Browsing by Author "Ivanova I.A."

Now showing 1 - 6 of 6
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    ANTIMICROBIAL AND CYTOTOXIC PROPERTIES OF METAL NANOPARTICLES AND GRAPHENE MATERIALS (REVIEW)
    (2020-01-01) Ivanova I.A.; Stoyanova D.; Nenova E.; Kostadinova A.; Staneva A.
    The nanotechnology is the fastest developing branch of science in the border of physics, chemistry, biology and electronics. The ecological effect of nanomaterials on various organisms is still not enough understood. This review of the literature presents the mechanisms of action of nanomaterials: eluted metal ions, size and form of nanoparticles, reactive oxygen species and non-ionic interactions. The results obtained by different authors on the effects of graphene, metal nanoparticles, their oxides and nanocomposites on different types of organisms - prokaryotes and eukaryotes are described. Antimicrobial and cytotoxic properties of the new materials are discussed in respect to their medical and environmental significance
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    BIOLOGICAL ACTIVITY OF GRAPHENE NANOCOMPOSITES WITH ZINC OXIDE, Cu AND Ag NANOPARTICLES
    (2023-01-01) Martinov B.; Pavlova E.; Ivanova I.A.; Yocheva L.; Kostadinova A.; Staneva A.
    The aim of this research is to obtain collagenе nanocomposites based on graphene, graphene oxide, GO, zinc oxide and metal nanoparticles and to evaluate their pro-, antioxidant and biological activities by luminescent and standard microbiological assays. The antimicrobial activity of graphene composites with added nanosized zinc oxide, silver and copper nanoparticles was tested on Firmicutes bacteria Staphylococcus epidermidis (ATCC 1228) and Gracillicutes Escherichia coli (ATCC 25922). The method of diffusion in agar was used in three variants - spot diffusion, well and paper-disc diffusion. The spot and diffusion disc approaches of the method have shown better effect than the well diffusion for testing the effect of graphene composites on bacteria. The composites with high ZnO content had the best antimicrobial properties against the tested bacteria. The cytotoxicity of the nanocomposites using normal MDCK and A549 epithelial sarcoma cells were tested for 24 h at a concentration of 100 mg mL-1. Cancer cells were found to be more sensitive than normal to the graphene composites, proving antitumor activity. The pro and antioxidant effects of the tested nanomaterials depend on the pH level. At physiological conditions, in the Fenton's system, all but RGO+Cu do not appear to be suitable as an implant nanomaterial. In the H2O2 oxidation system all materials present stable antioxidant effects; only ZnO+RGO+Cu is close to control prooxidant levels. When the nanomaterials are tested for oxidation by O2.- radicals, ZnO+RGO and Zn+RGO+Cu show prooxidant effects, as the prooxidant activity is kept for ZnO+RGO even at physiological acidity pH 7.4.
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    Comparative Study of the Marinobacter hydrocarbonoclasticus Biofilm Formation on Antioxidants Containing Siloxane Composite Coatings
    (2022-07-01) Vladkova T.G.; Monov D.M.; Akuzov D.T.; Ivanova I.A.; Gospodinova D.
    No systematic study of antioxidant containing coatings and their anti-biofilm action has been reported so far. The utilization of antioxidants in protective coatings to inhibit marine biofilm formation is a current challenge. The aim of this preliminary study was to prepare, characterize and compare the efficiency of low adhesive siloxane composite coatings equally loaded with different antioxidants against mono-species biofilms formation. Most often participating in the marine bio-films formation, Marinobacter hydrocarbonoclasticus was the test bacterium. Both the biofilm covered surface area (BCSA) and corrected total cell fluorescence (CTCF) (by fluorescent microscopy) were selected as the parameters for quantification of the biofilm after 1 h and 4 h incubation. Differing extents of altered surface characteristics (physical-chemical; physical-mechanical) and the specific affection of M. hydrocarbonoclasticus biofilm formation in both reduction and stimulation, were found in the studied antioxidant containing coatings, depending on the chemical nature of the used antioxidant. It was concluded that not all antioxidants reduce mono-species biofilm formation; an-tioxidant chemical reactivity stipulates the formation of an altered vulcanization network of the siloxane composites and thus microbial adhesion which influences the surface characteristics of the vulcanized coatings; and low surface energy combined with a low indentation elastic modulus are probably pre-requisites of low microbial adhesion.
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    Early stage anti-bioadhesion behavior of superhydrophobic soot based coatings towards Pseudomonas putida
    (2018-12-15) Esmeryan K.D.; Avramova I.A.; Castano C.E.; Ivanova I.A.; Mohammadi R.; Radeva E.I.; Stoyanova D.S.; Vladkova T.G.
    Biofilm development, associated with the adherence of microbial cells on various solid substrates, has an adverse economic impact and is the main reason for the spreading of microbial infections. The present article reports novel findings about the anti-bioadhesion performance of four types of superhydrophobic soot coatings, deposited via combustion flame synthesis and further functionalized using plasma polymerization and/or fluorination, towards a Gram-negative bacterial strain Pseudomonas putida. The real-time sensor response of four representative soot coated 5 MHz quartz crystal microbalances, along with scanning electron microscopy, fluorescence microscopy and contact angle measurements on the model soot surfaces, reveal reversible and irreversible bioadhesion on the soot during the first hour of cell colonization. Each adhesion mode is related to the presence and distribution of morphological features within the size of bacteria, but the prolonged 7-day exposure to the bacterial suspensions unifies the number of attached cells (only 3 times difference from coating-to-coating). Nevertheless, the soot coatings inhibit the proliferation of Pseudomonas species and reduce their quantity by two orders of magnitude compared to an uncoated glass slide, which demonstrates the importance of surface characteristics for precise control of the initial cell attachment and development of multifunctional soot coatings with anti-bioadhesion properties.
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    Fucoidan-Containing, Low-Adhesive Siloxane Coatings for Medical Applications: Inhibition of Bacterial Growth and Biofilm Development
    (2023-05-01) Vladkova T.G.; Staneva A.D.; Avramova I.A.; Ivanova I.A.; Gospodinova D.N.
    The deposition of low-adhesive siloxane coatings is a current trend for the non-toxic control of bacterial growth and biofilm formation. Total elimination of biofilm formation has not been reported so far. The aim of this investigation was to study the ability of a non-toxic, natural, biologically active substance, such as fucoidan, to inhibit bacterial growth on similar medical coatings. The fucoidan amount was varied, and its impact on the bioadhesion-influencing surface characteristics, as well as on bacterial cell growth, was investigated. The inclusion of up to 3–4 wt.% brown algae-derived fucoidan in the coatings increases their inhibitory effect, more significantly on the Gram-positive bacterium S. aureus than on the Gram-negative bacterium Escherichia coli. The biological activity of the studied siloxane coatings was ascribed to the formation of a low-adhesive, biologically active surface top layer consisting of siloxane oil and dispersed water-soluble fucoidan particles. This is the first report on the antibacterial activity of fucoidan-containing medical siloxane coatings. The experimental results give reason to expect that relevantly selected, natural biologically active substances can be efficient in the non-toxic control of bacterial growth on medical devices and, as a result, medical device-associated infections.
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    PREPARATION AND ANTIMICROBIAL ACTIVITY OF FUCOIDAN CONTAINING COLLAGEN/(ZnTiO3/SiO2) COMPOSITES
    (2023-01-01) Vladkova T.G.; Martinov B.L.; Staneva A.D.; Ivanova I.A.; Gospodinova D.N.; Albu-Kaya M.G.
    The aim of this investigation was to develop collagen based composite biomaterial with improved antimicrobial activity using a combination of antimicrobial agents consisting of zinc titanate embedded in a silane matrix, (ZnTiO3/ SiO2) and fucoidan at varied concentrations. The morphology of the investigated porous collagen/(ZnTiO3/SiO2)/ fucoidan composites was observed by SEM and their antimicrobial activity was evaluated against four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Pseudomonas putida, Salmonela holeresius), two Grampositive bacteria (Staphylococcus epidermidis, Bacillus cereus) and two fungi (Candida Lusitania, Saccharomyces cerevisiae) by disk diffusion test. Broad-spectrum antimicrobial activity of the studied porous collagen/(ZnTiO3/SiO2)/fucoidan composites was demonstrated, specific toward the different test microbial strains and dependent on the fucoidan concentration. The specific activity toward different microbial cultures was ascribed to the features of the microbial cells (size, shape, cell wall and membrane) and differences in the composition of the secreted exopolymeric substances. It was found that both, the formed interconnected open porous structure of the mixed collagen/fucoidan matrix with fine dispersed submicron ZnTiO3/SiO2 particles along the marix fibrils and the own antibacterial activity of the fucoidan, contribute to the increased wide spectrum antibacterial activity compared to that of similar collagen composites do not containing fucoidan.