Polysilazane-derived antibacterial silver-ceramic nanocomposites

Functional ceramic composites consisting of a dispersion of silver nanoparticles in a silicon (carbon)nitride matrix (nc-Ag/Si(C)N) were prepared via the polymer-ceramic route. Mixtures of 3 wt% as-synthesized Ag nanoparticles with a commercial polysilazane were pyrolysed under flowing nitrogen and/or ammonia. Bulk samples as well as coatings were investigated. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal analysis (TGA, DTA), absorption spectroscopy (UV-vis) and infra red (IR) spectroscopy were used to characterize the products. The results indicate that the silver nanoparticles do not influence the cross-linking and pyroylsis process of the polysilazane precursor. At temperatures in the range of 800-1000 degrees C (H)Si(C)N matrices are obtained, which contain silver particles with an average size of 5-7 nm. Antibacterial tests on the pyrolysed material revealed strong activity against Escherichia coli and Staphylococcus aureus, suggesting the composites to be promising candidates for applications in fields such as the biomedical or food industries. (C) 2007 Elsevier Ltd. All rights reserved.