Oksan Karal-Yilmaz

Wound infections remain a significant challenge, often complicating the healing process. Consequently, there is a growing need for innovative alternatives to conventional treatment strategies. In recent years, electrospun nanofibers (NFs) made from natural or synthetic polymers have gained popularity as wound dressing materials due to their structural similarity to the extracellular matrix and ability to incorporate bioactive agents. This study aimed to develop multifunctional wound dressings by incorporating zinc oxide nanoparticles (ZnO NPs) and titanium dioxide nanoparticles (TiO ₂ NPs) separately into polymeric NFs made of chitosan (CS), silk fibroin (SF), and polyethylene oxide (PEO). The NFs were fabricated using the electrospinning technique, and three formulations were prepared: plain CS/SF NFs, CS/SF/ZnO NFs, and CS/SF/TiO ₂ NFs. These were systematically characterized and compared in terms of their physicochemical, mechanical, and biological properties to evaluate their potential for wound dressing applications. The chemical composition, thermal stability, morphology, and mechanical properties of the prepared NFs were evaluated using FTIR, TGA, SEM, and tensile strength tests, respectively. FTIR analysis confirmed the successful integration of the polymers and nanoparticles. The addition of ZnO and TiO ₂ NPs improved the thermal stability and mechanical strength of the NFs. SEM images revealed that all NFs exhibited long, continuous, and bead‐free morphologies. Additionally, the swelling ratio, degradation behavior, and water vapor transmission rate (WVTR) were assessed. Swelling studies indicated a high water absorption capacity with pH‐dependent behavior, especially under acidic conditions. Biodegradation tests showed a slower degradation rate in the NFs containing NPs. The WVTR results confirmed that all NF formulations are suitable for maintaining an optimal moisture environment for wound healing. Cell viability assays demonstrated good biocompatibility, while antimicrobial studies revealed strong bactericidal activity in CS/SF/ZnO NFs. In contrast, CS/SF/TiO ₂ NFs exhibited limited antimicrobial activity in the absence of UV light. Overall, the findings suggest that CS/SF‐based NFs, particularly those containing ZnO, are promising candidates for advanced wound dressing applications due to their enhanced structural integrity and biological functionality.

Multilayer antibacterial hydrogel wound dressings were fabricated and characterized for wound healing applications. Dressings are designed to achieve infection control, moisture management in the wound area and to support wound healing. Multilayer wound dressings were prepared as three layers by solvent casting method. The upper layer is composed of kappa carrageenan and green synthesized silver nanoparticles (AgNPs, ~122 nm in size, zeta potential of –35 mV) to provide the moist control, and to form a barrier against microorganism attack. Lidocaine HCl loaded polyvinyl alcohol and chitosan‐based middle layer was designed to achieve controlled drug release and to add strength to the hydrogel structure. The lower layer is composed of hyaluronic acid and ovalbumin to serve a controlling membrane for controlled drug release, and to further support wound healing. Different amounts of AgNPs were used in formulations to evaluate their impact on multilayer wound dressings. The incorporation of AgNPs resulted in reduced swelling values and degradation rates of the multilayer wound dressings, enhanced mechanical capabilities, and no significant change in water vapor permeability values. They have demonstrated enhanced antibacterial efficacy against Klebsiella pneumoniae , Bacillus subtilis and Candida albicans . The optimal multilayered hydrogel, incorporating AgNPs and loaded with lidocaine HCl, has shown biocompatibility and hemocompatibility, exhibiting 60% degradation by day 14, water vapor permeability of 2022 ± 460 g/m ² over 24 h, a tensile strength of 6.71 ± 0.62 MPa, 36.38% ± 3.62% elongation at break, and 65.72% ± 14.80% drug release within 10 h, making it a promising candidate for facilitating the wound healing process.

Developing efficient hydrogel‐based wound dressings has gained increasing attention in improved wound healing capabilities. In this study, the biocomposite hydrogel films consisting of polyvinyl alcohol (PVA), chitosan (CS), and zinc oxide nanoparticles (ZnO NPs) were prepared using the solvent casting method. The biocomposite hydrogel films were also loaded (5% w/w) with Amphotericin B (AmB) as a model drug to develop a new suitable material with potential application as high‐performance wound dressing with controlled drug release. The chemical nature, thermal properties, and morphology of the PVA/CS and PVA/CS‐ZnO biocomposite hydrogels were analyzed and compared by FTIR, TGA, and SEM–EDX analysis. The effect of ZnO NPs on swelling behavior in the PVA/CS films was studied. PVA/CS‐ZnO biocomposite hydrogels presented a lesser degree of swelling compared to ZnO‐free hydrogels. The AmB‐loaded hydrogel films exhibited a sustained release rate during 72 h in PBS at pH 7.4. Biocompatibility of all hydrogel types (with or without ZnO and AmB) using L929 and HaCaT cell lines was evaluated with high cell viability examined by MTT assay. The antimicrobial activity of the films was evaluated against Escherichia coli , Staphylococcus aureus , and Candida albicans using a modified AATCC 100 method, whereby the R value represents the log reduction in the number of surviving colonies. The mean R values for drug‐free PVA/CS‐ZnO hydrogel films were 6.81 for E. coli , 6.03 for S. aureus , and 6.82 for C. albicans . The addition of AmB further enhanced the antimicrobial activity, increasing the R values for E. coli to 7.16, for S. aureus to 6.38, and for C. albicans to 7.31, demonstrating a significant synergistic effect with maximum antimicrobial efficacy. The results showed that the AmB‐loaded biocomposite hydrogel films (PVA/CS‐ZnO‐AmB) can be used as a new wound dressing material.

Alumina (α-Al2O3) and hydroxyapatite (HA, Ca10(PO4)6(OH)2) are well-known for being clinically successful bioceramic materials. In this work, in-vitro biological characterization of the sol-gel alumina-bovine hydroxyapatite composite powders was realized. Alumina powders were synthesized through the sol-gel process. First, boehmite (AlOOH) sol was prepared utilizing aluminium isopropoxide (Al(OC3H7)3, AIP) as the starting precursor. Bovine hydroxyapatite (BHA) powders, which can be defined as naturally derived calcium phosphate powders were added as 10, 20, 30, and 50% wt. of AIP to each AlOOH sol. Homogeneous dispersion of the BHA powders in the AlOOH sol was managed due to employing Na-alginate as a kind of thickener. Gelation of the AlOOH-BHA mixtures was carried out at 110 ºC for 3h. After drying, AlOOH-BHA mixtures were heat-treated at 1300 ºC for 2h. Chemical, microstructural, thermal, and physical properties of the precursors/process products were characterized with X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Fluorescence Spectroscopy (XRF), Differential Thermal Analysis (DTA), and Scanning Electron Microscopy - Energy Dispersive Spectroscopy (SEM-EDS) analyses. Indirect MTT assay was done to evaluate the biocompatibility of the Al2O3-BHA based biocomposite extracts using the L929 cell line. It is found that all Al2O3-BHA composite extracts with varying doses of 25% and 50% had no negative effect on the cell viability. In addition, % cell viability decreased with the increasing of the extract concentration. It can be concluded that the prepared Al2O3-BHA composites can be a good candidate for biomedical applications.

In this study, chitosan/alginic acid/zinc oxide (CHI/AA/ZnO) nanostructured hydrogel sponges were fabricated by incorporating ZnO nanoparticles (Staphylococcus aureus. The cytotoxicity and hemostatic efficacy of crosslinked CHI/AA/ZnO sponge like‐nanostructured hydrogels was evaluated in vitro and in vivo, respectively. The results of this study demonstrated that the prepared CHI/AA/ZnO nanostructured sponge had the potential to be an antibacterial topical hemostat. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47522.

A series of graft copolymers consisting of polystyrene backbone with biocompatible side chains based on (co)polymers of l-lactic acid and glycolic acid were synthesised by combination two controlled polymerisations, namely, nitroxide mediated radical polymerisation (NMRP) and ring opening polymerisation (ROP) with “Click” chemistry. The main goal of this work was to design new biodegradable microspheres using obtained graft copolymers for long-term sustained release of imatinib mesylate (IMM) as a model drug. The IMM loaded microspheres of the graft copolymers, polystyrene-g-poly(lactide-co-glycolide) (PS-g-PLLGA), polystyrene-g-poly(lactic acid) (PS-g-PLLA) and poly(lactic-coglycolic acid) (PLLGA) were then prepared by a modified water-in-oil-in-water (w₁/o/w₂) double emulsion/solvent evaporation technique. The optimised microspheres were characterised by particle size, encapsulation efficiency, and surface morphology also; their degradation and release properties were studied in vitro. The degradation studies of three different types of microspheres showed that the PS backbone of the graft copolymers slows down the degradation rate compared to PLLGA.

Poly(lactic-co-glycolic acid) microspheres loaded with imatinib mesylate has been developed as a new therapeutic strategy to prevent craniopharyngioma recurrence. Microspheres composed of different lactic/glycolic acid ratios, molecular weights and drug compositions were synthesized and loaded with imatinib mesylate by modified double-emulsion/solvent evaporation technique and subsequently characterized by particle-size distribution, scanning electron microscopy, encapsulation efficiency and in vitro drug release. Inhibitory potential of imatinib containing microspheres on tumor neovascularization was investigated on craniopharyngioma tumor samples by rat cornea angiogenesis assay. Results showed that microspheres in different LA:GA ratios [LA:GA 50:50 (G50), 75:25 (G25), 85:15 (G15)] considerably reduced neovascularization induced by recurrent tumor samples in an in vivo angiogenesis assay (P < 0.01). Our data indicate that local delivery of imatinib mesylate to the post-surgical tumoral cavity using biodegradable microspheres may be a promising biologically selective approach to prevent the recurrence of craniopharyngiomas, via inhibition of neovascularization.