Synthesis of poly(epsilon-caprolactone)-b-poly(gamma-benzyl-L-glutamic acid) block copolymer using amino organic calcium catalyst

A biodegradable two block copolymer, poly(epsilon-caprolactone)-b- poly(gamma-benzyl-L-glutamic acid) (PCL-PBLG) was synthesized successfully by ring-opening polymerization of N-carboxyanhydride of gamma-benzyl-L-glutamate (BLG-NCA) with aminophenyl-terminated PCL as a macroinitiator. The aminophenethoxyl-terminated PCL was prepared via hydrogenation of a 4-nitrophenethoxyl-teminated PCL, which was novelly obtained from the polymerization of c-caprolactone (CL) initiated by amino calcium 4-nitrobenzoxide. The structures of the block copolymer and its precursors from the initial step of PCL were confirmed and investigated by H-1 NMR, FT-IR, GPC, and FT-ICRMS analyses and DSC measurements.

Electrocatalytic oxidation of dopamine at a cobalt hexacyanoferrate modified glassy carbon electrode prepared by a new method

A stable electroactive thin film of cobalt hexacyanoferrate (CoHCF) was electrochemically deposited on the surface of a glassy carbon (GC) electrode with a new and simple method. The cyclic voltammograms of the CoHCF Film modified GC (CoHCF/GC) electrode prepared by this method exhibit two pairs of well-defined redox peaks, at scan rates up to 200 mV s(-1). The advantage of this method is that it is easy to manipulate and to control the surface coverage of CoHCF on the electrode surface. The modified electrode shows good electrocatalytic activity towards the electrochemical reaction of dopamine (DA) in a 0.1 mol dm (3) KNO3 + phosphate buffer solution (pH 7.0). The rate constant of the electrocatalytic oxidation of DA at the CoHCF/GC electrode is determined by employing rotating disk electrode measurements.

The structural transition of DNA-Tris(1,10-phenanthroline) cobalt(III) complexes in ethanol-water solution

The interaction of DNA with Tris(1,10-phenanthroline) cobalt(III) was studied by means of atomic force microscopy. Changes in the morphologies of DNA complex in the presence of ethanol may well indicate the crucial role of electrostatic force in causing DNA condensation. With the increase of the concentration of ethanol, electrostatic interaction is enhanced corresponding to a lower dielectric constant. Counterions condense along the sugar phosphate backbone of DNA when e is lowered and the phosphate charge density can thus be neutralized to the level of DNA condensation. Electroanalytical measurement of DNA condensed with Co(phen)(3)(3+) in ethanol solution indicated that intercalating reaction remains existing. According to both the microscopic and spectroscopic results, it can be found that no secondary structure transition occurs upon DNA condensing. B-A conformation transition takes place at more than 60% ethanol solution.