Surface silver-doping of biocompatible glasses to induce antibacterial properties. Part II: Plasma sprayed glass-coatings.

A 57% SiO(2), 3% Al(2)O(3), 34% CaO and 6% Na(2)O glass (SCNA) has been produced in form of powders and deposited by plasma spray on titanium alloy and stainless steel substrates. The obtained coatings have been subjected to a patented ion-exchange treatment to introduce silver ions in the surface inducing an antibacterial behavior. Silver surface-enriched samples have been characterized by means of X-ray diffraction, SEM observation, EDS analysis, in vitro bioactivity tests, leaching tests by GFAAS (graphite furnace atomic adsorption spectroscopy) analyses, cells adhesion and proliferation, and antibacterial tests using Staphylococcus Aureus strain. In vitro tests results showed that the modified samples acquired an antimicrobial action against tested bacteria maintaining unaffected the biocompatibility of the glass. Furthermore the ion-exchange treatment can be successfully applied to glass-coated samples without affecting the properties of the coatings; the simplicity and reproducibility of the method make it suitable for glass or glass-ceramic coatings of different composition in order to produce coated devices for bone healing and/or prostheses, able to reduce bacterial colonization and infections risks.

Surface silver-doping of biocompatible glass to induce antibacterial properties. Part I: Massive glass.

A glass belonging to the system SiO(2)-Al(2)O(3)-CaO-Na(2)O has been subjected to a patented ion-exchange treatment to induce surface antibacterial activity by doping with silver ions. Doped samples have been characterized by means of X-Ray diffraction (XRD), scanning electron microscopy (SEM) observation, energy dispersion spectrometry (EDS) analysis, in vitro bioactivity test, Ag(+) leaching test by graphite furnace atomic absorption spectroscopy (GFAAS) analyses, cytotoxicity tests by fibroblasts adhesion and proliferation, adsorption of IgA and IgG on to the material to evaluate its inflammatory property and antibacterial tests (cultures with Staphylococcus aureus and Escherichia coli). In vitro tests results demonstrated that the modified glass maintains the same biocompatibility of the untreated one and, moreover, it acquires an antimicrobial action against tested bacteria. This method can be selected to realize glass or glass-ceramic bone substitutes as well as coatings on bio-inert devices, providing safety against bacterial colonization thus reducing the risks of infections nearby the implant site. The present work is the carrying on of a previous research activity, concerning the application of an ion-exchange treatment on glasses belonging to the ternary system SiO(2)-CaO-Na(2)O. On the basis of previous results the glass composition was refined and the ion-exchange process was adapted to it, in order to tune the final material properties. The addition of Al(2)O(3) to the original glass system and the optimization of the ion-exchange conditions allowed a better control of the treatment, leading to an antibacterial material, without affecting both bioactivity and biocompatibility.

[Evaluation of a rapid agglutination method for the identification of Staphylococcus aureus]. / Valutazione di un metodo rapido di agglutinazione per l'identificazione dello Stafilococco aureo.

It has been valued a new quick latex method (Staphaurex Wellcome) for the identification of the aureus Staphylococcus. This shown simultaneously the Clumping Factor (CF) and the A protein; the production of the free Coagulase (CL) and the Thermonuclease (TNase), has been utilized as methods of remarking. On 120 bacterial stocks isolated by many biological materials, belonging to the family of the Micrococcaceae, 56 stocks was identified as aureus. St. and 64 as not aureus St. For what concerns the quick Staphaurex method, it has shown a sensitivity of 83.4, with 8 false negatives on 120 cases, while it proved very satisfactory as specification with one false positive.