Preparation of Three‐Dimensional Ordered Macroporous Prussian Blue Film Electrode for Glucose Biosensor Application

Ordered 3D interconnected macroporous Prussian blue (PB) films were electrochemically fabricated by using colloidal crystals of polystyrene beads as sacrificial templates. The prepared PB film electrodes have excellent catalytic activity towards the reduction of hydrogen peroxide. The PB structure was further used as functional interface for fabricating an enzyme‐based glucose sensor by using surface modification technique based on the electrostatic interactions. The resulted sensor has higher functional density, and larger surface area. The interconnected macroporous structure allows enhanced mass transport. These characteristics of the sensor enable us to detect glucose with high sensitivity. Therefore, the present 3D ordered macroporous film sensor exhibits wide linear detection range towards glucose, acceptable reproducibility and operational and storage stability. The present approach is promising for the generation of high‐enzyme‐content thin films with tailored bioactivity.     

Immobilization of glucose oxidase on the films prepared by electrochemical copolymerization of pyrrole and 1-(2-carboxyethyl)pyrrole for glucose sensing

Glucose oxidase (GOx) was immobilized through amide linkages on the surfaces of the conducting polymer films prepared by electrochemical copolymerization of pyrrole (Py) and 1-(2-carboxyethyl)pyrrole (Py-COOH) for the purpose of fabricating GOx-immobilized electrodes for amperometric sensing of glucose. The conductivity of the copolymer film was in the range 10⁻⁸-10⁻³ S/cm and showed a tendency to decrease with increasing content of Py-COOH units in the copolymer. The amount of immobilized GOx increased significantly with increasing content of Py-COOH units in the copolymer film up to 30%, and showed a tendency to level off when the content of Py-COOH units became larger. The activity of immobilized GOx per area of the copolymer film decreased slightly with increasing content of Py-COOH units in the copolymer. Although the GOx-immobilized copolymer films gave the amperometric response to glucose depending on its concentration, the magnitude of the response to a given concentration was found to decrease with increasing content of Py-COOH units in the copolymer. The variation in the amperometric response was attributed to the difference in conductivity of the copolymer film. The appropriate content of Py-COOH units in the copolymer was considered to be 5% or less for the amperometric sensing of glucose with the GOx-immobilized copolymer film.     

Covalent immobilization of glucose oxidase on films prepared by electrochemical copolymerization of 3-methylthiophene and thiophene-3-acetic acid for amperometric sensing of glucose: Effects of polymerization conditions on sensing properties

For the purpose of glucose sensing, enzyme electrodes were fabricated via covalent immobilization of glucose oxidase on the films of conducting polymer. The films were prepared electrochemically by the copolymerization of 3-methylthiophene and thiophene-3-acetic acid. The properties of the films were investigated by taking into account the polymerization conditions (the kind of supporting electrodes, the current, the amount of passed charge, and the monomer concentration) and the dedoping treatment. The glucose sensing performance of the enzyme electrode was found to be affected markedly by the following three factors of the conducting polymer film: surface morphology, conductivity and cohesion with support electrodes. It was suggested that the ideal conducting polymer used for the enzyme electrode should be a thin film having high conductivity and ordered nanostructure.     

Conducting polymer based amperometric enzyme electrodes

The construction and the properties of conducting-polymer based amperometric enzyme electrodes are reviewed. The main aim is to focus on the properties of conducting polymer films which are important for the construction of amperometric enzyme electrodes. Additionally, the review is focused on electron-transfer pathways between conducting-polymer integrated immobilized enzyme molecules and the modified electrode using free-diffusing redox mediators as well as direct electron transfer via the conducting-polymer wires. Possible future applications using microstructured conducting-polymer films will be discussed.     

Inverted Opal Fluorescent Film Chemosensor for the Detection of Explosive Nitroaromatic Vapors through Fluorescence Resonance Energy Transfer

This paper reports an inverted opal fluorescence chemosensor for the ultrasensitive detection of explosive nitroaromatic vapors through resonance‐energy‐transfer‐amplified fluorescence quenching. The inverted opal silica film with amino ligands was first fabricated by the acid–base interaction between 3‐aminopropyltriethoxysilane and surface sulfonic groups on polystyrene microsphere templates. The fluorescent dye was then chemically anchored onto the interconnected porous surface to form a hybrid monolayer of amino ligands and dye molecules. The amino ligands can efficiently capture vapor molecules of nitroaromatics such as 2,4,6‐trinitrotoluene (TNT) through the charge‐transfer complexing interaction between electron‐rich amino ligands and electron‐deficient aromatic rings. Meanwhile, the resultant TNT–amine complexes can strongly suppress the fluorescence emission of the chosen dye by the fluorescent resonance energy transfer (FRET) from the dye donor to the irradiative TNT–amino acceptor through intermolecular polar–polar resonance at spatial proximity. The quenching response of the highly ordered porous films with TNT is greatly amplified by at least 10‐fold that of the amorphous silica films, due to the interconnected porous structure and large surface‐to‐volume ratio. The inverted opal film with a stable fluorescence brightness and strong analyte affinity has lead to an ultrasensitive detection of several ppb of TNT vapor in air.     

Macroporous Oxide Platforms Templated by Non‐Close‐Packed Spherical Copolymer Aggregates

Exclusive organic templating of macroporous oxide films is reported by using non‐close and lose packing of spherical copolymer aggregates, in combination with facile control of condensation degree/density of inorganic oxide frameworks. Unique macroporous oxide films, mainly titania showing highly porous, crystalline, and versatile properties, can be fabricated with continuous design from unusual 3‐D net‐shape to tunable spherical macrostructures, which expands the preparation of other inorganic oxide films (silica, alumina, and zirconia) and possibly adapts the use of other assembled organic polymers. The macroporous structures are helpful for effective accommodation of bulky biomoleculeshigh and diffusivity of organic molecules (useful for photocatalysts). Unusual structural variation, expansion of spherical voids, is also observed, being useful for fine tuning of optical property.     

A glucose/oxygen enzymatic fuel cell based on redox polymer and enzyme immobilisation at highly-ordered macroporous gold electrodes

Highly ordered macroporous electrodes are prepared by electro-deposition of gold through a polystyrene sphere template. Drop-coating redox polymer and either glucose oxidase, for the anode, or Melanocarpus albomyces laccase, for the cathode on the macroporous gold provides film-coated electrodes for assembly of membrane-less glucose/oxygen enzymatic fuel cells (EFC) in pH 7.4 buffer containing 10 mM glucose and 0.15 M NaCl. Under these conditions the maximum power density of 17 μW cm(-2) for EFCs using films adsorbed to planar gold electrodes increased to 38 μW cm(-2) for films adsorbed to 2? sphere gold macroporous electrodes.     

Electrochemical synthesis of PEDOT and PPP macroporous films and nanowire architectures from ionic liquids

We report on the electrochemical synthesis of macroporous films and on nanowire architectures of conducting polymers from ionic liquids. The electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) and of poly(para-phenylene) (PPP) from the air and water stable ionic liquids 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]TFSA) and from 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIm]FAP) within the voids of a polystyrene opal structure on gold and on platinum substrates yield macroporous films. For this purpose, polystyrene spheres with an average diameter of about 600?nm were applied onto the employed electrodes by a simple dipping process resulting in a layer thickness of about 10?μm. The macroporous films turn into yellow, orange, blue, and green colors owing to the Bragg reflection of the incident artificial white light. PPP and PEDOT nanowires were electrochemically prepared in a track-etched polycarbonate (PC) membrane with an average pore diameter of 90?nm. One side of the membrane was sputtered with a thin gold film to serve as a working electrode. Electrodeposition occurs along the pores of the template. Nanowires with an average diameter of 90?nm and a length of up to 17?μm can be easily synthesized by this electrochemical template-assisted method. Such materials are of interest as catalyst in metal/air batteries and as cathode material in, e.g., microbatteries.     

Practical approach for macroporous structure embedded microfluidic system and the catalytic microchemical application

We present a low cost and practical approach to integrate 3D ordered macroporous polyfluoropolyether (PFPE) patterns into a microchannel by a series of porous pattern fabrication processes and subsequent photolithography in a site- and shape-selective manner. The 3D ordered macroporous patterns with high-resolution edges were firstly fabricated by microtransfer molding (μ-TM) of the sacrificial polystyrene (PS) template infiltrated with PFPE as a non-adhesive and solvent-resistant skeletal material. The resulting robust PFPE porous structures with high solvent resistance on a silicon wafer can easily be embedded into the microchannel with the aid of conventional photolithography, leading to a microfluidic system with a built-in microstructure. Moreover, catalytic Pd nanoparticles implanted on the surface of the porous structure were obtained by use of Pd nanoparticle deposited PS spheres, the porous structure embedded channel was utilized to perform a Suzuki coupling reaction.     

Ferrocenyl and permethylferrocenyl cyclic and polyhedral siloxane polymers as mediators in amperometric biosensors

Cyclosiloxane and silsesquioxane-based ferrocenyl and permethylferrocenyl polymers have been used as mediators in amperometric enzyme electrodes for the detection of glucose. Biosensors have been prepared by electrostatically immobilizing the enzyme glucose oxidase (GOx) on electrodes modified with the polymers. The steady-state amperometric response of the sensors is investigated as a function of the applied potential and substrate concentration. The dependence of the sensors response on the structure of the siloxane-framework and on the presence or not of methyl groups on the ferrocenyl units is discussed.     

Electrochemical Behavior and Amperometric Detection of 4‐Chlorophenol on Nano‐Au Thin Films Modified Glassy Carbon Electrode

An amperometric sensor based on nano‐Au thin films was fabricated, by means of which a fast response to 4‐chlorophenol (4‐CP) can be achieved in the range of mM concentrations. The nanostructured Au thin film was prepared on glassy carbon electrodes by a template‐free, double‐potential step electrodeposition technique. Its structural feature can be controlled well by adjusting the deposition time. The amperometric detection of 4‐CP was performed at +0.85 V with a linear detection range from 0.2 to 4.8 mM and a detection limit of 0.11 mM (S/N=3). Besides, the effect of concentrations on the electrochemical behavior of 4‐CP on the Au thin film was investigated by linear sweep voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy.     

Preparation of porous solids composed of layered niobate walls from colloidal mixtures of niobate nanosheets and polystyrene spheres

Macroporous solids with crystalline layered walls were fabricated from colloidal mixtures of size-controlled niobate nanosheets and polystyrene spheres. The macroporous solids, obtained after burning off the spheres, were characterized by scanning electron microscopy and X-ray diffraction. The obtained structures strongly depended on the lateral dimension L of the nanosheets used. When small nanosheets (L=100 nm) were used, partly ordered macroporous solids with interconnected pores were obtained, whereas sponge-like random macroporous structures were obtained with larger nanosheets (L=190 and 270 nm). Peapod-like hollow structures were obtained when we used small (L=190 nm) and very large (L=3 microm) nanosheets at the same time. The microstructure of the pore walls was controllable by changing the calcination conditions. The walls were composed of propylammonium/K(4)Nb(6)O(17) intercalation compound which has a layered structure with exchangeable cations in the interlayer space, stable up to 350 degrees C for 6 h on calcination. The walls were converted to crystalline K(8)Nb(18)O(49) after calcination at 500 degrees C for 6 h.     

Direct electrochemistry of cytochrome c immobilized on a novel macroporous gold film coated with a self-assembled 11-mercaptoundecanoic acid monolayer

We have successfully constructed a novel gold film with open interconnected macroporous walls of nanoparticles by combining the hydrogen bubble dynamic template synthesis with galvanic replacement reaction. After modified by a self-assembled monolayer (SAM) of 11-mercaptoundecanoic acid (MUA), the three-dimensionally (3D) interconnected macroporous Au film has been used as a biocompatible substrate for the immobilization of cytochrome c. The morphology, structure and electrochemical features of the modified and unmodified macroporous Au films were characterized by field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results reveal that the resultant films had a large electroactive surface area for high protein loading, enhanced electron transfer of cytochrome c, retained electrochemical activity, good stability and repeatability. And the excellent electrochemical behaviors could be attributed to the hierarchical structure of the macroporous Au film constructed by nanoparticles.     

Rapid Fabrication of Mesoporous Titania Films with Controlled Macroporosity to Improve Photocatalytic Property

Hierarchically porous titania films were fabricated by dual templating using a triblock copolymer such as Pluronic F127 and polystyrene (PS) beads, affording mesoporous films with controlled macroporosity. The presence of the triblock copolymer in the precursor solutions suppressed a regular accumulation of spherical PS beads, and PS‐derived macropores could be dispersed over the whole mesoporous titania film through rapid fabrication by spin‐coating. Some of the macropores were clustered, but the presence of the large spaces was important for keeping the mesostructure after calcination. Photodegradation of methylene blue (MB) was investigated by using the photoactive anatase films. The photodegradation of MB over the porous anatase films was accelerated by effective diffusion of MB molecules in the PS‐derived macropores, but it was important for improving photocatalytic performance to regulate the balance between the effectiveness of the diffusion in the macropores and the decrease of the surface area from the embedded macropores, as well as the reduction in the transparency of the porous films.     

纳米材料修饰电极上吸附态葡萄糖氧化酶的酶活性和电活性的比较

采用石英晶体微天平(QCM)技术, 监测了裸金(Au)电极、电沉积纳米金的金电极(Au_ed/Au)、多壁碳纳米管(MWCNTs)修饰的金电极(MWCNTs/Au)以及MWCNTs 修饰后再电沉积纳米金的金电极(Au_ed/MWCNTs/Au)上葡萄糖氧化酶(GOx)的吸附过程, 测算了吸附固定的GOx质量. 通过阳极恒电位检测吸附酶与葡萄糖发生酶反应所产生的过氧化氢, 考察了这些酶电极的安培响应, 并测算了各吸附态GOx的质量比生物活性(MSBAi).也通过循环伏安法研究酶的直接电化学, 测算了各吸附态GOx的电活性百分数(EAP_i). 实验结果表明, 酶吸附量和酶电极的安培响应满足MWCNTs/Au > Au_ed/MWCNTs/Au > Au_ed/Au > Au 的顺序; MSBA_i满足Au > Au_ed/MWCNTs/Au > Au_ed/Au > MWCNTs/Au的顺序; 而EAP_i则满足MWCNTs/Au > Au_ed/MWCNTs/Au > Au_ed /Au > Au的顺序. 根据酶和纳米材料的亲疏水作用以及酶的吸附量对实验结果进行了合理解释, 也定量验证了电极上吸附酶分子的总生物活性与酶电极的安培响应呈正相关关系, 所得数据和结论有助于纳米材料固定酶及其安培酶电极的研究.     

Field effect transistors with organic semiconductor layers assembled from aqueous colloidal nanocomposites

We demonstrate field effect transistors based on organic semiconductor molecules dispersed in a self-organized polystyrene (PS) latex bead matrix. An aqueous colloidal composite made of PS and tetrahexylsexithiophene (H4T6) is deposited with a micropipet into the channel of a bottom-contact field effect transistor. The beads self-organize into a network whose characteristic distances are governed by their packing. The semiconductor molecules crystallize in the interstitial voids, leading to the growth of large interconnected domains. Depending on the bead size and the ratio between H4T6 and PS, the fraction of the different phases in the polymorph can be controlled. In the transistors where the H4T6 metastable "red phase" is the largest, the device response and the charge mobility are comparable to those of sexithienyl thin films grown by high-vacuum sublimation.     

三维有序大孔Al2O3制备的新方法及表征

以聚苯乙烯胶晶为模板,用Al(NO3)3•9H2O为前驱物,使用柠檬酸为配体,成功地制备了孔径为250～350 nm的三维有序大孔Al2O3材料.SEM观察表明,所得大孔材料孔结构规则排列,孔与孔之间通过小孔相连,形成了一个三维有序排列的蜂窝状结构.实验发现,以Al(NO3)3•9H2O为前驱物,加入柠檬酸可以防止团聚粒子的产生,有利于三维有序结构的形成.前驱物浓度在0.5～0.8 mol•L－1范围内均能得到较好的三维有序大孔结构.在1 100 ℃焙烧2 h后,Al2O3大孔材料仍能保持完整的规则孔结构特征,表现出较高的热稳定性.     

Colloidal crystal-derived nanoporous electrode materials of Cut SWNTs-assembly and TiO2/SWNTs nanocomposite

Relatively ordered macroporous films of a cut single-walled carbon nanotubes (c-SWNTs) assembly and a TiO 2/c-SWNTs nanocomposite were successfully fabricated by colloidal crystal template processes using polystyrene particles. The macroporous TiO2/c-SWNTs nanocomposite film showed excellent rate capability of Li-insertion/extraction. The rate-dependent Li-insertion/extraction capacities were close to theoretical values expected from Li-diffusion in anatase--TiO2 thin layer without blocking electrolyte-ion and electron access.     

聚乙二醇对苯二甲酸酯-b-聚对苯二甲酸丁二醇酯多嵌段共聚物内部贯通多孔支架的制备方法

以天然或合成的可生物降解材料制备细胞外基质支架是组织工程所涉及到的关键问题之一.常用的制备方法由于涉及到有机溶剂的使用、较高的加工温度以及致孔剂的残余问题,对于活性物质的引入均带来不利影响,相关的改进工作(如不使用有机溶剂和消除残余致孔剂等)尽管也获得了具有良好孔结构的支架,但却使制备过程更趋复杂.     

Evaluation of Poly(o‐phenylenediamine) Films for Application as Insulating Layers upon Carbon Substrates for Use within Sonochemically Fabricated Microelectrode Arrays

The formation of insulating layers of poly(o‐phenylenediamine) via electropolymerization was performed on single carbon screen‐printed electrodes. The effects of experimental parameters on the properties of the film were investigated, allowing for technique optimization. These conditions were then used to deposit films upon surfaces of 100 interconnected electrodes, with cyclic voltammetry used to study the electroactivity of the resulting electrodes. The insulating property of the film, for use in the formation of microelectrode array amperometric sensors, was evaluated. Finally, the insulated sensors were exposed to ultrasonic ablation to form microelectrode arrays, and these were subsequently assessed using optical and electrochemical techniques.