PEGDA hydrogels as a replacement for animal tissues in mucoadhesion testing.

Utilization of animal parts in ex-vivo mucoadhesion assays is a common approach that presents many difficulties due to animal rights issues and large variance between animals. This study examines the suitability of two PEGDA (poly(ethylene glycol) diacrylate) based hydrogels to serve as tissue mimetics for mucoadhesion evaluation. One hydrogel, termed PEGDA-QT, was composed of pentaerythritol tetrakis (3-mercaptopropionate) and PEG and contained free thiol groups mimicking those found in natural mucosa.

Reaction mechanism for the highly efficient catalytic decomposition of peroxynitrite by the amphipolar iron(III) corrole 1-Fe.

The amphipolar iron(III) corrole 1-Fe is one of the most efficient catalysts for the decomposition of peroxynitrite, the toxin involved in numerous diseases. This research focused on the mechanism of that reaction at physiological pH, where peroxynitrite is in equilibrium with its much more reactive conjugated acid, by focusing on the elementary steps involved in the catalytic cycle. Kinetic investigations uncovered the formation of a reaction intermediate in a process that is complete within a few milliseconds (k1 ∼ 3 × 10(7) M(-1) s(-1) at 5 °C, about 7 orders of magnitude larger than the first order rate constant for the non-catalyzed process).