Browsing by Author "Atanasova D."

Now showing 1 - 8 of 8
  • No Thumbnail Available
    Item
    Antimicrobial Properties of Chitosan-Modified Cotton Fabric Treated with Aldehydes and Zinc Oxide Particles
    (2023-07-01) Staneva D.; Atanasova D.; Angelova D.; Grozdanov P.; Nikolova I.; Grabchev I.
    Chitosan is a natural biopolymer with a proven ability to impart textile materials with antimicrobial properties when loaded onto them. The mechanism of its bacteriological activity depends on the contact between the positive and negative charges of the amino groups located on the surface of the microbes. Unfortunately, the type of microorganisms and pH influence this action–shortcomings that can be avoided by chitosan modification and by loading its film with substances possessing antimicrobial properties. In this study, chitosan was modified with benzaldehyde and crosslinked with glutaraldehyde to form a film on the surface of cotton fabric (CB). Also, another material was obtained by including zinc oxide particles (CBZ) synthesized in situ into the chitosan coating. The performed analyses (contact angle measurement, optical and scanning electron microscopy, FTIR, XRD, and thermal analysis) evidenced the modification of the cotton fabric and the alteration of the film properties after zinc oxide inclusion. A comparison of the antimicrobial properties of the new CB with materials prepared with chitosan without benzaldehyde from our previous study verified the influence of the hydrophobicity and surface roughness of the fabric surface on the enhancement of antimicrobial activity. The microbial growth inhibition increased in the following order: fungal strain Candida lipolytica >Gram-positive bacteria Bacillus cereus >Gram-negative bacteria Pseudomonas aeruginosa. The samples containing zinc oxide particles completely inhibited the growth of all three model strains. The virucidal activity of the CB was higher against human adenovirus serotype 5 (HAdV-5) than against human respiratory syncytial virus (HRSV-S2) after 60 min of exposure. The CBZ displayed higher virucidal activity with a Δlog of 0.9 against both viruses.
  • No Thumbnail Available
    Item
    Cotton fabric modified with a pamam dendrimer with encapsulated copper nanoparticles: Antimicrobial activity
    (2021-12-01) Staneva D.; Atanasova D.; Nenova A.; Vasileva-Tonkova E.; Grabchev I.
    A new methodology for modifying textile materials with dendrimers containing nanoparticles was developed. This involved a combination of eosin Y and N-methyldiethanolamine (MDEA) for reducing the copper ions in the dendrimer complex by enabling a photochemical reaction under visible light and ambient conditions. The conversion of copper ions into nanoparticles was monitored using scanning electron microscopy (SEM) and by performing colorimetric, fluorescence, and electron paramagnetic resonance (EPR) studies. Regardless of the concentration of the photoinitiator eosin Y, it discolored completely upon illumination. Three types of cotton fabrics were compared as antimicrobial materials against Bacillus cereus. One of the fabrics was dyed with a first-generation PAMAM dendrimer which had been functionalized with eight 1,8-naphthalimide fluorophores. Another fabric was dyed with a dendrimer–copper complex, and the third was treated by conversion of the complex into copper nanoparticles encapsulated into the dendrimer. An enhancement in the antimicrobial activity of the textiles was achieved at higher dendrimer concentrations, under illumination with visible light. The fabric modified with the copper nanoparticles encapsulated inside the dendrimer exhibited the best antibacterial activity because it had two photosensitizers (PS), as both 1,8-naphthalimide fluorophores and copper nanoparticles were contained in the dendrimer molecules. The presence of oxygen and suitable illumination activated the photosensitizers to generate the reactive oxygen species (singlet oxygen (1O2) and other oxygenated products, e.g., anion radicals, hydroxyl radicals, and hydrogen peroxide) responsible for destroying the bacteria.
  • No Thumbnail Available
    Item
    Design of a Composite Based on Polyamide Fabric-Hydrogel-Zinc Oxide Particles to Act as Adsorbent and Photocatalyst
    (2022-10-01) Atanasova D.; Irikova M.; Staneva D.; Grabchev I.
    Surface-initiated photopolymerization has been run to synthesize a hydrogel with ZnO particles distributed uniformly along its structure, which has been loaded onto a polyamide fabric. Three samples have been obtained at different concentrations of zinc nitrate (10% (sample PA10); 20% (sample PA20) and 30% (sample PA30) of the weight of the fabric, respectively)) and subjected to gravimetric analysis, scanning electron microscopy and transmission electron microscopy. The effect of the adsorption parameters of the composite material on the removal Drimaren Rot K-7B dye from water has been studied. The Freundlich isotherm describes this process better than the Langmuir isotherm. As the results of the adsorption kinetics show, the process fits well with a pseudo-second-order equation and depends both on the boundary layer and on the structure of the adsorbent itself. The thermodynamic parameters have demonstrated that the process is endothermic and physical. When exposed to ultraviolet light, the discoloration of the dye solution accelerates due to the photocatalytic properties of the composite materials. The addition of H2O2 also speeds up further the process, while the reuse of the materials slows it down, gradually changing the kinetic parameters. The reaction has been attributed to first-order kinetic model, when the active centers of the materials and the number of oxidative radicals formed are numerous and to the second-order kinetic model at a lower reaction activity. Moreover, 52% decolorization of the dye solution (50 mg L−1) in the dark was achieved from composite material PA 30 (13.3 g L−1) in 120 min and 89% under UV light irradiation. The H2O2 addition (0.14 mmol L−1) enhanced it up to 98%. In the second and third use of the photocatalyst, the dye removal decreased to 80% and 60%. Composite material PA30 exhibits antibacterial activity against Gram-negative bacteria E. coli, being most effective at eliminating Gram-positive bacteria S. aureus.
  • No Thumbnail Available
    Item
    EFFECT OF TEMPERATURE ON THE MODIFICATION OF COTTON FABRIC WITH CROSSLINKED CHITOSAN
    (2025-11-02) Atanasova D.; Staneva D.
    This study aimed to compare the properties of the cotton fabric coated with a layer of chitosan crosslinked with citric acid at room temperature or after thermal treatment (at 80oC for 180 min). The applied conditions assume the formation of ionic bonds between the coating components in the first case and their covalent interactions in the second case. Various analyses have been used to confirm this statement. The quantity of the obtained coating on the fabric and the colour characteristics of the materials was characterised with gravimetric and colorimetric analysis. The changes in the bands of functional groups in FT-IR analysis and thermal behaviour of modified fabrics compared to pristine cotton fabric were studied. The surface morphology was investigated using the contact angle measurement. It was found that after thermal treatment, the fabric surface hydrophobicity increases, and the antimicrobial activity against both Gram-negative Pseudomonas aeruginosa and Gram-positive Bacillus cereus strains also increases.
  • No Thumbnail Available
    Item
    Fluorescent Composite Cotton Fabric Modified with Crosslinked Chitosan for Theranostic Applications
    (2023-12-01) Staneva D.; Atanasova D.; Grabchev I.
    Developing multifunctional textile material for wound dressing is challenging due to the variety of wounds and their differing healing stages. Therefore, theranostics replaces the traditional approach to provide patient comfort and accelerated healing. In this study, we developed and compared three different materials. For this purpose, for the first time, chitosan was modified with 4-nitro-1,8-naphthalic anhydride in N,N-dimethylformamide (DMF) suspension, and subsequent nucleophilic substitution of the nitro group with N,N-dimethylamino group, whereby chitosan with a yellow color and fluorescence was obtained. Cotton fabric was impregnated successively with a citric acid solution and solution from chitosan and chitosan modified with 1,8-naphthalimide fluorophore (CN material). The same experimental protocol was applied for the second material, but indomethacin was added to the chitosan solution (CNI material). The third material was prepared similarly to the second but was immersed in an alginate solution as a last step (CNIA material). The obtained materials have been characterized by optical and scanning electron microscopy and thermal analysis (TG-DTA-DTG). Indomethacin release from composite materials and hydrogel swelling and erosion in phosphate buffer pH 7.4 at 37 °C was examined using gravimetric analysis, UV-vis absorption, and fluorescence spectroscopy. The antimicrobial activity of the cotton samples has been evaluated against B. cereus and P. aeruginosa as model bacterial strains. The analysis showed that CN material inhibited about 98.8% of the growth of P. aeruginosa and about 95.5% of the growth of B. cereus. Other composite materials combine antimicrobial properties with a sustained release of biologically active substances that can observed visually.
  • No Thumbnail Available
    Item
    Photodynamic Microbial Defense of Cotton Fabric with 4-Amino-1,8-naphthalimide-Labeled PAMAM Dendrimer
    (2025-12-01) Staneva D.; Atanasova D.; Grabchev I.
    The article describes the interaction between 4-amino-1,8-naphthalic anhydride and the terminal amine groups of the first-generation poly(amidoamine) (PAMAM) dendrimer. Cotton fabric was treated with the newly obtained photoactive dendrimer (DA) to achieve its antimicrobial photodynamic inactivation. The photodynamic inactivation method is an innovative approach in which, upon irradiation with visible light, photosensitizers generate highly reactive oxygen species, specifically singlet oxygen (1O2), which destroys microbial cells. In the dark, the DA dendrimer strongly inhibits the development of the model bacteria Bacillus cereus (a Gram-positive bacterium) and Pseudomonas aeruginosa (a Gram-negative bacterium) in solution. Upon irradiation with visible light, the inhibition is significantly enhanced, achieving almost complete inactivation of B. cereus and 94% of P. aeruginosa. Cotton fabric was treated with the DA dendrimer at two concentrations (0.15% and 0.30% weight of fabric). It was found that the dendrimer molecules are adherent to the cellulose fiber surfaces and do not leach in washing. Treatment of the fabric with DA partially increases its hydrophobicity, which prevents the adhesion of some bacteria. In the dark, the treated fabric shows weak antibacterial activity because the dendrimer DA molecules are attached to the textile surface, and inactivation depends solely on the microorganism’s surface contact. However, upon irradiation, a significant increase in the fabric’s antimicrobial activity is observed, as the fixed dendrimer participates in the release of singlet oxygen, which effectively attacks microorganism cell membranes and components. For the fabric with the higher concentration (DA30), 94% inactivation of B. cereus and 89% inactivation of P. aeruginosa were achieved. Thus, a synergistic effect between photodynamic activity and increased hydrophobicity was achieved, making the modified cotton fabric an example of a high-tech textile with permanent, renewable disinfection.
  • No Thumbnail Available
    Item
    PREPARATION AND CHARACTERIZATION OF COTTON FABRIC MODIFIED WITH CHITOSAN CONTAINING DICLOFENAC SODIUM FOR WOUND DRESSING
    (2025-11-02) Atanasova D.; Staneva D.
    Due to the different types of wounds and stages of their healing, the development of bioactive textile wound dressings is a challenge. In many cases, the dressing is expected to be multifunctional. It must actively support wound healing by absorbing excess exudate, but also provide a moist environment, inhibit microbial growth, and, if necessary, deliver bioactive substances in a controlled manner. This study aims to modify cotton fabric with a layer of chitosan crosslinked with citric acid, involving diclofenac sodium. Different methods were applied to obtain two composite materials. The first treatment used the pad-dry technique at room temperature (CRTD), and the second applied pad-cure at 80oC for 180 min (CHTD). The new materials were characterised by optical microscopy and thermal analysis. The surface properties of the pristine cotton fabric were compared with the modified samples by determining the contact angle of a droplet of distilled water. The composites exhibit hydrophobic properties and antibacterial activity against model bacterial strains, Bacillus cereus and Pseudomonas Aeruginosa. The material CHTD inhibits approximately 78.0 % of the growth of P. Aeruginosa and approximately 31.6 % of B. Cereus. Using gravimetric and spectrophotometric analysis, the swelling of the obtained layers on the fabric surface and the release of diclofenac sodium in phosphate buffer with pH = 7.4 at 37oC were investigated. Therefore, the composite materials combine antibacterial efficacy with continued release of bioactive substances, making them promising for use as wound dressings.
  • No Thumbnail Available
    Item
    Textile materials modified with stimuli-responsive drug carrier for skin topical and transdermal delivery
    (2021-02-02) Atanasova D.; Staneva D.; Grabchev I.
    Textile materials, as a suitable matrix for different active substances facilitating their gradual release, can have an important role in skin topical or transdermal therapy. Characterized by compositional and structural variety, those materials readily meet the requirements for applications in specific therapies. Aromatherapy, antimicrobial substances and painkillers, hormone therapy, psoriasis treatment, atopic dermatitis, melanoma, etc., are some of the areas where textiles can be used as carriers. There are versatile optional methods for loading the biologically active substances onto textile materials. The oldest ones are by exhaustion, spraying, and a pad-dry-cure method. Another widespread method is the microencapsulation. The modification of textile materials with stimuliresponsive polymers is a perspective route to obtaining new textiles of improved multifunctional properties and intelligent response. In recent years, research has focused on new structures such as dendrimers, polymer micelles, liposomes, polymer nanoparticles, and hydrogels. Numerous functional groups and the ability to encapsulate different substances define dendrimer molecules as promising carriers for drug delivery. Hydrogels are also high molecular hydrophilic structures that can be used to modify textile material. They absorb a large amount of water or biological fluids and can support the delivery of medicines. These characteristics correspond to one of the current trends in the development of materials used in transdermal therapy, namely production of intelligent materials, i.e., such that allow controlled concentration and time delivery of the active substance and simultaneous visualization of the process, which can only be achieved with appropriate and purposeful modification of the textile material.