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XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society PB 12 Bacterial cellulose: A new material for cell immobilization in biosensors Manuel J. Matos 1,2 , Nelson A. F. Silva 2 , Amin Karmali 2 , Edison Pecoraro 3 1 Instituto de Telecomunicações, Pólo de Lisboa, Portugal 2 CIEQB-ISEL - Instituto Superior de Engenharia de Lisboa, Portugal 3 Instituto de Telecomunicações, Pólo de Aveiro, Portugal mmatos@deq.isel.ipl.pt A biosensor is an analytical device capable of quantifying the amount of a given analyte by means of a transduction process of a biochemical signal that results from an interaction between a biological recognition element and the analyte itself. A particular a concerns the immobilization of the biological element, which can be made directly on the surface of the transducing element or by means of an auxiliary support which, then, is placed in its immediate vicinity. Encapsulation matrices, polymeric membranes or sol-gel technology are examples of these immobilization methods. However, these matrices or immobilization supports are mostly synthetic, which, may result in a biologic incompatibility between the recognition element and the immobilization support. This aspect may lead to some limitations such as reduction of biological activity, premature To overcome this limitation, our group was able to successfully immobilize living microorganisms (whole bacterial cells) on a new material that consists of a biological substance resulting from the metabolism of other microorganisms, processed in order to fulfill our main immobilization purposes. This material, referred to as bacterial cellulose or biocellulose, allowed us to achieve very promising results in living cells immobilization [1, 2]. In this presentation we compare some analytical characteristics of an electrochemical biosensor with potentiometric transduction, used for acrylamide detection, when using biocellulose and other traditional matrices, such as polymeric membranes, for the immobilization of whole cells of Pseudomonas aeruginosa [3]. Parameters such as linear rangewere considered. References [1] Iguchi, M.; Yamanaka, S.; Budhiono, A.; J. Mat. Sci, 2000, 35, 261. [2] Pecoraro, E.; D. M. Manzani; Y. M. Messaddeq; S. J. L. R. Ribeiro; Monomers, Oligomers, Polymers and Composites from Renewable Resources, Ed. by Naceur Belgacem and Alessandro Gandini, Elsevier Science, 2008. [3] Silva, N.; Gil, D.; Karmali, A.; Matos, M.; Biocat Biotransf, 2009, 27, 143. September, 811, 2010. ISEL - Lisbon 78
XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society PC 01 A Conducting Polymer / Self-Assembled Monolayer Modified Electrode for the Determination of Ascorbic Acid José Carlos A. Mesquita 1 , Sónia Maria A. Fernandes 1,2 , Jorge M. G. Teixeira 2 1 Centro de Química da Madeira. LQCMM/CQM, Universidade da Madeira, Campus da Penteada, 9000-390 Funchal 2 Departamento de Química da Universidade de Évora, Colégio Luís Verney, 7000 Évora jcm@uma.pt Self-assembled monolayers (SAMs) have become a convenient way of surface modification in order to obtain highly organized structures with well-defined properties, in particular through the incorporation of appropriate terminate functional groups [1, 2]. The technique of electrostatic self-assembly layer-by-layer proposed by Decher et al in the 90s, which allows obtaining multilayer thin films, also enables the self-assembly of conducting polymers [1]. However, several authors electropolymerize directly conducting polymers on SAMs [3] with particularly the intention of obtaining polymer layers with increased adherence. In this work, it is compared the voltammetric behaviour of the polyaniline (PANI) electrodeposited on 3-mercapto-1-propanesulfonic acid (MPS) self-assembled on a carbon electrode (C) with that of the PANI chemically synthesized self-assembled by electrostatic interaction equally on MPS. Complementarily, the cyclic voltammetric study of the PANI deposited on MPS self-assembled on carbon provided valuable information about the modified electrodes thus obtained. Additionally, it is verified by cyclic voltammetry that with the C/MPS/PANI modified electrode it is possible to well define the oxidation of the acid ascorbic (AA), besides not arise any further oxidation of this chemical species. Furthermore, it is observed with C/MPS/PANI modified electrodes a good correlation of the acid ascorbic voltammetric current with their concentration. What gives a positive perspective for the use of this kind of modified electrode in the determination of AA. Acknowledgments: Sónia Fernandes acknowledges Secretaria Regional da Educação da Madeira for the grant. We gratefully acknowledge the NMR Portuguese Networks (REDE/1517/RMN/2005). The support from F CT (Pluriannual base funding) and CS Madeira is also gratefully acknowledged. References [1] Paterno, L.G.; Mattoso, L.H.C.; Oliveira Jr. O.N. Quim. Nova, 2001, 24, 228. [2] Love, J.C.; Estroff, L.A.; Kriebel, J.K.; Nuzzo, R.G.; Whitesides G.M. Chem. Rev., 2005, 105, 1103. [3] Mazur, M.; Krysinski, P.; Jackowska K. Thin Solid Films, 1998, 330, 167. September, 811, 2010. ISEL - Lisbon 79
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