Browsing by Author "Albu-Kaya M."

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    Collagen/(ZnTiO3/SiO2) composites of an wide spectrum antimicrobial activity
    (2020-01-01) Vladkova T.; Staneva A.; Albu-Kaya M.; Martinov B.; Ivanova I.
    The aim of this study is to prepare collagen composites of an increased wide spectrum antimicrobial activity using zinc titanate embedded in a silane matrix (ZnTiO3 /SiO2). Aiming to improve the predictability between the patient outcome and the in vitro antimicrobial testing, four Gram-negative, two Gram-positive bacterial strains, two fungi and seven mixed cultures are used in this study. A higher antimicrobial activity of Collagen/(ZnTiO3/SiO2) composites as compared to that of Collagen/ZnTiO3 ones is found against all test mono-microbial strains. Collagen/(ZnTiO3 /SiO2) composites demonstrate also an well expressed action against the mixed test bacterial cultures, in the most cases a better one compared to that against the bacteria participating in the corresponding mixed bacterial cultures. The increased antimicrobial effect is due to a more homogeneous distribution of the submicron ZnTiO3 aggregates embedded in a silane matrix along the collagen fibrils and a formation of a specific, snail-like structure depicted by SEM. The specific activity against different microbial cells and mixed bacterial cultures is ascribed to features of the microbial cells: size, shape, cell membrane and walls as well as to different exopolymeric substances (EPSs) and their concurrent adsorption in cases of mixed bacterial cultures, as well as the EPSs concurrent adsorption being similar to the concurrent protein adsorption from blood plasma known as Vroman's effect. The wide spectrum high activity against fungi, mono-and multi-specie bacterial cultures makes the studied Collagen/(ZnTiO3 /SiO2) composites a promising antimicrobial biomaterial.
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    Preparation and antimicrobial activity of collagen/(RGO/ZnO/TiO2/SiO2) composites
    (2020-01-01) Staneva A.; Albu-Kaya M.; Martinov B.; Ivanova I.; Vladkova T.
    A serial investigation is initiated aiming to explore the biological activity of some newly synthetized chemical compounds for the development of novel antimicrobial collagen based biomaterials. Collagen/ZnTiO3, Collagen/RGO, Collagen/(Ag/RGO), Collagen/(Ag/RGO/SiO2) and Collagen/(ZnTiO3/SiO2) composites have been so far studied and all of them demonstrate a specific antimicrobial activity against Gram-negative and Gram-positive bacteria and in some cases against fungi. The aim of this investigation is to develop new antimicrobial collagen biomaterials using RGO, ZnO, and TiO2 embedded in TEOS as another antimicrobial agent, combining the biological activity of RGO, ZnO and TiO2 with the dispersing effect of SiO2. The new Collagen/(RGO/ZnO/TiO2/SiO2) composites demonstrate an antimicrobial activity dependent on the agent loading level. It is specific in respect to Gram-negative, Grampositive bacteria and fungi. An optimal balance between the antimicrobial activity and the cytotoxicity is achieved by varying the concentration of the antimicrobial agent, RGO/ZnO/TiO2/SiO2, in Collagen/(RGO/ZnO/TiO2/SiO2) composites. It is suggested that the mechanism of the antimicrobial action includes the simultaneous proceeding of (i) metal ions chelation; (ii) free oxygen radicals formation due to the interactions between the microbial cells and the antimicrobial agent; (iii) mechanical demolition of the cell walls and membranes by RGO crystal nanoparticles. The broad spectrum antibacterial and anti-fungal activity combined with the low cytotoxicity at an optimal Collagen/ Antimicrobial agent ratio makes the studied Collagen/(RGO/ZnO/TiO2/SiO2) composites a promising antimicrobial material increasing the medical biomaterials assortment. © 2020 by the authors.