Electrochemical and CD-spectroelectrochemical studies of the interaction between BSA and the complex [Cu(Bztpen)]2+, (Bztpen = (N-benzyl-N, N', N'-tris (pyridin-2-ylmethyl) ethylenediamine).

In this work we report the electrochemical, spectroscopical and spectro-electrochemical studies of a model complex [CuΙΙ(Bztpen)]2+, (Bztpen = (N-benzyl-N,N',N'-tris(pyridin-2-ylmethyl)ethylenediamine) in order to propose a methodology to evaluate the interaction of potential metal based anticancer agents during electron transfer processes, with transport proteins such as Bovine Serum Albumin (BSA). It was possible to establish a reversible electron transfer [CuΙΙ(Bztpen)]2+ +1e â†’ [CuΙ(Bztpen)]+ and a weak interaction energy between BSA and [CuΙΙ(Bztpen)] and [CuΙ(Bztpen)] species, with no adsorption of protein over the electrode surface. Circular Dichroism (CD) Spectroelectrochemistry, not reported before, reveals no significant changes in BSA structure during the electron transfer [CuΙΙ(Bztpen)]2+ + 1e â†’ [CuΙ(Bztpen)]+. CD experiments at variable temperature for BSA denaturalization in the absence and in the presence of [CuΙΙ(Bztpen)]2+, shown no change in thermodynamic parameters due to low interaction between the transport protein and copper complex.

Self-Assembled Monolayer of Monomercaptoundecahydro-closo-dodecaborate on a Polycrystalline Gold Surface.

In this work, we present an electrochemical study of the boron cage monomercaptoundecahydro-closo-dodecaborate [B12H11SH]2- in solution and in a self-assembled monolayer over a polycrystalline gold electrode. Cyclic voltammetry of the anion [B12H11SH]2- in solution showed a shift in the peak potentials related to the redox processes of gold hydroxides, which evidences the interaction between the boron cage and the gold surface. For an Au electrode modified with the anion [B12H11SH]2-, cyclic voltammetry response of the probe Fe(CN)63-/Fe(CN)64- showed a ΔEp value typical for a surface modification. Electrochemical impedance spectroscopy presented Rtc and Cdl values related to the formation of a self-assembled monolayer (SAM). A comparison of electrochemical responses of a modified electrode with thioglycolic acid (TGA) reveals that the boron cage [B12H11SH]2- diminishes the actives sites over the Au surface due to the steric effects. Differential capacitance measurements for bare gold electrode and those modified with [B12H11SH]2- and (TGA), indicate that bulky thiols enhance charge accumulation at the electrode-solution interface. In addition to electrochemical experiments, DFT calculations and surface plasmon resonance measurements (SPR) were carried out to obtain quantum chemical descriptors and to evaluate the molecular length and the dielectric constant of the Boron cage. From SPR experiments, the adsorption kinetics of [B12H11SH]2- were studied. The data fit for a Langmuir kinetic equation, typical for the formation of a monolayer.

Effect of tunable redox behavior of bis chelate substituted 1,10-phenantroline Cu(II) complexes on its reaction with superoxide anion in DMSO. Toward a simple criterion to identify a SOD-like mechanism.

In this work we report a series of Cu(II) complexes [Cu(N-N)2(X)]+, (N-N=substituted 1,10-phenanthroline derivatives and X=Cl- or NO3-), with tunable E1/2 for electrochemical reduction [CuII(N-N)2(X)]++1e-⇌[CuI(N-N)2]+X-. The disproportion of O2•- was explored in presence of the electro-generated species [CuI(N-N)2]+ using cyclic voltammetry in a non-aqueous media, arising a new simple method to propose a SOD-like mechanism, which can be used as a quick guide test for a compound, before being proven in biological assays. It was found that complexes with high negative half wave potential values (E1/2) for Cu(II)/Cu(I) couple shown a current increment for oxygen reduction, related to the capability of the disproportion of this reactive oxygen species.