Electropolymerized polypyrrole film

Fig. 18.1. (A) Schematic presentation of the biotin-avidin complex with detailed configuration of biotin and surrounding polar residues. (B) Detailed (top) and simplified (bottom) representations of the complication possibilities of biotin and avidin. (C) Structure of an electropolymerizable biotin derivative and schematic presentation of an electropolymerized polypyrrole film bearing biotin groups on its surface. All three-dimensional representations of avidin have been generated using the program VMD [70] and subsequently rendered with PovRay.

Immobilization of Multicharged Porphyrins into Pro-Electropolymerized Polypyrrole Films Bearing Functional Groups... 

De Medeiros MAC, Gorgy K, Deronzier A, Cosnier S (2008) Design of new electropolymerized polypyrrole films of polyfluorinated Zn(II) and Mn(III) porphyrins towards electrochemical sensors. Mater Sci Eng C Biomim Supramol Syst 21 731-738... 

N. Diab and W. Schuhmann, Electropolymerized manganese porphyrin/polypyrrole films as catalytic surfaces for the oxidation of nitric oxide. Electrochim. Acta 47, 265-273 (2001). 

A molecularly imprinted polypyrrole film coating a quartz resonator of a QCM transducer was used for determination of sodium dodecyl sulphate (SDS) [147], Preparation of this film involved galvanostatic polymerization of pyrrole, in the presence of SDS, on the platinum-film-sputtered electrode of a quartz resonator. Typically, a 1-mA current was passed for 1 min through the solution, which was 0.1 mM in pyrrole, 1 mM in SDS and 0.1 M in the TRIS buffer (pH = 9.0). A carbon rod and the Pt-film electrode was used as the cathode and anode, respectively. The SDS template was then removed by rinsing the MlP-film coated Pt electrode with water. The chemosensor response was measured in a differential flow mode, at a flow rate of 1.2 mL min-1, with the TRIS buffer (pH = 9.0) as the reference solution. This response was affected by electropolymerization parameters, such as solution pH, electropolymerization time and monomer concentration. Apparently, electropolymerization of pyrrole at pH = 9.0 resulted in an MIP film featuring high sensitivity of 283.78 Hz per log(conc.) and a very wide linear concentration range of 10 pM to 0.1 mM SDS. 

A nitrate-selective potentiometric MIP chemosensor has been devised [197, 198]. For preparation of this chemosensor, a polypyrrole film was deposited by pyrrole electropolymerization on a glassy carbon electrode (GCE) in aqueous solution of the nitrate template. Potentiostatic conditions of electropolymerization used were optimized for enhanced affinity of the resulting MIP film towards this template. In effect, selectivity of the chemosensor towards nitrate was much higher than that to the interfering perchlorate ( o3 cio4 = 5.7 x 10-2) or iodide ( N03, r = x 10 2) anion. Moreover, with the use of this MIP chemosensor the selectivity of the nitrate detection has been improved, as compared to those of commercial ISEs, by four orders of magnitude at the linear concentration range of 50 pM to 0.5 M and LOD for nitrate of (20 10) pM [197]. 

R. Garjonyte and A. Malinauskas, Glucose biosensor based on glucose oxidase immobilized in electropolymerized polypyrrole and poly(o-phe-nylenediammine) films on a Prussian blue-modified electrode, Sens. Actuators B, 63 (2000) 122-128. 

An interesting composite material has been prepared by the electropolymerization of pyrrole on polyacetylene electrodes (45). Because oxidized polypyrrole is far more stable in air than polyacetylene, the resulting composite has the stability of polypyrrole. With different synthetic conditions, either a thin layer of polypyrrole was deposited over individual fibrils of the polyacetylene film or a dense polypyrrole film coated the entire film. When the dense polypyrrole film covered the entire polyacetylene film, the interior... 

Lowe and co-workers investigated covalent immobilization of enzyme in polypyrrole film [123,124]. First, pyrrole-modified enzyme was prepared by reacting glucose oxidase with either W-(3-aminopropyl)pyrrole or N- 2-carboxyethyl)pyrrole, then electropolymerized enzyme films, which covalently immobilize enzyme were deposited at platinum disk electrodes from solutions of free pyrrole and native or pyrrole modified enzyme of equivalent activity. They observed that sensors constructed of covalently electropolymerized GOx films demonstrated higher enzyme activity than those using entrapped native... 

More recently Bouzek et al. investigated the effect of the preparation conditions of Pt-modified polypyrrole films on their electrocatalytic properties for the HOR [26]. Three methods were considered (1) cathodic deposition of Pt from H2PtCl6 in the previously synthesized film, (2) incorporation of colloidal Pt particles during the electropolymerization of polypyrrole (3) incorporation of [PtCU] as a counter-ion during the electropolymerization process and its subsequent reduction. Only the first two methods lead to active electrocatalytic films, whereas the last one gives very poor catalysts, maybe because the Pt particles are embedded in the PPy structure and therefore are not accessible to the reactant. 

Electropolymerization of Polypyrrole Films in Aqueous Solution with Side-Coupler Agent to Hydrophobic Groups... 

By producing PPy films, electrical conductivities up to 150 S/cm can be obtained. Electropolymerized PPy films differ in their molecular structure according to polymerization conditions such as the electrochemical parameters of the polymerization. At low current densities (l.c.d.) below 3 mA/cm one-dimensional polypyrrole chain structures are mainly produced [3]. Higher current densities predominantly lead to two-dimensional molecular polymer structures. The electronic state of such PPy films produced with high current density (h.c.d.) has been investigated by several solid-state spectroscopic methods such as ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS), as well as temperature-dependent electrical conductivity measurements [4-6]. 

Bhat N. V., Gadre A. P, and Bambole V. A., Investigation of electropolymerized polypyrrole composite film Characterization and application to gas sensors, J. Appl. Polym. 

Illustration of this effect in the case of a two-step process for aniline electropolymerization on mild steel and zinc from an aqueous electrolyte was reported by Lacroix et In acidic medium (the usual conditions for the electrodeposition of PANI) the direct electropolymerization of aniline on zinc or steel fails, because large amounts of metal dissolve before the aniline polymerizes. This can be avoided if the surface is first treated by depositing a thin polypyrrole film in neutral salicylate medium. This PPy layer behaves as a thin noble-metal layer and can be used for the electrodeposition of a PANI film of controllable thickness in an acidic medium. Using this pretreatment, no or very little metal dissolution occurs in this second step. The films exhibit very stable electroactivity in acidic electrolytes, similar to that of PANI deposited on platinum, which indicates that the underlying oxidizable metal is fully protected (Figure 16.1). 

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