Studies On Polydopamine-based And Template-directed Preparation Of Manganese Oxide Nanotube Array And Polydopamine-based Electrochemical Analysis

Recently,polydopamine?PDA?as a new emerging polymer material exhibits outstanding properties such as easy coating,virtual adhesion,and biocompatibility.In this dissertation,first,PDA was used as the template to synthesize manganese dioxide?MnO₂?nanotube arrays.Furthermore,a new kind of electrochemical probe based on Prussian blue?PB?was applied to analyze the ion permeability properties of PDA coating.Influence factors such as pH and film thickness on the ion permeability of PDA coating were investigated and the possible mechanism was discussed.In addition,the effect of PDA coating on the electrochemical performance of PB-modified electrodes was studied.?1?Fabrication of manganese dioxide nanotube array through potassium permanganate reduction by polydopamine coatings formed on zinc oxide?ZnO?nanorod array templateIn this part,MnO₂ nanotube arrays are fabricated by using PDA coated-ZnO nanorods supported on quartz plates as template,followed by potassium permanganate reduction by PDA and the ZnO template removal.Characterization results show that the formed MnO₂ nanotubes have well-defined tube morphology and strongly adhere to the substrate.The formed MnO₂ nanotube arrays are amorphous.PDA coated ZnO nanostructures as template exhibit several advantages.For example,ZnO possesses diverse surface morphologies,and is easy to be synthesized and removed.The formation of PDA is also facile.These advantages may pave the way towards facile synthesis of various MnO₂ nanostructures.?2?Ion permeability of PDA films revealed by using a PB-based electrochemical methodPDA is fast becoming a popular surface modification technique.Detailed understanding of the ion permeability properties of PDA films will improve their applications on a variety of fields such as adsorption,isolation,catalysis and electrochemistry.Herein,we use PB-based electrochemical method including cyclic voltammetry and electrochemical impedance spectroscopy,to evaluate the ion permeability of PDA films.Ion permeability of PDA coating can be detected by observing the changes in electrochemical behaviors of the PB-coated by PDA coatings with different thickness??23,60,113 nm?.It is found that ion permeability of PDA coating is thickness-and pH-dependent,and the possible mechanisms are discussed.?3?Current control by electrode coatings formed by polymerization of dopamine at PB modified electrodesIn this part,we investigate the use of PDA as electrode coatings of PB.Electrochemical characterizations of the PDA-coated PB electrode reveal that the PDA coatings can stabilize the PB at neutral pH and allow the permeation of hydrogen peroxide?H₂O₂?.PDA-coated PB electrodes show excellent electrocatalytic ability towards H₂O₂.Moreover,the PDA coatings are found to effectively exclude the common interfering compounds such as L-cysteine,ascorbic acid and uric acid,and exhibit selective electrocatalysis towards H₂O₂.Accordingly,the PDA-coated PB electrodes are applied for determination of H₂O₂ released from live cells.