In the present paper, the reaction of chemical immobilization of catalase on a crosslinked macromolecular carrier of a polysaccharide structure (gellan) is studied. The influence of some reaction parameters (enzyme/carrier, activator/carrier ratios, duration) on the activity of enzymatic products is analyzed. The kinetics of the biocatalytic process, stability under different pH and temperature conditions, and the inhibitors effect were studied for the immobilized enzymes.

The paper deals with the obtainment of a polymer-drug system with controlled release of the biological active principle, based on furazolidone included in a hydrogel obtained by crosslinking of carboxymethylcellulose with epichlorohydrine. The influence of temperature and duration of crosslinking reaction on the<br />crosslinking degree of carboxymethylcellulose (indirectly appreciated by its swelling capacity in polar liquids as water and dimethylformamide/water mixtures) is studied. Kinetic data concerning the inclusion of furazolidone from solution, in the hydrogel of crosslinked carboxymethylcellulose, as well as the release of the drug from the obtained polymer-drug system, are performed. The obtained results evidence that the inclusion<br />rate as well as the amount of furazolidone diffused into the support depend on the dymethylformamide/water ratio utilized as solvent, and on the drug concentration in solution. The product obtained through the insertion of furazolidone from a DMF/water mixture = 5/1 (with a content of 8.9 mg drug/hydrogel) was studied as to the kinetics of the active principle’s release, in vitro, by using as an eluent a buffer solution, which simulates the gastric fluid (pH = 2.4). The experimental results prove the obtention of a polymerdrug system with controlled release of the biologically active principle, conform to a zero order kinetic, in the time interval ranging between 3–12 hours.