Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 Electroc hemical inve stigations of the interac tion of Albumin with Cibac ron Blue F3GA chemically immobilized on a modified glas sy carbon electrode as a nanofilm Sümeyra Akkaya 1 * , Mustafa Uçar 1 ,Remziye Güzel 2 , 3 , 4 and Ali Osman Solak 4 1 Afyon Kocatepe University, Faculty of Arts and Sciences, Dept. Of Chemistry, Afyonkarahisar, Turkey 2 3 mistry, Kütahya, Turkey 4 Ankara University, Faculty of Science, Department of Chemistry, Ankara, Turkey Abstract- Benzoic acid modified glassy carbon electrode was prepared at a glassy carbon surface by the electrochemical reduction of diazobenzoic acid tetrafluoroborate salt. Subsequently, albumin from an albumin suspension was attached to the benzoic acid modified surface to prepare a benzoic acid-albumin nano composite film. Onto the nanocomposite film, Cibacron Blue F3GA molecules were deposited by self-assembling technique to form GC-BA/Alb/CB-Dye surfaces. These surfaces were characterized by cyclic voltammetry, electrochemical impedance spectroscopy , X-ray photoelectron spectroscopy, reflectance-absorption infrared spectroscopy in each step during the fabrication process. Human serum albumin (HSA) consists of a single polypeptide chain containing 585 amino acid residues and is the major soluble protein component in serum. It has many physiological functions which contributes to colloid osmotic blood pressure and aids in the transport, distribution, and metabolism of many endogenous and exogenous substances [1,2]. Cibacron Blue F3GA is a monochlorotriazine dye and has the group specificity for albumin, dehydrogenase and lysozyme [3]. Via the nucleophilic reaction between chloride of its triazine ring and reactive groups of the supports including hydroxyl or amino, Cibacron Blue F3GA can be immobilized onto the supports for protein affinity adsorption [4]. In this study the glassy carbon electrode surfaces were modified with the electrochemical reduction of diazonium salt of benzoic acid by cyclic voltammetry (CV) in the potential range of +0.2 V and -0.8 V at a scan rate of 200 mVs -1 for ten cycles vs. Ag/AgNO 3 electrode in acetonitrile containing 0.1 M tetrabutylammoniumtetraflouro-borate (TBATFB). Modification voltammogram recorded is very characteristic for the reduction of diazonium salt, in which an irreversible reduction CV wave of diazonium salt is indicative of the loss of N and the formation of a diazobenzoic acid radical 2 followed by covalent binding to the carbon surface [5-6]. Modified electrodes were characterized electrochemically using redox probes of ferricyanide, dopamine and ferrocene by CV and electrochemical impedence spectrpscopy (EIS). In BA modified GC electrodes, carboxylic acid groups of the BA film were further activated by covering the GC surface with 10 μL of 4 mM EDC/ 1 mM NHS in 10 mM PBS (pH 7.6) and incubated at room temperature for 1 h, followed by a rinse with deionized water. After that, 4 μL of albumin in BR buffer solution was placed on the BA-GC electrode surface as dropping with micropipettes and dried at 4 ºC overnight. The albumin-BA modified GC electrode was then rinsed throughly with 10 mM PBS (pH 7.6) to remove the weakly adsorbed protein. Electrochemical impedance spectroscopy were used to investigate the formation of GC-BA, GC-BA/Alb and GC- BA/Alb/Cibacron Blue F3GA. Here, EIS was used to monitor the fabrication process of the benzoic acid surface modification of GC, the albumin attachment and self assembling of organic dye layers to modified surfaces. To investigate the interaction between albumin and dye, the Nyquist plots of bare GC, GC-BA, GC-BA/Alb and GC- BA/Alb/CB-Dye surfaces were recorded for the redox couple of 1 mM Fe(CN) 3-/4- 6 mixture prepared in BR buffer of pH 2 and 6,7. NH O C CB-Dye O NH C Figure 1. Schematic figure of nanofilm product. I would like to thank Prof. Dr. Ali Osman SOLAK who presenting us his research laboratory for our experiments. *Corresponding author: sakkaya@aku.edu.tr [1] Tietz, N.W., 1976. Fundamentals of clinical chemistry, Saunders,Philadelphia. [2] He, X-M., Carter, D-C., 1992. Atomic structure and chemistry of huma serum albumin. Nature, 358: 209. [3] Yu, Y-H., Xue, B. Sun, Y. 2001. Dye-ligand poly( GMA- TAIC-DVB) affinity adsorbent for protein adsorption. Bioprocess and Biosystem Engineering, 24: 25-31. [4] Suen, S-Y., Lin, S-Y., Chiu, H-C., 2000. Effects of spacer using regenerated cellulose membrane discs. Ind. Eng. Chem. Res., 39(2): 478-487. [5] Liu, G., Liu, J., Böcking, T.,Eggers, P-K., Gooding, J-J., 2005. The modification of glassy carbon and gold electrodes with aryl diaznium salt: The impact of the electrode materials on the rate of heterogenous electron transfer. Chemical Physics, 319: 136-146. [6] Ustundag, Z., Solak, A-O. 2009. EDTA modified galssy carbon electrode: preparation and characterization. Electrochimica Acta, 54: 6426-6432. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 381
Poster Session, Tuesday, June 15 Theme A1 - B702 Continuum Buckling Analysis of Double-Walled Carbon Nanotubes with Different Inner and Outer Boundary Conditions Seckin Filiz 1 , Metin Aydogdu 2 * 1 Graduate School of Natural and Applied Sciences, Trakya University, Edirne, Turkey 2 Department of Mechanical Engineering, Trakya University, Edirne, 22180, Turkey Abstract- Buckling of in-plane loaded doublewalled carbon nanotubes is studied by using continuum Euler-Bernoulli beam theory. Different boundary conditions are assumed for inner and outer carbon nanotubes. A finite difference method is proposed for the solution of governing equations. In recent years, small scale engineering members have been used in many scientific and industrial applications. Carbon nanotubes are one of these small elements which are used due to their extraordinary mechanical, electrical, low weight and optical properties [1-4]. Mechanical properties of CNTs were studied by some researchers in the last two decades. Buckling is one of the problems which occur due to external loads. Studies related with static and dynamic analysis of CNTs can be divided in to two parts: molecular dynamic simulations [5-7] and continuum mechanics models [8-10]. In the previous studies it was shown that molecular dynamic simulations are limited with small number of atoms and short time intervals. Due to this fact continuum beam and shell models were used in the previous analysis [8-10]. It is important to mention that previous studies are limited to simply supported boundary conditions or same boundary conditions for all nested carbon nanotubes. In the real engineering applications it is possible to have different boundary conditions for nested CNTs. Actually it is not possible to have a classical boundary conditions for inner tubes other then free one. This important issue is not considered in the previous studies. In the present study, a finite difference continuum beam model based on classical Euler-Bernoulli beam theory is proposed to analyze buckling of multiwalled CNTs. After general formulation, buckling of double walled carbon nanotubes is studied using classical Euler-Bernoulli beam model. Different boundary conditions are assumed for inner and outer CNTs. It is believed that using different boundary conditions for nested tubes is more realistic when compared with previous studies. In the present study, the deflections of the nested tubes are coupled through the van der Waals intertube interaction pressure. Nondimensional critical buckling loads will be given for different boundary conditions and mode numbers. The proposed finite difference formulation of multiwalled CNT can also be used for other dynamic and static analysis of CNT related problems. [8] J. Yoon, C.Q. Ru, A. Mioduchowski, Compos. Part B-Eng. 35, 87(2004). [9] M. Aydogdu, M.C. Ece, Turkish J. Eng. Env. Sci. 31, 305 (2007). [10] M. Aydogdu, Physica E. 41, 1651 (2009). *Corresponding author: metina@trakya.edu.tr [1] S. Iijima, Nature (London) 354, 56 (1991). [2] P. Kim and C.M. Lieber, Science 286, 2148 (1999). [3] J. Kong, Science 287, 622 (2000). [4] E.T. Thostenson, Z. Ren and T.W. Chou, Comp.Sci. Techno l. 61, 1899 ( 2001). [5] B.I. Yakobson, C.J. Brabec and J.Bernholc, Phys. Rev.Lett. 76, 19 71 (1996). [6] B.I. Yakobson and R.E. Smalley, Am.Sci., 85, 324 (1997). [7] Y.G. Hu, K.M. Liew, Q. Wang, X.Q. He, B.I. Yakobson, J. Mech. Phys. Solids 56, 3475 (2008). 6th Nanoscience and Nanotechnology Conference, zmir, 2010 382
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