Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 Protein Adsorption and In vitro Biodegradat ion of MEVVA Ion Implanted Chitosan Membranes 1 , Emel Sokullu Urkaç 2 ,Ahmet Öztarhan 2 , Funda Tihminlioglu 3 * 1 Biotechnology and Bioengineering Department, zmir Institute of Technology, Urla,zmir,Turkey 2 Bioengineering Department, Ege University,Bornova,zmir,Turkey 3 Chemical Enginzmir Institute of Technology,Turkey Abstract-This study investigates the effect of ion implantation on the protein adsorption behavior and in vitro degradation of chitosan films before and after the ion implantation. The chitosan films were prepared by solvent casting method for dense films, and dry/wet phase separation method is used to obtain asymmetric chitosan membranes. Characterization studies of these membranes were performed by using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Differential Scanning Calorimetry (DSC). The ion implantion effect on the contact angle changes, water absorption, protein adsorption and biodegradation mechanism on the films were also investigated. Chitosan has been studied for various practical applications because of functions such as biodegradability, low toxicity, and acceleration of fibroblast formation in animal body, acceleration blood clotting, drug delivery, antimicrobial act ivity and high solubility in water. In this study, we attempted to prepare and characterize the chitosan membrane surfaces induced by metal–gas (MEVVA) ion implantation. Chitosan membranes were prepared in two different microstructures to investigate the structure effects on the protein adsorption and in vitro degradation. Dense and asymmetric chitosan membranes prepared by dissolving in acetic acid solution. For dense membrane production, solvent casting method was used. For asymmetric membrane preparation dry/wet phase separation method was used by using 20 minutes pre treatment time. By changing this time pore size and thickness of the membrane is changed that also effects the membrane properties like diffusion ratio, water absorption, degradation time etc. Chitosan membranes were implanted by C and C+N ions by using MEVVA ion implanter with 10 16 cm -2 dose, and 1 pps frequency, 20 kV acceleration voltage. Protein adsorption onto the foreign surface occurs within seconds of implantation. This shows that cells arriving at the biomaterial surface probably interact with the adsorbed protein layer rather than directly with the material itself [1]. Thus, the initial protein adsorption onto a biomaterial surface plays a key role in how the body responds to an implanted biomaterial. In nature, biodegradation is time independent as long as the eco-system is kept in balance. In biomedical applications, the time scale of biodegradation is critical since it has a significant limitation for the material’s application area. For examp le, in the tissue applications, the degradation rate of polymeric material must be equal to time of the tissue formation rate of the organism. [2] In the protein adsorption studies, HSA is used at pH=7. Adsorption of the protein onto membrane was carried at 37 ºC. The effects of microstructure and ion implantation on the in vitro degradation behavior of chitosan membranes were studied at 37 ºC in PBS solution. The change in molecular weight using viscosity measurements and mass as a function of degradation time was monitored. FTIR peaks of the films were shown in Figure 1. For the treated membrane, the peaks at 2925 cm -1 , 1375 cm -1 , and 1060 cm -1 decrease remarkably. These results show the changes in hydrophilicity after ion implantation. After ion implantation membrane surfaces increases hydrophobicity which is in agreement with the contact angle studies as seen in Table 1. Figure 1. FTIR results of dense chitosan membranes Table 1. Contact angle change after ion implantation Sample Contact Angle Chitosan 68 C Implanted Chitosan 76 C+N Implanted Chitosan 84 The SEM picture of the assymetric chitosan membrane is shown in Figure 2. Pore size of the membrane was changed by the changing pre-treatment time. Figure 2: SEM image of asymmetric chitosan membrane Corresponding author: 0Tfundatihminlioglu@iyte.edu.tr [1] S. Lousinian, and S. Logothetidis, Optical properties of proteins and protein adsorption study, Biomaterials: Protein– Surface Interactions (2007) 84: 479–485. [2] G. Lu, L. Kong, Baiyang Sheng, Gan Wang,,Yandao Gong, Xiufang Zhang, Degradation of covalently cross-linked carboxymethyl chitosan and its potential application for peripheral nerve regeneration, European Polymer Journal 43 (2007) 3807–3818. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 316
Poster Session, Tuesday, June 15 Theme A1 - B702 The Influence of Nanoparticles on Performance of Portland Cement Paste and Mortar Ali Farsi 1 *, Mohamad Mehdi Afsahi 1 ,Sattar Ghader 1 , Vahid Shadravan 1 , Seyed Soheil Mansouri 1 , Shahla Ahmadi Pour 1 and Akbar Danaei 2 1 Department of Chemical Engineering, Shahid Bahonar University of Kerman, Kerman, Iran 2 Kerman Momtazan Cement Company, Kerman, Iran Abstract- In this work we discus about Sol-Gel Chemistry Based Nanocomposites method and preparation of nano particles for addition into the Portland cement. Then the influence of nano particles on several Portland cements is investigated. Addition of nano particles to Portland cement can improve its physical properties such as compressive strength and p ermeability coefficient. Portland cement is usually a mixture of limestone (calcium carbonate, CaCO 3 ) and a second material as a source of alu mino-silicate. The principal clinker minerals of the Portland cement are Tri-calciu m silicate, C3S (A lite), Calciu m silicate, b-C2S (Belite), Tri-calciu m alu minate, C3A, and Ferrite phase; Tetra-calcium alumino ferrite, C4AF (Celite). In recent years, the use of nano-particles has received particular attention in many applications to fabricate materials with new functionalities. When ultra-fine particles are incorporated into Portland-cement paste, mortar or concrete, materials with different characteristics from the conventional materials were obtained. Nano particles enhanced the compressive strength of cement paste much more than silica fu me. It is due to the filling effect and pozzolanic reaction activation. It was concluded that the rate of pozzolanic reaction depends on the Blaine surface area available for react ion. Nano aluminate and silicate have been integrated with cement mortar as a new building material For and durability of the material. In this work we discus about Sol-Gel Chemistry Based Nanocomposites method and preparation of nano particles for addition into the Portland cement. Then the influence of nano particles on several Portland cements is investigated. Addition of nano particles to Portland cement can improve its physical properties such as compressive strength and permeability coefficient. - In this work we d iscus about Sol-Gel Chemistry Based Nanocomposites method and preparation of nano particles for addition into the Portland cement. Then the influence of nano particles on several Portland cements is investigated. Addition of nano particles to Portland cement can improve its physical properties such as compressive strength and permeability coefficient. *Corresponding author: ali.farsi@gmail.com [1] B. Yilmaz, A. Olgun, Cem. Concr. Compos. 30 (2008) 194. [2] N. Voglis, G. Kakali, E.Chaniotakis, S. Tsivilis, Cem Concr Compos. 27 (2005) 91. [3] M.S. Morsy, S.S Shebl, J. Ceram. Silicaty. 51 (2007) 40. [4] J. Jortner, C.N.R. Rao, Pure. Appl. Chem. 74 (2002) 1491. instance Nanoparticles of SiO 2 (NS) can fill the spaces between particles of gel of C–S–H, acting as a nano-filler. Furthermore, by the pozzolanic reaction with calcium hydroxide, the amount of C–S–H increases which results in a higher densification of the matrix that improves the strength [5] M.J. Pitkethly Material. Today. 7 (2004) 20. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 317
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