Hazer, Derya Burcu | Kılıçay, Ebru | Hazer, Baki
Review | 2012 | Materials Science and Engineering C32 ( 4 ) , pp.637 - 647
Biomaterials have played an important role in the treatment of disease and the improvement of health care. Synthetic and naturally occurring biodegradable and biocompatible polymers have been used as biomaterials. Polyhydroxyalkanoates (PHAs) are promising materials for biomedical applications because they are biodegradable, non-toxic and biocompatible. We will shortly summarize the modification reactions, which include functionalization and grafting reactions, to improve the mechanical, thermal and hydrophilic properties of PHAs. The use of the modified PHAs in numerous biomedical applications, such as sutures, cardiovascular patch . . .es, wound dressings, scaffolds in tissue engineering, tissue repair/regeneration devices, drug carriers will be discussed in this review. © 2012 Elsevier B.V. All rights reserved Daha fazlası Daha az
Keleş, Elif | Hazer, Baki | Cömert, Füsun B.
Article | 2013 | Materials Science and Engineering C33 ( 3 ) , pp.1061 - 1066
A new type of amphiphilic antibacterial elastomer has been described. Thermoplastic elastomer, polystyrene-block-polyisoprene-block-polystyrene (PS-b-PI-b-PS) triblock copolymer was functionalized in toluene solution by free radical mercaptan addition in order to obtain an amphiphilic antibacterial elastomer. Thiol terminated PEG was grafted through the double bonds of PS-b-PI-b-PS via free radical thiol-ene coupling reaction. The antibacterial properties of the amphiphilic graft copolymers were observed. The original and the modified polymers were used to create microfibers in an electro-spinning process. Topology of the electrospu . . .n micro/nanofibers were studied by using scanning electron microscopy (SEM). The chemical structures of the amphiphilic comb type graft copolymers were elucidated by the combination of elemental analysis, 1H NMR, 13C NMR, GPC and FTIR. © 2012 Elsevier B.V. All Rights Reserved Daha fazlası Daha az
Kılıç, Muhammet Samet | Korkut, Şeyda | Hazer, Baki
Article | 2015 | Materials Science and Engineering C47 , pp.165 - 171
This study describes the construction of an enzymatic fuel cell comprised of novel gold nanoparticles embedded poly(propylene-co-imidazole) coated anode and cathode. Working electrode fabrication steps and operational conditions for the fuel cell have been optimized to get enhanced power output. Electrical generation capacity of the optimized cell was tested by using the municipal wastewater sample. The enzymatic fuel cell system reached to maximum power density with 1 µg and 8 µg of polymer quantity and bilirubin oxidase on electrode surface, respectively. The maximum power output was calculated to be 5 µW cm- 2 at + 0.56 V (vs. Ag . . ./AgCl) in phosphate buffer (pH 7.4, 100 mM, 20 °C) by the addition of 15 mM of glucose as a fuel source. The optimized enzymatic fuel cell generated a power density of 0.46 µW cm- 2 for the municipal wastewater sample. Poly(propylene-co-imidazole) was easily used for a fuel cell system owing to its metallic nanoparticle content. The developed fuel cell will play a significant role for energy conversion by using glucose readily found in wastewater and in vivo mediums. © 2014 Elsevier B.V. All rights reserved Daha fazlası Daha az
Korkut, Şeyda | Kılıç, Muhammet Samet | Sanal, Timur | Hazer, Baki
Article | 2017 | Materials Science and Engineering C76 , pp.787 - 793
This study describes construction of an enzymatic fuel cell comprised of poly(caprolactone-g-ethylene glycol) coated novel glucose oxidase anode and laccase cathode. Rationally designed poly(caprolactone-g-ethylene glycol) containing various poly(ethylene glycol) percentages ranging between 2.67 and 15.04% were synthesized chemically and tested separately for operation of the fuel cell system to achieve the best energy generation. The maximum power density was found to be 80.55 µW cm- 2 at 0.91 V (vs. Ag/AgCl) in pH 5, 100 mM citrate buffer (20 °C) by the addition of 30 mM of glucose from the electrodes coated with 11.34% poly(ethyl . . .ene glycol) containing polymer with a quantity of 600 µg. High poly(ethylene glycol) percentages with more numbers of long poly(ethylene glycol) brushes lead to the creation of a complexity in the polymer morphology and steric hindrance effect for electron transport. The graft copolymer was easily used for the fuel cell system owing to its biocompatible and microporous film morphology. The grafted polymer was able to facilitate enzymatic glucose oxidation and oxygen reduction while simultaneously producing high catalytic electrical currents. © 2017 Elsevier B.V Daha fazlası Daha az
Hazer, Baki | Kalaycı, Özlem A.
Article | 2017 | Materials Science and Engineering C74 , pp.259 - 269
Autoxidation of poly unsaturated fatty acids makes negative effect on foods. In this work, this negative effect was turned to a great advantage using autoxidized soybean oil as a macroperoxide nanocomposite initiator containing silver nano particles in free radical polymerization of vinyl monomers. The synthesis of soybean oil macro peroxide was carried out by exposing soybean oil to air oxygen with the presence of silver nanoparticles (Ag NPs) at room temperature. Autoxidized soybean oil macroperoxide containing silver nanoparticles (Agsbox) successfully initiated the free radical polymerization of styrene in order to obtain Polyst . . .yrene (PS)-g-soybean oil graft copolymer containing Ag NPs. Both autoxidized soybean oil and PS-g-sbox with Ag NPs showed a surface plasmon resonance and high fluorescence emission. Overall rate constant (K) of styrene polymerization initiated by autoxidized soybean oil macroperoxide with Ag NPs was found to be K = 1.95.10- 4 Lmol- 1 s- 1 at 95 °C. Antibacterial efficiency was observed in the PS-g-soybean oil graft copolymer film samples containing Ag NPs. 1H NMR and GPC techniques were used for the structural analysis of the fractionated polymeric oils. © 2016 Elsevier B.V Daha fazlası Daha az
Moncal K.K. | Aydin R.S.T. | Abu-Laban M. | Heo D.N. | Rizk E. | Tucker S.M. | Lewis G.S.
Article | 2019 | Materials Science and Engineering C105 , pp.259 - 269
Differentiation of progenitors in a controlled environment improves the repair of critical-sized calvarial bone defects; however, integrating micro RNA (miRNA) therapy with 3D printed scaffolds still remains a challenge for craniofacial reconstruction. In this study, we aimed to engineer three-dimensional (3D) printed hybrid scaffolds as a new ex situ miR-148b expressing delivery system for osteogenic induction of rat bone marrow stem cells (rBMSCs) in vitro, and also in vivo in critical-sized rat calvarial defects. miR-148b-transfected rBMSCs underwent early differentiation in collagen-infilled 3D printed hybrid scaffolds, expressi . . .ng significant levels of osteogenic markers compared to non-transfected rBMSCs, as confirmed by gene expression and immunohistochemical staining. Furthermore, after eight weeks of implantation, micro-computed tomography, histology and immunohistochemical staining results indicated that scaffolds loaded with miR-148b-transfected rBMSCs improved bone regeneration considerably compared to the scaffolds loaded with non-transfected rBMSCs and facilitated near-complete repair of critical-sized calvarial defects. In conclusion, our results demonstrate that collagen-infilled 3D printed scaffolds serve as an effective system for miRNA transfected progenitor cells, which has a promising potential for stimulating osteogenesis and calvarial bone repair. © 2019 Elsevier B.V Daha fazlası Daha az
Yetmez M. | Erkmen Z.E. | Kalkandelen C. | Ficai A. | Oktar F.N.
Article | 2017 | Materials Science and Engineering C77 , pp.470 - 475
In this study, sintering effects on microstructural behavior of bovine derived hydroxyapatite doped with powder mullite are considered in the temperature range between 1000 °C and 1300 °C. Results show that maximum values of both compressive strength and microhardness are achieved in the samples sintered at 1200 °C for all mullite additions of 5, 7.5, 10 and 12.5 wt%. Moreover, above 1000 °C, decomposition of HA and new phase formations such as whitlockite and gehlenite play a major role in both compressive strength and microhardness properties which increase up to 10 wt% mullite reinforcement. © 2017 Elsevier B.V.