Chitosan-carboxymethylcellulose hydrogels as supports for cell immobilization

The preparation of hydrogels from the polyelectrolyte complexation (PEG) of carboxymethylcellulose (CMC) and hydrogels from the complexation with an additional or simultaneous ionotropic gelation is reported. The reaction yield is high enough and depends strongly on the additional ionotropic gelation (IG). Infrared spectroscopy was used to confirm complexation between the carboxylic (in CMC) and amine (in chitosan) groups. The scanning electron microscope images show the formation of a fibrillar structure with characteristic pore sizes between 0.1 and 1 mu m. The swelling capacity, Q, of PEC hydrogels is not high, but the Q value of hydrogels from PEC with an additional IG is high and depends strongly on the pH medium. These hydrogels are mechanically more stable than the PEC hydrogels; their mechanical strength is about 7 times higher than that of PEC hydrogels. The hydrogels were used to immobilize yeast cells with the cell density 1 x 10(9) cells/mL, about 100 times higher than that in the free-cell culture. Only the hydrogels with additional IG were stable enough for continuous fermentation over 10 days. These hydrogels proved to have higher affinity to substrate, which led to higher productivity than the ionotropic gel of CMC and aluminum ion.