Assembly of electroactive layer-by-layer films of myoglobin and small-molecular phytic acid

In the present work, small-molecular phytic acid (PA) with its unique structure was successfully assembled with myoglobin (Mb) into {PA/Mb}_n layer-by-layer films on solid surfaces. Quartz crystal microbalance (QCM) and cyclic voltammetry (CV) were used to monitor or confirm the assembly process. IR and UV–vis spectroscopy indicate that the Mb in {PA/Mb}_n films retains its near native structure. The direct electrochemistry of Mb was realized in this new kind of films at pyrolytic graphite (PG) electrodes, and was used to electrocatalyze the reduction of various substrates. The interaction between PA and Mb under different pH conditions was also explored. Not only the oppositely charged PA and Mb at pH 5.0, but also the likely charged PA and Mb at pH 9.0, could be assembled into {PA/Mb}_n films. This work provides a novel avenue to fabricate protein multilayer films with small molecules and realizes the direct electrochemistry of redox proteins in the films.     

Electrochemical Investigation of Myoglobin in Layer‐by‐Layer Films Assembled with Sulfonated‐β‐Cyclodextrin

In this work, myoglobin (Mb) and sulfonated‐β‐cyclodextrin (S‐CD) were assembled into {S‐CD/Mb}_n layer‐by‐layer films on solid substrates. In pH 7.0 buffers, the {S‐CD/Mb}_n films assembled on electrodes showed a pair of well‐defined and nearly reversible CV peaks at about ?0.35 V vs. SCE. The stable CV response of {S‐CD/Mb}_n films could be used to electrocatalyze reduction of oxygen and hydrogen peroxide in solution. For comparison, another modified β‐cyclodextrin, carboxyethyl‐β‐cyclodextrin (C‐CD), was also assembled with Mb into {C‐CD/Mb}_n multilayer films. The driving forces of the assembly were explored and discussed.     

Loading behavior of {chitosan/hyaluronic acid}n layer-by-layer assembly films toward myoglobin: an electrochemical study

When {CS/HA}n layer-by-layer films assembled by oppositely charged chitosan (CS) and hyaluronic acid (HA) were immersed in myoglobin (Mb) solution at pH 5.0, Mb was gradually loaded into the {CS/HA}n films, designated as {CS/HA}n-Mb. The cyclic voltammetric (CV) peak pair of Mb FeIII/FeII redox couple for {CS/HA}n-Mb films on pyrolytic graphite (PG) electrodes was used to investigate the loading behavior of {CS/HA}n films toward Mb. The various influencing factors, such as the number of bilayers (n), the pH of Mb loading solution, and the ionic strength of solution, were investigated by different electrochemical methods and other techniques. The results showed that the main driving force for the bulk loading of Mb was most probably the electrostatic interaction between oppositely charged Mb in solution and HA in the films, while other interactions such as hydrogen bonding and hydrophobic interaction may also play an important role. Other polyelectrolyte multilayer (PEM) films with different components were compared with {CS/HA}n films in permeability and Mb loading, and electroactive probes with different size and surface charge were compared in their incorporation into PEM films. The results suggest that due to the unique structure of CS and HA, {CS/HA}n films with relatively low charge density are packed more loosely and more easily swelled by water, and have better permeability, which may lead to the higher loading amount and shorter loading time for Mb. The protein-loaded PEM films provide a new route to immobilize redox proteins on electrodes and realize the direct electrochemistry of the proteins.     

Comparative Permeation Study of Different Types of Myoglobin Layer‐by‐Layer Films and the Effect of Film Permeability on Their Electrochemistry and Electrocatalysis

Three different types of myoglobin (Mb) layer‐by‐layer films were assembled respectively with TiO₂ sol‐gel by vapor‐surface deposition, TiO₂ nanoparticles, and poly(styrenesulfonate), designated as {SG‐TiO₂/Mb}_n, {NP‐TiO₂/Mb}_n, and {PSS/Mb}_n. The permeability of the films was studied and compared by rotating disk voltammetry (RDV) and electrochemical impedance spectroscopy (EIS) with different electroactive probes, showing a general permeability sequence of {SG‐TiO₂/Mb}_n>{NP‐TiO₂/Mb}_n>{PSS/Mb}_n. The electrochemical and electrocatalytic activity of Mb in these films were also investigated and compared by cyclic voltammetry (CV), RDV, and amperometry, indicating that among the three Mb films, {SG‐TiO₂/Mb}_n films demonstrated the highest maximum surface concentration of electroactive Mb and the best electrocatalytic performances toward reduction of H₂O₂. All these advantages could be attributed to the unique architecture and porous structure of {SG‐TiO₂/Mb}_n films, which could greatly facilitate the mass transport of small counterions and catalytic substrates within the films. The various influencing factors on the permeability, electrochemistry, and electrocatalysis of the Mb films were also investigated in detail.     

Influence of Ionic Strength on Electrochemical Responses of Myoglobin Loaded in Polysaccharide Layer‐by‐Layer Assembly Films

Two polysaccharides hydroxyethyl cellulose ethoxylate (HECE) and hyaluronic acid (HA) were assembled into {HECE/HA}_n layer‐by‐layer films on electrodes. The films were then immersed in myoglobin (Mb) solutions to load Mb into the films. The Mb‐loaded films showed a nearly reversible cyclic voltammetric (CV) peak pair at ?0.34 V vs. SCE in pH 7.0 buffers. The effect of ionic strength in Mb loading solutions and CV testing solutions on the CV response of the films was investigated. The direct electrochemistry of Mb loaded in the films could also be used to electrocatalyze the reduction of oxygen and H₂O₂ in solution.     

Direct Electrochemistry and Electrocatalysis of Myoglobin with Ionic Liquid through Multilayers Film on Carbon Ionic Liquid Electrode

Multilayers of myoglobin (Mb) with ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM]BF₄) was assembled on carbon ionic liquid electrode (CILE) based on the electrostatic attraction between the negatively charged Mb and the positively charged imidazolium ion of IL. The CILE was fabricated with 1‐ethyl‐3‐methylimidazolium ethylsulfate ([EMIM]EtOSO₃) as the modifier, which exhibited imidazolium ion on the electrode surface. Then Mb molecules were assembled on the surface of CILE step‐by‐step to get a {IL/Mb}_n multilayer film modified electrode. UV‐Vis adsorption and FT‐IR spectra indicated that Mb remained its native structure in the IL matrix. In deaerated phosphate buffer solution (pH 7.0) a pair of well‐defined quasi‐reversible redox peaks appeared with the apparent formal potential (E^0′) as ‐0.212 V (vs. SCE), which was the characteristic of Mb heme Fe(III)/Fe(II) redox couples. The results indicated that the direct electron transfer of Mb was realized on the modified electrode. The {IL/Mb}_n/CILE displayed excellent electrocatalytic ability to the trichloroacetic acid reduction in the concentration range from 2.0 to 22.0 mmol/L with the detection limit of 0.6 mmol/L (3σ). The proposed method provides a new platform to fabricate the third generation biosensor based on the self‐assembly of redox protein with ILs.     

Electrochemical myoglobin biosensor based on carbon ionic liquid electrode modified with Fe3O4@SiO2 microsphere

In this paper, a Fe₃O₄@SiO₂ core-shell structure microsphere was synthesized and used to investigate the direct electron transfer of myoglobin (Mb) with a 1-butylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the substrate electrode. The mixture of Mb and Fe₃O₄@SiO₂ microsphere could form an organic–inorganic composite, which was immobilized on the surface of CILE with a chitosan (CS) film. Cyclic voltammetric experiments indicated that a pair of well-defined quasi-reversible redox peaks appeared on CS/Mb-Fe₃O₄@SiO₂/CILE with the formal peak potential (E ^0′) located at ?0.31 V (vs. saturated calomel electrode), which was corresponded to the electroactive center of Mb heme Fe(III)/Fe(II) redox couples. Direct electrochemical behaviors of Mb in CS-Fe₃O₄@SiO₂ composite film were carefully investigated with the electrochemical parameters calculated. The CS/Mb-Fe₃O₄@SiO₂/CILE showed good electrocatalytic behaviors to the reduction of trichloroacetic acid in the concentration range from 0.2 to 11.0 mmol L^?1 with the detection limit of 0.18 mmol L^?1 (3σ). Based on CS/Mb-Fe₃O₄@SiO₂/CILE, a new third-generation reagentless electrochemical biosensor was constructed with higher sensitivity and reproducibility.     

Long Distance Electron Transfer Across >100 nm Thick Au Nanoparticle/Polyion Films to a Surface Redox Protein

Glutathione‐decorated 5 nm gold nanoparticles (AuNPs) and oppositely charged poly(allylamine hydrochloride) (PAH) were assembled into {PAH/AuNP}_n films fabricated layer‐by‐layer (LbL) on pyrolytic graphite (PG) electrodes. These AuNP/polyion films utilized the AuNPs as electron hopping relays to achieve direct electron transfer between underlying electrodes and redox proteins on the outer film surface across unprecedented distances >100 nm for the first time. As film thickness increased, voltammetric peak currents for surface myoglobin (Mb) on these films decreased but the electron transfer rate was relatively constant, consistent with a AuNP‐mediated electron hopping mechanism.     

Assembly of layer-by-layer films of heme proteins and single-walled carbon nanotubes: electrochemistry and electrocatalysis

After being treated by mixed acids, single-walled carbon nanotubes (SWNTs) were shortened and had negatively charged groups on the surface. Positively charged hemoglobin or myoglobin at pH 5.0 was successfully assembled with SWNTs into layer-by-layer films on solid surfaces, designated as {SWNT/protein} _n . While only those proteins in the first few bilayers closest to the electrode surface exhibited electroactivity, the {SWNT/protein} _n films demonstrated a much higher fraction of electroactive proteins and better controllability in film construction compared with cast films of the proteins and carbon nanotubes. The proteins in the {SWNT/protein} _n films retained their near-native structure at medium pH. The stable protein film electrode showed good electrocatalytic properties toward reduction of oxygen and hydrogen peroxide, demonstrating the potential application of the {SWNT/protein} _n films as a new type of biosensor based on the direct electrochemistry of proteins without using mediators. Figure Cyclic voltammograms at 0.2 V s⁻¹ in pH 7.0 buffers with different number of bilayers (n) for layer-by-layer {single-walled carbon nanotube/hemoglobin} _n films.     

Amperometric Hydrogen Peroxide Biosensor Based on the Immobilization of Horseradish Peroxidase (HRP) on the Layer‐by‐Layer Assembly Films of Gold Colloidal Nanoparticles and Toluidine Blue

The precursor film was first formed on the Au electrode surface based on the self‐assembly of L ‐cysteine and the adsorption of gold colloidal nanoparticles (nano‐Au). Layer‐by‐layer (LBL) assembly films of toluidine blue (TB) and nano‐Au were fabricated by alternately immersing the electrode with precursor film into the solution of toluidine blue and gold colloid. Cyclic voltammetry (CV) and quartz crystal microbalance (QCM) were adopted to monitor the regular growth of {TB/Au} bilayer films. The successful assembly of {TB/Au}_n films brings a new strategy for electrochemical devices to construct layer‐by‐layer assembly films of nanomaterials and low molecular weight materials. In this article, {TB/Au}_n films were used as model films to fabricate a mediated H₂O₂ biosensor based on horseradish peroxidase, which responded rapidly to H₂O₂ in the linear range from 1.5×10^?7 mol/L to 8.6×10^?3 mol/L with a detection limit of 7.0×10^?8 mol/L. Morphologies of the final assembly films were characterized with scanning probe microscopy (SPM).     

pH-dependent behaviors of electroactive myoglobin loaded into layer-by-layer films assembled with alginate and hydroxyethyl cellulose ethoxylate

In the present work, strong polybase quaternized hydroxyethyl cellulose ethoxylate (HECE) and weak polyacid alginate (AA) were assembled into {HECE/AA} n layer-by-layer (LBL) films on electrodes by electrostatic interaction between them, and the films were then immersed in myoglobin (Mb) solution to load Mb into the films, designated as {HECE/AA}n-Mb. The {HECE/AA}n-Mb films showed a nearly reversible cyclic voltammetric (CV) peak pair at about -0.34 V vs SCE in pH 7.0 buffers for Mb heme Fe(III)/Fe(II) redox couple, and the surface concentration of electroactive Mb in the films (Gamma*) was affected significantly by the pH of Mb loading solution and testing solution. The amount of Mb loaded from pH 5.0 solution was much larger than that from pH 9.0 solution, which is mainly attributed to the higher degree of swelling, porosity, and permeability of {HECE/AA}n films at pH 5.0 than at pH 9.0. In addition, the electrostatic interaction between Mb and the AA component in the films might also play an important role in Mb loading. The pH of the testing solution where {HECE/AA}n-Mb films were tested by CV also influenced the Gamma* value, showing that the fraction of electroactive Mb among the total Mb loaded into the films increased remarkably as the pH of the testing solution decreased. This result is rationalized in terms of the pH-dependent film permeability toward counterions and the electron-hopping mechanism in electron transfer of redox proteins in the film phase. This model system may provide a general and effective approach to control the electroactivity of immobilized redox proteins in the multilayer assembly containing weak polyions by adjusting pH and may guide us to develop the new kind of controllable electrochemical biosensors based on the direct electrochemistry of enzymes.     

Fabrication of electroactive layer-by-layer films of myoglobin with gold nanoparticles of different sizes

Alternate adsorption of oppositely charged myoglobin (Mb) and gold nanoparticles with different sizes were used to assemble {Au/Mb}n layer-by-layer films on solid surfaces by electrostatic interaction between them. The direct electrochemistry of Mb was realized in {Au/Mb}n films at pyrolytic graphite (PG) electrodes, showing a pair of well-defined, nearly reversible cyclic voltammetry (CV) peaks for the Mb heme FeIII/FeII redox couple. Quartz crystal microbalance (QCM), electrochemical impedance spectroscopy (EIS), and CV were used to monitor or confirm the growth of the films. Compared with other Mb layer-by-layer films with nonconductive nanoparticles or polyions, {Au/Mb}n films showed much improved properties, such as smaller electron-transfer resistance (Rct) measured by EIS with Fe(CN)3-/4- redox probe, higher maximum surface concentration of electroactive Mb (Gamma*max), and better electrocatalytic activity toward reduction of O2 and H2O2, mainly because of the good conductivity of Au nanoparticles. Because of the high biocompatibility of Au nanoparticles, adsorbed Mb in the films retained its near native structure and biocatalytic activity. The size effect of Au nanoparticles on the electrochemical and electrocatalytic activity of Mb in {Au/Mb}n films was investigated, demonstrating that the {Au/Mb}n films assembled with smaller-sized Au nanoparticles have smaller Rct, higher Gamma*max, and better biocatalytic reactivity than those with larger size.     

Fabrication of Chitosan‐Multiwall Carbon Nanotube Nanocomposite Containing Ferri/Ferrocyanide: Application for Simultaneous Detection of D‐Penicillamine and Tryptophan

We report a simple and effective strategy for fabrication of the nanocomposite containing chitosan (CS) and multiwall carbon nanotube (MWNT) coated on a glassy carbon electrode (GCE). The characterization of the modified electrode (CS‐MWNT/GC) was carried out using scanning electron microscopy (SEM) and UV–vis absorption spectroscopy. The electrochemical behavior of CS‐MWNT/GC electrode was investigated and compared with the electrochemical behavior of chitosan modified GC (CS/GC), multiwalled carbon nanotube modified GC (MWNT/GC) and unmodified GC using cyclic voltammetry (CV) and electron impedance spectroscopy (EIS). The chitosan films are electrochemically inactive; similar background charging currents are observed at bare GC. The chitosan films are permeable to anionic Fe(CN)₆^3?/4? (FC) redox couple. Electrochemical parameters, including apparent diffusion coefficient for the Fe(CN)₆^3?/4? redox probe at FC/CS‐MWNT/GC electrode is comparable to values reported for cast chitosan films. This modified electrode also showed electrocatalytic effect for the simultaneous determination of D‐penicillamine (D‐PA) and tryptophan (Trp). The detection limit of 0.9 μM and 4.0 μM for D‐PA and Trp, respectively, makes this nanocomposite very suitable for determination of them with good sensitivity.     

Electron Transfer in the Cs⊂{Mn4Fe4} Cubic Switch: A Soluble Molecular Model of the MnFe Prussian-Blue Analogues

A mixed-valence {Mn^II₃Mn^IIIFe^II₂Fe^III₂} cyanide-bridged molecular cube hosting a caesium cation, Cs⊂{Mn₄Fe₄}, was synthesized and structurally characterized by X-ray diffraction. Cyclic-voltammetry measurements show that its electronic state can be switched between five different redox states, which results in a remarkable electrochromic effect. Magnetic measurements on fresh samples point to the occurrence of a spin-state change near room temperature, which could be ascribed to a metal-to-metal electron transfer converting the {Fe^II−CN−Mn^III} pair into a {Fe^III−CN−Mn^II} pair. This feature was only previously observed in the polymeric MnFe Prussian-blue analogues (PBAs). Moreover, this novel switchable molecule proved to be soluble and stable in organic solvents, paving the way for its integration into advanced materials.     

Layer-by-layer deposition of open-pore mesoporous TiO<Subscript>2</Subscript>-Nafion® film electrodes

The formation of variable thickness TiO₂ nanoparticle-Nafion® composite films with open pores is demonstrated via a layer-by-layer deposition process. Films of about 6 nm diameter TiO₂ nanoparticles grow in the presence of Nafion® by “clustering” of nanoparticles into bigger aggregates, and the resulting hierarchical structure thickens with about 25 nm per deposition cycle. Film growth is characterized by electron microscopy, atomic force microscopy, and quartz crystal microbalance techniques. Simultaneous small-angle X-ray scattering and wide-angle X-ray scattering measurements for films before and after calcination demonstrate the effect of Nafion® binder causing aggregation. Electrochemical methods are employed to characterize the electrical conductivity and diffusivity of charge through the TiO₂-Nafion® composite films. Characteristic electrochemical responses are observed for cationic redox systems (diheptylviologen^2+/+, \({\text{Ru}}{\left( {{\text{NH}}_{3} } \right)}^{{3 + /2 + }}_{6} \), and ferrocenylmethyl-trimethylammonium^2+/+) immobilized into the TiO₂-Nafion® nanocomposite material. Charge conduction is dependent on the type of redox system and is proposed to occur either via direct conduction through the TiO₂ backbone (at sufficiently negative potentials) or via redox-center-based diffusion/electron hopping (at more positive potentials).     

Electron Transfer in the Cs⊂{Mn4Fe4} Cubic Switch: A Soluble Molecular Model of the MnFe Prussian‐Blue Analogues

A mixed‐valence {Mn^II₃Mn^IIIFe^II₂Fe^III₂} cyanide‐bridged molecular cube hosting a caesium cation, Cs?{Mn₄Fe₄}, was synthesized and structurally characterized by X‐ray diffraction. Cyclic‐voltammetry measurements show that its electronic state can be switched between five different redox states, which results in a remarkable electrochromic effect. Magnetic measurements on fresh samples point to the occurrence of a spin‐state change near room temperature, which could be ascribed to a metal‐to‐metal electron transfer converting the {Fe^II?CN?Mn^III} pair into a {Fe^III?CN?Mn^II} pair. This feature was only previously observed in the polymeric MnFe Prussian‐blue analogues (PBAs). Moreover, this novel switchable molecule proved to be soluble and stable in organic solvents, paving the way for its integration into advanced materials.     

Multilayer Assembly of Hemoglobin and Colloidal Gold Nanoparticles on Multiwall Carbon Nanotubes/Chitosan Composite for Detecting Hydrogen Peroxide

Chitosan (CS) was chosen for dispersing multi‐wall carbon nanotubes (MWNTs) to form a stable CS‐MWNTs composite, which was first coated on the surface of a glassy carbon electrode to provide a containing amino groups interface for assembling colloidal gold nanoparticles (GNPs), followed by the adsorption of hemoglobin (Hb). Repeating the assembly step of GNPs and Hb resulted in {Hb/GNPs}_n multilayers. The assembly of GNPs onto CS‐MWNTs composites was confirmed by transmission electron microscopy. The consecutive growth of {Hb/GNPs}_n multilayers was confirmed by cyclic voltammetry and UV‐vis absorption spectroscopy. The resulting system brings a new platform for electrochemical devices by using the synergistic action of the electrocatalytic activity of GNPs and MWNTs. The resulting biosensor displays an excellent electrocatalytic activity and rapid response for hydrogen peroxide. The linear range for the determination of H₂O₂ was from 5.0×10^?7 to 2.0×10^?3 M with a detection limit of 2.1×10^?7 M at 3σ and a Michaelis–Menten constant K_M^app value of 0.19 mM.     

Electrochemical and thermodynamic properties of thulium trichloride in a molten NaCl-KCl-CsCl eutectic

Potentiometric method was used to measure the redox potentials of Tm³⁺/Tm²⁺ in a eutectic melt of sodium, potassium, and cesium chlorides relative to a chlorine reference electrode in the temperature range 823–973 K. The main thermodynamic characteristics of the redox reaction TmCl_2(solution) + 1/2Cl_2(g) ⇆ TmCl_3(solution) were calculate from the conditional standard potentials $ E_{{{Tm^{3 + } } \mathord{\left/ {\vphantom {{Tm^{3 + } } {Tm^{2 + } }}} \right. \kern-\nulldelimiterspace} {Tm^{2 + } }}}^* $ E_{{{Tm^{3 + } } \mathord{\left/ {\vphantom {{Tm^{3 + } } {Tm^{2 + } }}} \right. \kern-\nulldelimiterspace} {Tm^{2 + } }}}^* .     

Layer-by-layer self-assembly and electrocatalytic properties of poly(ethylenimine)-silicotungstate multilayer composite films

Hybrid multilayer films composed of poly(ethylenimine) and the Keggin-type polyoxometalates [ SiW₁₁O₃₉ ]^{8 -} ( SiW₁₁ ) {\left[ {{\hbox{Si}}{{\hbox{W}}_{{11}}}{{\hbox{O}}_{{39}}}} \right]^{{8} - }}\left( {{\hbox{Si}}{{\hbox{W}}_{{11}}}} \right) and [ SiW₁₁Co^II( H₂O )O₃₉ ]^{6 -} ( SiW₁₁Co ) {\left[ {{\hbox{Si}}{{\hbox{W}}_{{11}}}{\hbox{C}}{{\hbox{o}}^{\rm{II}}}\left( {{{\hbox{H}}_2}{\hbox{O}}} \right){{\hbox{O}}_{{39}}}} \right]^{{6} - }}\left( {{\hbox{Si}}{{\hbox{W}}_{{11}}}{\hbox{Co}}} \right) were prepared on glassy carbon electrodes by layer-by-layer self-assembly, and were characterized by cyclic voltammetry and scanning electron microscopy. UV-vis absorption spectroscopy of films deposited on quartz slides was used to monitor film growth, showing that the absorbance values at characteristic wavelengths of the multilayer films increase almost linearly with the number of bilayers. Cyclic voltammetry indicates that the electrochemical properties of the polyoxometalates are maintained in the multilayer films, and that the first tungsten reduction process for immobilized SiW₁₁ and SiW₁₁Co is a surface-confined process. Electron transfer to [ Fe( CN )₆ ]^{3 - /4 -} {\left[ {{\hbox{Fe}}{{\left( {\hbox{CN}} \right)}_6}} \right]^{{3} - /{4} - }} and [ Ru( NH₃ )₆ ]^{3 + /2 +} {\left[ {{\hbox{Ru}}{{\left( {{\hbox{N}}{{\hbox{H}}_3}} \right)}_6}} \right]^{{3} + /{2} + }} as electrochemical probes was also investigated by cyclic voltammetry. The (PEI/SiW₁₁Co)_n multilayer films showed excellent electrocatalytic reduction properties towards nitrite, bromate and iodate.     

Effect of the electropolymerisation conditions on the electrochemical, morphological and structural properties of PEDOTh films

Poly(3,4-ethylenedioxythiophene) (PEDOTh) films were deposited on platinum electrodes by consecutive potential scanning from acetonitrile solutions with 50 mM EDOTh. The effect of the supporting electrolyte used during electropolymerisation, namely LiClO₄, TBAClO₄ and TBAPF₆, in the redox behaviour, surface morphology and degree of crystallinity of the films has been investigated by cyclic voltammetry, X-ray diffraction analysis and scanning electron microscopy, respectively. The use of LiClO₄ leads to a higher electropolymerisation efficiency and an increase of electroactivity and crystallinity of the polymers. This electrolyte promotes the formation of a more compact morphology with clusters of different sizes. The film porosity increases when Li⁺ is substituted by a larger cation, TBA⁺. The PEDOTh layer obtained with as counter ion is more porous than the obtained with and presents a fibrillar aspect. The influence of the scan rate was also studied for films obtained in TBAClO₄, and high electropolymerisation efficiency and an increase of crystallinity were observed for a low scan rate. PEDOTh films with different number of growing cycles were obtained in LiClO₄, pointing their redox behaviour to structural rearrangement during thickening; the thicker film presents higher structural organization. It was possible to prepare films in different conditions, but with the same electroactivity, showing the same structural arrangement.