poorly understood. Here we demonstrate that clathrin-independent dynamin 2-mediated caveolar uptake of surface-functionalized silica nanoparticles (SiNPs) impairs cell viability due to lysosomal dysfunction. We show that internalized SiNPs accumulate in lysosomes resulting in inhibition of autophagy-mediated protein turnover and impaired degradation of internalized epidermal growth factor, whereas endosomal recycling proceeds unperturbed. This phenotype is caused by perturbed delivery of cargo via autophagosomes and late endosomes to SiNP-filled cathepsin B/L-containing lysosomes rather than elevated lysosomal pH or altered mTOR activity. Given the importance of autophagy and lysosomal protein degradation for cellular proteostasis and clearance of aggregated proteins, these results raise the question of beneficial use of NPs in biomedicine and beyond. Nanoparticles (NPs)2 are widely used as components of drugs or cosmetics and hold great promise as tools in biomedicine to improve the detection and treatment of diseases (1). For example, nanoparticle technology has enabled improvements in cancer treatment, ranging from improved efficacy of drug delivery (2) to enhanced immunogenicity of cancer vaccines (3). Moreover, NPs are used as biosensors and biomarkers (4, 5) or for DNA/drug delivery (6). Hence, it is necessary to understand the mechanisms of interaction of NPs with living cells and tissues to assess the biological consequences associated with their application in biomedicine (7). At present, the risks associated with the biomedical application of NPs at the cellular and organismic levels remain incompletely understood (1). Among the phenotypic changes reported to be associated with the biomedical application of NPs are cellular stress responses (i.e. redox imbalance, oxidative stress), DNA damage, and altered gene expression (8,9). Which of these phenotypes can be considered a direct consequence of cellular NP association or uptake and the underlying molecular mechanisms have remained in many cases unknown.Upon cellular application, NPs initially interact with the plasma membrane, often followed by their internalization into the cell interior (10 -12) via clathrin-dependent as well as clathrin-independent endocytosis routes (i.e. via caveolae), which may require the membrane-severing GTPase dynamin (13,14). Due to the questionable specificity of many commonly used pharmacological tools toward these pathways (15) the precise mechanisms of cellular uptake of NPs often have remained elusive. After cell entry NPs are delivered to the endolysosomal system (16), where they may accumulate. Lysosomes play essential roles in cell physiology ranging from the degradation of malfunctional or aggregated proteins (e.g. via autophagy) or lipids to nutrient signaling and cellular growth control (17). For example, internalized growth factors such as EGF are sorted to la...

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Section: Resultsmentioning

confidence: 99%

Lysosomal Dysfunction Caused by Cellular Accumulation of Silica Nanoparticles

Schütz

López-Hernández

Gao

et al. 2016

Journal of Biological Chemistry

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“…To obtain much smaller nano-particles, e.g., about 10 nm in diameter, preparation of silica nanoparticles by modified Stöber method using basic amino acid such as L-lysine [8 ,9] or by water in oil micro-emulsion process [10,11] have been reported. In the industrial scale, colloidal silica with small diameter has been prepared using water glass 3 [12].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of monodispersed silica nanoparticles with high concentration by the Stöber process

Tadanaga

Morita

Mori

et al. 2013

J Sol-Gel Sci Technol

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Silica nanoparticles with high concentration were prepared by the sol-gel process based on the Stöber method using tetraethoxysilane (TEOS) as a starting material. It was found that silica sol with about 4 wt% in concentration and with a diameter of about 10 nm was obtained by controlling the reaction conditions in the Stöber process. By removing the solvent under a reduced pressure, the particle concentration was increased up to 15 wt% without aggregation.

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“…The formation of silica sols has been documented by a variety of different methods including Stöber's method and reverse micelle 1,[24][25] . The specific mechanism governing the formation of SiO 2 is limited to the rate of condensation of the silicon species, which is directly controlled by the local environment of the silicon species.…”

Section: Discussionmentioning

confidence: 99%

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Owens

Seeber

et al. 2013

JoVE

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Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan δ solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials' morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by Stöber's methods, which have smooth surfaces. Video LinkThe video component of this article can be found at

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Synthesis of Nanosize Silica in a Nonionic Water-in-Oil Microemulsion: Effects of the Water/Surfactant Molar Ratio and Ammonia Concentration

Cited by 397 publications

References 47 publications

Lysosomal Dysfunction Caused by Cellular Accumulation of Silica Nanoparticles

Lysosomal Dysfunction Caused by Cellular Accumulation of Silica Nanoparticles

Synthesis of monodispersed silica nanoparticles with high concentration by the Stöber process

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

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