Ion-exchange fibers and drugs: a novel device for the screening of iontophoretic systems.

The objective of this study was to theoretically model and experimentally measure the extent of drug release from ion-exchange fibers. The release was measured as a function of current density and NaCl concentration using a novel iontophoretic cell. The fibers tested contained weak carboxylate (-COOH) ion-exchange groups.

Ion-exchange fibers and drugs: a transient study.

The objective of this study was to theoretically model and experimentally measure the kinetics and extent of drug release from different ion-exchange materials using an in-house-designed flow-cell. Ion-exchange fibers (staple fibers and fiber cloth) were compared with commercially available ion-exchange materials (resins and gels). The functional ion-exchange groups in all the materials were weak -COOH or strong -SO3H groups.

Engineering of multiple arginines into the Ser/Thr surface of Trichoderma reesei endo-1,4-beta-xylanase II increases the thermotolerance and shifts the pH optimum towards alkaline pH.

We studied the effects of increase in the number of surface arginines on the enzyme activity and stability of Trichoderma reesei endo-1,4-beta-xylanase II. The number of arginines was increased in two mutant series. The first set contained six arginines on different sides of the protein surface.

Ion-exchange fibers and drugs: an equilibrium study.

The purpose of this study was to investigate the mechanisms of drug binding into and drug release from cation-exchange fibers in vitro under equilibrium conditions. Ion-exchange groups of the fibers were weakly drug binding carboxylic acid groups (-COOH), strongly drug binding sulphonic acid groups (-SO(3)H), or combinations thereof. Parameters determining the drug absorption and drug release properties of the fibers were: (i) the lipophilicity of the drug (tacrine and propranolol are lipophilic compounds, nadolol is a relatively hydrophilic molecule), (ii) the ion-exchange capacity of the fibers, which was increased by activating the cation-exchange groups with NaOH, (iii) the ionic strength of the extracting salt (NaCl), which was studied in a range of 1.