The objective of the study was to develop and evaluate aminosilanes-modified silicate impregnated with silver (Ag) nanoparticles, in which Ag dispersion is stabilized, to create a composite that protects against biological warfare agents. A composite based on Ag and organically modified silicate (Ormosil) was prepared by an in situ reduction method, in which silver nitrate, tetraethoxysilane (TEOS) and 3-(2-aminoethylaminopropyl)trimethoxysilane (AES) acted as precursor, linker and colloidal suspension stabilizer, respectively. The physical properties of the Ormosil hybrid and Ormosil/Ag composite were examined using NMR, ESR, SEM, TEM, and TGA spectroscopy, the results of which indicated that Ag was incorporated in the Ormosil matrix after impregnation. Morphological analysis by TEM showed the resulting Ag nanoparticles to be spherical and of a mean size of less than 50 nm. The antibacterial effects of the Ormosil hybrid and the Ormosil/Ag composite were assessed by the zone of inhibition and plate-counting methods, and an excellent antibacterial performance was discovered. (C) 2010 Elsevier B.V. All rights reserved.