CHO immobilization in alginate/poly-L: -lysine microcapsules: an understanding of potential and limitations.

Microencapsulation offers a unique potential for high cell density, high productivity mammalian cell cultures. However, for successful exploitation there is the need for microcapsules of defined size, properties and mechanical stability. Four types of alginate/poly-L: -Lysine microcapsules, containing recombinant CHO cells, have been investigated: (a) 800 mum liquid core microcapsules, (b) 500 mum liquid core microcapsules, (c) 880 mum liquid core microcapsules with a double PLL membrane and (d) 740 mum semi-liquid core microcapsules.

Formation of microcapsules from polyelectrolyte and covalent interactions.

A new approach combining electrostatic and covalent bonds was established for the formation of resistant capsules with long-term stability under physiological conditions. Three kinds of interactions were generated in the same membrane: (1) electrostatic bonds between alginate and poly-L-lysine (PLL), (2) covalent bonds (amides) between propylene-glycol-alginate (PGA) and PLL, and (3) covalent bonds (amides) between BSA and PGA. Down-scaling of the capsules size (< or =1 mm diameter) with a jet break-up technology was achieved by modifying the rheological properties of the polymer solution.

On-line biomass monitoring of CHO perfusion culture with scanning dielectric spectroscopy.

In this work, dielectric spectroscopy was used to monitor two CHO perfusion culture experiments (B14 and B16). The capacitance of the cell suspension was recorded every 20 minutes over an excitation frequency range of 0.2 MHz to 10.