Preparation, purification, and characterization of aminopropyl-functionalized silica sol

Marcell Pálmai, Lívia Naszályi Nagy, Judith Mihály, Zoltán Varga, Gábor Tárkányi, Réka Mizsei, Imola Csilla Szigyártó, Teréz Kiss, Tibor Kremmer, Attila Bóta

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


A new, simple, and "green" method was developed for the surface modification of 20nm 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), 13C and 29Si 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.

Original languageEnglish (US)
Pages (from-to)34-40
Number of pages7
JournalJournal of Colloid And Interface Science
Issue number1
StatePublished - Jan 15 2013

Bibliographical note

Copyright 2013 Elsevier B.V., All rights reserved.


  • 3-Aminopropyl(diethoxy)methylsilane
  • Aminopropyl silica nanoparticles
  • Silylation in sol
  • Surface modification

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