On the Growth and Shape of Sodium Taurodeoxycholate Micellar Aggregates: A Spin Label and Quasi – Elastic Light Scattering Investigation

Electron spin resonance (ESR) and quasielastic laser scattering (QELS) measurements have been carried out on sodium taurodeoxycholate (NaTDC) micellar aqueous solutions. Computer simulation of the ESR line shape has been used to quantitatively analyze the rotational dynamics of the cholestan-spin label (CSL) dissolved by the NaTDC micellar aggregates as a function of temperature and NaCl concentration. The local reorientation of CSL has been accounted for motionally-averaged g- and A-tensors assuming fast oscillation around the spin-probe long molecular axis. The overall Brownian tumbling of CSL-micelle complexes has been modeled by an axially symmetric rotational tensor. Good agreement with experimental spectra is obtained. Best-fit rotational parameters and QELS data suggest that, in the circumstance of large aggregation, NaTDC micelles have cylindrical shape and micellar growth occurs along the cylinder axis. (C) 2004 American Institute of Physics

Metal ions implantation onto acidic resins upon reaction of metal acetates and carbamates: Part I. Synthetic results

Moderately cross-linked gel-type resins bearing –SO3H, –COOH and –OH groups undergo facile metallation with PdII, CuII and NiII acetates with concomitant release of acetic acid. Successful and facile metallation is also observed upon reaction with PdII, CuII and NiII carbamates

Catalytic activity of bovine lactoperoxidase supported on macroporous poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate)

2-Hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) (molar ratio 85/15) are copolymerised upon c-ray exposure at 78 C in the presence of water to give a hydrophilic resin with a porosity that favours the anchoring of bovine-lactoperoxidase (LPO). The resin, after mincing and sieving, is obtained as irregular microparticles with size ranging from 80 to 1000 lm. The morphology of the resin in the swollen state is investigated with Inverse Steric Exclusion Chromatography and ESR. The catalytic activity of immobilised and soluble LPO is monitored and compared for 14 days at 4 C as well as enzyme stability toward thermal inactivation and resistance to denaturing agents (acidity, urea, organic solvents). The results reveal a higher stability of supported LPO both in aqueous and organic media as compared with the free enzyme. Evaluation of kinetic parameters of immobilised LPO suggests that the enzyme turns out to be mainly linked to the external surface of the supporting particles

Gel-type polyacrylic resins cross-linked with trimethylolpropanetrimethacrylate: the issue of their nanostructure unveiled with a combination of Inverse Steric Exclusion Chromatography (ISEC), ESR and CP MAS 13C NMR spectrometries

Abstract: Six gel-type functional resins, that is, three poly-DMAA-co-TMPTP (DMAA=N,N-dimethylacrylamide, TMPTP=trimethylolpropyltrimethacrylate) samples with different degrees of cross-linking (0.6, 1.2, 1.7% mol) and three poly-DMAA-co-MA-co- TMPTP (MA=methacrylic acid, ca. 5.5% mol) samples with 1.7, 3.5, and 7% mol cross-linking were investigated with ISEC (inverse steric exclusion chromatography), and ESR and CPMAS (cross polarization magic angle spinning) 13C NMR spectroscopy after swelling in water and other solvents. This unprecedented combination of conceptually independent physicochemical techniques provides a thorough overall consistent picture of the morphology of the resins on the nanometer scale and of the molecular accessibility of the swollen polymer framework to the paramagnetic probe TEMPONE (2,2,6,6-tetramethyl-4-oxo-1- oxypiperidine) and to selected solvents