The charge transport properties of the redox gels formed from the copolymerization of vinylferrocene (VF) with acrylamide and N,N‘-methylenebisacrylamide (PVAB gels) are described. The apparent electron diffusion coefficients (D ap) measured by cyclic voltammetry and chronocoulometry exhibit an upward bowlike curvature vs immobilized VF concentration ([VF]imm) within the range 0.1−1.60 mM in 0.10 M supporting electrolyte (NaH2PO4/Na2HPO4, NaClO4, or NaNO3). The range of measured D ap values [(0.6−6.0) × 10-7 cm2 s-1] can be interpreted in terms of the mean-field model developed by Blauch and Savéant (Blauch, D. N.; Savéant, J. M. J. Am. Chem. Soc. 1992, 114, 3323). The large D ap values are attributed to the large λ (range of molecular motion permitted to the ferrocene residues) and large k ex (bimolecular electron self-exchange rate constant of the ferrocenes in the PVAB gels). It was further observed that D ap decreases on increasing the electrolyte (NaClO4 or NaNO3) concentration from 0.10 to 0.50 M, especially at low (0.1−0.6 mM) and high (1.1−1.6 mM) [VF]imm, resulting in almost flat D ap vs [VF]imm profiles at 0.50 M electrolyte. This observation is attributed to increased nonbonded interactions between the polymer matrix, the redox sites, and the electrolyte upon increasing the electrolyte concentration.

The degradation of S-nitrosothiols (RSNOs) to release NO is believed to be catalyzed by CuI ions, but the mechanism remains unclear. Kinetic experiments have shown that decomposition rates vary significantly with the chemical nature of the RSNO considered. On the basis of first-principles calculations, the catalytic role of CuI ion is investigated for the decomposition of S-nitrosocysteine and its N-acetylated and ethyl ester derivatives, and for S-nitrosohomocysteine. This preliminary study focuses on the CuI-RSNO intermediates involved in the decomposition pathway. The model chemistry has been validated by comparing calculated CuI-ligand binding energies and S-N bond homolysis energies with available experimental data. Calculations show that the formation of CuI-RSNO intermediates results in weakening of the S-N bond and strengthening of the N-O bond, which would promote S-N bond breaking and NO release from S-nitrosothiols.

Enzyme electrodes were fabricated by entrapping glucose oxidase (GOx) in charged ferrocene-containing redox gels formed by the copolymerization of vinylferrocenehydroxypropyl-β-cyclodextrin inclusion complex, acrylamide, and N,N ′-methylenebis(acrylamide), together with a positively or negatively charged monomer at pH 7, in the presence of GOx in aqueous solution. The one-step polymerization procedure was initiated by a ternary catalyst system consisting of flavin mononucleotide, H 2 O 2 , and N,N,N ′,N ′-tetramethylethylenediamine. The effects of varying the concentration and structure of the charged monomers on the electrochemical properties of the charged redox gels with and without GOx were investigated, and the pH-activity profiles of entrapped GOx were examined. The storage and operational stabilities of the sensors were established, and the influence of the interferents ascorbic acid, acetaminophen, and uric acid, which are present in body fluids, on the amperometric signals of the sensors was determined.