Hybrid nickel hexacyanoferrate/polypyrrole composite as mediator for hydrogen peroxide detection and its application in oxidase-based biosensors

The synthesis and electrochemical characterization of a new organic/inorganic hybrid material was performed by combining polypyrrole and a hexacyano metalate (nickel hexacyanoferrate (NiHCNFe)) aiming to obtain an electrocatalyst for H₂O₂ reduction in the presence of either Na⁺ or K⁺ ions. The use of this material as a redox mediator in an oxalate biosensor based on the immobilization of oxalate oxidase enzyme was also discussed. The electrochemical properties of the hybrid material were investigated by using impedance measurements and compared with those of the nickel hexacyanoferrate film alone. The electrocatalytic properties of the hybrid for reducing H₂O₂, in the presence of both Na⁺ and K⁺ ions, are higher than those of the NiHCNFe film due to the presence of polypyrrole chains that enhances the electronic conductivity of the material.     

Review of emerging temporomandibular joint total joint replacement systems

Total temporomandibular joint (TMJ) replacement has been documented as a viable option for the management of end-stage TMJ disease, but data on long-term outcomes have been reported for only two established systems: TMJ Concepts, and Zimmer Biomet. Other devices are now emerging globally, but reports of preclinical laboratory and clinical outcomes are limited. We retrieved information on the design, material composition, preclinical laboratory tests, regulatory status, and clinical outcomes of new TMJ replacement systems from PubMed and Google, and from personal correspondence with surgeons worldwide. Fifteen countries have developed, or are developing, 27 TMJ replacement systems, of which 21 are custom-designed, but to date, only four have been given regulatory approval. All the devices are designed to have both a skull-based glenoid fossa component and a mandibular ramus or condyle, and 22/27 are similar to the designs of the two established systems. Twenty-one devices use an ultra-high-molecular-weight polyethylene (UHMWPE) fossa-bearing surface, and 10 have a titanium alloy condyle. Nineteen manufacturers report that a titanium alloy is used for the ramus portion of the condyle/ramus component. Preclinical laboratory tests on 12 of the systems have been reported but, to our knowledge, no outcomes have yet been reported on nine of the 27 reviewed. Not all systems are equal in terms of design, material composition, preclinical laboratory testing, manufacturing methods, regulatory status, and reports of clinical outcomes.     

Novel conducting polyaniline bearing functional groups

A copolymer formed from aniline and o-aminobenzylamine (ABA) was electrochemically synthesized from a solution of ABA and aniline with a mole ratio of 85:15. Its properties were studied by cyclic voltammetry. Relative conductivity measurements have been carried out showing that the copolymer's conductivity can be switched in the same way as that of poly(aniline) (PANI); they also indicate the presence of primary amino groups that allow a later derivatization.Ferrocene carboxaldehyde (FeCp₂CHO) was coupled to the copolymer showing the presence of primary amino groups. This modified polymer also has switching conductivity properties.     

A two-dimensional Born–Oppenheimer treatment of intramolecular electron transfer reactions

The Born–Oppenheimer (BO) formulation of polar solvation is developed and implemented at the semiemperical (PM3) configuration interaction (CI) level, yielding estimates of electron transfer (ET) coupling elements (V₀) for intramolecular ET in several families of radical ion systems. In contrast to the traditional treatment based on a single solvent coordinate and a fixed gas-phase coupling element, the present treatment yields a self-consistent characterization of kinetic parameters in a 2-dimensional solvent framework which includes an exchange coordinate. The dependence of V₀ on inertial solvent contributions and on donor/acceptor separation (r_DA) is discussed.     

Dependence of dimerization of electrogenerated methylalkylviologen radical cations on the length of alkyl chain in the presence of γ-cyclodextrin

The effect of γ-cyclodextrin (γ-CD) on the monomer-dimer equilibria of 1-methyl-1′-alkylviologen radical cations (C₁C_nV⁺: n = 1?10) has been studied by electrochemical and spectroelectrochemical techniques. The apparent dimerization is enhanced upon addition of γ-CD for n = 1?8 and the effect of γ-CD is a maximum for n = 4. This is attributed to the stabilization of dimers by the inclusion of the dimer in the cavity of γ-CD. However, the dimerization of C₁C₉V^?+ and C₁C₁₀V^?+, which exhibits strong tendencies of dimerization in the absence of γ-CD due to electrodeposition of the radical cations, is suppressed upon addition of γ-CD. From the dependence of the apparent dimerization constants on the concentration of γ-CD, the association constants of the dimer (K_C2) and monomer (K_C1) with γ-CD were determined for n = 1?8. Comparing the present results with our previous report with dialkylviologen radical cations (C_nCV^?+: n = 1?5), we show that the dimers with the longer alkyl substituents in the same and opposite sides have little difference in their stability in the absence of γ-CD, but the former type of dimer is included preferentially in the cavity of γ-CD.