Electrodeposition polymers as immobilization matrices in amperometric biosensors: improved polymer synthesis and biosensor fabrication

Electrodeposition polymers can be precipitated on electrode surfaces upon electrochemical-induced modulations of the pH value in the diffusion zone in front of the electrode. The formed polymer films can be used as immobilization matrices in amperometric biosensors. In order to rationally control the thus obtained biosensor properties, it is indispensable to develop strategies for the reproducible synthesis of electrodeposition polymers as well as methods for the non-manual and reproducible sensor fabrication. Based on instrumental developments such as a specifically designed parallel synthesizer with improved stirring and temperature control, an automatic pipetting robot for the preparation of the monomer mixtures and controlled removal of polymerization inhibitors, the reproducible synthesis of libraries of electrodeposition polymers was achieved. Moreover, the polymerization process could be monitored using in-line thermocouples, and it could be shown that the chosen strategies led to reproducible polymerization reactions. By adaptation of an electrochemical robotic system integrating a Au microtiter plate and automatic electrode cleaning by means of a polishing wheel reproducible biosensor fabrication using glucose oxidase as a model enzyme could be demonstrated. These results open the route for the rational development of biosensors and control of the sensor properties by choosing specifically designed electrodeposition polymers.      

Synthesis,electrochemistry and in situ spectroelectrochemistry of water-soluble phthalocyanines

The synthesis, characterization and voltammetric and spectroelectrochemical properties of newly synthesized metal-free and metallo phthalocyanines (M = Co, Cu, Zn) containing four dialkylaminophenoxy or trialkylammoniumphenoxy substituents on peripheral positions have been presented in this work. The new compounds have been characterized by using elemental analysis, UV–Vis, FT-IR, ¹H NMR and MS spectroscopic data. Phthalocyanines with trialkylammoniumphenoxy substituents are soluble in aqueous solution over a wide pH range, and these compounds are present as aggregated species in solution as confirmed by the blue shift of Q-bands in their electronic spectra. The electrochemical behavior of the phthalocyanines was investigated by cyclic voltammetry and differential pulse voltammetry on a platinum-working electrode in DCM and DMSO. The voltammetric and spectroelectrochemical measurements of the complexes show that while cobalt phthalocyanine gives both ligand- and metal-based redox processes, metal-free, zinc and copper phthalocyanine complexes give only ligand-based processes in harmony with common phthalocyanine complexes.     

Synthesis of phenylacetylene containing 1,2,3-triazole group

Bromination of (E)-1-[4-(2-carboxy-vinyl)phenyl]-[1,2,3]triazole-4-carboxylic acid ethyl ester, which was synthesized in 90% yield by a Huisgen-type [3 + 2]-cycloaddition reaction between 3-(4-azidophenyl) acrylic acid and ethyl propiolate, in CHCl₃ followed by a debrominative decarboxylation reaction with Et₃N in DMF under microwave irradiation condition afforded stereoselective (Z)-1-(4-(2-bromovinyl)phenyl)-1,2,3-triazole-4-carboxylic acid ethyl ester in 94% yield. Treatment of (Z)-1-(4-(2-bromovinyl)phenyl)-1,2,3-triazole-4-carboxylic acid ethyl ester with EtONa in DMF afforded 1-(4-ethynylphenyl)-1,2,3-triazole-4-carboxylic acid ethyl ester in a yield of 90%.     

Structure and conductivity in CeNb<Subscript>3</Subscript>O<Subscript>9-δ</Subscript>

Abstract  In the search of new materials for solid oxide fuel cells, a study of the structure and electrical conductivity of Mg-doped and nominally pure CeNb₃O_9-δ was undertaken. This material exhibits an orthorhombic crystal structure as determined by Rietveld refinement. Through a combined study of 4-point DC and AC impedance spectroscopy, it was determined that the material presents oxygen ion conductivity, electron conductivity and electron-hole conductivity according to the partial pressure of oxygen and temperature in agreement with a simple defect chemistry model. Finally, some experiments seem to indicate the presence of proton conduction. Graphical Abstract        

Micro-solid oxide fuel cells: status,challenges, and chances

Abstract  Micro-solid oxide fuel cells (micro-SOFC) are predicted to be of high energy density and are potential power sources for portable electronic devices. A micro-SOFC system consists of a fuel cell comprising a positive electrode-electrolyte-negative electrode (i.e. PEN) element, a gas-processing unit, and a thermal system where processing is based on micro-electro-mechanical-systems fabrication techniques. A possible system approach is presented. The critical properties of the thin film materials used in the PEN membrane are discussed, and the unsolved subtasks related to micro-SOFC membrane development are pointed out. Such a micro-SOFC system approach seems feasible and offers a promising alternative to state-of-the-art batteries in portable electronics. Graphical abstract  Graphical Abstract text      

Key side products due to reactivity of dimethylmaleoyl moiety as amine protective group

Dimethylmaleoyl (DMM) moiety has become an important amine protective group in sugar chemistry. We disclose herein that DMM-containing D-glucosamine analogues, because of their electrophilic nature, are prone to reactions with strong nucleophiles, such as hydrazine, resulting in a set of undesired side products that are difficult to detect, yet proved to be problematic for organic synthesis.     

Study on preparation of modified lubricant containing nano-Schiff base and Schiff base copper complex in W/O microemulsion reactor

A successful preparation of Schiff base and Schiff base copper complex was carried out directly in polar base oil (vegetable oil) using a water/oil microemulsion reactor. The prepared nanometer sized Schiff base and Schiff base copper complex dispersed uniformly and spontaneously in the oil. The nanometer sized particles of the Cu(II) chelate of bissalicylaldehyde-ethylenediamine and the bissalicylaldehyde-ethylenediamine in oil were observed directly by SEM. Owing to a modification of the polar base oil (vegetable oil) by 1 wt % of nano-scale Cu(II) chelate of bissalicylaldehyde-ethylenediamine and 1 wt % of bissalicylaldehyde-ethylenediamine, the last nonseizure load had gone up 40% over that of the original ones. It was verified by AES analysis that steel/steel rubbing pairs went through a selective transfer process under lubrication with the modified polar lubricant. It was suggested that the mechanism of the improvement of tribological characteristics of the modified lubricant was selective transfer effect. An antibacterial activity of the modified lubricant was inspected also. The article is published in the original.     

Preparation of diatomite–TiO<Subscript>2</Subscript> composite for photodegradation of bisphenol-A in water

To enhance the photodegradation performance of pure titanium dioxide (TiO₂), diatomite was used as a porous carrier to immobilize TiO₂ powders using calcination method. The photodegradation of bisphenol-A (BPA; 4,4′-isopropylidenediphenol), which has been listed as one of endocrine disrupting chemicals, was carried out in a batch suspension reactor using pure TiO₂ powders and diatomite–TiO₂ composites, respectively. Under the controlled conditions, the photocatalytic efficiencies of the BPA degradation by the diatomite–TiO₂ composites can be found to be higher than those by pure TiO₂ powders. This result should be attributable to the accessibility of the BPA molecules to the surface of TiO₂ particle in the modified photocatalysts, showing that the enrichment of the organic solute enhanced the rate of photodegradation on the diatomite–TiO₂ composite. However, the photodegradation efficiency was not dependent on the pore properties of these TiO₂ photocatalysts. The experimental results further indicated that the photodegradation kinetics for the destruction of BPA in water followed the first-order model well. The apparent first-order reaction constants (k _obs), thus obtained from the fittings of the model, were in line with the destruction-removal efficiencies of BPA in all the photocatalytic experiments.     

Enzyme-functionalized mesoporous silica for bioanalytical applications

The unique properties of mesoporous silica materials (MPs) have attracted substantial interest for use as enzyme-immobilization matrices. These features include high surface area, chemical, thermal, and mechanical stability, highly uniform pore distribution and tunable pore size, high adsorption capacity, and an ordered porous network for free diffusion of substrates and reaction products. Research demonstrated that enzymes encapsulated or entrapped in MPs retain their biocatalytic activity and are more stable than enzymes in solution. This review discusses recent advances in the study and use of mesoporous silica for enzyme immobilization and application in biosensor technology. Different types of MPs, their morphological and structural characteristics, and strategies used for their functionalization with enzymes are discussed. Finally, prospective and potential benefits of these materials for bioanalytical applications and biosensor technology are also presented. Figure Enzyme-functionalized mesoporous silica fibers and their integration in a biosensor design. The immobilization process takes place essentially in the silica micropores.     

Batch Experiments for the Determination of the Ti(IV,III) Couple Formal Potential in 1 mol⋅dm<Superscript>−3</Superscript> HCl, 2 mol⋅dm<Superscript>−3</Superscript> NaCl Medium at 25 °C

The determination of the Ti(IV,III) redox couple formal potential in 1 mol⋅dm⁻³ HCl, 2 mol⋅dm⁻³ NaCl medium at 25 °C through batch experiments involving the preparation of Ti(IV) and Ti(III) mixtures via the reaction of Ti(IV) with zinc amalgam, has been carried out with Emf measurements in order to verify the correctness of the previous value that the authors obtained by a coulometric-potentiometric investigation in the same conditions. The results from the two independent methods are in good agreement: (9±1) mV by the first method and (9±2) mV by the average batch result.