Versatile Synthesis of Thiol- and Amine-Bifunctionalized Silica Nanoparticles Based on the Ouzo Effect

Abstract

In this article, we report a novel, nanoprecipitation-based method for preparing silica nanoparticles with thiol and amine cofunctionalization. (3-Mercaptopropyl)trimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APTMS) were used as the organosilane precursors, which were subjected to acid-catalyzed polycondensation in an organic phase containing a water-miscible solvent (e.g., dimethyl sulfoxide). A pale colloidal solution could be immediately formed when the preincubated organic phase was directly injected into water. The initial composition ratio between MPTMS and APTMS is an important factor governing the formation of nanoparticles. Specifically, large, unstable micrometer-sized particles were formed for preparation using MPTMS as the sole silane source. In contrast, when APTMS was used alone, no particles could be formed. By reducing the fraction of APTMS (or increasing that of MPTMS) in the initial mixture of organosilanes, the formation of nanometer-sized particles occurred at a critical fraction of APTMS (i.e., 25%). Remarkably, a tiny fraction (e.g., 1%) of APTMS was sufficient to produce stable nanoparticles with a hydrodynamic diameter of about 200 nm. Other factors that would also affect particle formation were determined. Moreover, an interesting temperature effect on particle formation was observed. The TEM micrographs show spherical nanospheres with mean sizes of 130-150 nm in diameter. The solid-state (29)Si NMR spectra demonstrate that the hybrid silica materials contain fully and partially condensed silicon structures. The bifunctionalized silica nanoparticles have positive zeta potentials whose magnitudes are positively correlated with the amount of APTMS. The total thiol content, however, is negatively correlated with the amount of APTMS. The cationic nanoparticles can bind an antisense oligonucleotide in a composition-dependent manner.

Silica Nanoparticles in Transmucosal Drug Delivery

“…The molar ratio of MPMS/APMS in the reaction mixture was directly proportional to the zeta potential but inversely proportional to the thiol content. As these nanoparticles had positively charged surfaces (their zeta potential ranged from 30 to 50 mV), they bound to antisense oligodeoxyribonucleotide (G3139) efficiently as a result of electrostatic attraction between the cationic nanoparticles and the anionic therapeutic [38].…”

“…It is also possible to synthesise bifunctional silica nanoparticles by combining two organosilicate precursors with different functional groups. For instance, using a nanoprecipitation method, Chiu et al [ 38 ] synthesised silica nanoparticles (~150 nm) with both thiol and amine functionalities from MPMS and 3-aminopropyltrimethoxysilane (APMS). Typically, the organic phase contained MPMS and APMS, DMSO, diethylenetriaminepentaacetic acid (a reducing agent to minimise thiol oxidation) and HCl.…”

Carbofunctional sulfur‐containing organosilicon compounds

“…A novel, nanoprecipitation‐based method for preparing silica nanoparticles with thiol and amine co‐functionalization was described . (3‐Mercaptopropyl)trimethoxysilane (MPTMS) and 3‐aminopropyltrimethoxysilane (APTMS) were used as the organosilane precursors, which were subjected to acid‐catalyzed polycondensation in an organic phase containing a water‐miscible solvent (e.g.…”

Kinetics of fluoride-catalysed synthesis of organosilica colloids in aqueous solutions of amphiphiles

“…SH, amine, and various alkyl groups). [25][26][27][28][29][30][31] The reported methods oen involved acid-or basecatalysis, and organic solvents were frequently used. [25][26][27][28][29][30][31] Previously, there have been several attempts to prepare organosilica particles in a solvent-free system, based mainly on acidic or basic routes.…”

“…[25][26][27][28][29][30][31] The reported methods oen involved acid-or basecatalysis, and organic solvents were frequently used. [25][26][27][28][29][30][31] Previously, there have been several attempts to prepare organosilica particles in a solvent-free system, based mainly on acidic or basic routes. [32][33][34][35][36][37] Most recently, we have demonstrated a general "salt route" for efficiently synthesizing organosilica nanospheres in purely aqueous reaction systems containing common salts and common surfactants or polymers.…”