Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 OPTICAL CHEMICAL SENSOR BASED ON POLYMER NANOFIBERS FOR SILVER(I) ION DETECTION Sibel Kaçmaz 1* , Kadriye Ertekin 1 , Yavuz Ergün 1 , Mehtap Özdemir 2 , Ümit Cöcen 2 1 University of Dokuz Eylul, Faculty of Arts and Sciences, Department of Chemistry, 35160, Izmir,Turkey 2 University of Dokuz Eylul, Faculty Engineering, Department of Metallurgical and Materials Engineering, 35160, Izmir,Turkey Abstract- In this work, Ag + sensing nanofibers were produced by electrospinning of composites containing Y-5 (4(dimethylamino)benzaldehyde2-[[4(dimethylamino)phenyl]methylene]hydrazone) dye, ethyl cellulose (EC) and/or polymethyl-methacrylate (PMMA). The fluorescence spectra of the embedded dyes in fiber and thin film form were recorded. Presence of ionic liquid in the matrix material enhanced electrospinning process providing ionic conductivity. Results of the studies performed in liquid phase provide valuable information for researchers; however, they remain far from applications in sensor technology at this stage. The integration of liquid components with solid state optics is not practical and molecule-based solid state approaches employing polymeric media should be developed. In this context, recently, a number of ultrasensitive fluorescent optical sensors for a variety of analytes have been demonstrated; new strategies are still being developed [1-3]. Electrospinning is a relatively simple and versatile method for creating high-surface-area polymeric fibrous membranes. In a typical process, a large static voltage is applied to a polymer solution to generate fine jets of solution that dry into an interconnected membrane like web of small fibers [4]. Electrospun fibres can be functionalized by the use of proper indicator and auxiliary additives for desired purposes. In this work, we reported the use of electrospun polymer fibers as highly responsive fluorescent optical sensors for Ag+ ions. A series of Ag + sensitive nanofibers with various compositions of poly-methyl-methacrylate (PMMA), ethyl cellulose (EC), plasticizer and ionic liquid (1- ethyl-3-methylimidazolium tetrafluoroborate) were produced and characterized by Scanning Electron Microscopy (SEM). The Ag + sensitive dye Y-5 4(dimethylamin)benzaldehyde2[[4(dimethylamino)ph enyl]methylene]hydrazone dyes has been used as sensing agent. (See Fig.1). The fiber diameters were measured between 480- 680 nm for 40% DOP, 10% IL and 50% EC containing composites and 1.72-2.43 μm for 25% DOP, 25% IL and 50% PMMA containing composites. Upon exposure to Ag + ions the Y-5 dye exhibited fluorescence quenching based response at 580 nm. Fig. 3 reveals response of the sensing agent to Ag+ ions in the concentration range of 3.51×10 -07 - 1.43×10 -02 M. Figure 2. Scanning electron microscopy (SEM) images of EC (40% DOP, 10% IL) based nanofiber. 300 250 200 150 100 50 g ı h c d e f a b g h ı c d e f a b 0 400 500 600 700 Wavelength (nm) H 3 C C H 3 N N N Figure 1. Chemical structure of Y-5 dye N CH 3 CH 3 Electrospinning was performed at 25 kV voltage and at 0.3 mL/h flow rate. SEM micrograph of EC based nanofibers were shown in Fig. 2. Figure 3. Response of EC based sensing nanofibers to Ag+ ions. *Corresponding author: sibel.kacmaz@ogr.deu.edu.tr [1]. J. S. Yang, and T. M. Swager, J. Am. Chem. Soc., 120, 11864-11873(1998). [2] L. H. Chen, D. W. Mcbranch, H. L. Wang, R. Helgeson, F. Wudl, and D. G. Whitten, Proc. Natl. Acad. Sci., 96, 12287-12292 (1999). [3] C. Fan, K. W. Plaxco, A. J. Heeger, J. Am. Chem. Soc., 124, 5642-5643 (2002). [4] D. H. Reneker, and I. Chun, Nanotechnology, 7, 215 (1996). 6th Nanoscience and Nanotechnology Conference, zmir, 2010 387
Poster Session, Tuesday, June 15 Theme A1 - B702 Growth and luminescence properties of Zinc Oxide nanowires S.H. Mousavi 1,* , H. Haratizadeh 1 1 Department of Physics Shahrood University of Technology, 3619995161, Shahrood, Iran Abstract— In this work, 1-D nanostructures were synthesized in a horizontal tube furnace by chemical vapour deposition method. The effect of substrate, evaporation temperature, gas flow flux and vacuum conditions are investigated on the structural and morphological studies by means of the field emission SEM, EDX, XRD and Photoluminescence (PL) studies. Zinc oxide (ZnO) is an exclusive material that exhibits optical and semiconducting properties such as wide band gap (3.37 eV) and large binding energy (60 meV). Recently, onedimensional structures of ZnO attract great attention due to sensing, optoelectronic applications and nanodevices [1, 2]. In this work, 1-D nanostructures were synthesized in a horizontal tube furnace by chemical vapour deposition method. The effect of substrate, evaporation temperature, gas flow flux and vacuum conditions are investigated on the structural and morphological studies by means of the field emission SEM, EDX and XRD. Photoluminescence (PL) spectroscopy has been used for the optical studies and PL spectra show green and green-blue wavelength strong emissions at RT. The synthesized nanowires with the average width 70 nm are shown in Fig.(1-a). The EDX measurement indicates the volume ratio 1:5 of oxygen:zinc components respectively (Fig. (1-b)). purpose, the variations of PL spectra for different morphologies are investigated and the high intensity light emitting is detected for visible wavelengths that are great interest for light emitting devices at room temperature (RT) [3-5]. Intensity (a. u.) PL spectrum of ZnO nanowires at RT 400 500 600 700 800 Wavelength (nm) Figure 2: PL spectrum of ZnO nanowires at room temperature *Corresponding author: hadi_mousavi@yahoo.com (a) [1] X.W. Sun, J.Z. Huang, J.X. Wang and Z. Xu, Nano Lett. 8, 1219 (2008). [2] A. Khan and M.E. Kordesch, Mater. Res. Soc. Symp. Proc. 872, J 18.16.1 (2005). [3] Yong Qin, Rusen Yang, and Zhong Lin Wang J. Phys. Chem. C, 112, 48, 18734-18736 (2008) [4] Yaguang Wei, Yong Ding, Cheng Li,Sheng Xu,Jae-Hyun Ryo, Russell Dupuis, Ashok K.Sood, Dennis L.Polla, and Zhong Lin Wang, J. Phys. Chem., 112 , 48, 18935-18937 (2008) . [5] R.S. Yang and Z.L. Wang Philos. Mag., 87, 2097-2014 (2007). (b) Figure 1: (a) SEM image, (b) EDX analysis of ZnO nanowires. PL spectrum of the same sample exhibits two peaks, a sharp peak at 390 nm and a strong broad peak at 487 nm (Fig. 2). As a direct band gap semiconductor, the near band-edge emission appears at 390 nm, while vacancy oxygen defects lead to visible emission at mentioned wavelengths. As another 6th Nanoscience and Nanotechnology Conference, zmir, 2010 388
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