Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 Analysis of Osteoblast and Fibroblast Cell Adhesion on ISO 5832-2 Grade-4 Titanium Samples in vitro Implanted by Nano Tachnological Methods with Low Ene rgy P.Kes 1 , A.Oztarhan 1 , S.G.Iz 1 , I.D.Gurhan 1 , 1 Ege University, Faculty of Engineering, Department of Bioengineering, Izmir, TURKEY Abstract-The aim of this study is to understant the cell attachment behaviour of osteoblasts and fibroblasts on zirconium implanted “ISO 5832-2 Grade 4” titanium samples, which are used in implant dentistry attachment zirconium ion implanted with the help of MEVVA Ion Implantation technology, which is one of the most important surface modification technologies and which has ascendant specifications when compared with coating, investigation of on ion implanted surfaces. In the light of this aim, the material for ion implantation is chosen as titanium which is the most common material used dentistry. Zirconium element known as 100% tissue compatible is chosen for creating ions. In this study attachment of osteoblasts and fibroblasts on is investigated in vitro for comparing the roughnesses and ion implantation surface modification. With this study, in case of zirconium ion implantation on “ISO 5832-2 Grade 4” titanium samples known as biocompatible, the increase of in vitro fibroblast and osteoblast cell attachment is observed. Also this study has proved the attachment of fibroblast and osteoblast cells on rough surfaces is beter than other surfaces, once again. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 258
Poster Session, Tuesday, June 15 Theme A1 - B702 Effect of surfactants on the synthesis of Zn-Al layered double hydroxides Ceren Yılmaz, Uğur Ünal, Funda Yağcı Acar 1 Department of Chemistry, Koç University, Istanbul 34450, Turkey Abstract— In the current study, the effect of various surfactants on the crystallization of Zn-Al layered double hydroxide was investigated. Synthesis in the presence of dodecyl sulfate resulted in ring-like and rose-like structures depending on the concentration. We have also found that replacement of the surfactant with laurate salt resulted in the formation of large ZnO platelets intercalated with the surfactant formation. The crystallization mechanism was discussed. Layered double hydroxides (LDHs) are hydrotalcite-like layered compounds composed of piled-up positively charged brucite-like layers and charge balancing anions as well as water molecules in the interlayer domain. The general formula of layered double hydroxides is represented by [M 2+ 1-x M 3+ x(OH) 2 ] q+ [A n- x/n·mH 2 O], where M 2+ and M 3+ are divalent and trivalent metal cations, and A is n-valent interlayer guest anion, which might be Cl - , CO 2- 3 , NO - 3 , OH - , etc [1]. The synthesis of LDHs can be carried out with various methods. Coprecipitation in the presence of NaOH or hydrolysis of ammonia releasing agent result in well crystallized LDH crystals [2]. In this study, we have investigated the crystallization and intercalation behavior LDHs in the presence of surfactants. LDHs were synthesized in the presence of surfactants at different concentrations and concentrations below and above critical micelle concentration. Zn/Al ratio was 2 and the concentration of ammonia releasing agent was 2.33 times higher than the total metal cation concentration. Reaction was carried out at 90 0 C under continuous stirring. Sampling during the reaction was done at different times in the range 24- 120 h in order to observe the crystallization of LDHs. Characterization was carried out with X-ray diffraction, scanning electron microscopy, Fourier Transform infrared spectrometer, UV-vis absorbance spectroscopy and Inductively coupled plasma spectroscopy. For the LDHs, synthesized under critical micelle formation for dodecyl sulfate we have observed platelet like structures. When the concentration increased above critical limit, ring like structure was observed. The ring formation was attributed to the crystallization of LDH at the anionic end of the surfactant where metal cations are concentrated in the beginning of the reaction. According to SEM micrographs we have speculated that the crystallization starts with the formation of central metal hydroxide seed and the crystallization occurs in a circular path around the central seed [3]. The mechanism is under investigation. An important observation during the study was the formation of large ZnO platelets and Al 3+ was not embedded in the crystal structure when the synthesis was carried out in the presence of laurate salt. Energy dispersive X-ray spectroscopy (EDX) study showed that the platelets are mainly formed from zinc and oxygen. According to XRD data as seen in figure 1, ZnO was crystallized as a layered structure and laurate molecules are placed between the layers. The size of ZnO platelets is in the range 10-50 m in length as seen in figure 2. Further study about the structure and properties of ZnO platelets is in progress. In conclusion, we have presented the crystallization of LDHs under different surfactant concentrations. The type of the surfactant has also substantial effect on the crystallization behavior. We are grateful to Assoc. Prof. Mehmet Ali Gülgün for doing the SEM and XRD analysis of the powders. The work was supported by Koc University. Figure 1. XRD pattern of the LDH synthesized in the presence of laurate salt. Figure 2. SEM micrograph of ZnO structure formed in the presence of laurate salt. Corresponding author: fyagci@ku.edu.tr [1]S. Miyata, Clays Clay Miner. 23 (1975) 369. [2] A. de Roy, C. Forano, J.P. Besse, in: V. Rives (Ed.), Layered Double Hydroxides: Present and Future, Nova Science Publishers, New York, 2001 p. 1 [3] K. Okamoto, N. Iyi, T. Sasaki, Appl. Clay Sci., 37, (2007) 23-31. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 259
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