INVESTIGADORES
CERE silvia
congresos y reuniones científicas
Título:
Silver dopped sol-gel hybrid coatings for antibacterial surfaces
Autor/es:
S. PELLICE; J. BALLARRE,; A. CAVALIERI; S. CERÉ
Lugar:
Porto de Galhinas, Brsil
Reunión:
Congreso; . xvth international sol-gel conference; 2009
Resumen:
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Materials enriched with noble metal ions, such as
of silver, cobalt or copper, are of great interest in the field of hygienic and
healthiness products through its action against fungus and bacteria. Although a
large number of commercial products are chemically active against
microorganisms, they are usually limited to fabrics for medical bandages and
sportswear in order to avoid, respectively, infections and odor. Although many
of those products are based on the biocide properties of silver nanoparticles,
it is well known Ag+ has an effective action against bacteria life inhibiting their
DNA replication process, increasing the permeability of the cytoplasmic
membrane and inhibiting the respiratory enzymes causing asphyxia of the
bacteria. Taking this feature in account, reduction of silver ions must be
strongly avoided in order to maximize the biocide character of the functional
coating.
In
this work, the development of silver doped hybrid organic-inorganic sol-gel
coatings is focused. A hybrid organic-inorganic matrix was obtained through the
hydrolytic condensation of tetraethoxysilane (TEOS) and methyl-triethoxysilane
(MTES). Silver nitrate (AgNO3) was added as supplier of Ag+ and,
which was complexed with pyridine (C5H5N). Silica
nanoparticles were added in different proportions in order to increase the
coating density and control the silver diffusion through the hybrid matrix.
UV-visible
spectroscopy of precursor sols evidenced the chemical stability of silver upon
more than two weeks in storing at 4 ºC. Colorless dip-coated films were
obtained on glass slides at a withdrawal speed of 25 cm/min and thermal treated
at 450 ºC during 30 min in air atmosphere. Lixiviation tests were performed along
30 days at 30 ºC in immersion in deionized water at a ratio of 1 cm2/ml.
The ratio of silver releasing from coatings was analyzed by Atomic-Absorption
Spectroscopy (AAS) and X-Ray Fluorescence (XRF).
Contact
angle of inoculated PBS on the sample surface and adhesion of bacteria were
analyzed. Samples inoculated 2 h at 25 ºC in PBS solution were observed by fluorescence
microscopy. The biocide potential was determined by the agar diffusion test of the
obtained coatings. After incubation period of 24 h, the inhibition halo
developed around samples in Petri dishes was measured.