Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 Evaluation and characterization of nanocrystalline hydroxyapatite powder prepared by a sol–gel method Feray Bakan 1 *, Oral Laçin 1 and Hanifi Saraç 1 1 Department of Chemical Engineering, Erzurum 25240, Turkey Abstract-A novel water-based sol-gel method to synthesize nano crystalline hydroxyapatite with calcium nitrate tetrahydrate and ammonium dihydrogenphosphate as starting calcium and phosphorous precursors is presented. The p hase transformations, composition and microstructural features in the nano crystalline samples were studied by thermo analytical methods (STA), infrared spectroscopy (IR), X-ray powder diffraction analysis (XRD) and transmission electron microscopy (TEM). It is proposed that the nano-structure of hydroxyapatite will have the best biomedical properties in the biomaterials applications. In recent years synthetic hydroxyapatite, [Ca 10 (PO 4 ) 6 (OH) 2 ], has been recognized as one of the most important bone substitute materials in orthopedics and dentistry because of its chemical and biological similarity to the natural Ca phosphate mineral present in a biological hard tissue Different type of clinical applications of hydroxyapatite involve repair of bone defects, bone augmentation, as well as coating for human body metallic implants, proteins purification, drug delivery agent for anti-tumor and antibodies in the treatment of osteomyelitis and HA has also been used as an acidic catalyst for different chemical reactions [1]. All these HA specific applications are dependent on properties such as particle size, dimensional anisotropy, morphology, real microstructure, etc. which are of critical importance for optimization and applications. Several different HA synthesis techniques have been developed due to its growing importance and applications [2,3]. Main techniques being used are solid-state reaction [4], co precipitation [5,6], and hydrothermal method [7] and sol–gel route [8–9]. Among these methods, an increasing attention has been given to the sol–gel method, due to advantages such as: the possibility of mixing the calcium and phosphorus precursors at a molecular level and that it requires incomparably milder conditions for the synthesis process, compared with the conventional methods [10]. In this study, hydoxyapatite (HA) nanoparticles with approximetaly 20 nm diameter was synthesized using a novel water-based sol-gel route with calcium nitrate tetrahydrate (Merck) and ammonium dihydrogenphosphate (Carlo Erba) as starting calcium and phosphorous precursors respectively. The effects of reaction temperature, reaction time, aging time and sintering temperature on particle size were carried out and results were compared with literature findings. The crystalline degree and morphology of the obtained nanopowder are dependent on the sintering temperature. Fourier transform infrared (FTIR) spectroscopy analysis was carried out to identify the functional groups. In order to investigate the thermal behaviour of the particles STA analysis was carried out. Transmission electron microscope (TEM) was used to observe the particle morphology and size of the powders. Phase analysis was performed by X-ray diffractro metry (XRD) and the mean crystallite size of the particles (n m), was calculated fro m the XRD line broadening measurement using the Scherrer equation [11]. The prepared crystalline nanopowder HA is able to improve the contact reaction and the stability at the artificial/natural bone interface for medical applications. [1] Sebti, S., Tahir, R., Nazih, R., Saber, A., & Boulaajaj, S.,2002. Hydroxyapatite as a new solid support for the Knoevenagel reaction in heterogeneous media without solvent. Applied Catalysis A, 228, 155–159. [2] J.W. Evans, T.L.C. De Jonge, Production of Inorganic Materials, Macmillan, New York, 1991. [3] D.W. Hess, K.F. Jensen, T.J. Anderson, Rev. Chem. Eng.3 (1985) 130. [4] R. Ramachandra Rao, H.N. Roopa, T.S. Kannan,J. Mater. Sci. Mater. Med. 8 (1997) 511. [5] A. Cuney Tas, F. Korkusuz, M. Timicin, N. Aakas,J. Mater. Sci. Mater. Med. 8 (1997) 91. [6] S.H. Rhee, J. Tanaka, J. Am. Ceram Soc. 81 (1998) 3029. [7] H.S. Liu, T.S. Chin, L.S. Lai, S.Y. Chiu, K.H. Chung, C.S.Chang, M.T. Lui, Ceram. Int. 23 (1997) 23. [8] P. Layrolle, A. Ito, T.S. Teteishi, J. Am. Ceram Soc. 81 (1998) 1421. [9] T.K. Anee, M. Ashok, M. Palanichamy, S.N. Kalkura, Mater. Chem. Phys. 80 (2003) 725. [10] D.M. Liu, T. Troczynski, W.J. Tseng, Biomaterials 22 (2001) 1721. [11]Jenkins, R., Snyder, R.L., 1996. Introduction to X-ray Powder Diffractometry. John Wiley and Sons, New York. * Corresponding author:0Tferaybakan@atauni.edu.tr 6th Nanoscience and Nanotechnology Conference, zmir, 2010 222
Poster Session, Tuesday, June 15 Theme A1 - B702 Preparation of aluminum-doped zinc oxide (AZO) nano particles by hydrothermal synthesis Nadir Kiraz 1,2,* , Esin Burunkaya 1,2 , Ömer Kesmez 1,2 , Zerin Yeil 1,2 , Meltem Asiltürk 3 , Erturul Arpaç 1,2 1 Department of Chemistry, Akdeniz University, 07058, Antalya, Turkey 2 NANOen R&D Ltd., Antalya Technopolis, Akdeniz University Campus, Antalya, Turkey 3 Prof.Dr.Hikmet Saylkan Research and Development Laboratory for Advanced Materials, nönü University 44280, Malatya, Turkey Abstract-Aluminum doped zinc oxide (AZO) nano particles were synthesized by hydrothermal method. Synthesized particles have amphiphilic character, thus they can be dispersed in both polar and non-polar media. The obtained powder is intended to be utilized in the form of thin films for optical purposes, due to the high refractive index of AZO. Zinc oxide (ZnO) has attracted scientific and technological attention due to its employment in various fields such as in varistors [1], in piezoelectric transducers [2], in organic light emitting diodes [3], in gas sensing devices [4], as transparent conductive oxide in solar cells [2]; in addition to its widespread utilization in paints and ceramics. Doping of ZnO with impurities such as Al, In and Ga results in formation of an n-type semiconductor and decreases electrical resistivity [5]. Aluminum doped ZnO (AZO) is taking the place of indium tin oxide (ITO) in many applications due to its lower cost, non-toxicity, chemical and thermal stability [5,6]. Another attractive property of AZO is its high refractive index [7]. Aluminum doped zinc oxide (AZO) nanometric particles were synthesized by hydrothermal method. Aluminum nitrate, aluminum sec-butoxide and zinc nitrate were used as the starting materials and n-propanol, 2- buthanol were used as solvents. Ratio of Al 2 O 3 in ZnO was kept at 10 wt%. Reaction was conducted in a Teflon autoclave at 175-225 o C for 5 h. Ratios of alcohol, H 2 O and HCl to zinc nitrate were altered and 6 different sets of parameters were investigated. Obtained products were subjected to powder-XRD, particle size measurement and TEM examination. Single phase AZO particles smaller than 10 nm were obtained when alcohol to zinc nitrate ratio was increased from 10 to 35. Figure 2. TEM image of AZO-6 particles This provided preserving the nanometric particle size of the ZnO powder. Synthesized particles have amphiphilic character; therefore it is possible to disperse them in both polar and non-polar media. They can be utilized in the form of thin films for optical and electronic purposes. This study was support by NANOen. We thank Nedim ERNÇ for his contrubition. *nadirkiraz@akdeniz.edu.tr Figure 1. XRD patterns of the products obtained from the systems The aim of this study is to synthesize crystalline AZO nanoparticles through a hydrothermal route, without an additional calcination step for crystallization. For this purpose; ratios of acid, water and alcohol to zinc nitrate were altered in addition to alteration of synthesis temperature. Crystalline ZnO could be obtained as a result of hydrothermal treatment at 225 o C, thus calcination step at higher temperatures was eliminated. [1] Gupta, T. K., 1990. Application of zinc-oxide varistors, J. Am. Ceram. Soc., 73:1817-1840 [2] Vale, G. G., Hammer, P., Pulcinelli, S. H., Santilli, C. V., 2004. Transparent and conductive ZnO : Al thin films prepared by sol-gel dip-coating, J. Eur. Ceram. Soc., 24:1009-1013 [3] Kim, H., Horwitz, J. S., Kim, W. H., Makinen, A. J., Kafafi, Z. H., Chrisey, D. B., 2002. Doped ZnO thin films as anode materials for organic light emitting diyotes, Thin Solid Films, 420-421, 539-543 [4] Baruwati, B., Kumar, D. K., Manorama, S. V., 2006. Hydrothermal synthesis of highly crystalline ZnO nanoparticles: A competitive sensor for LPG and EtOH Sensor. Actuat., 119:676-682 [5] Yim, K., Lee, C., 2006. Optical properties of Al-doped ZnO thin films deposited by two different sputtering methods, Cryst. Res. Technol., 41:1198-1202 [6] Singh, A. V., Kumar, M., Mehra, R. M., Wakahara, A., Yoshida, A., 2001. Al-doped zinc oxide (ZnO:Al) thin films by pulsed laser ablation, J. Indian Inst. Sci., 81: 527-533 [7] Schuler, T., Aegerter, M. A., 1999. Optical, electrical and structural properties of sol gel ZnO : Al coatings, Thin Solid Films, 351:125-131 6th Nanoscience and Nanotechnology Conference, zmir, 2010 223
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