murat demirbilek | Hacettepe University (original) (raw)

Papers by murat demirbilek

European Journal of Trauma and Emergency Surgery, 2016

Journal of Biomedical Nanotechnology, Oct 1, 2012

Hacettepe journal of biology and chemistry, 2008

The biodegradability, morphology, and mechanical properties of composite materials consisting of ... more The biodegradability, morphology, and mechanical properties of composite materials consisting of acrylic acid-grafted poly(hydroxyalkanoate) (PHA-g-AA) and rice husk (RH) were evaluated. Composites containing PHA-g-AA (PHA-g-AA/RH) exhibited noticeably superior mechanical properties compared with those of PHA/RH because of greater compatibility with RH. The dispersion of RH in the PHA-g-AA matrix was homogeneous because of ester formation and the consequent creation of branched and crosslinked macromolecules, between the carboxyl groups of PHAg-AA and hydroxyl groups in RH. The water resistance of PHA-g-AA/RH was higher than that of PHA/RH, although the weight loss of composites buried in soil compost indicated that both were biodegradable, especially at high levels of RH substitution. After 60 days, the weight loss of the PHA-g-AA/ RH (40 wt%) composite was greater than 90 %. PHA/RH exhibited a weight loss of approximately 4-8 wt% more than PHA-g-AA/RH. The PHA/RH and PHA-g-AA/RH composites were more biodegradable than pure PHA, which implies a strong connection between RH content and biodegradability.

Journal of Bioactive and Compatible Polymers, Mar 13, 2023

Several polymers are used for the preparation of biomaterials as membranes and films for tissue e... more Several polymers are used for the preparation of biomaterials as membranes and films for tissue engineering applications. The most common plasticizer is PEG to obtain polymer-based biomaterials. On the other hand, triacetin is a non-toxic, FDA-approved plasticizer mostly used in the food industry. In this study, we used triacetin as a plasticizer to obtain hydrophobic membranes for the prevention of intra-abdominal adhesion. We selected a well-known polymer named PHBHHx which is a bacterial polyester generally used as supporting material for cell attachments in regenerative tissue applications. We evaluated the triacetin as a plasticizer and its effect on mechanical, thermal, surface area, pore size, and surface energy. The hydrophobic/hydrophilic contrast of a biomaterial surface determines the biological response. Surface hydrophobicity is critical for the cellular response. The contact angle tests of PHBHHx revealed that the hydrophilicity of the membrane was decreased following triacetin blending. Modification of the PHBHHx membrane by blending with triacetin caused a significant decrease in cell adhesion. The cell attachment rates of PHBHHx membranes were as 95 ± 5% on the first day, 34.5 ± 0.9% on third day, and 23 ± 1.5% on the fifth day, respectively. The rates of cell attachments on PHBHHx/triacetin membranes were determined as 79 ± 2.5% for the first day, 33 ± 2.7% for the third day, and 13 ± 2.1% for the fifth day, respectively. Besides, triacetin blending decreased the surface area from 38.790 to 32.379 m2/g. The elongation at breaks was observed as 128% for PHBHHx and 171% for PHBHHx/triacetin. Graphical abstract [Formula: see text]

Journal of Biomaterials and Tissue Engineering, Sep 1, 2017

Research Journal of Biotechnology, Jun 15, 2023

Surfactants play a major role in solid lipid nanoparticles’ (SLNs) composition and properties, es... more Surfactants play a major role in solid lipid nanoparticles’ (SLNs) composition and properties, especially in terms of particle size and zeta potential. Not only the type of the surfactants but also their amounts and chemical compatibility with the lipid core within the formulation cause good changes. In this study, our goal was to determine the effect of tween 80 (a non-ionic surfactant) on octadecylamine (cationic lipid)-based SLN formulation and its influence on SLNs properties. Also, we examined the effect of sonication and filtration as mechanical forces on the particle size, zeta potential and PDI features. Five different formulations were performed by the emulsion solvent evaporation method. Particle size distribution, zeta potential and PDI values were determined by Zetasizer via the dynamic light scattering method. We obtained SLNs resulting from different formulations and one formulation was selected with the most suitable properties for further studies. The stability of the SLNs was examined by incubating them at 4 °C in the dark for particular time intervals and the results revealed not only minimal changes in particle size but also no significant changes in zeta potential and PDI values. The nanoparticles were characterized morphologically with Transmission electron microscopy (TEM) and Atomic force microscopy (AFM). The chemical characterization was performed by Fourier-transform infrared spectroscopy (FT-IR). In vitro cytotoxicity via MTT assay on L929 mouse fibroblast cell line was performed and cell viability was determined over 63% for all concentrations.

European Journal of Trauma and Emergency Surgery, Jul 11, 2016

Drug and Chemical Toxicology, 2006

Considering the vast use of sweeteners by the Brazilian population and the constant need for toxi... more Considering the vast use of sweeteners by the Brazilian population and the constant need for toxicological studies of food additives, this study aimed to evaluate the cytotoxic and mutagenic potentials of the sodium saccharin and/or sodium cyclamate sweeteners in plant (Allium cepa) and animal (Mus musculus) test systems based on concentrations permitted by the Brazilian laws. In A. cepa, both the sweeteners individually and their combinations concentration and exposure time (ET: 48, 72 and 168 h) dependently exerted cytotoxic and mutagenic effects. Similarly, an increased in micronuclei formation was also observed by the sweeteners in peripheral blood cells in mice. More toxic effects were observed with the combination doses at 168 ET. There may be a synergistic effect and DNA damage with an increasing concentration and ET. In conclusion, the concentrations considered safe by the Brazilian laws had significant cytotoxic and mutagenic activity on the eukaryotic cells.

Journal of Microbiological Methods

Journal of Biomedical Materials Research Part B: Applied Biomaterials

Alginate (ALG) is a biocompatible and biodegradable polymer. Mechanical weakness is one of the ma... more Alginate (ALG) is a biocompatible and biodegradable polymer. Mechanical weakness is one of the main problems for the alginate‐based scaffolds. Various plasticizer additives or modifications tested to improve the mechanical properties. In the presented study, ALG plasticized with triacetin (TA), and tributyl citrate (TBC) than tested on bone healing. In the presented study, the alginate modified with triacetin or tributyl citrate. In‐vitro, and in‐vivo efficiency of the scaffolds tested on bone tissue regeneration. Scaffolds fabricated by solvent casting, and physicochemical characterizations performed. Monocytes (THP‐1) cultured with scaffolds, and macrophage‐released cytokines was determined. In‐vivo efficacy of the scaffolds was tested in the rat drill hole model. Alginate and tributyl citrate‐modified scaffolds have no cytotoxic effect on osteoblastic cells (MC‐3T3). Tributyl citrate modification increased tumor necrosis factor‐alpha (TNF‐alpha) level but did not increase interle...

DRP is a disease consisting of all the structural and functional changes that develop in the reti... more DRP is a disease consisting of all the structural and functional changes that develop in the retinal layer of the eye due to diabetes. DRP is the most important cause of blindness between the ages of 20-74 in the world, and the most successful standard treatment option in the treatment of DRP is intravitreal injections. To synthesize acetazolamide loaded nanoparticles to be applied intravitreal treatment of DRP and to examine the in vitro efficacy of the nanoparticles. ACZ loaded PHBV nanoparticles (PHBV-ACZ NPs) formulations were prepared. Nanoparticles with a particle size of 253.20±0.55nm. A DRP model was established and characterized in HRMEC cells. The effect of the nanoparticles on permeability has been investigated and carrier proteins in BRB due to the development of DRP has been investigated. To establish the in vitro DRP model, HRMEC was stimulated with Recombinant human 165 Vascular Endothelial Growth Factor (VEGF), thereby temporarily reducing the expression levels of en...

Hacettepe Journal of Biology and Chemistry, 2020

N öronal hücrelerin kendi kendilerini tamir mekanizmaları olmamasından dolayı, hasarlı sinir doku... more N öronal hücrelerin kendi kendilerini tamir mekanizmaları olmamasından dolayı, hasarlı sinir dokularının rejenerasyonunda biyomateryaller yaygın bir şekilde çalışılmıştır. Avantajları olmasına rağmen, nanomateryaller oksidatif strese neden olabilir ve bu durum tedaviyi etkileyebilir. Bu çalışmada, aksonal rejenerasyon için kullanılan PHBV [poly (3-hydroxybutyrateco-3-hydroxyvalerate)]'nin ratlarda lipid peroksidasyonuna ve protein oksidayonuna neden olup olmadığı ve ayrıca antioksidan molekülleri etkileyip etkilemediği araştırıldı. Çalışmada, elektrospinning ile PHBV yönlendirilmiş nanofiber membranlar hazırlandı ve bunlar kullanılarak graftler oluşturuldu. Sıçan peritoneal sinirlerinde 1 cm boşluk oluşturulduktan sonra PHBV graftler yerleştirildi. Hayvanlar operasyon sonrası 17. haftada feda edildi. Ratların kan, karaciğer ve graft yerleştirilen perioneal sinir demeti çevre kas dokusu malondialdehit (MDA), ileri oksidasyon protein ürünleri (AOPP), glutatyon (GSH) seviyeleri ve süperoksit dismutaz (SOD) aktiviteleri ölçüldü. Kontrol grubu ile karşılaştırıldığında, tüm graft grubu serum MDA, AOPP ve GSH düzeyleri ve SOD aktivitelerinde anlamlı bir artış gözlenirken, dokularda sadece MDA ve AOPP seviyeleri istatistiksel olarak yüksek bulundu. Bu bulgular perioneal sinir defektleri için kullanılan PHBV graftinin sıçanlarda oksidatif strese neden olabileceğini düşündürmektedir.

Connective Tissue Research

Purpose/Aim of the study: The ultimate goal of periodontal treatment is to regenerate the lost pe... more Purpose/Aim of the study: The ultimate goal of periodontal treatment is to regenerate the lost periodontal tissues. The interest in nanomaterials in dentistry is growing rapidly and has focused on improvements in various biomedical applications, such as periodontal regeneration and periodontal tissue engineering. To enhance periodontal tissue regeneration, hydroxyapatite (HA) was used in conjunction with other scaffold materials, such as Poly lactic-co-glycolic-acid (PLGA) and collagen (C). The main target of this study was to compare the effects of nano and macrostructures of the tissue scaffolds on cell behavior in vitro for periodontal tissue engineering.Materials and Methods: Nanofibrillar and macroporous-spongious composite tissue scaffolds were produced using PLGA/C/HA. Subgroups with BMP-2 signal molecule and without HA were also created. The scaffolds were characterized by FTIR, SEM/EDX techniques, and mechanical tests. The scaffolds were compared in the periodontal ligament (PDL) and MCT3-E1 cell cultures. The cell behaviors; adhesions by SEM, proliferation by WST-1, differentiation by ALP and mineralization with Alizarin Red Tests were determined.Results: Cell adhesion and mineralization were higher in the nanofibrillar scaffolds compared to the macroporous-spongious scaffolds. Macroporous-spongious scaffolds seemed better for the proliferation of PDL cells and differentiation of MC3T3-E1-preosteoblastic cells, while nanofibrillar scaffolds were more convenient for the differentiation of PDL cells and proliferation of MC3T3-E1-preosteoblastic cells.Conclusions: In general, nanofibrillar scaffolds showed more favorable results in cell behaviors, compared to the macroporous-spongious scaffolds, and mostly, BMP-2 and HA promoted the activities of the cells.

Journal of Biomedical Nanotechnology, 2012

Polyhydroxyalkanoates (PHA) are natural, thermoplastic polyesters and due to their biocompatible ... more Polyhydroxyalkanoates (PHA) are natural, thermoplastic polyesters and due to their biocompatible and biodegradable properties they are good alternatives for the production of scaffolds for engineered tissues or nanoparticles for drug delivery. As a member of polyhydroxyalkanoate family, polyhydroxybutyrates (PHB) have been widely used as a biomaterial for in vitro and in vivo studies since their mechanical properties are very similar to conventional plastics. By using multi-emulsion technique, iron oxide particles were coated with polyhydroxybutyrate (PHB) polymer synthesized from Alcaligenes eutrophus bacteria and the magnetic carrier system was prepared accordingly. The bare nanoparticles and magnetic nanoparticles were morphologically, structurally and magnetically characterized by using Scanning electron microscope (SEM) and Atomic force microscope (AFM); Fourier Transform Infrared Spectrometry (FTIR), and Electron Spin Resonance (ESR) and Vibrating Sample Magnetometer (VSM) tec...

Proceedings of the 4th World Congress on Recent Advances in Nanotechnology

In this paper, a microfluidic platform with bottom and upper microchannels separated by a polycar... more In this paper, a microfluidic platform with bottom and upper microchannels separated by a polycarbonate membrane is studied for three-dimensional cell culture applications. Microfluidic chips were designed and fabricated using standard soft lithography and micromolding methods. The effect of surface modification by NaOH of polycarbonate membranes on the cell viability was investigated. Mouse fibroblast cells were cultured on modified and non-modified membrane integrated microfluidic chips. On 2nd, 3rd and 4th day of cultivation, cell concentrations were recorded and it was found that the cell concentration on modified membranes was always higher at all time intervals, and after four days, the cell concentration on the modified membrane was about 55 % higher than that of unmodified case.

Medical Imaging Contrast Agents: A Clinical Manual

In this study, we present that medical grade titanium based plaques were oxidized with anodic oxi... more In this study, we present that medical grade titanium based plaques were oxidized with anodic oxidation in electrolyte solution. The resulting oxide layer is tube patterned with approximately 50 nm in diameter. Anodized titanium plaques were immersed into vancomycin containing simulated body fluid in order to load with antibiotics. The cell culture and related in vitro tests were carried out. Titania nanotube formation affected positively in osteoblast proliferation and bacterial inhibition. Orthopedic implants have been largely used in people in both developed and developing countries with the prolonged lifetime. Complications such as bacterial infections and insufficient osseointegration are the primary disadvantages of post implantation. If not prevented, bacterial infection can result in serious and life threatening conditions such as osteomyelitis (1). Although titanium and titanium alloys are all cytocompatible and show proper mechanical strength, in order to reduce chances of...

Polyhydroxyalkanoates (PHA) are good alternatives on account of biocompatible and biodegradable p... more Polyhydroxyalkanoates (PHA) are good alternatives on account of biocompatible and biodegradable properties to produce materials as scaffolds for engineered tissues. Polyhydroxybutyrate (PHB) which is a member of polyhydroxyalkanoate family have been widely used as a biomaterial for in vitro and in vivo studies due to its unique properties such as improved flexibility and processability. In this study polyhydroxybutyrate scaffolds were prepared for tissue engineering applications. In order to improve cell attachment on the scaffolds they were modified. During the modification three different immunologically inactive compounds, polyetyhylene glycol (PEG), 2-hydroxyethyl methacrylate (HEMA) and ethylenediamine (EDA) were used in radio frequency glow discharge (RFGD) plasma polymerization system. Morphological evaluations were obtained by using scanning electron microscopy. Obtained results showed high and interconnected porosity. In vitro weight loss profiles of the scaffolds were inve...