Browsing by Author "Stoyanova R."
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Item A new cu(Ii) complex of pamam dendrimer modified with 1,8-naphthalimide: Antibacterial and anticancer activity(2022-08-15) Manov H.; Staneva D.; Vasileva-Tonkova E.; Kukeva R.; Stoyanov S.; Grabchev I.; Alexandrova R.; Stoyanova R.A new fluorescent PAMAM copper complex ([Cu2 (D)(NO3 )4 ]) has been synthesized and identified. The formation of the complex has been investigated by fluorescence spectroscopy which revealed two copper ions to be bound to the dendrimer ligand. That has also been confirmed upon subjecting the solid copper complex to electron paramagnetic spectroscopy. The antimicrobial activity of the copper complex against Gram-negative bacterium Pseudomonas aeruginosa in light and the dark has been studied. The results demonstrate an increase in its activity when irradiated with daylight. This activity of the copper complex is retained even after being loaded onto a cotton cloth. The antitumor activity of the copper complex and dendrimer ligand against triple-negative breast cancer MDA-MB-231 cells has been investigated as well.Item EPR as a tool for the evaluation of novel lyophilized blood products as absorbents for chemical gas masks(2011-04-01) Ivanov V.; Arora R.; Hadjiiliev V.; Stoyanova R.; Ruseva R.; Nikolov R.; Kumar R.; Sharma R.Item Hyperbranched polymers modified with Dansyl units and their Cu(II) complexes. bioactivity studies(2020-10-02) Bosch P.; Staneva D.; Vasileva-Tonkova E.; Grozdanov P.; Nikolova I.; Kukeva R.; Stoyanova R.; Grabchev I.Two new copper complexes of hyperbranched polymers modified with dansyl units were synthesized and characterized by infrared spectroscopy (IR) and electron paramagnetic resonance (EPR) techniques. It was found that copper ions coordinate predominantly with nitrogen or oxygen atoms of the polymer molecule. The place of the formation of complexes and the number of copper ions involved depend on the chemical structure of the polymer. The antimicrobial activity of the new polymers and their Cu(II) complexes was tested against Gram-negative and Gram-positive bacterial and fungal strains. Copper complexes were found to have activity better than that of the corresponding ligands. The deposition of the modified branched polymers onto cotton fabrics prevents the formation of bacterial biofilms, which indicates that the studied polymers can find application in antibacterial textiles.Item New Poly(Propylene Imine) dendrimer modified with acridine and its Cu(II) complex: Synthesis, characterization and antimicrobial activity(2019-09-01) Bosch P.; Staneva D.; Vasileva-Tonkova E.; Grozdanov P.; Nikolova I.; Kukeva R.; Stoyanova R.; Grabchev I.A second-generation poly(propylene imine) dendrimer modified with acridine and its Cu(II) complex have been synthesized for the first time. It has been found that two copper ions form complexes with the nitrogen atoms of the dendrimeric core by coordinate bonds. The new compounds have been characterized by nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), fourier-transform infrared spectroscopy (FTIR) and fluorescence spectroscopy. The spectral characteristics of the modified dendrimer have been measured in different organic solvents, and a negative fluorescence solvatochromism has been observed. The antimicrobial activity of the dendrimers has been tested against model pathogenic microorganisms in agar and by broth dilution method. The cotton fabric treated with both dendrimers has been evaluated towards pathogenic microorganisms. The obtained modified cotton fabrics have been shown to hamper bacterial growth and to prevent biofilm formation. Dendrimer cytotoxicity has been investigated in vitro in the model HEp-2 cell line.Item Synthesis, Spectral Characteristics, Sensing Properties and Microbiological Activity of New Water-Soluble 4-Sulfo-1,8-naphthalimides(2024-05-01) Said A.I.; Staneva D.; Vasileva-Tonkova E.; Grozdanov P.; Nikolova I.; Stoyanova R.; Jordanova A.; Grabchev I.A new water-soluble polyamidoamine (PAMAM) dendrimer modified with 4-sulfo-1,8-naphthalimide (DSNI) and its monomeric structural analogue (MSDI) were synthesized. Their photophysical properties were investigated in organic solvents of different polarities and aqueous solutions. The effect of pH on fluorescence intensity was determined. It was found that the dendrimer emits blue fluorescence in an acidic medium, which is quenched in an alkaline environment. This phenomenon is due to the possibility of suppression of nonradiative photoinduced electron transfer in acidic media. The influence of different metal ions (Cu2+, Pb2+, Sn2+, Sr2+, Mg2+, Ba2+, Co2+, Hg2+, Zn2+, Ni2+, Fe3+, Al3+) and anions (CN−, S2−, S2O52−, HPO42−, H2PO4−, F−, CH3COO−, NO2−, CO32−, SO42−) on the intensity of the emitted fluorescence was studied. Quenching was only found in the presence of Cu2+. This makes the dendrimer suitable for determining copper ions in water solutions in the presence of other metal ions and anions. Additionally, DSNI was used as a ligand to obtain a stable copper complex, the structure of which was investigated by electron paramagnetic resonance (EPR), infrared spectrum, and elemental analysis. Two copper ions were found to form a complex with one dendrimer. The in vitro microbiological activity of the new compounds against bacteria Pseudomonas aeruginosa and two viruses HRSV-2 and HAdV-5 was investigated. With a view to obtaining antibacterial and anti-viral textiles, cotton fabrics were treated with the three compounds, and then their activity against the same microbial strains was investigated. It was found that the microbiological activity was preserved after the application of the new compounds to the cotton fabrics.