Silica Hollow Spheres by Templating of Catanionic Vesicles

Abstract

A simple and effective means for obtaining hollow silica particles of controlled diameter from about 60 to 120 nm is presented. The synthesis utilizes equilibrium vesicles as templates for the directed growth of silica. Two different surfactant systems are used to form the vesicular templates: (a) mixtures of cetyltrimethylammonium bromide (CTAB) and sodium perfluorooctanoate (FC7) and (b) mixtures of cetyltrimethylammonium tosylate (CTAT) and sodium dodecylbenzenesulfonate (SDBS). These templates were chosen because these mixtures of surfactants in water form unilamellar vesicles spontaneously that appear stable in the chemical environment required for silica synthesis. Tetramethoxysilane (TMOS) is added to the vesicular templates as a precursor for silica formation via acid-catalyzed hydrolysis and polycondensation. The morphology of the silica products as observed with transmission electron microscopy (TEM), quasi-elastic light scattering (QLS), and small-angle neutron scattering (SANS) is consistent with silica deposition at the vesicle surface, creating hollow silica particles with a 1-2-nm-thick shell and with a core diameter identical to that of the template. TEM reveals under different conditions either discrete hollow particles or networks of linked or aggregated hollow silica shells.

Silica‐Coated Liposomes for Insulin Delivery

“…Protective coating of soft drug delivery vehicles are of immense importance to deliver the drug in its active state from the deleterious action of gastric enzymes and pH effect. Hollow silica vesicles obtained at higher temperature by hydrothermal synthesis using zwitterionic, cationic and catanionic surfactant vesicle as template have been reported earlier for various applications [28][29][30]. Here, silica coated insulin loaded liposomes were prepared at room temperature by acid catalyzed polymerisation of silica precursor.…”

Surface-Functionalized Periodic Mesoporous Organosilica Hollow Spheres

“…The well-organized pores and hollow morphology can make it suitable for applications in confined nanocatalysts, biosensors, targeted drug and gene delivery, enzyme encapsulation, and nanoreactors. [1][2][3][4][5][6] There have been reports about synthesis of silica hollow spheres by several methods such as sonochemical, 7 solid particle templates, [8][9][10] surfactant/vesicle templates, [11][12][13][14][15][16][17] and emulsion templating technology. 18,19 However, only several reports have occasionally involved the synthesis of hollow spheres with ordered porous wall structures.…”

Preparation of Giant Polyion Complex Vesicles (G-PICsomes) with Polyphosphobetaine Shells Composed of Oppositely Charged Diblock Copolymers

“…Vesicles formed from phospholipids, 1 low-molecularweight surfactants, 2 and block copolymers 3 have been studied intensively for a wide range of applications such as drug carriers, 4 cell membrane models, 5 and templates for hollow particles. 6,7 Vesicles formed from block copolymers are called polymer vesicles or polymersomes. 8 To prepare polymersomes, reaction conditions, such as the choice of the solvent, composition of the polymer, water content, ionic strength, and temperature, should be optimized.…”

“…6,7 Vesicles formed from block copolymers are called polymer vesicles or polymersomes. 8 To prepare polymersomes, reaction conditions, such as the choice of the solvent, composition of the polymer, water content, ionic strength, and temperature, should be optimized.…”