Electrochemical synthesis of polypyrrole nanowires and application of biosensor

- MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY INTERNATIONAL TRAINING INSTITUTE FOR MATERIALS SCIENCE BUI DAI NHAN ELECTROCHEMICAL SYNTHESIS OF POLYPYRROLE NANOWIRES AND APPLICATION OF BIOSENSOR MASTER OF SCIENCE THESIS MATERIALS SCIENCE SUPERVISOR : Dr.
- MAI ANH TUAN HANOI - 2011 Bui Dai Nhan Master Thesis 2011 1 ACKNOWLEDGMENTS I would like to express my appreciation to my supervisor, Dr.
- Tran Trung, Hung Yen University of Education and Technology for giving me a chance to attend master course in ITIMS and providing me the necessary facilities for my master thesis.
- ITIMS, Hanoi, November 2011 Bui Dai Nhan Master Thesis 2011 2 I hereby declare that all the result in this document has been obtained and presented in accordance with academic rules and ethical conduct.
- The author of this thesis Bui Dai Nhan Bui Dai Nhan Master Thesis 2011 3 CONTENTS Acknowledgement Reassure words Contents List of Abbreviation List of Table List of Figure Preface Chapter1.
- Overview of conducting polymers.
- Historical back ground of the development of conducting polymers.
- Current synthesis of conducting polymers.
- Polypyrrole (PPy) and Electrochemical polymerization of PPy.
- Properties of Polypyrrole.
- Electrochemical synthesis of Polypyrrole.
- General Introduction to DNA sensor.
- Aim of the Study.
- Electrochemical polymerization of polypyrrole.
- 42 Bui Dai Nhan Master Thesis .
- Electrochemical synthesis of PPy nanowires.
- Electroactivities of Polypyrrole.
- Effects of parameters on electrochemical polymerization of polypyrrole.
- Chemical composition and functional groups of obtained PPy nanowires.
- Characteristics of DNA sensor is a function of time.
- Hybridization detection using DNA sensor.
- The reproducibility of DNA sensor.
- 78 Bui Dai Nhan Master Thesis 2011 5 LIST OF ABBREVATION CPs Conducting Polymers PPy Polypyrrole PAc Polyacetylene PAni Polyaniline PTh Polythiophene WE Working Electrode CE Counter Electrode RE Reference Electrode DNA Deoxyribonucleic Acid PCR Polymerase Chains Reaction EDC 1-Ethy-3-(3-dimethyl-aminopropyl)-carbodiimide MIA 1-methyl-imidazole VB Valence Band CB Conduction Band PBS Phosphate Buffer Solution SEM Scanning Electron Microscopy FT-IR Fourier Transform Infrared Spectroscopy SERS Surface Enhanced Raman Spectroscopy Bui Dai Nhan Master Thesis 2011 6 LIST OF TABLE Table 1.1.
- The chronology of the development of some important conducting polymers Table 1.2.
- Advantages and disadvantages of chemical and electrochemical synthesis of conducting polymers.
- Advantages and Disadvantages of Chemical and Electrochemical synthesis of PPy.
- Bui Dai Nhan Master Thesis 2011 7 LIST OF FIGURE Figure 1.1.
- Conductivity of conducting polymer compared with other materials.
- Three typical types of conducting polymer.
- Band theory and doping-induced structural transitions of polypyrrole.
- Three steps of polymerization process of Polypyrrole.
- Aromatic and Quinoid structrure of PPy Figure 1.6.
- Cyclic voltammogram of PPy nanowires and cauliflower-like in KCl solution at scan rate of 25 mV/s.
- Potentiostat curve of the synthesis of PPy on Nikel electrode and ITO electrode.
- Figure 1.10 The schematic of a biosensor.
- Figure 1.11.
- General DNA sensor design based on CPs.
- Figure 1.12.
- The principle of DNA sensor.
- Figure 1.13.
- Figure 1.14.
- Four base types of DNA.
- Figure 1.15.
- Hydrogen bonds between the A-T and G-C bases of the two trands of DNA Figure 2.1.
- Schematic of electrochemical synthesis system of polypyrrole Figure 2.2.
- The wave form of the Lock-in Amplifier SR830 Figure 2.5.
- Equivalent electrical circuit of differential system Bui Dai Nhan Master Thesis 2011 8 Figure 3.1.
- Cyclic voltammogram of Ppy between -1.0 V and +1.0 V at 250 mV/s scan rate Figure 3.2.
- Potentiostatic polymerization curve for the electrodeposition of Polypyrrole.
- Potentiostatic curves for the electrodeposition of Polypyrrole from 0.1M LiClO4 electrolyte at different conditions.
- The saturated current density of the electrochemical curve vs.pyrrole monomer concentration.
- Figure 3.5 SEM images of Ppy structrures synthesized at different added volume of pyrrole.
- SEM images of Ppy structures potentiostatically synthesized at different of gelatin concentration.
- SEM images of Ppy structures potentiostatically synthesized at different reaction time.
- Morphologies of PPy nanowires prepared at optimized condition Figure 3.11.
- FI-IR spectra of obtained Ppy nanowires Fig 3.12.
- Path of the stylus over the sample in the measurement of Pt thickness.
- Figure 3.13.
- Distribution of PPy nanowires over Pt surface electrode.
- Figure 3.15.
- Surface Enhanced Raman Spectroscope of polypyrrole film deposited on Platinum surface Figure 3.16.
- Response time and Reaction time of the DNA sensor.
- Figure 3.17.
- Figure 3.18.
- The reproducibility of DNA sensor Bui Dai Nhan Master Thesis 2011 9 PREFACES Recently, Polypyrrole (PPy) is one of the most extensively used conducting polymers in biosensor designs due to its good biocompatibility and polymerization at neutral pH [30].
- The electronic structure of PPy is highly sensitive to change in polymeric chain environment and other perturbations in the chain conformation caused by, for example, a biological recognition event such as DNA hybridization [30].
- These advantages of conducting PPy make them suitable for biosensors and chemical sensors which play important role in public health and environment [18].
- The drawback of DNA sensor based PPy membrane includes limited sensitivity and reproducibility due to the low conductivity of PPy in film and cauliflower-like form, presented in previous work (1).
- In this thesis, we aim at the synthesis of PPy nanowires using electrochemical technique with the desire of obtaining better characteristics of DNA sensor for Ecoli bacteria DNA detection.
- The synthesis of PPy nanowires was obtained by using potentiostat method at 0.75V, in LiClO4 0.1M (PBS, pH =7) electrolyte containing 0.5 mL pyrrole monomer and 0.08%wt gelatin.
- It should be noted that gelatin is used as a ‘soft template’ to orientate the growth of PPy nanowires.
- The PPy nanowires 50 nm of diameter provide large and fine surface.
- Especially, N-H group of PPy nanowires was orientated upward from the surface which takes advantage for DNA probe immobilization.
- As the result, the DNA based PPy nanowires has good characteristics for Ecoli DNA detection, including a short response time (~10 seconds), small detection limit (0.1 nM) as well as good reproducibility.
- Tam et al.
- Materials Science and Engineering C Bui Dai Nhan Master Thesis 2011 10 The dissertation, divided into 4 chapters, reports a proper potentiostat technique to prepare conducting polypyrrole nanowires on Pt electrode, and then initial applications of DNA sensor using microelectrode based PPy nanowires.
- In chapter one, the fundamental of conducting polymers, Polypyrrole and DNA sensor will be introduced.
- In chapter 2, experiments for electrochemical polymerization of PPy films and the application of PPy based electrode for DNA sensor will be described.
- In chapter 3, achieved results of the thesis will be presented.
- Different electrochemical parameters were studied to establish the synthesis condition to obtain PPy nanowires.
- The electrochemical behaviors, morphologies and chemical composition of polypyrrole nanowires obtained potentiostatically have been analyzed and discussed.
- Later on, the trial application of DNA sensor and the detection of target DNA sequence of Ecoli bacteria were studied.
- Bui Dai Nhan Master Thesis 2011 11 Chapter 1.
- Overview of conducting polymers 1.1.1.
- That property is due to the presence of ‘free electron’ within the body of the specimen.
- Conductivity (S.cm Polyanilin 12 doped Polypyrrole AsF5 doped Poly  phenyl Mercury 12 doped polyacetylen AsF5 doped polyacetylen Copper Bui Dai Nhan Master Thesis 2011 12 Conducting polymer can be classified into three distinct groups: electron-conducting polymer, ion-conducting polymer, redox polymer (Fig.1.2).
- Ion-exchange conducting polymer xy2322222-CFOO32+336+Na+336+SolutionLayerLoaded ionomers(CF CF)(CF CF )CF CF SHO NaCF CFRu(NH )Ru(NH )FeII/IIIPolyvinylferrocene HNN NNH HHPolyanilinePolyparaphenylenePolypyrrole Redox conducting polymer Electron conducting polymers Figure 1.2.
- Three typical types of conducting polymers.
- NH.+-ClFe(CN)63-Fe(CN)63-Cl-ProtonatedPolyvynilpyridineLayerSolution Bui Dai Nhan Master Thesis 2011 13 The chemical stability of a polymer in atmospheric conditions depends on the value of the redox potential.
- Electron-rich heterocycle based polymers such as polythiophene and polypyrrole are very stable in the p-doped form and this has made these systems two of the most studied conducting polymers.
- Therefore, polypyrrole seems to be a good candidate for researchers now to attempt at the synthesis of conducting polymers, in particular for biosensing application.
- Historical back ground of the development of conducting polymers Polyaniline (PAni), known as ‘aniline black’, is one of the oldest conductive polymers known.
- The modern era of conducting polymers began at the end of 1970s when the discovery that polyacetylene (PAc) could be synthesized to form highly conducting doped films [16] by Alan Heeger, Alan MacDiarmid and Hideki Shirakawa (2000 Nobel Prize in Chemistry).
- Bui Dai Nhan Master Thesis 2011 14 (SN)x synthesized by Burt 1910 Metallic conductivity of (SN)x reported by Waltaka et al 1973 Semiconductivity P.A discovered by Shirakawa et al 1971 Doping of PA by Shirakawa et al 1977 Electrochemical synthesis of PPy by Diaz et al 1979 Conducting PPP by Ivory et al 1979 Conducting PPS by Rabolt et al 1980 PTh by Tourillon et al 1982 Conducting polyppara phenylene sulfide by J.E.
- Forder 1983 Polymer surface modification, Chan et al 1993 PPy, by Tat’yanan V Vernitskaya et al 1997 Nobel prize 2000 for MacDiarmid, Heeger, Shirakawa 2000 PANi by Z.Wei, M.Wan 2002 poly (aniline-co-o-anisidine-co-o-toluidine) by Borole, Kapadi et al 2006 PPy & PTh byThapa et al, USA.
- P3HT by Park, Korea Poly (3-hexylthiophene) 2007 Table 1.1.The chronology of the development of some important conducting polymers [19].
- Bui Dai Nhan Master Thesis 2011 15 After the first publication, there has been an explosive growth of research into the whole range of conjugated polymer structures, table 1.1.
- Mechanism of electrical conduction in CPs The conduction properties of conducting polymers have previously been explained on the basics of the band theory of solids.
- To explain the conduction mechanism in conducting polymers, a new model called soliton model was introduced by MacDiarmid et al in 1983 [2].
- It should be noted that this theory agreed with PAc (because it has a degenerate ground state, two geometric structures corresponding to the same energy) but not with all other conducting polymers having non-degenerate ground state

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