Agar-carrageenan hydrogel blend as a carrier for the covalent immobilization of beta-D-galactosidase

kappa-Carrageenan (Car) was mixed with agar in order to improve the treated gel's ability to covalently immobilize enzymes. The treatment process of the produced agar-Car gel involved reacting with both polyethyleneimine and glutaraldehyde so as to provide the functional groups necessary for the covalent binding of enzymes. The positive effect imparted by the addition of Car to agar was confirmed through the statistical Plackett-Burman design (PBD). The PBD was employed to investigate the effects of 11 factors on the preparation of the treated agar-Car gel disks, and the immobilization of beta-D-galactosidase (beta-gal) onto these disks. The PBD provided recommendations on the levels at which 10 of the tested factors should be employed in the future as these factors were shown to be insignificant. On the other hand, the significant factor, the loading enzyme's activity, was optimized in order to attain the maximum observed activity of immobilized beta-gal which amounted to 166.2 U/g gel. It was also shown that the agar-Car immobilized beta-gal maintained 97.7% of its initial observed activity during its fifteenth reusability cycle.