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A low melting point soda-lime glass powder containing copper nanoparticles with high antibacterial (against gram-positive and gram-negative bacteria) and antifungal activity has been obtained. Sepiolite fibres containing monodispersed copper nanoparticles (d(50) approximately 30 +/- 5 nm) were used as the source of the copper nanoparticles. The observed high activity of the obtained glass powder, particularly against yeast, has been explained by considering the inhibitory synergistic effect of the Ca(2+) lixiviated from the glass on the growth of the colonies.

The antibacterial and antifungal activity of a low melting point soda-lime glass powder containing silver nanoparticles has been studied. Nano-Ag sepiolite fibres containing monodispersed silver nanoparticles (d(50) approximately 11 +/- 9 nm) were used as the source of silver. This powder presents a high antibacterial (against gram-positive and gram-negative bacteria) as well as antifungal (against I. orientalis) activity. The observed high activity against yeast has been explained by considering the inhibitory effect of the Ca(2+) lixiviated from the glass on the growth of the yeast colonies.

Surface modification reactions on needle-like sepiolite using alkyl and functional silanes have been carried out in the form of aqueous gels. In contrast with modifications in organic solvents, reactions in water make it possible to modify the surface of almost-individual sepiolite fibers and produce either a continuous coating or a nanotexturization of the sepiolite fiber surface, depending on the reaction conditions. This clean procedure substitutes advantageously organic solvent surface modifications and allows the tuning of surface properties such as specific surface area, wetting behavior, and chemical functionalization. A consequence of such tuning is, for example, the excellent dispersion of modified sepiolite nanofibers in a great variety of polymers by routine compounding and processing techniques.

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The preparation of large quantities of heterogeneous materials containing non-agglomerated and monodispersed nanoparticles is becoming one of the bottlenecks that hinders the development of commercial devices. Here we describe a method to prepare monodispersed metallic (Cu, Ag, Au, Ni, Co, and Fe) nanoparticles in a silicate matrix (sepiolite) by means of a reduction process of metallic cations associated with a dehydration process of the matrix. This process is characterized by the huge amount of monodispersed metallic nanoparticles that it produces. Additionally, these nanoparticles have been revealed to be remarkably stable against oxidation because the transformed sepiolite matrix becomes a diffusion barrier for oxygen. Furthermore, the nanoparticles present suitable properties to be used for optical and magnetic applications.

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