Alper Akkaya

Biodegradation of Direct Blue 15 by free and immobilized Trametes versicolor.

To investigate biodegradability by Trametes versicolor, five structurally different direct azo-dyes--Direct Black 38, Direct Blue 15 (DB 15), Direct Orange 26, Direct Green 6, and Direct Yellow 12--were studied. The DB 15 was determined as the best biodegradable dye by this white-rot fungus. Laccase and manganese peroxidase activities were monitored with the biodegradation process; it was observed that laccase played an important role in the dye degradation, while manganese peroxidase activity could not be detected. Possible degradation products also were examined by gas chromatography-mass spectrometry, but no metabolite was detected after the degradation and/or decolorization process. To enhance performance of the fungi during the degradation, Trametes versicolor cells were immobilized in alginate beads. Then, DB 15 decolorization by immobilized Trametes versicolor was studied in a small-scale packed-bed reactor. The color removal efficiency in repeated batches was found to be 98 and 93% for 50 mg/L DB 15.

Development of a new antibacterial biomaterial by tetracycline immobilization on calcium-alginate beads

In recent years, increasing risk of infection, caused by resistant microorganism to antibiotics, has become the limelight discovery of new and natural antibacterial materials. Heavy metals, such as silver, copper, mercury and titanium, have antibacterial activity. Products, which improved these metals, do not have stable antibacterial property. Therefore, use of these products is restricted. The aim of this study was to immobilize tetracycline to alginate and improve an antibacterial biomaterial. For this purpose, calcium-alginate beads were formed by dropping to calcium-chloride solution and tetracycline was immobilized to beads using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide at optimum conditions. After immobilization, actualization of immobilization was investigated by analyzing ATR-FTIR spectrum and SEM images. Also, antibacterial property of obtained product was tested. Improved product demonstrated antibacterial property. It has potential for open wound, surgical drapes, bed and pillow sheath in hospitals and it may also be used for increasing human comfort in daily life.

Covalent immobilization of urease to modified ethyl cellulose

Graft polymerization technology is a good way to modify polymers. New functional groups are added to polymer structure using graft polymerization. Enzyme immobilization could be done from these added functional groups. Ethyl cellulose was selected as a support for enzyme immobilization and no many studies has been conducted about it. It is insoluble in water and suitable for reuse. In this study, methacrylic acid was graft polymerized to ethyl cellulose using benzophenone. In graft polymerization studies, optimum amounts of methacrylic acid and benzophenone were determined as 60 mmol and 0.6 g, respectively. Percentage of graft polymerization was maximum in toluene as solvent and optimum graft polymerization time was found as 3 hours. The graft polymerization percentage was 225.7 % at optimum conditions. This value was very good for UV-induced graft polymerization technique. FT-IR spectra of ethyl cellulose and methacrylic acid graft polymerized ethyl cellulose showed that graft polymerization was carried out successfully. -COOH groups were added to ethyl cellulose structure after graft polymerization. Then, urease was immobilized to methacrylic acid graft polymerized ethyl cellulose using 1-ethyl-3-(3-dimetylaminopropyl)-carbodiimide as the condensing agent which accelerates the reaction between -COOH from methacrylic acid graft polymerized ethyl cellulose and -NH2 from urease. Optimization studies were also performed for the immobilization of urease. Optimized values for urease immobilization; optimum amount of 1-ethyl-3-(3-dimetylaminopropyl)-carbodiimide was found as 5 mg, temperature was determined as 37 °C, 2 hours were selected as optimum time, pH and amount of urease were found to be pH 7 and 10 mg, respectively. Remained activity of immobilized urease was 1.74 % before optimization studies. After optimization of immobilization studies, this ratio has increased to 29.85 %. The immobilized urease activity was increased 17.2 times.

THROMBIN IMMOBILIZATION TO METHACRYLIC ACID GRAFTED POLY(3-HYDROXYBUTYRATE) AND ITS IN VITRO APPLICATION

Poly(3-hydroxybutyrate) is nontoxic and biodegradable, with good biocompatibility and potential support for long-term implants. For this reason, it is a good support for enzyme immobilization. Enzyme immobilization could not be done directly because poly(3-hydroxybutyrate) has no functional groups. Therefore, modification should be done for enzyme immobilization. In this study, methacrylic acid was graft polymerized to poly(3-hydroxybutyrate) and thrombin was immobilized to polymethacrylic acid grafted poly(3-hydroxybutyrate). In fact, graft polymerization of methacrylic acid to poly(3-hydroxybutyrate) and thrombin immobilization was a model study. Biomolecule immobilized poly(3-hydroxybutyrate) could be used as an implant. Thrombin was selected as a biomolecule for this model study and it was immobilized to methacrylic acid grafted poly(3-hydroxybutyrate). Then the developed product was used to stop bleeding.

Thrombin immobilization to Poly(Methacrylicacid) graft polymerized PET and PAN fabrics

Poly(ethylene terephthalate) and poly(acrylonitrile) fabrics are the most produced synthetic fabrics in the world. Their production and usage increase at medical textile. There is no functional group in their structure for enzyme immobilization. Hence, they are not inclined to react. However, functional groups could be added to their structure using graft polymerization. In this study, methacrylic acid was graft polymerized to poly(ethylene terephthalate) and poly(acylonitrile) fabrics. Characterization of modified fabrics was carried out and thrombin was immobilized to poly(methacrylic acid) graft polymerized poly(ethylene terephthalate) and poly(acylonitrile) fabrics using 1-Ethyl-3-(3-dimetylaminopropyl)-carbodiimide. Optimization studies were also performed for the immobilization of thrombin. Thrombin immobilized poly(methacrylic acid) graft polymerized poly(ethylene terephtalate) and poly(acrylonitrile) fabrics were reduced recalcification time 30 % and 25 %, respectively. It is the first time, an enzyme was immobilized to fabric and its in vitro applications were performed. Thrombin has not been immobilized to synthetic fabric, yet.

Pyranose 2-oxidase (P2O): Production from Trametes versicolor in Stirred Tank Reactor andits Partial Characterization

Abstract Optimization of pyranose-2-oxidase (P2O) production conditions from Trametes versicolor was carried out in shaking cultures containing glucose, malt, and yeast extracts; the optimum concentration values were found to be 1.5% glucose, 1.0% yeast extract, and 1.0% malt extract, pH 5.0, temperature, 26°C, and agitation rate 150 rpm. For the first time, P2O production was also carried out in a stirred tank reactor (STR) with 2.2 L working volume in the optimized medium composition, and biomass, P2O activity, protein, nitrogen and glucose concentrations were also monitored besides pH and dissolved oxygen (DO). In the STR, P2O activity peaked on day 9. Partial enzyme characterization occurred and optimum pH and temperature were detected as 7.0 and 37°C, respectively. K m value was found to be 1.009 mM.

MOLECULARLY IMPRINTED POLYMERS FOR SOME REACTIVE DYES

Depending upon their structure, azo- and anthraquinonic dyes are the two major classes and together represent 90% of all organic colorants. Adsorption of dye molecules onto a sorbent can be an effective, low-cost method of color removal. Most of the techniques used for removal of dyes are of high production cost, and the regeneration also makes them uneconomical. There is much interest in the development of cheaper and effective newer materials for use as adsorbents. Molecular imprinting is a new kind of materials that can be alternative adsorbents. In this study, molecularly imprinted polymers of three textile dyes (Cibacron Orange P-4R, Cibacron Red P-4B, Cibacron Black PSG) were prepared. Methacrylic acid was used as a monomer for red and orange dyes and acrylamide was used for black dye. Methanol:acetonitrile was used as a porogen. The selective recognition ability of the molecularly imprinted polymers was studied by an equilibrium–adsorption batch method. The adsorption data are for Cibacron Black PSG 65% and nonimprinted polymer (NIP) 25%; Cibacron Red P-4B 72% and NIP 18%; and Cibacron Orange P-4R 45% and NIP 10%, respectively. Dye-imprinted polymers were used as a solid-phase extraction material for selective adsorption from wastewater of textile factory.

Thrombin immobilization to enzymatic modified PET and PAN fabrics and their applications

Enzymatic modification of synthetic materials has immense potential both of the functionalization of polymeric materials, such as poly(acrylonitrile) or polyesters, and the production of polymers for special applications, such as medical devices and enzyme immobilization. In this study, poly(ethyleneterephtalate) and poly(acrylonitrile) fabrics were modified with commercial laccase and nitrilase, respectively. Contact angles of enzymatic modified and unmodified fabrics were measured and it was found contact angles of enzymatic modified fabrics were less than those of unmodified fabrics. Attenuated-Total-Reflection-Fourier-Transform infrared spectroscopy showed that carboxylic acid groups occurred on fabrics after enzymatic modifications. Surfaces of modified and unmodified fabrics were investigated using scanning electron microscopy. Surfaces of unmodified fabrics were smooth but surfaces of modified fabrics were rugged and cracked. Thrombin was immobilized in modified fabrics by using 1-Ethyl-3-(3-dimetylaminopropyl)-carbodiimide. Optimization studies were also performed for the immobilization of thrombin. After prepared material was tested to stop bleeding in vitro conditions and it was found that thrombin immobilized poly(ethyleneterephtalate) and poly(acrylonitrile) fabrics had a reduced recalcification time to 51 % and 89 %, respectively. Thrombin immobilized poly(ethyleneterephtalate) fabric was also tested in in vivo conditions by using Cavia porcellus and it was observed that this material caused bleeding to stop at a ratio of 24.6 %. The results were statistically significant.

Immobilization of thrombin to bio/chemically modified synthetic fabrics

Processed synthetic polymers used in medical textile are used directly or functionalized by immobilization of bioactive molecules. Textile products made by synthetic polymers are durable, resistant to chemical reactions and have inert structures. Textile products made by synthetic polymers usually have not functional groups for immobilization. So modification could be done for formation of functional groups. Immobilization of bioactive molecules could be done by functional groups. In this study, thrombin was immobilized to textile products made by synthetic polymers. So Textile products made by synthetic polymers was added a new character which was blood stopper. The product was reliable because of source.