Browsing by Author "Martinov B.L."

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    ANTI-BIOFILM AGENTS FROM MARINE BIOTA
    (2023-01-01) Vladkova T.G.; Martinov B.L.; Gospodinova D.N.
    Microbial biofilm forms on any living or non-living material surface contacting with microbial species. It is a persistent world-weight spread problem with very high prize. This explains the exclusive interest to development of anti-biofilm material surfaces. The continuously increasing microbial resistance to currently used antimicrobial agents requires looking for new ones. Marine biota is a rich source of biologically active substances with anti-biofilm potential that is scarily studied. The aim of this review is to outline the variety of marine sources delivering antimicrobial agents and their ability to inhibit different stages of the biofilm development, expecting to give some ideas for their utilization in the creation of improved antibiofilm material surfaces. It includes short information about the negative impact and cost, mode of development and composition of the microbial biofilms, as well as principle approaches to the inhibition with focus on the sources of biologically active substances and anti-biofilm agents from marine biota. The main conclusion is that the antibiofilm activity of many marine biota derived biologically active substances is not enough investigated although their strong bactericidal, antioxidant, surfactant and other activities are already proved and utilized in the medicine, cosmetic, food industry and others. This review is an update of the known to day on the marine sources derived anti-biofilm agents.
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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.
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    Recent Progress in Terrestrial Biota Derived Antibacterial Agents for Medical Applications
    (2024-10-01) Vladkova T.G.; Smani Y.; Martinov B.L.; Gospodinova D.N.
    Conventional antibiotic and multidrug treatments are becoming less and less effective and the discovery of new effective and safe antibacterial agents is becoming a global priority. Returning to a natural antibacterial product is a relatively new current trend. Terrestrial biota is a rich source of biologically active substances whose antibacterial potential has not been fully utilized. The aim of this review is to present the current state-of-the-art terrestrial biota-derived antibacterial agents inspired by natural treatments. It summarizes the most important sources and newly identified or modified antibacterial agents and treatments from the last five years. It focuses on the significance of plant- animal- and bacteria-derived biologically active agents as powerful alternatives to antibiotics, as well as the advantages of utilizing natural antibacterial molecules alone or in combination with antibiotics. The main conclusion is that terrestrial biota-derived antibacterial products and substances open a variety of new ways for modern improved therapeutic strategies. New terrestrial sources of known antibacterial agents and new antibacterial agents from terrestrial biota were discovered during the last 5 years, which are under investigation together with some long-ago known but now experiencing their renaissance for the development of new medical treatments. The use of natural antibacterial peptides as well as combinational therapy by commercial antibiotics and natural products is outlined as the most promising method for treating bacterial infections. In vivo testing and clinical trials are necessary to reach clinical application.
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    Recent Progress in Terrestrial Biota-Derived Anti-Biofilm Agents for Medical Applications
    (2024-09-01) Vladkova T.G.; Smani Y.; Martinov B.L.; Gospodinova D.N.
    The terrestrial biota is a rich source of biologically active substances whose anti-biofilm potential is not studied enough. The aim of this review is to outline a variety of terrestrial sources of antimicrobial agents with the ability to inhibit different stages of biofilm development, expecting to give some ideas for their utilization in improved anti-biofilm treatments. It provides an update for the last 5 years on anti-biofilm plant products and derivatives, essential oils, antimicrobial peptides, biosurfactants, etc., that are promising candidates for providing novel alternative approaches to combating multidrug-resistant biofilm-associated infections. Based on the reduction in bacterial adhesion to material and cell surfaces, the anti-adhesion strategy appears interesting for the prevention of bacterial attachment in combating a broad range of mono- and multispecies bacterial biofilms. So far, few studies have been carried out in this direction. Anti-biofilm coatings made by or containing biologically active products from terrestrial biota have scarcely been studied although they are of significant interest for a reduction in infections associated with medical devices. Combination therapy with commercial antibiotics and natural products is accepted now as a promising base for future advances in anti-biofilm treatment. In vivo testing and clinical trials are necessary for clinical application.
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    Synthesis and characterization of nanosized ZnTiO3doped with reduced graphene oxide (RGO)
    (2021-02-16) Martinov B.L.; Staneva A.D.; Vlakhov T.E.; Slavov S.; Dimitrov D.; Marinov Y.G.; Hadjichristov G.B.
    Composite materials based on nanosized zinc titanate (ZnTiO3) doped with reduced graphene oxide (RGO) were obtained by means of ultrasonically assisted precipitation. In these composites, the concentration of RGO nanopartiles was varied from 1 wt.% to 20 wt.%. The ZnTiO3 ceramic was produced by sol-gel method. RGO was prepared by a modified Hammers method and subsequent chemical reduction with sodium borohydride. Structural and phase characterization of the fabricated composites was performed by XRD, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). It was identified that for all of the studied samples of the RGO/ZnTiO3 series, the two phases are uniformly distributed over the observed areas, which proves the formation of homogeneous nanocomposite materials. The electrical properties of the series of RGO/ZnTiO3 samples were characterized by complex electrochemical impedance spectroscopy (EIS) in the frequency range from 0.1 Hz to 1 MHz. The results obtained by EIS for the electrical conductance of RGO-doped ZnTiO3 as a function of the concentration of RGO nanoparticles were correlated with the data from structural studies.