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Öğe Aliphatic Polyurethane Films Based on Hexamethylene Diisocyanate and Saccharides for Biocompatible Transparent Coating on Optic Medical Devices(Wiley-V C H Verlag Gmbh, 2022) Gurses, Canbolat; Karaaslan-Tunc, Merve Goksin; Kelestemur, Unzile; Balcioglu, Sevgi; Gulgen, Selam; Koytepe, Suleyman; Ates, BurhanPolyurethanes are widely used in daily life, from the textile industry to medical applications. In this study, a biocompatible and transparent coating from polyethylene glycol-based polyurethanes including different type of saccharide (xylose as monosaccharide, sucrose as disaccharide, or starch as polysaccharide) is prepared. Prepared optically transparent polyurethanes are characterized with different instrumental analysis techniques and contact-angle measurements. Thermogravimetric analysis data allow understanding that the synthesized saccharide based polyurethanes are resistant to high temperatures, which means that medical devices can be easily coated with one of the saccharide-based polymers during the manufacturing process. The study results also show that synthesized polyurethane samples having a different kind of saccharides present high biocompatibility and transparency properties via In vitro cytotoxicity analysis and optic transparency tests. For xylose, sucrose, or starch containing polyurethanes, the tranmittance values are 97.72%, 85.20%, and 89.23%, respectively. In addition, scanning electron microscope images show that the samples also have smooth surfaces which can be used for proper coating of medical devices. Consequently, this manuscript addresses synthesis and characterization of the optically transparent polyurethanes based on specific saccharides for biocompatible and transparent surfaces especially in optic medical devices such as colonoscopy applications and laparoscopic detection probes.Öğe Amperometric Simultaneous Measurement of Copper and Cobalt Ions with Polythiophene Incorporating Pendant Terpyridine Groups(Taylor & Francis Inc, 2014) Savan, Ebru Kuyumcu; Koytepe, Suleyman; Pasahan, Aziz; Erdogdu, Gamze; Seckin, TurgayTerpyridine containing thiophene monomer was synthesized. Electrochemical behavior of the monomer was studied by cyclic voltammetry. This monomer was polymerized via electrochemical methods and the resultant polymer was characterized. The stepwise fabrication process of the polymeric film electrode and its electrochemical sensing performance towards simultaneously Co and Cu ions were evaluated. The sensing parameters of the polymer electrode were investigated in detail, and the determination conditions were optimized. Under the optimal conditions, sensor response peak is linear to the Co ion concentration in the range of 1.0-50.0 mu M and the Cu ion concentration in the range of 1.0-20.0 mu M. Detection limit of terpyridine-based polythiophene film electrode for Co and Cu is respectively 100 nM and 0.05 nM.Öğe ?-Amylase Immobilization on P(HEMA-co-PEGMA) Hydrogels: Preparation, Characterization, and Catalytic Investigation(Wiley-V C H Verlag Gmbh, 2021) Dogan, Demet; Ulu, Ahmet; Sel, Evren; Koytepe, Suleyman; Ates, BurhanThe aims of this study are to synthesize and characterize poly (2-hydroxyethyl methacrylate-co-poly (ethylene glycol) methacrylate) (P(HEMA-co-PEG500MA)) structures containing polyethylene glycol (PEG) side groups and to investigate their possible use in alpha-amylase immobilization. For this purpose, P(HEMA-co-PEG500MA) copolymer structures are synthesized by using different monomer ratios. P(HEMA-co-PEG500MA) copolymer structures are confirmed by Fourier transform infrared spectroscopy (FTIR), and elemental analysis techniques. In addition, thermal, and morphological properties of the copolymers are investigated by thermal gravimetric analysis/differential scanning calorimetry, and scanning electron microscopy (SEM). Afterward, alpha-amylase from Aspergillus oryzae is immobilized on synthesized copolymer support by using physical interactions. The success of immobilization is elucidated via FTIR, SEM, and energy dispersive X-ray spectroscopy (EDX) methods. In addition, the influences of temperature, pH, storage time, and repeated uses on the activity of free and immobilized alpha-amylase are investigated. According to the outcomes, the immobilized alpha-amylase possesses a better pH and thermal resistance than the free one. Additionally, the immobilized alpha-amylase maintains about 53% of its original activity after eight reuses and it exhibits about 50% relative activity after 28 days of storage. In conclusion, the immobilized alpha-amylase can be utilized as a potential efficient catalyst to produce maltose from the hydrolysis of starch.Öğe Assessing short-term effects of magnetite ferrite nanoparticles on Daphnia magna(Springer Heidelberg, 2020) Gokce, Didem; Koytepe, Suleyman; Ozcan, ImrenMagnetic nanoparticles (MNPs) are used in a wide range of sectors ranging from electronics to biomedicine, as well as in eutrophicated lake restoration due to their high P, N, and heavy metal adsorption capacity. This study assessed the effects of MNPs on mortality and morphometric changes of D. magna. According to the SEM, the synthesised MNPs were found to have spherical nanoparticles, be uniformly distributed, and have a homolithic size distribution of 50-110 nm. The EDX spectra confirmed the elemental structure and purities of these MNPs. A total of 396 neonates were used for short-term bioassays (96 h) through the MNPs in the laboratory (16:8 photoperiod). Experiments were applied in triplicate for each concentration of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs and their respective control groups. Mortality and morphological measurements of each individual were recorded every 24 h. In the probit analysis, the 96-h LC50 (p < 0.05) for CuFe2O4, CoFe2O4, and NiFe2O4 MNPs was calculated to be 1.455 mg L-1, 39.834 mg L-1, and 21.730 mg L-1, respectively. CuFe2O4 MNPs were found to be more toxic than the other two MNPs. The concentrations of CuFe2O4, CoFe2O4, and NiFe2O4 MNPs drastically affected life span and morphologic growth of D. magna as a result of a short time exposure. The results of this study are useful for assessing what risks they pose to freshwater ecosystems.Öğe Biodegradable non-aromatic adhesive polyurethanes based on disaccharides for medical applications(Elsevier Sci Ltd, 2014) Ates, Burhan; Koytepe, Suleyman; Karaaslan, Merve Goksin; Balcioglu, Sevgi; Gulgen, SelamThis work addresses synthesis, characterization, adhesive properties, protein adsorption and in vitro biodegradation of non-aromatic polyurethanes (NPUs). The following reactants were used in the syntheses of polyurethanes (PUs): non-aromatic 4,4'-Methylenebis(cyclohexyl isocyanate) (MCI), disaccharides (maltose and sucrose) and polyethylene glycol 200 (PEG 200). The NPUs exhibited low glass transition temperature (T-g) and good thermal stability. The dynamic contact angles on NPUs were influenced by the ratios of PEG 200-disaccharide monomer and the hard segment of the NPUs. The highest adhesion strength in whole polyurethanes was found as 307.6 +/- 50.1 kPa for 15% sucrose containing polyurethane. Protein adsorptions of polyurethane films were measured as average 10 pg Bovine Serum Albumin (BSA)/cm(2) and 5 mu g fibrinogen/cm(2) for maltose, and 15 mu g BSA/cm(2) and 5 mu g fibrinogen/cm(2) for sucrose. Biodegradability ratios of NPUs were in the range of 15-35% for 8 weeks depending on the disaccharides containing NPUs. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Biomedical applications of hybrid polymer composite materials(Woodhead Publ Ltd, 2017) Ates, Burhan; Koytepe, Suleyman; Balcioglu, Sevgi; Ulu, Ahmet; Gurses, Canbolat[Abstract Not Available]Öğe Biomimetic approach to tunable adhesion of polyurethane adhesives through Fe3+ crosslinking and hydrophobic tween units with balance of adhesion/cohesion forces(Elsevier Sci Ltd, 2019) Ates, Burhan; Koytepe, Suleyman; Balcioglu, Sevgi; Karaaslan, Merve Goksin; Kelestemur, Unzile; Gulgen, Selam; Ozhan, OnuralBiocompatible adhesives have some limitations such as weak adhesion and low flexibility. To overcome these limitations, we described multiple strategies to provide strong adhesion and high flexibility through Tweens, chlorogenic acid (CLA) and polyethylene glycol (PEG) by reducing excessive interaction between tissue and the adhesive. We synthesized polyurethane-based adhesives using aliphatic 4,4'-methylenebis(cyclohexyl isocyanate) (HMDI), PEG, CLA and Tween units. Hydrophobic side chains in polymer resulted in lower Tg (- 36.95-30.36 degrees C) which indicated more flexibility. The highest adhesion strengths were found as almost 346 kPa for bare polyurethane and 492 kPa for chelated polymer (PU-T40-CLA-15% (5% Tween 40, 15% chlorogenic acid and 80% PEG 200 containing polymer)) with FeCl3. The addition of Tween units provided more stable structure to polymers which proved with in vitro erosion studies. Relatively low erosion values were seen as 5.7, 5.6 and 8.2% in PU-T40-CLA-5% (15% Tween 40, 5% chlorogenic acid and 80% PEG 200 containing polymer), PU-T40-CLA-10% (10% Tween 40, 10% chlorogenic acid and 80% PEG 200 containing polymer), and PU-T40-CLA-15% (5% Tween 40, 15% chlorogenic acid and 80% PEG 200 containing polymer), respectively. In vitro biocompatibility results showed high cell viability in PU-T40-15% as more than 100%. Overall, our findings indicated that these material designs (PU-T-CLAs) provided to overcome the significant challenges of tissue adhesives by improving the flexible character and adhesive strength of the adhesives.Öğe Ce/Sm co-doped hydroxyapatites: synthesis, characterization, and band structure calculation(Springer, 2021) Kaygili, Omer; Vural, Gulay; Keser, Serhat; Yahia, I. S.; Bulut, Niyazi; Ates, Tankut; Koytepe, SuleymanIn this paper, Ce/Sm co-doped hydroxyapatites (HAps) were synthesized by a wet chemical route. The amount of Ce was kept at constant at the value of at.% 0.4, and the second dopant of Sm was used at different amounts of at.% 0, 0.6, 1.2, and 1.8, respectively. The effects of these co-dopants on the crystal structure, morphology, and thermal properties of HAp were determined experimentally using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA), and thermogravimetric analysis (TGA). Furthermore, the band structure of the prepared samples was modeled theoretically using the quantum calculations of the density of states and band structure. A gradual increase from 26.56 to 36.23 nm in the crystallite size was observed. Although the amounts of the co-dopants of Ce and Sm did not affect the thermal stability and microstructure of HAp, its crystal structure-related parameters were affected by the amount of these co-additives. The partial substitution of both co-dopants was detected. The 0.4Ce-1.2Sm-HAp sample may be considered as the best crystal structure with a steady-state. It was seen that the band structure and density of states were also affected by these co-dopants. The bandgap value decreased gradually from 4.6078 to 4.0477 eV due to these dopants.Öğe Chemistry, Structures, and Advanced Applications of Nanocomposites from Biorenewable Resources(Amer Chemical Soc, 2020) Ates, Burhan; Koytepe, Suleyman; Ulu, Ahmet; Gurses, Canbolat; Thakur, Vijay KumarResearchers have recently focused on the advancement of new materials from biorenewable and sustainable sources because of great concerns about the environment, waste accumulation and destruction, and the inevitable depletion of fossil resources. Biorenewable materials have been extensively used as a matrix or reinforcement in many applications. In the development of innovative methods and materials, composites offer important advantages because of their excellent properties such as ease of fabrication, higher mechanical properties, high thermal stability, and many more. Especially, nanocomposites (obtained by using biorenewable sources) have significant advantages when compared to conventional composites. Nanocomposites have been utilized in many applications including food, biomedical, electroanalysis, energy storage, wastewater treatment, automotive, etc. This comprehensive review provides chemistry, structures, advanced applications, and recent developments about nanocomposites obtained from biorenewable sources.Öğe Chitosan/polypropylene glycol hydrogel composite film designed with TiO2 nanoparticles: A promising scaffold of biomedical applications(Elsevier, 2020) Ulu, Ahmet; Birhanli, Emre; Koytepe, Suleyman; Ates, BurhanThe present study explores the preparation and characterization of chitosan/poly (propylene glycol)/titanium dioxide (CH/PPG/TiO2) composite hydrogels in view of their developing applications such as antimicrobial packaging, wound dressing and antibacterial materials. The prepared CH/PPG/TiO2 films were comprehensively characterized by several methods. The size distribution showed the average size of the TiO2 nanoparticles (NPs) was about 40 nm. Additionally, other properties including swelling ratio, water retention, water contact angle, porosity, water uptake, in vitro enzymatic degradation, water vapor transmission rate, in vitro biomineralization studies, and mechanical tests were evaluated in detailed. Besides these characterizations, the antimicrobial activity of CH/PPG/TiO2 composite film against Staphylococcus aureus, Escherichia coli, and Candida lipolytica was evaluated by using disc diffusion method. Based on the obtained results, the CH/PPG/TiO2 composite hydrogels showed enhanced water vapor permeability, porosity, water retention, and swelling ratio. An improvement was observed in the examined mechanical and thermal properties with the addition of TiO2 NPs. The tensile strength and elongation at break values of CH/PPG/TiO2 were 3.0 MPa and 31%, respectively. Most importantly, the CH/PPG/TiO2 composite hydrogels showed strong antimicrobial properties. Finally, the developed composite scaffold prepared in this study may possess potentially useful in biomedical applications. (C) 2020 Elsevier B.V. All rights reserved.Öğe Chitosan/Polyvinylpyrrolidone/MCM-41 Composite Hydrogel Films: Structural, Thermal, Surface, and Antibacterial Properties(Wiley-V C H Verlag Gmbh, 2018) Ulu, Ahmet; Noma, Samir A. A.; Gurses, Canbolat; Koytepe, Suleyman; Ates, BurhanThe aim of this study is to characterize and investigate the effects of the Mobil Composition of Matter No. 41 (MCM-41) concentrations (0.5, 1, 3, 5, and 10 wt%) on structural, thermal, wettability, water content, oxygen (O-2) permeability, and swelling properties as well as morphological characteristics of chitosan/polyvinylpyrrolidone/MCM-41 (CH/PVP/MCM-41) composite hydrogel films. In addition, hydrolytic degradability, optic transmittance, and antibacterial properties of composite hydrogels films are determined as in vitro. With increasing of MCM-41 content, the composite hydrogels showed higher thermal stability, as expected. The morphologic properties of the composite hydrogel films are studied using scanning electron microscope (SEM) technique that provide evidence for good miscibility of CH, PVP, and MCM-41. The swelling and water-absorbing properties of the composite hydrogel films are significantly improved because of enhanced hydrophilic profile. Furthermore, the antimicrobial properties of the prepared composite hydrogel films are studied against Bacillus subtilis, Escherichia coli, and Candida albicans yeast. The results showed excellent antibacterial behavior of the composite hydrogel films. The study clearly demonstrates that the prepared CH/PVP/MCM-41 composite hydrogel films may be used as a promising candidate material in various fields such as drug delivery, wound healing material, and adsorbent materials.Öğe Chloro-Modified Magnetic Fe3O4@MCM-41 Core-Shell Nanoparticles for L-Asparaginase Immobilization with Improved Catalytic Activity, Reusability, and Storage Stability(Springer, 2019) Ulu, Ahmet; Noma, Samir Abbas Ali; Koytepe, Suleyman; Ates, BurhanThis paper describes a new support that permits to efficient immobilization of L-asparaginase (L-ASNase). For this purpose, Fe3O4 magnetic nanoparticles were synthesized and coated by MCM-41. 3-chloropropyltrimethoxysilane (CPTMS) was used as a surface modifying agent for covalent immobilization of L-ASNase on the magnetic nanoparticles. The chemical structure; thermal, morphological, and magnetic properties; chemical composition; and zeta potential value of Fe3O4@MCM-41-Cl were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction patterns (XRD), and zeta-potential measurement. The immobilization efficiency onto Fe3O4@MCM-41-Cl was detected as 63%. The reusability, storage, pH, and thermal stabilities of the immobilized L-ASNase were investigated and compared to that of soluble one. The immobilized enzyme maintained 42.2% of its original activity after 18cycles of reuse. Furthermore, it was more stable towards pH and temperature compared with soluble enzyme. The Michaelis-Menten kinetic properties of immobilized L-ASNase showed a lower V-max and a similar K-m compared to soluble L-ASNase. Immobilized enzyme had around 47 and 32.5% residual activity upon storage a period of 28days at 4 and 25 degrees C, respectively. In conclusion, the Fe3O4@MCM-41-Cl@L-ASNase core-shell nanoparticles could successfully be used in industrial and medical applications.Öğe Chlorogenic Acid Containing Bioinspired Polyurethanes: Biodegradable Medical Adhesive Materials(Taylor & Francis As, 2015) Ates, Burhan; Koytepe, Suleyman; Karaaslan, Merve Goksin; Balcioglu, Sevgi; Gulgen, Selam; Demirbilek, Murat; Denkbas, Emir BakiHighly adhesive bioinspired polyurethanes (PUs) based on the chlorogenic acid (CLA) were prepared from 4,4'-methylenebis (cyclohexyl isocyanate) (MCI) and polyethylene glycol 200 (PEG 200). The polyurethanes exhibited the lowest glass transition temperature (T-g), improved thermal stability and good adhesive properties. The highest adhesion strength was found as 373.3 +/- 47.5 kPa for 10% CLA containing PUs. The polyurethanes were observed to be biodegradable and were in the range of 19-24% for 8 weeks as depending on chlorogenic acid containing of PUs. As a result, prepared biocompatible-adhesive bioinspired polyurethanes are good candidates for medical applications as a tissue adhesive material. [GRAPHICS] .Öğe Chronic and Acute Water-Soluble Microplastics Uptake and Effects on Growth and Reproduction of Daphnia magna(Springer Int Publ Ag, 2022) Gokce, Didem; Seftalicioglu, Merve Duygu; Erden, Busra Aksoy; Koytepe, SuleymanThis study focuses on the evaluation of chronic and acute effects of the water-soluble microplastics polyvinyl alcohol (PVA) and polymethacrylic acid (PMA) on the growth and reproduction of Daphnia magna. Within the scope of this study, first of all, PVA and PMA microplastics structures were structurally, thermally, and morphologically characterized. The size distributions and dimensional stability of these structures were determined. Then, the microplastics structures, whose structural and dimensional properties were determined, were applied to the growth and reproduction environments of D. magna at different concentrations. The effects of these microplastics on survival parameters, population growth, morphometric data, and lethal concentration were evaluated through short (96-h) and long (21-day) term analyses. In the long-term study, reproductive strategies affecting population density were examined. Acute and chronic experiments were performed in parthenogenetic females. In chronic triplicate experiments evaluating the population structure from which the reproductive data were obtained, the male neonate was recorded only at a concentration of 5 mgL(-1) MP-PVA. Decreased lifespan, ephippium production, embryo development, immature eggs, sexual differentiation, and morphologic deformations have been observed in D. magna due to different concentrations of microplastics polymers exposures.Öğe Comparative study of catalase immobilization via adsorption on P(MMA-co-PEG500MA) structures as an effective polymer support(Springer, 2021) Sel, Evren; Ulu, Ahmet; Ates, Burhan; Koytepe, SuleymanIn this study, poly[methyl methacrylate-co-poly(ethylene glycol) methacrylate] (P(MMA-co-PEG500MA)) copolymers were used for catalase (CAT) immobilization. Firstly, P(MMA-co-PEG500MA) copolymers were synthesized by using different amount of methyl methacrylate (MMA) and poly(ethylene glycol) methacrylate (PEG500MA) monomers. The synthesized copolymers were characterized by different analysis techniques. Afterward, CAT enzyme was immobilized via physical adsorption method onto the P(MMA-co-PEG500MA) copolymers. P3 sample containing 1:1 (PEG500MA:MMA) monomer molar ratio was selected as model support because of exhibiting optimum surface porosity and thermal stability. A high immobilization yield (76%) was achieved under optimized conditions. The immobilized enzyme displayed improved tolerance towards pH and temperature changes. After immobilization, the optimum pH shifted from 7.5 to 7.0, whereas the optimum temperature remained unchanged at 35 degrees C. Immobilized enzyme showed good reuse potential and excellent storage stability. After 10 consecutive uses, immobilized enzyme maintained about 51.0% of its initial activity. Furthermore, free enzyme completely lost its initial activity after 4 weeks, while immobilized enzyme maintained approximately 65% of the initial activity at 25 degrees C. Approximately twofold decrease in Km was obtained which means that the affinity of enzyme to the substrate improved after immobilization. Finally, it can be concluded that the prepared P(MMA-co-PEG500MA) copolymer structure can be an ideal matrix for CAT immobilization.Öğe Comparison dielectric and thermal properties of polyurethane/organoclay nanocomposites(Elsevier, 2013) Baysal, Gulay; Aydin, Haluk; Koytepe, Suleyman; Seckin, TurgayPolyurethane composites were obtained with different organoclay contents. The organoclay Na+-montmorillonite was dispersed in the PU matrix by mixing method from solution. Na+-montmorillonite was modified with dodecyl ammonium sulphate and 1-methyl-3-octyl imidazolium tetrafluoroborate. The nanocomposites obtained by using different modifier were compared in terms of dielectric and thermal properties. The dispersion state of the organoclay particles and its effect on the thermogravimetric and dielectric properties of the composites was investigated. The characterization of PU/organoocl ay composites was carried out by means of scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis and X-ray diffraction. The dielectric properties of the PU/organoclay nanocomposites were studied in detail. The obtained PU/organoclay intercalated nanocomposites exhibited better thermal stability and improved lower dielectric constants than the pure PU. (C) 2013 Elsevier B.V. All rights reserved.Öğe The Cytotoxicity, DNA Fragmentation, and Decreasing Velocity Induced By Chromium(III) Oxide on Rainbow Trout Spermatozoa(Springernature, 2023) Ozgur, Mustafa Erkan; Ulu, Ahmet; Gurses, Canbolat; Ozcan, Imren; Noma, Samir Abbas Ali; Koytepe, Suleyman; Ates, BurhanThe present study aimed to determine the cytotoxicity of chromium(III) oxide micro particles (Cr2O3-Ps) in rainbow trout (Oncorhynchus mykiss) spermatozoa. Firstly, Cr2O3-Ps were synthesized and structurally characterized the surface, morphological for particle size and thermal properties. In addition, its structural and elemental purity was determined using energy-dispersive X-ray (EDX) spectrum and elemental maps. Structural purity, thermal properties, and stability of Cr2O3 -Ps were also examined in detail by performing thermal analysis techniques. The cytotoxicity of Cr2O3-Ps was measured by the observation of velocities, antioxidant activities, and DNA damages in rainbow trout spermatozoa after exposure during 3 h in vitro incubation. The straight line velocity (VSL), the curvilinear velocity (VCL), and the angular path velocity (VAP) of spermatozoa decreased after exposure to Cr2O3-Ps. While the superoxide dismutase (SOD) and the catalase (CAT) decreased, the lipid peroxidation increased in a dose-dependent manner. However, the total glutathione (tGSH) was not affected in this period. DNA damages were also determined in spermatozoa using Comet assay. According to DNA in tail (%) data, DNA damages have been detected with gradually increasing concentrations of Cr2O3-Ps. Furthermore, all of class types which are categorized as the intensity of DNA fragmentation has been observed between 50 and 500 mu g/L concentrations of Cr2O3-Ps exposed to rainbow trout spermatozoa. At the end of this study, we determined that the effective concentrations (EC50) were 76.67 mu g/L for VSL and 87.77 mu g/L for VCL. Finally, these results about Cr2O3-Ps may say to be major risk concentrations over 70 mu g/L for fish reproduction in aquatic environments.Öğe Design of epoxy-functionalized Fe3O4@MCM-41 core-shell nanoparticles for enzyme immobilization(Elsevier, 2018) Ulu, Ahmet; Ozcan, Imren; Koytepe, Suleyman; Ates, BurhanThe scope of our research was to prepare the organosilane-modified Fe3O4@MCM-41 core-shell magnetic nano particles, used for L-ASNase immobilization and explored screening of immobilization conditions such as pH, temperature, thermal stability, kinetic parameters, reusability and storage stability. In this content, Fe3O4 core shell magnetic nanoparticles were prepared via co-precipitation method and coated with MCM-41. Then, Fe3O4@MCM-41 magnetic nanoparticles were functionalized by (3-glycidyloxypropyl) trimethoxysilane (GPTMS) as an organosilane compound. Subsequently, L-ASNase was covalently immobilized on epoxyfunctionalized Fe3O4@MCM-41 magnetic nanoparticles. The immobilized L-ASNase had greater activity at high pH and temperature values. It also maintained >92% of the initial activity after incubation at 55 degrees C for 3 h. Regarding kinetic values, immobilized L-ASNase showed a higher Vmax and lower Km compared to native L-ASNase. In addition, it displayed excellent reusability for 12 successive cycles. After 30 days of storage at 4 degrees C and 25 degrees C, immobilized L-ASNase retained 54% and 26% of its initial activities while native L-ASNase lost about 68% and 84% of its initial activity, respectively. As a result, the immobilization of L-ASNase onto magnetic nanoparticles may provide an advantage in terms of removal of L-ASNase from reaction media. (C) 2018 Elsevier B.V. All rights reserved.Öğe Design of starch functionalized biodegradable P(MAA-co-MMA) as carrier matrix for L-asparaginase immobilization(Elsevier Sci Ltd, 2016) Ulu, Ahmet; Koytepe, Suleyman; Ates, BurhanWe prepared biodegradable P(MAA-co-MMA)-starch composite as carrier matrix for the immobilization of L-asparaginase (L-ASNase), an important chemotherapeutic agent in acute lymphoblastic leukemia. Chemical characteristics and thermal stability of the prepared composites were determined by FT-IR, TGA, DTA and, DSC, respectively. Also, biodegradability measurements of P(MAA-co-MMA)-starch composites were carried out to examine the effects of degradation of the starch. Then, L-ASNase was immobilized on the P(MAA-co-MMA)-starch composites. The surface morphology of the composite before and after immobilization was characterized by SEM, EDX, and AFM. The properties of the immobilized L-ASNase were investigated and compared with the free enzyme. The immobilized L-ASNase had better showed thermal and pH stability, and remained stable after 30 days of storage at 25 degrees C. Thus, based on the findings of the present work, the P(MAA-co-MMA)-starch composite can be exploited as the biocompatible matrix used for L-ASNase immobilization for medical applications due to biocompatibility and biodegradability. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Determination of characterization, antibacterial and drug release properties of POSS- based film synthesized with sol-gel technique(Tubitak Scientific & Technological Research Council Turkey, 2021) Acari, Idil Karaca; Koytepe, Suleyman; Ates, Burhan; Yilmaz, Ismet; Seckin, Turgaythe study, antibacterial film synthesis was aimed using sol-gel technique from POSS structure with various functional groups. For this purpose, antibacterial properties have been acquired by metronidazole to the films to be synthesized. The films obtained were coated on glass surface samples by dip coating method. Antibacterial activities of surface coated glass samples were observed in E.coli and S. aureus bacteria. Metronidazole release studies in the film samples were followed by UV spectrophotometer. It was observed that drug release reached 68.90% at the end of the 24th h. As a result, it is thought that the synthesized film will be a good candidate especially for biomedical surface coating areas.
