Preparation, purification, and characterization of aminopropyl-functionalized silica sol.
A new, simple, and "green" method was developed for the surface modification of 20 nm diameter Stöber silica particles with 3-aminopropyl(diethoxy)methylsilane in ethanol. The bulk polycondensation of the reagent was inhibited and the stability of the sol preserved by adding a small amount of glacial acetic acid after appropriate reaction time. Centrifugation, ultrafiltration, and dialysis were compared in order to choose a convenient purification technique that allows the separation of unreacted silylating agent from the nanoparticles without destabilizing the sol. The exchange of the solvent to acidic water during the purification yielded a stable colloid, as well. Structural and morphological analysis of the obtained aminopropyl silica was performed using transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential measurements, Fourier-transform infrared (FTIR), (13)C and (29)Si MAS nuclear magnetic resonance (NMR) spectroscopies, as well as small angle X-ray scattering (SAXS). Our investigations revealed that the silica nanoparticle surfaces were partially covered with aminopropyl groups, and multilayer adsorption followed by polycondensation of the silylating reagent was successfully avoided. The resulting stable aminopropyl silica sol (ethanolic or aqueous) is suitable for biomedical uses due to its purity.
Department of Biological Nanochemistry, Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences (IMP RCNS HAS), Budapest, Hungary.
Marcell
M
Pálmai
Lívia Naszályi
LN
Nagy
Judith
J
Mihály
Zoltán
Z
Varga
Gábor
G
Tárkányi
Réka
R
Mizsei
Imola Csilla
IC
Szigyártó
Teréz
T
Kiss
Tibor
T
Kremmer
Attila
A
Bóta
D019342:Acetic Acid / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D003102:Colloids; D000431:Ethanol / Q000737:chemistry*; D010316:Particle Size; D012821:Silanes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
D000588:Amines; D003102:Colloids; D012821:Silanes; D000431:Ethanol; D012822:Silicon Dioxide; D019342:Acetic Acid