Trivalent cation stabilization of alginate gel for cell immobilization

Abstract

Introduction The immobilization of living whole cells in bioreactors is an attractive method to achieve high cell density and continuous operation. The entrapment of cells in calcium alginate gel beads is a popular procedure because of the simplicity of the method. However, calcium alginate gels are mechanically fragile and chemically unstable in high concentrations of phosphate anion. Many attempts have been made to improve the stability of calcium alginate gels but most procedures are time consuming and/or costly. The objective of this short note is to illustrate that treatment with a trivalent cation could provide a simple solution. A cormnon approach to improve the stability of calcium alginate is to further crosslink the gel with glutaraldehyde. Other methods generally employs impregnation of the gel with another polymer or polycation. Birnbaum et al. (1981) attempted several methods which included treatment of alginate gel with polyethyleneimine followed by glutaraldehyde, and with carbodimmide and N-hydroxysuccinimide followed by polyethyleneimine. Veliky and Williams (1981) used polycations such as polyethyleneimine or polypropyleneimine. Kuu and Polack (1983) impregnated aiginate with polyacrylamide. These procedures all led to improved gel strength, but it is apparent that these methods were not particularly attractive, as none were pursued any further. Better understanding of the gel formation kinetics is crucial in improving the aiginate gel strength. Alginic acid contains polymannuronic and polyguluronic acid, the composition of which is dependent on the source of brown algae. The gelling is a result of the formation of an "egg-box" structure consisting of chains of either guluronic acid or mannuronic acid units in parallel being held together (crosslinked) by divalent cations such as calcium (Grant et al., 1973). The gelling process is dependent on many factors, one of which is the apparent calcium ion concentration. If the calcium ion concentration

DOI: 10.1007/BF01048468

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@article{Rochefort2005TrivalentCS, title={Trivalent cation stabilization of alginate gel for cell immobilization}, author={Willie E. Rochefort and Tim Rehg and P. C. Chau}, journal={Biotechnology Letters}, year={2005}, volume={8}, pages={115-120} }