Milena Ignatova | Bulgarian Academy of Sciences (original) (raw)
Papers by Milena Ignatova
Antioxidants
A new type of fibrous mat based on a cellulose derivative—cellulose acetate (CA) or CA and water-... more A new type of fibrous mat based on a cellulose derivative—cellulose acetate (CA) or CA and water-soluble polymers (polyvinylpyrrolidone, PVP or poly(vinyl alcohol), PVA)—loaded with the model drug 5-nitro-8-hydroxyquinoline (5N) was fabricated via electrospinning or electrospinning in conjunction with electrospraying. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), water contact angle measurements and ultraviolet-visible spectroscopy (UV-Vis) were used for the complex characterization of the obtained novel material. The decoration of CA fibers with a water-soluble polymer containing the drug resulted in the facilitation of wetting and fast drug release. The 5N-containing fibrous material showed antioxidant activity. Moreover, the proposed materials’ antibacterial and antifungal properties were tested against S. aureus, E. coli, P. aeruginosa and C. albicans. Well-distinguished, sterile zones with diameters above 3...
Polymers
Esca is a grapevine disease known for centuries which pertains to the group of so-called vine tru... more Esca is a grapevine disease known for centuries which pertains to the group of so-called vine trunk diseases. Phaeomoniella chlamydospora (P. chlamydospora) and Phaeoacremonium aleophilum (P. aleophilum) are the two main fungal pathogens associated with esca. Novel fibrous materials with antifungal properties based on poly(3-hydroxybutyrate) (PHB), polyvinylpyrrolidone (PVP) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol, CQ) were developed. One-pot electrospinning (“in” strategy) or electrospinning in conjunction with electrospraying (“on” strategy) were applied to obtain the materials. The materials’ morphology and their surface chemical composition were examined using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). CQ incorporated in the bulk of the fibers or in PVP particles deposited on the fibers was in the amorphous phase, which was confirmed by differential scan...
Materials Science and Engineering: C, 2020
Journal of Bioactive and Compatible Polymers, 2000
International journal of pharmaceutics, Jan 15, 2010
Nanofibrous implants containing quaternized chitosan (QCh), poly(L-lactide-co-D,L-lactide) (coPLA... more Nanofibrous implants containing quaternized chitosan (QCh), poly(L-lactide-co-D,L-lactide) (coPLA), and the antitumor drug doxorubicin (DOX) were fabricated by electrospinning. The surface chemical composition and the morphology of the implants were characterized by XPS and SEM. In vitro cell viability studies demonstrated that QCh- and DOX-based implants exhibited high cytotoxicity against Graffi tumor cells. The implants efficiently inhibited the growth of Graffi tumor in hamsters with minimum weight loss. Insertion of QCh/coPLA/DOX implants in the place of removed tumor led to an increase in the animal survival rate and to a decrease in the percentage of recurrences.
Colloid and Polymer Science, 2014
ABSTRACT Polyelectrolyte complexes (PECs) were prepared from N,N,N-trimethylchitosan iodide (TMCh... more ABSTRACT Polyelectrolyte complexes (PECs) were prepared from N,N,N-trimethylchitosan iodide (TMCh) of different molar mass and a weak polyacid-poly(acrylic acid) (PAA) or a strong polyacid-poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS). The quaternization of the amino groups of chitosan enabled the formation of water-insoluble PECs in a broad pH range—from 3 to 12 and from 1 to 12 for TMCh/PAA and TMCh/PAMPS, respectively. Whereas the stoichiometry of the TMCh/PAA complex was pH dependant, the stoichiometry of the TMCh/PAMPS complex did not depend on pH. The stoichiometry and the yield of the complexes were influenced by the molar mass of TMCh. PEC nanoparticles were produced by mixing dilute solutions of the oppositely charged polyelectrolytes as revealed by dynamic light scattering analyses. The size of the particles was in the range of 135–924 nm and depended on the polyelectrolyte molar mass, the initial polyelectrolyte concentration, and the molar fraction of the TMCh units. Microbiological screening against Staphylococcus aureus and Escherichia coli revealed that PECs between TMCh and PAA or PAMPS have a good antibacterial effect, which is more slowly pronounced than that of the starting TMCh of different molar mass.
International Journal of Pharmaceutics, 2012
Plant and soil, 2000
The efficacy of Fe 3+ complexes of polyethers with 8-quinolinol (8QOH) chelating groups attached ... more The efficacy of Fe 3+ complexes of polyethers with 8-quinolinol (8QOH) chelating groups attached to the polymer chain at different positions of the aromatic ring or having different chain length for remedying the iron-deficient maize plants was evaluated. The ...
Macromolecular Research, 2013
Macromolecular Rapid Communications, 2008
... G. Bonchev 103A, 1113 Sofia, Bulgaria ... solutions was measured using a Brookfield LVT visco... more ... G. Bonchev 103A, 1113 Sofia, Bulgaria ... solutions was measured using a Brookfield LVT viscometer equipped with a small-sample thermostated adapter, spindle and ... 18/13R, at 25 ± 0.1 °C. The electrical resistance of the spinning solutions was measured in a specially designed ...
Macromolecular Chemistry and Physics, 1995
Poly(ether‐ester)s of poly(ethylene glycol)s (PEGs) and 2,6‐pyridinedicarboxylic acid (PDA) were ... more Poly(ether‐ester)s of poly(ethylene glycol)s (PEGs) and 2,6‐pyridinedicarboxylic acid (PDA) were synthesized by polycondensation of PDA and PEG in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine and by polycondensation of acyl chloride of PDA and PEG in the presence of triethylamine at 45°C. The polymers were characterized by GPC, UV, IR and 1H and 13C NMR spectroscopy. The complex formation between poly(acrylic acid) (PAA) or poly(methacrylic acid) (PMA) and the poly(ether‐ester)s was studied. It occurs below the critical polyether chain length necessary for complex formation because of the stabilizing effect of the PDA hydrophobic residues.
Macromolecular Chemistry and Physics, 1998
Macromolecular Bioscience, 2009
Macromolecular Bioscience, 2013
Macromolecular Bioscience, 2010
New antimicrobial microfibrous electrospun mats from styrene/maleic anhydride copolymers were pre... more New antimicrobial microfibrous electrospun mats from styrene/maleic anhydride copolymers were prepared. Two approaches were applied: (i) grafting of poly(propylene glycol) monoamine (Jeffamine® M‐600) on the mats followed by formation of complex with iodine; (ii) modification of the mats with amines of 8‐hydroxyquinoline or biguanide type with antimicrobial activity. Microbiological screening against S. aureus, E. coli and C. albicans revealed that both the formation of complex with iodine and the covalent attachment of 5‐amino‐8‐hydroxyquinoline or of chlorhexidine impart high antimicrobial activity to the mats. In addition, S. aureus bacteria did not adhere to modified mats.magnified image
Journal of Biomaterials Science, Polymer Edition, 2008
... These properties render this type of new electrospun nanofibrous mats promising for variety o... more ... These properties render this type of new electrospun nanofibrous mats promising for variety of biomedical uses including wound-dressing applications. Acknowledgements ... Problems Surg. 24, 341 (1987). 4. M. Dekock, AE Vandermerue and FC Houghton, S. Afr. Med. ...
Journal of Biomaterials Science, Polymer Edition, 2013
ABSTRACT Nanofibrous poly(L-lactide-co-D,L-lactide) (coPLA) or coPLA/poly(ethylene glycol) implan... more ABSTRACT Nanofibrous poly(L-lactide-co-D,L-lactide) (coPLA) or coPLA/poly(ethylene glycol) implants loaded with plant polyphenolic compound gossypol (GOS) with anti-tumor activity were fabricated by electrospinning. Implants containing quaternized chitosan (QCh) were prepared by coating of the obtained fibrous materials with a thin film of cross-linked QCh. The morphology of the implants and chemical composition of the implant surface were studied by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). In vitro cytotoxicity assay showed that GOS-loaded nanofibrous implants, both non-coated and QCh-coated displayed about two-fold higher inhibitory activity against Graffi tumor cells than that of free GOS at the 72nd h of incubation. As evidenced by the performed fluorescence microscopy analyses and SEM observations, the anti-tumor activity of the fibrous implants was mainly due to induction of apoptosis. The experiments in which the implants containing both QCh and GOS were placed locally into the tumor site after the tumor extirpation showed an increase in the survival rate and a lower rate of recurrence in the operative field and of metastases in regional lymph nodes. In this case, 40% of hamsters were alive on the 45th day of implantation and they did not show any clinical sign of recurrence in the operative field and metastases in the regional lymph nodes.
Journal of Bioactive and Compatible Polymers, 2011
The antiproliferative activity of electrospun mats of poly(L-lactide- co-D,L-lactide) (coPLA) con... more The antiproliferative activity of electrospun mats of poly(L-lactide- co-D,L-lactide) (coPLA) containing quaternized chitosan (QCh) and/or doxorubicin hydrochloride (DOX) was evaluated against the Michigan Cancer Foundation-7(MCF-7) human breast carcinoma cell line. QCh- and DOX-containing nanofibrous mats possess good antiproliferative activity and decrease considerably the viability of the MCF-7 cells for the different periods of cell incubation as confirmed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Fluorescent microscopy analyses and scanning electron microscopy observations revealed that apoptosis was one of the major mechanisms of MCF-7 cell death induced by the QCh- and DOX-containing mats.
Expert Opinion on Drug Delivery, 2013
During the last decade, the use of electrospinning for the fabrication of nanofibrous materials l... more During the last decade, the use of electrospinning for the fabrication of nanofibrous materials loaded with antibacterial agents or anticancer drugs for biomedical applications such as dressing materials for wound treatment and for local cancer treatment has evoked considerable interest. Different drugs can be easily incorporated in electrospun materials and their release profile can be controlled through changes in the fibers morphology, porosity and composition. The large specific surface area of the electrospun materials, the possibility for gradual release and site-specific local delivery of the active compounds lead to cytotoxicity decrease and enhancement of the therapeutic effect of the drugs. The most recent studies on drug-loaded electrospun mats as materials for wound dressing or local cancer treatment are briefly summarized. The possibility for local drug delivery in cancer therapy using electrospun materials allows avoiding the oral or systemic drug application, thus leading to decrease in some deleterious side effects. The recent achievements in the comprehension of the electrospinning, in control over the surface chemical composition of the electrospun materials, and in diversifying the applied approaches and techniques, propound larger prospects for creating new materials for wound dressing and local cancer treatment.
Antioxidants
A new type of fibrous mat based on a cellulose derivative—cellulose acetate (CA) or CA and water-... more A new type of fibrous mat based on a cellulose derivative—cellulose acetate (CA) or CA and water-soluble polymers (polyvinylpyrrolidone, PVP or poly(vinyl alcohol), PVA)—loaded with the model drug 5-nitro-8-hydroxyquinoline (5N) was fabricated via electrospinning or electrospinning in conjunction with electrospraying. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), water contact angle measurements and ultraviolet-visible spectroscopy (UV-Vis) were used for the complex characterization of the obtained novel material. The decoration of CA fibers with a water-soluble polymer containing the drug resulted in the facilitation of wetting and fast drug release. The 5N-containing fibrous material showed antioxidant activity. Moreover, the proposed materials’ antibacterial and antifungal properties were tested against S. aureus, E. coli, P. aeruginosa and C. albicans. Well-distinguished, sterile zones with diameters above 3...
Polymers
Esca is a grapevine disease known for centuries which pertains to the group of so-called vine tru... more Esca is a grapevine disease known for centuries which pertains to the group of so-called vine trunk diseases. Phaeomoniella chlamydospora (P. chlamydospora) and Phaeoacremonium aleophilum (P. aleophilum) are the two main fungal pathogens associated with esca. Novel fibrous materials with antifungal properties based on poly(3-hydroxybutyrate) (PHB), polyvinylpyrrolidone (PVP) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol, CQ) were developed. One-pot electrospinning (“in” strategy) or electrospinning in conjunction with electrospraying (“on” strategy) were applied to obtain the materials. The materials’ morphology and their surface chemical composition were examined using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). CQ incorporated in the bulk of the fibers or in PVP particles deposited on the fibers was in the amorphous phase, which was confirmed by differential scan...
Materials Science and Engineering: C, 2020
Journal of Bioactive and Compatible Polymers, 2000
International journal of pharmaceutics, Jan 15, 2010
Nanofibrous implants containing quaternized chitosan (QCh), poly(L-lactide-co-D,L-lactide) (coPLA... more Nanofibrous implants containing quaternized chitosan (QCh), poly(L-lactide-co-D,L-lactide) (coPLA), and the antitumor drug doxorubicin (DOX) were fabricated by electrospinning. The surface chemical composition and the morphology of the implants were characterized by XPS and SEM. In vitro cell viability studies demonstrated that QCh- and DOX-based implants exhibited high cytotoxicity against Graffi tumor cells. The implants efficiently inhibited the growth of Graffi tumor in hamsters with minimum weight loss. Insertion of QCh/coPLA/DOX implants in the place of removed tumor led to an increase in the animal survival rate and to a decrease in the percentage of recurrences.
Colloid and Polymer Science, 2014
ABSTRACT Polyelectrolyte complexes (PECs) were prepared from N,N,N-trimethylchitosan iodide (TMCh... more ABSTRACT Polyelectrolyte complexes (PECs) were prepared from N,N,N-trimethylchitosan iodide (TMCh) of different molar mass and a weak polyacid-poly(acrylic acid) (PAA) or a strong polyacid-poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS). The quaternization of the amino groups of chitosan enabled the formation of water-insoluble PECs in a broad pH range—from 3 to 12 and from 1 to 12 for TMCh/PAA and TMCh/PAMPS, respectively. Whereas the stoichiometry of the TMCh/PAA complex was pH dependant, the stoichiometry of the TMCh/PAMPS complex did not depend on pH. The stoichiometry and the yield of the complexes were influenced by the molar mass of TMCh. PEC nanoparticles were produced by mixing dilute solutions of the oppositely charged polyelectrolytes as revealed by dynamic light scattering analyses. The size of the particles was in the range of 135–924 nm and depended on the polyelectrolyte molar mass, the initial polyelectrolyte concentration, and the molar fraction of the TMCh units. Microbiological screening against Staphylococcus aureus and Escherichia coli revealed that PECs between TMCh and PAA or PAMPS have a good antibacterial effect, which is more slowly pronounced than that of the starting TMCh of different molar mass.
International Journal of Pharmaceutics, 2012
Plant and soil, 2000
The efficacy of Fe 3+ complexes of polyethers with 8-quinolinol (8QOH) chelating groups attached ... more The efficacy of Fe 3+ complexes of polyethers with 8-quinolinol (8QOH) chelating groups attached to the polymer chain at different positions of the aromatic ring or having different chain length for remedying the iron-deficient maize plants was evaluated. The ...
Macromolecular Research, 2013
Macromolecular Rapid Communications, 2008
... G. Bonchev 103A, 1113 Sofia, Bulgaria ... solutions was measured using a Brookfield LVT visco... more ... G. Bonchev 103A, 1113 Sofia, Bulgaria ... solutions was measured using a Brookfield LVT viscometer equipped with a small-sample thermostated adapter, spindle and ... 18/13R, at 25 ± 0.1 °C. The electrical resistance of the spinning solutions was measured in a specially designed ...
Macromolecular Chemistry and Physics, 1995
Poly(ether‐ester)s of poly(ethylene glycol)s (PEGs) and 2,6‐pyridinedicarboxylic acid (PDA) were ... more Poly(ether‐ester)s of poly(ethylene glycol)s (PEGs) and 2,6‐pyridinedicarboxylic acid (PDA) were synthesized by polycondensation of PDA and PEG in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine and by polycondensation of acyl chloride of PDA and PEG in the presence of triethylamine at 45°C. The polymers were characterized by GPC, UV, IR and 1H and 13C NMR spectroscopy. The complex formation between poly(acrylic acid) (PAA) or poly(methacrylic acid) (PMA) and the poly(ether‐ester)s was studied. It occurs below the critical polyether chain length necessary for complex formation because of the stabilizing effect of the PDA hydrophobic residues.
Macromolecular Chemistry and Physics, 1998
Macromolecular Bioscience, 2009
Macromolecular Bioscience, 2013
Macromolecular Bioscience, 2010
New antimicrobial microfibrous electrospun mats from styrene/maleic anhydride copolymers were pre... more New antimicrobial microfibrous electrospun mats from styrene/maleic anhydride copolymers were prepared. Two approaches were applied: (i) grafting of poly(propylene glycol) monoamine (Jeffamine® M‐600) on the mats followed by formation of complex with iodine; (ii) modification of the mats with amines of 8‐hydroxyquinoline or biguanide type with antimicrobial activity. Microbiological screening against S. aureus, E. coli and C. albicans revealed that both the formation of complex with iodine and the covalent attachment of 5‐amino‐8‐hydroxyquinoline or of chlorhexidine impart high antimicrobial activity to the mats. In addition, S. aureus bacteria did not adhere to modified mats.magnified image
Journal of Biomaterials Science, Polymer Edition, 2008
... These properties render this type of new electrospun nanofibrous mats promising for variety o... more ... These properties render this type of new electrospun nanofibrous mats promising for variety of biomedical uses including wound-dressing applications. Acknowledgements ... Problems Surg. 24, 341 (1987). 4. M. Dekock, AE Vandermerue and FC Houghton, S. Afr. Med. ...
Journal of Biomaterials Science, Polymer Edition, 2013
ABSTRACT Nanofibrous poly(L-lactide-co-D,L-lactide) (coPLA) or coPLA/poly(ethylene glycol) implan... more ABSTRACT Nanofibrous poly(L-lactide-co-D,L-lactide) (coPLA) or coPLA/poly(ethylene glycol) implants loaded with plant polyphenolic compound gossypol (GOS) with anti-tumor activity were fabricated by electrospinning. Implants containing quaternized chitosan (QCh) were prepared by coating of the obtained fibrous materials with a thin film of cross-linked QCh. The morphology of the implants and chemical composition of the implant surface were studied by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). In vitro cytotoxicity assay showed that GOS-loaded nanofibrous implants, both non-coated and QCh-coated displayed about two-fold higher inhibitory activity against Graffi tumor cells than that of free GOS at the 72nd h of incubation. As evidenced by the performed fluorescence microscopy analyses and SEM observations, the anti-tumor activity of the fibrous implants was mainly due to induction of apoptosis. The experiments in which the implants containing both QCh and GOS were placed locally into the tumor site after the tumor extirpation showed an increase in the survival rate and a lower rate of recurrence in the operative field and of metastases in regional lymph nodes. In this case, 40% of hamsters were alive on the 45th day of implantation and they did not show any clinical sign of recurrence in the operative field and metastases in the regional lymph nodes.
Journal of Bioactive and Compatible Polymers, 2011
The antiproliferative activity of electrospun mats of poly(L-lactide- co-D,L-lactide) (coPLA) con... more The antiproliferative activity of electrospun mats of poly(L-lactide- co-D,L-lactide) (coPLA) containing quaternized chitosan (QCh) and/or doxorubicin hydrochloride (DOX) was evaluated against the Michigan Cancer Foundation-7(MCF-7) human breast carcinoma cell line. QCh- and DOX-containing nanofibrous mats possess good antiproliferative activity and decrease considerably the viability of the MCF-7 cells for the different periods of cell incubation as confirmed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Fluorescent microscopy analyses and scanning electron microscopy observations revealed that apoptosis was one of the major mechanisms of MCF-7 cell death induced by the QCh- and DOX-containing mats.
Expert Opinion on Drug Delivery, 2013
During the last decade, the use of electrospinning for the fabrication of nanofibrous materials l... more During the last decade, the use of electrospinning for the fabrication of nanofibrous materials loaded with antibacterial agents or anticancer drugs for biomedical applications such as dressing materials for wound treatment and for local cancer treatment has evoked considerable interest. Different drugs can be easily incorporated in electrospun materials and their release profile can be controlled through changes in the fibers morphology, porosity and composition. The large specific surface area of the electrospun materials, the possibility for gradual release and site-specific local delivery of the active compounds lead to cytotoxicity decrease and enhancement of the therapeutic effect of the drugs. The most recent studies on drug-loaded electrospun mats as materials for wound dressing or local cancer treatment are briefly summarized. The possibility for local drug delivery in cancer therapy using electrospun materials allows avoiding the oral or systemic drug application, thus leading to decrease in some deleterious side effects. The recent achievements in the comprehension of the electrospinning, in control over the surface chemical composition of the electrospun materials, and in diversifying the applied approaches and techniques, propound larger prospects for creating new materials for wound dressing and local cancer treatment.