Novel antibacterial bioactive glass nanocomposite functionalized with tetracycline hydrochloride

To prevent the high frequency of wound infections, anti-bacterial agents can be loaded onto composites. In the present study, the antibiotic tetracycline hydrochloride (TC)was incorporated, for the first time, in collagen type I membranes coated with nano-sized SiO2-CaOP2O5 bioactive glass (n-BG) obtained by a sol-gel chemical route. Collagen membranes coated with n-BG were immersed in simulated body fluid (SBF) containing 0.25, 0.75 or 1.25 mg mL−1 of TC for 48 h at 37∘C following a coprecipitation method. The antibiotic was released in distilledwater at 37∘C for up to 72 h. The antibacterial activity of the composites was evaluated in vitro by the inhibition zone test and plate count method. Two different Staphylococcus aureus strains, S. aureus ATCC29213 and S. aureus ATCC25923, were exposed to the biomaterials. The results showed that the incorporation but not the release of TC was dependent on the initial concentration of TC in SBF. The biomaterials inhibited S. aureus growth, although the efficacy was similar for all the concentrations. The results allow us to conclude that the new composite could have potential in the prevention of wound infections.Fil: Rivadeneira, Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Luz, Gisela M.. Universidade Do Minho; PortugalFil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones Para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones Para la Industria Química; ArgentinaFil: Mano, Joao F.. Universidade Do Minho; PortugalFil: Gorustovich Alonso, Alejandro Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentin

45S5 Bioglass® concentrations modulate the release of vancomycin hydrochloride from gelatin-starch films: evaluation of antibacterial and cytotoxic effects

The aim of this work was to evaluate the release profile of vancomycinhydrochloride (VC), as well as the degradation, in vitro antistaphylococcal effect and cytotoxicity in MG-63 osteoblast-like cells of gelatin–starch (GS) films added with different concentrations of microparticles of the bioactive glass 45S5 (m-BG). The biomaterials were obtained through the gel-casting method. Four different composites were prepared at four different weight percentages of m-BG: 0, 5, 10, and 15 %. Glutaraldehyde 0.25 wt% (GA) was used as the cross-linker. The composites were characterized by scanning electron microscopy and the in vitro degradation of the filmswas studied bymeasuring thewater uptake and weight loss. The drug release kinetics was quantified spectrophotometrically. The inhibition zone test and the plate count method were used to evaluate the antibacterial activity of the samples. Three staphylococcus strains were evaluated: Staphylococcus aureus ATCC6538, S. aureus ATCC29213, and Staphylococcus epidermidis ATCC12228. Cytotoxicity effects were evaluatedthrough the MTT assay.The addition of m-BG to GS films showedno effects on the amount of water uptake, but led to an increase in the weight loss over time, even with m-BG content. The release rate of VC was also affected by the increasing concentration of m-BG in the composite films.However, the antibacterial effects of the composites were not improved by this modulation. All composites strongly inhibited staphylococcal cells with similar strength. On the other hand, liquid extracts from the composites resultedin cytotoxic effects onMG-63 osteoblastlike cells due to the presence of GA, but not to the concentration of VC or m-BG.Facultad de Ciencias Exacta

Bacteriocin from Honeybee Beebread Enterococcus avium, Active against Listeria monocytogenes

Enterococcus avium isolated from Apis mellifera beebread produces a thermoresistant bacteriocin with a strain-dependent inhibitory effect on Listeria and without effect on gram-negative bacteria. The bacteriocin appeared to be a polypeptide of about 6 kDa. Genetic analyses revealed no extrachromosomal material in E. avium