https://hdl.handle.net/20.500.12619/1045 2026-04-13T14:14:05Z 2026-04-13T14:14:05Z Ayseguel Hos Tunç, Kenan Ugursoy Olgun https://hdl.handle.net/20.500.12619/33354 2020-02-13T10:53:07Z 2019-01-01T00:00:00Z

Antibacterial nano biocomposite poly(epsilon-caprolactone) films with nano Ag-hydroxyapatite filler particles Ayseguel Hos; Tunç, Kenan; Ugursoy Olgun This study describes the development of new antimicrobial nanocomposite poly(epsilon-caprolactone) (PCL) films by using the nanosilver coated hydroxyapatite particles. Firstly, the synthesis of hydroxyapatite (HAP) powder was performed using the chemical precipitation method. Next, the nanosilver coating of HAP powder was performed in acetone at 20 degrees C using the poly(dimethylsiloxane) fluid as the reducing agent. Then, the nano Ag-HAP-PCL composite materials containing 30% HAP and 0.13-1.90% Ag were prepared by incorporating nano Ag-HAP powder into the poly(epsilon-caprolactone) (PCL) melt at 100 degrees C. Finally, the nano Ag-HAP-PCL films were prepared by using the roll mill process. The nano Ag-HAP powder and the nanocomposite films were characterized by XRD, SEM, TEM, ICP-OES, UV-vis and FTIR analysis. The TEM analysis of the nano Ag-HAP powder showed that the size of the nanosilver particles is about 0-30 nm. The use of 0.13% nano-Ag in HAP-PCL composite films provided 100% effective antibacterial surface against Escherichia coli and Staphylococcus epidermidis. On the other hand, the use of 1.9% nano-Ag in HAP-PCL composite films provided 100% antibacterial effectiveness against Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. The prepared antibacterial nano Ag-HAP-PCL biocomposites are promising materials for biomedical applications, implants and reconstructive orthopedic parts.

2019-01-01T00:00:00Z Serkan Yılmaz Fatma Ünal Deniz Yüzbaşıoğlu Aksoy, Hüseyin https://hdl.handle.net/20.500.12619/33352 2020-02-13T10:51:05Z 2008-01-01T00:00:00Z

Clastogenic effects of food additive citric acid in human peripheral lymphocytes Serkan Yılmaz; Fatma Ünal; Deniz Yüzbaşıoğlu; Aksoy, Hüseyin Clastogenic properties of the food additive citric acid, commonly used as an antioxidant, were analysed in human peripheral blood lymphocytes. Citric acid induced a significant increase of chromosomal aberrations (CAs) at all the concentrations and treatment periods tested. Citric acid significantly decreased mitotic index (MI) at 100 and 200 mu g ml(-1) concentrations at 24 h, and in all concentrations at 48 h. However, it did not decrease the replication index (RI) significantly. Citric acid also significantly increased sister chromatid exchanges (SCEs) at 100 and 200 mu g ml(-1) concentrations at 24 h, and in all concentrations at 48 h. This chemical significantly increased the micronuclei frequency (MN) compared to the negative control. It also decreased the cytokinesis-block proliferation index (CBPI), but this result was not statistically significant.

2008-01-01T00:00:00Z Birol Baser Sukru Hayta Gulden Dogan Sezgin Celik Aksoy, Hüseyin https://hdl.handle.net/20.500.12619/33353 2020-02-13T11:27:52Z 2019-01-01T00:00:00Z

Micromorphological study of Centaurea L. (Asteraceae); some taxa of eight sections analysed with scanning electron microscopy and light microscopy Birol Baser; Sukru Hayta; Gulden Dogan; Sezgin Celik; Aksoy, Hüseyin This study deals with the pollen morphological characterization of 36 taxa (Sections; Cheirolepis 3, Cynaroides 14, Rhizocalathium 5, Grossheimia 3, Chartolepis 3, Pseudophaeopappus 1, Plumosipappus 1 and Phaeopappus 6) belonging to the genus Centaurea. Pollen slides were prepared using the Acetolysis technique. Light Microscope examination showed pollen grains to be tricolporate, isopolar, radially symmetrical, oblate-spheroidal, prolate-spheroidal, subprolate, tectum perforate and scabrate. We identified two basic types of pollen grains, designated type I (Scabrate), type II (Microechinate). 34 taxa evaluated resemble Wagenitz's Jacea pollen type and 2 taxa Montana pollen type. We present micrographs of pollen grains, together with descriptions of the characteristics of their structure. We found that the pollen characters (shape, exine structure, sculpturing) were useful for classification.

2019-01-01T00:00:00Z Hediye Elif Kilic Hatice Tunca Ongun Sevindik, Tuğba Ali Dogru https://hdl.handle.net/20.500.12619/33356 2021-06-09T11:13:59Z 2019-01-01T00:00:00Z

Assessment of the effects of zinc on the growth and antioxidant enzymes in Scenedesmus ellipsoideus Chodat Hediye Elif Kilic; Hatice Tunca; Ongun Sevindik, Tuğba; Ali Dogru This study explores the activity of total superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR), biomass accumulation and chlorophyll a content in Scenedesmus ellipsoideus Chodat grown under conditions of varying zinc (Zn) concentrations. In addition, the activity of different SOD isozymes (MnSOD, FeSOD and CuZnSOD) was measured separately to determine the intracellular extent of oxidative stress resulting from Zn toxicity. We found that the activity of FeSOD and MnSOD was induced by lower Zn concentration (2 mu g ml(-1) and 4 mu g ml(-1), respectively), whereas CuZnSOD activity was not affected, which indicates that chloroplasts are the first location in S. ellipsoideus cells where superoxide accumulation is accelerated by Zn toxicity. The activity of total SOD and APX was significantly increased by moderate Zn concentrations, probably due to some oxidative stress caused by Zn toxicity. The higher level of Zn application, however, led not only to the inhibition of total SOD and APX activity, but also to the reduction of biomass accumulation and chlorophyll a content. As a result, it can be concluded that the accumulation of superoxide radicals and H2O2 in S. ellipsoideus cells induced by Zn toxicity may be responsible for the reduced growth rate and the impairment of photosynthetic pigments.

2019-01-01T00:00:00Z