Browsing by Author "Gospodinova D.N."
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Item 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.Item Antibiofouling activity of graphene materials and graphene-based antimicrobial coatings(2021-09-01) Staneva A.D.; Dimitrov D.K.; Gospodinova D.N.; Vladkova T.G.Microbial adhesion and biofilm formation is a common, nondesirable phenomenon at any living or nonliving material surface in contact with microbial species. Despite the enormous efforts made so far, the protection of material surfaces against microbial adhesion and biofilm formation remains a significant challenge. Deposition of antimicrobial coatings is one approach to mitigate the problem. Examples of such are those based on heparin, cationic polymers, antimicrobial peptides, drug-delivering systems, and other coatings, each one with its advantages and shortcomings. The increasing microbial resistance to the conventional antimicrobial treatments leads to an increasing necessity for new antimicrobial agents, among which is a variety of carbon nanomaterials. The current review paper presents the last 5 years’ progress in the development of graphene antimicrobial materials and graphene-based antimicrobial coatings that are among the most studied. Brief information about the significance of the biofouling, as well as the general mode of development and composition of microbial biofilms, are included. Preparation, antibacterial activity, and bactericidal mechanisms of new graphene materials, deposition techniques, characterization, and parameters influencing the biological activity of graphene-based coatings are focused upon. It is expected that this review will raise some ideas for perfecting the composition, structure, antimicrobial activity, and deposition techniques of graphene materials and coatings in order to provide better antimicrobial protection of medical devices.Item 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.Item Plasma Based Approaches for Deposition and Grafting of Antimicrobial Agents to Polymer Surfaces(2022-01-01) Vladkova T.G.; Gospodinova D.N.Improved protection of urinary stents against infections is a significant current challenge because of the increasing microbial resistance to the conventional antibiotics and negative issues for the patients. Formation of crystalline biofilms of pathogenic microbial cells is the leading cause of urinary stent associated infections. A lot of approaches, antimicrobial agents and techniques are under a study to mitigate the problem by creation of contact killing; releasing or low adhesive surfaces do not allow attachment of microbial cells. The plasma treatment has a number of advantages that make it preferable in many strategies for the development of antimicrobial biomaterials. The control over the plasma processing parameters allows control over the surface chemistry, charge, structure, morphology, hydrophilic/hydrophobic balance, etc. Due to a variety of biomaterials and bacteria, causing urinary tract infections, plasma assisted antibacterial strategies need in tailoring to each specific surface. Plasma treatment of polymers under corresponding operation conditions allows deposition of contact killing, releasing (including controlled release) or low-adhesive antimicrobial coatings, as well as polymer surface functionalization and durable immobilization of antimicrobial molecules. Most of the plasma technologies are developed in laboratory and the surface engineered biomaterials are tested in vitro.Item 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.