Photonic crystals in biology

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P P P Hacettepe P Hacettepe P P Poster Session, Tuesday, June 15 Theme A1 - B702 Preparation and Characterization of Bacterial Polyester Based Nanoparticlesfor Targeted Delivery of Etoposide 1 2 3 1 2,3 UEbru KlçayUP P, Eylem GüvenP P, Mustafa TürkP P, Baki HazerP P, Emir Baki DenkbaP P* 1 2 3 PKaraelmas University, Chemistry Department, Physical Chemistry Division, , Zonguldak, Turkey University, Nanotechnology and Nanomedicine Division, 06532, Beytepe, Ankara, Turkey University, Chemistry Department, Biochemistry Division, 06532 Beytepe, Ankara, Turkey 4 PKırıkkale University, Biology Department, Biochemistry Division, Kırıkkale, Turkey Abstract-Tumour-specific nano-structured drug delivery systems have received much attention due to their unique accumulation at tumour region. Among them polymeric nanoparticles made from natural polymers have drawn major attention due to higher stability, maneuverability for industrial manufacture, and opportunity for further surface nanoengineering. Aim of this study was to to prepare and characterize etoposideloaded, folic acid conjugated poly(3- hydroxybutyrate-co-3 hydroxyhexanoate) (PHBHHx) nanoparticles for using in targeted cancer therapy. Resulting data showed that etoposide-loaded and folic acid modified PHBHHX nanoparticles show promise for targeted delivery of etoposide to cancer cells. Nanotechnology is an emerging multidisciplinary field for current research and development in all technical disciplines. Nanoparticulate drug delivery systems which are nanometric carriers used to deliver drugs or biomolecules have received great attention over the last decades. Polymeric nanoparticles have been widely investigated for both diagnosis and targeted treatment of cancer; because they (a) can show controlled release properties, (b) can pass through the smallest capillary vessels and avoid rapid clearance by phagocytes, (c) can penetrate cells and tissue gap in order to arrive at target organs, (d) can reduce side effects of drugs, (e) can increase drug efficacy, etc [1,2]. Polyhydroxyalkanoates (PHAs) are a promising class of new emerging biopolymers. They are the polyesthers of hydroxyalkanoate produced by a variety of bacterial species as an intracellular carbon and energy compound under nutrientlimiting conditions with excess carbon. There has been considerable interest in using them as drug carriers due to their biodegradability and biocompatibility. A newer member of PHA family, poly(3-hydroxybutyrate-co-3 hydroxyhexanoate) (PHBHHx), is currently being produced in large scale [3,4]. Studies have demonstrated that PHBHHx, a microbially synthesized polyester with good biodegradability and biocompatibility, as well as strong mechanical properties, consequently, is very promising for biomedical applications. In the presented study poly(3-hydroxybutyrate-co-3- hydroxyhexanoate) nanoparticles were prepared to use in targeted cancer therapy. PHBHHX nanoparticles were prepared by solvent evaporation technique using dichloromethane as the solvent and tween-80 as the emulsifier. Morphological evaluations of the prepared nanoparticles were investigated by using atomic force microscopy (AFM). Effect of stirring rate, amount of surfactant and polymer concentration on nanoparticle size were investigated by Zeta Size Analyser. The size of the smallest nanoparticles obtained was in the range of 190-220 nm. Etoposide, an antineoplastic agent was loaded into nanoparticles and drug release profiles were obtained. 16-30 % drug loading was observed in drug loading studies depending on the initial drug content. Release studies of etoposide were also evaluated. For ‘active’ targeting of cancerous cells; nanoparticles were modified with folic acid as the model ligand for targeting nanoparticles to cancer cells. The receptor for folic acid is upregulated in many human cancers, including malignancies of the ovary, kidney, brain, breast myeloid cells and lung. Therefore it can be utilized as a useful target for tumor-specific drug delivery [5]. Different concentrations of folic acid was used in order to investigate the effect of ligand concentration on ligand binding efficiency. Ligand binding efficiency was found to be between 71-93%. Additionally physicochemical structures of nanoparticles were analyzed by using FTIR and the system was optimized for further in vitro and in vivo applications. Obtained results showed that etoposide-loaded and folic acid modified PHBHHX nanoparticles show promise for targeted cancer therapy. *Corresponding author: denkbas@hacettepe.edu.tr [1] Paul, D.R., Robeson, L.M. ‘’Polymer nanotechnology: Nanocomposites’’, Polymer 49 (2008) 3187-3204. [2] Ferrari, M. Cancer nanotechnology: Opportunities and challenges. Nat Rev Cancer (2005) 161–71. [3] Bayram, C., Denkbas, E.B., Kiliçay, E., Hazer, B., Çakmak, H.B. ‘Preparation and Characterization of Triamcinolone Acetonideloaded Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHx) Microspheres’ Journal of Bioactive and Compatible Polymers 2008; 23; 334. [4] Zinn, M., Witholt, B., Egli, T. ‘’Occurrence, synthesis and medical application of bacterial polyhydroxyalkanoate’’Advanced Drug Delivery Reviews, 53 (2001) 5-21. [5] Lu, Y., Low, P.S. ‘’Folate-mediated delivery of macromolecular anticancer therapeutic agents’’ Advanced Drug Delivery Review,. 54 (2002) 675-693. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 264
Poster Session, Tuesday, June 15 Theme A1 - B702 Electrolysis and Characterization of Nanoporous Platinum A.Cahit Karaoglanli 1,2* Elif Tastaban 2 and Esref Avci 2 1 Department of Metallurgical and Materials Engineering Bartin University, Bartin 74100, Turkey 2 Department of Metallurgical and Materials Engineering, Sakarya University, Sakarya 54187, Turkey Abstract— In this study, a change of the DC electrical conductivity of a nanoporous platinum was observed when surface charge was induced on the nanomaterial by making it a working electrode in an electrochemical cell. Existing and reasonable new technological applications of solids deviation from charge neutrality are discussed. Most materials studied and/or used technologically today are electrically neutral, i.e the positive and negative electric charges are balanced. The properties of these materials are varied prodominantly by modifying the atomic structure [1]. The basic idea is that the immersion of a nanoporous material in an electrolyte leads to induced charges on the surface regions of a material by the application of a potential across the electrolyte– material interface, where a capacitive double layer is formed. The voltage range has to be restricted where no adsorption or reaction takes place at the electrode [1,2]. As many properties of solid materials depend on their electronic structure, significant deviations from charge neutrality result in materials with new, yet mostly unexplored properties such as modified electric, ferromagnetic, optical etc. properties. Weissmuller et al. reported the charge-induced reversible strain in nanoporous platinum metal. A practical application of this effect as actuators was also demonstrated. Similarly, the magnetization of nanoporous Ni–Pd alloys was also observed to be tunable by externally applied voltages on the material in an electrochemical cell. Similarly, electrochemical charging of thin gold films was studied by Anderson and Hansen in Na 2 SO 4 electrolyte and by Tucceri et al. in H 2 SO 4 electrolyte, where a change in resistance proportional to the surface charge was also observed [3-6]. *Corresponding author: karaoglanli@bartin.edu.tr [1] Gleiter, H., Scripta mater. 44, 1161–1168, Germany, (2001). [2] Gleiter, H.,Weissmuller, J.,and Wollersheim, Acta Mater.49, S.737-745, (2001). [3] J. Weissmuller, R.N. Viswanath, D. Kramer, P. Zimmer, R. Wurschum, H. Gleiter, Science 300, 312, (2003). [4] D. Kramer, R.N. Viswanath, J. Weissmuller, Nano Lett. 4,793, (2004). [5] C. Lemier, S. Ghosh, R.N. Viswanath, G.T. Fei, J. Weissmuller, Mater. Res. Soc. Symp. 876E (2005). [6] Bansal, C., Sarkar, S., Mishra, A.K., Abraham, T.,Lemierb, C., Hahn C., Scripta Materialia 56, S:705-708, (2007). In this study, a change of the DC electrical conductivity of a nanoporous platinum was observed when surface charge was induced on the nanomaterial by making it a working electrode in an electrochemical cell. Existing and reasonable new technological applications of solids deviation from charge neutrality are discussed. This work was partially supported Germany Forschungszentrum, Institute of Nanotechnology. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 265
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