Browsing by Author "Kostadinova A."

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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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    DFT calculations, characterization and in vitro cytotoxicity of platinum(II) complex of 3-amino-1,2,4-triazole
    (2020-01-01) Yankova R.; Kostadinova A.; Radev L.
    A platinum(II) complex of 3-amino-1,2,4-triazole is synthesized and characterized by using 1H, 13C NMR and FT-IR spectroscopies. The molecular geometry and the chemical reactivity of the complex are studied using the Density Functional Theory at B3LYP/6-311++G(d, p) basis set of H, C, N, Cl and LANL2DZ for Pt. The molecular electrostatic potential surface, the natural bond orbital and the natural charge population are estimated. The frontier molecular orbital analyses are conducted. The intramolecular interactions in [Pt(3-amino-1,2,4-triazole)2Cl2] are investigated using the quantum theory Atoms in Molecules. It is observed that the complex is stabilized via two hydrogen bonds, N-H···Cl, which are weak and electrostatic in nature. They determine the different energy and bond length of Pt-Cl and Pt-N. The compound cytotoxicity is evaluated using 2 type eukaryotic cells: MDCK II kidney epithelial cell line and A549 cancer alveolar cell line. The results of this investigation demonstrate the high cytotoxic effect of [Pt(3-amino-1,2,4-triazole)2Cl2] especially to cancer cells. This Pt(II) complex is a promising nanomaterial for a variety of biomedical applications, including cancer therapy.
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    Facile Synthesized Cu–RGO and Ag–RGO Nanocomposites with Potential Biomedical Applications
    (2022-06-01) Kichukova D.; Spassova I.; Kostadinova A.; Staneva A.; Kovacheva D.
    In the present study, we report on the facile prepared nanocomposites of reduced graphene oxide RGO with Cu and Ag. The synthesis was performed through an environmentally friendly and easy method by simultaneous reduction in solutions containing Cu2+ or Ag+ and graphene oxide (GO) using zinc powder as a reducing agent in aqueous acidic media. The composites are characterized by powder X-ray diffraction, low-temperature nitrogen adsorption, X-ray photoelectron and FTIR and Raman spectroscopies, as well as Scanning and Transmission electron microscopies. The antibacterial activity of the composites was tested for Staphylococcus aureus, Escherichia coli and antifungal activity for Candida albicans. The cytotoxicity of the materials was studied towards two types of eukaryotic cells—MDCK II and A549 cell lines. The composites obtained consist of homogeneously distributed Cu and Ag nanoparticles on the surface of graphene sheets and manifest good antimicrobial activity and high cytotoxicity. The results clearly show that both metal–RGO composites can be successfully used as antimicrobial and anticancer agents.