Diffusion in cell-free and cell immobilising ?-carrageenan gel beads with and without chemical reaction

Model-based experimental analysis of enzyme kinetics in aqueous–organic biphasic systems

“…4-15 the overall diffusion coefficient in the hydrogel is in the order of 85% of the one in free solution indicating a strong reduction in comparison with the free diffusion due to the hydrogel matrix. A similar reduction was observed by Mateus et al (1999) for κ-carrageenan hydrogel beads.…”

“…Two strategies are compared in Figure 4-10 − concentration measurements in the bulk phase and in the bead center. The first strategy has already been applied by Mateus et al (1999) to κ-carrageenan hydrogel beads. Figure 4-10 shows that the normalized sensitivity of the diffusion coefficient of DMBA is more than three orders of magnitude higher in the bead center.…”

Interaction between hepatocytes and collagen gel in hollow fibers

“…From this table, it can be seen that high collagen concentrations alone significantly reduced diffusion (Ramanujan et al 2002;Kanamori et al 2000). In addition, the entrapment of bacterial or mammalian cells in gel obviously inhibits mass transfer by decreasing the diffusivity as a result of enhanced tortuosity (Mateus et al 1999;Nicholson and Phillips 1981;Nicholson and Sykova 1998). As the embedded viable cells mentioned above possibly exacerbate the reduced diffusivity, our previous entrapment of dead cells without causing contraction could better reflect the contribution of cells alone to the reduced diffusivity (Wu et al 2005).…”

A diffusion model and optimal cell loading for immobilized cell biocatalysts

“…However, as observed by many investigators, the diffusional resistance of the cells to substrates and products is usually higher than the resistance in the support matrixes (Westrin and Axelsson, 1991). In this case, the effectiveness factor of the immobilized cell biocatalysts monotonically decreases with the increase of the cell concentration (Mateus et al, 1999;Sakaki et al, 1988). This competition between intrinsic reaction rate and diffusional resistance raises the question to be addressed here as to the most advantageous amount of cells to be incorporated into the support matrix.…”

“…There are two diffusion models that reflect a cellular diffusion component (Mateus et al, 1999). A general diffusion model for the prediction of the D e was first proposed for a mammalian tumor cell-agar gel system (Chresand et al, 1988) based on the Maxwell's model for effective conductivities (Maxwell, 1973) as…”