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    A bi-layer electrospun polyurethane/silicone membrane scaffold: drug delivery and cytotoxicity studies
    (Indian Acad Sciences, 2023) Mohsenzadeh, Elham; Demir, Didem; Ceylan, Seda; Khenoussi, Nabyl; Schacher, Laurence; Adolphe, Dominique; Bolgen, Nimet
    In this study, a bi-layer scaffold combining polyurethane nanofibrous and silicone membrane layers was produced. Chemical, morphological and physical properties of the scaffolds were determined by Fourier-transform infrared spectroscopy, scanning electron microscope (SEM) and Brunauer-Emmett-Teller analyses, respectively. The surface properties were examined with the contact angle test. To evaluate the encapsulation and release behaviour of the scaffolds Rhodamine B and Nile red were used as model drugs. Further, the cytotoxicity and cell proliferation investigations were carried out using mouse embryonic fibroblasts cell lines. 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide assay and SEM were used to investigate the cell viability and cell-scaffold interactions, respectively. The results of the study were evaluated in order to develop a bimodal drug release system that has the potential to be used in tissue engineering applications.
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    A review on three dimensional scaffolds for tumor engineering
    (Techno-Press, 2016) Ceylan, Seda; Bolgen, Nimet
    Two-dimensional (2D) cell culture and in vivo cancer model systems have been used to understand cancer biology and develop drug delivery systems for cancer therapy. Although cell culture and in vivo model studies have provided critical contribution about disease mechanism, these models present important problems. 2D tissue culture models lack of three dimensional (3D) structure, while animal models are expensive, time consuming, and inadequate to reflect human tumor biology. Up to the present, scaffolds and 3D matrices have been used for many different clinical applications in regenerative medicine such as heart valves, corneal implants and artificial cartilage. While tissue engineering has focused on clinical applications in regenerative medicine, scaffolds can be used in in vitro tumor models to better understand tumor relapse and metastasis. Because 3D in vitro models can partially mimic the tumor microenvironment as follows. This review focuses on different scaffold production techniques and polymer types for tumor model applications in cancer tissue engineering and reports recent studies about in vitro 3D polymeric tumor models including breast, ewing sarcoma, pancreas, oral, prostate and brain cancers.
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    Assessment of chitosan:gum tragacanth cryogels for tissue engineering applications
    (Wiley, 2022) Demir, Didem; Ugurlu, Muge Asik; Ceylan, Seda; Sakim, Burcu; Genc, Rukan; Bolgen, Nimet
    Gum tragacanth is one of the most widely used natural gums in food, medicine, cosmetics and personal care products, and its use as polysaccharide-based scaffolds in tissue engineering applications has attracted great attention in recent years. The fabrication of pure gum tragacanth as a scaffold poses many challenges because of the high viscosity, poor mechanical properties and repulsive interaction between the polyanions. To overcome these, facilitate the formation of scaffolds and improve their final properties, chitosan and gum tragacanth were used together as natural, biocompatible and biodegradable polysaccharides. The scaffolds based on chitosan and gum tragacanth were successfully fabricated through cryotropic gelation and were characterized using different chemical, morphological, mechanical and biocompatibility analyses. All cryogel scaffolds exhibited a porous structure with an average diameter of 96.56-30.21 mu m, exhibiting high liquid absorption capacity, appropriate mechanical stability and controlled degradation behavior. According to the biocompatibility results, mouse embryonic fibroblast cells adhered well to the scaffolds and achieved high viability. The results are also discussed in the light of their potential usefulness as a scaffold for tissue engineering applications. (c) 2022 Society of Industrial Chemistry.
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    Chitosan based injectable cryospheres as a potential biopolymeric carrier for drug delivery systems: Characterization, biocompatibility and drug release
    (Elsevier, 2024) Demir, Didem; Ceylan, Seda; Bolgen, Nimet
    Three-dimensional scaffolds with the right design to support cell metabolism and the right physico-chemical, mechanical, and biological qualities have become more interesting for tissue engineering because of the complexity and diversity of the tissues involved. Moreover, three-dimensional scaffolds with tuneable drug delivery capabilities have drawn more attention in the field of soft tissue engineering. In this research, chitosanbased microspheres (called cryospheres) were fabricated in spherical shapes micron-sized with highly interconnected porous structures as a result of combining emulsification and cryogelation methods. The characterization of cryospheres was evaluated using morphological, physicochemical, and biological analyses. According to the results of the in vitro and in vivo biocompatibility investigation, the microspheres had no toxic effects on cell survival, and they even enhanced cell viability at the implantation site when compared to the control group. After the cryospheres were characterized, research was done on drug loading, drug release, and release processes using two distinct dyes (Nile Red: NR and Rhodamine-B: RB) in simulated body fluids (simulated intestinal, stomach, and tear fluids). The results showed that the maximum drug loading capacities for RB and NR were 89.32 +/- 1.57 % and 61.51 +/- 0.70 %, respectively. This study contributed to the development of minimally invasive biomaterials that have the potential to provide both drug release and tissue formation/regeneration at damaged implantation sites by carrying not only drugs but also active substances such as hormones/growth factors that will trigger new tissue formation.
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    Comparison of additive effects on the PVA/starch cryogels: Synthesis, characterization, cytotoxicity, and genotoxicity studies
    (Taylor & Francis As, 2018) Ceylan, Seda; Gokturk, Dilek; Demir, Didem; Ozdemir, M. Damla; Bolgen, Nimet
    The research goal of this study is to produce suitable scaffolds for tissue engineering applications. Different ratios of polyvinyl alcohol (PVA)/starch (90:10, 70:30, 50:50) and crosslinking methods have been used to prepare cryogels. Chemically crosslinked cryogels were synthesized using glutaraldehyde as the crosslinking agent. For the physically crosslinked cryogels, sodium dodecyl sulfate was used during cryogelation as the foaming agent. Chemical structure and pore morphology were demonstrated by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). Swelling ratio and degradation profile of the scaffolds were also determined. 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide assay and SEM were used to investigate the biocompatibility of the scaffolds and cell morphology. Genotoxicity test was performed to show DNA fragmentation. The overall results demonstrated that PVA/starch cryogels could have potentially appealing application as scaffolds for tissue engineering applications and additives affect the architecture and characteristic properties of the cryogels. [GRAPHICS] .
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    Effect of crosslinking methods on the structure and biocompatibility of polyvinyl alcohol/gelatin cryogels
    (Ios Press, 2016) Ceylan, Seda; Gokturk, Dilek; Bolgen, Nimet
    In this study, polyvinyl alcohol (PVA) and gelatin based cryogels were prepared by crosslinking chemically or physically for tissue engineering applications. Different PVA/Gelatin ratios (100: 0, 90: 10, 70: 30, 50: 50) and crosslinking methods have been used to prepare cryogels; chemical and physical structure of the prepared matrices were analysed by FTIR and SEM; swelling and degradation profiles were followed. Chemical and physical crosslinking was obtained by using glutaraldehyde as crosslinker and by applying freeze thawing cycle, respectively. Gelatin concentration and crosslinking method had significant effect on the pore size, swelling ratio and degradation profiles of the cryogels. Biocompatibility of the cryogels were also investigated by MTT assay. SEM was used to investigate the cell morphology on the scaffolds. The MTT assay findings prove that physically crosslinked PVA/Gelatin scaffolds are more biocompatible and enhance more the adhesion and proliferation of mouse embryonic fibroblast cells (MEF) than chemically crosslinked PVA/Gelatin scaffolds. The overall results demonstrated that, the PVA/Gelatin cyrogels as a suitable biomaterial for tissue engineering applications and crosslinking methods affect the architecture and characteristic properties of the cryogels.
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    Effect of polymer concentration in cryogelation of gelatin and poly (vinyl alcohol) scaffolds
    (Techno-Press, 2019) Ceylan, Seda; Demir, Didem; Gul, Gulsah; Bolgen, Nimet
    The aim of this study was to investigate the effect of total polymer concentration on the chemical structure, morphology of pores, porosity, swelling ratio, degradation of gelatin-poly (vinyl alcohol) (Gel-PVA) cryogel scaffolds. Porous cryogels were prepared with cryogelation technique by using glutaraldehyde as a crosslinker. Functional group composition of cryogels after crosslinking was investigated by Fourier Transform Infrared (FTIR). The morphology of cryogels was characterized via scanning electron microscopy (SEM) and porosity analysis. All of the cryogels had a porous structure with an average pore size between 45.58 +/- 14.28 and 50.14 +/- 4.26 mu m. The cryogels were biodegradable and started to degrade in 14 days. As the polymer concentration increased the swelling ratio, the porosity and the degradation rate decreased. Spongy and mechanically stable Gel-PVA cryogels, with tunable properties, can be potential candidates as scaffolds for tissue engineering applications.
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    Electrospun Composite Nanofibers Based on Poly (epsilon-Caprolactone) and Styrax Liquidus (Liquidambar orientalis Miller) as a Wound Dressing: Preparation, Characterization, Biological and Cytocompatibility Results
    (Springer, 2022) Demir, Didem; Ozdemir, Sadin; Ceylan, Seda; Yalcin, M. Serkan; Sakim, Burcu; Bolgen, Nimet
    In this study, styrax liquidus (sweet gum balsam) extracted from Liquidambar orientalis Mill. incorporated PCL fibrous scaffolds were prepared using the electrospinning method. The effects of the styrax liquidus content on the prepared scaffolds were investigated using different physico-chemical and morphological analyses. Then, the styrax-loaded nanofibers were examined for their antioxidant activity, anti-biofilm, metal chelating, antimicrobial and DNA cleavage properties. The results obtained from these studies showed that the nanofibers exhibited effective biological activity depending on the weight ratio of the styrax liquidus. In light of the data obtained from the characterization and biological studies, a sample with high ratio of balsam was built for determining the cytocompatibility analysis in vitro. The cytotoxicity studies of the selected membrane were conducted using mouse embryonic fibroblast cells. The fibrous scaffolds lead to increase the cell number as a result of high viability. According to the results, we propose a novel biocompatible electrospun hybrid scaffold with antioxidant and antimicrobial properties that can be used as wound healing material for potential tissue engineering applications.
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    Extraction of pectin from albedo of lemon peels for preparation of tissue engineering scaffolds
    (Springer, 2021) Demir, Didem; Ceylan, Seda; Gokturk, Dilek; Bolgen, Nimet
    Pectin is a type of anionic polysaccharide naturally found in a number of fruits and vegetables. Although pectin is widely used for food industry, its biomedical applications such as wound dressing, drug delivery and cancer targeting have also been investigated. In our study, we combined extracted pectin (from albedo of lemon peels) with chitosan (as a natural polymer) to synthesize chitosan/pectin cryogels. The extracted pectin was subjected to qualitative and quantitative analyses. Chitosan/pectin spongy supermacroporous cryogels were produced by cryogelation method at different combinations (100:0, 80:20, 60:40 and 40:60, w/w). Polyelectrolyte interactions between pectin and chitosan and crosslinking of chitosan with glutaraldehyde were verified by using FTIR. The porosity, swelling ratio, degradation behaviors and mechanical properties of cryogels were determined. SEM analysis demonstrated the pore morphology and average pore diameters of cryogels. After all analysis, 40:60 chitosan/pectin cryogel was selected for cytotoxicity studies. Glioblastoma (U-87 MG) cell line was used to evaluate the in vitro cytotoxicity of scaffolds. MTT assay and SEM analyses demonstrated the scaffolds were nontoxic, and supported cell attachment and viability.
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    GREEN SYNTHESIZED SILVER NANOPARTICLES LOADED PVA/STARCH CRYOGEL SCAFFOLDS WITH ANTIBACTERIAL PROPERTIES
    (Univ North, 2019) Demir, Didem; Ceylan, Seda; Gul, Gulsah; Iyigundogdu, Zeynep; Bolgen, Nimet
    In this study, Polyvinyl alcohol/Starch (PVA/Starch) cryogel scaffolds were combined with antibacterial silver nanoparticles (AgNPs), and the antimicrobial properties of composite scaffolds were determined for potential in tissue engineering applications. The porous PVA/Starch scaffolds were prepared by cryogelation technique. The nanoparticles were prepared by green synthesis from Aloe barbadensis leaf extract and characterized. The antibacterial, antifungal and antiyeast properties of AgNPs and AgNPs loaded PVA/Starch cryogel scaffolds were investigated. The highest antimicrobial activity of composite scaffold was found against Pseudomonas aeruginosa. Based on our studies, the results indicate that biodegradable, biocompatible and antimicrobial AgNPs loaded PVA/Starch scaffolds have potential to be used at an infection site in tissue engineering applications.
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    Synthesis of silver nanoflakes on chitosan hydrogel beads and their antimicrobial potential
    (Taylor & Francis Ltd, 2020) Demir, Didem; Ceylan, Seda; Atakav, Yagmur; Bolgen, Nimet
    The present study involves the fabrication of CH and CH-Ag hydrogel beads and the investigation of the antimicrobial properties. The beads were fabricated using a simple coacervation method. The successfully synthesized beads were characterized by UV-Vis and FTIR. The surface morphology, shape and diameter of the samples were determined by optical microscopy and SEM. The antimicrobial activities were determined against potential human pathogens including bacterial and fungal species. Our results demonstrated that beads can be utilized as potential materials for use in biomedical approaches including delivery systems and tissue engineering applications to prevent microbial contamination and to inhibit the growth of microorganisms.
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    Tailoring the spatial filament organization within nanofibrous tissue engineering scaffolds
    (Taylor & Francis As, 2022) Shah Hosseini, Neda; Bolgen, Nimet; Khenoussi, Nabyl; Ceylan, Seda; Gokturk, Dilek; Schacher, Laurence; Adolphe, Dominique
    Fabricating scaffolds with biomimetic architectures is an important step toward engineering functional tissues. Electrospinning is a popular approach for creating nanofibrous substrates in which the filaments resembling the natural extracellular matrix (ECM) can provide topographical cues to cells directing their growth. One of the major challenges in electrospinning is tailoring the spatial organization of the filaments. To overcome this challenge, a hybrid static collector was utilized to form distinct filament organizations. The filament organization was characterized using image processing based on the Fourier Transforms Method. The effect of different filament orientation ratios on cellular growth is discussed.