Effective Diffusion Coefficients in Calcium Alginate Gel

Abstract

The effective diffusion coefficient of glucose, D, in calcium alginate gel determined at 35°C by two different methods gave values which, on average, were at least 24Vo less than in water. Assessment of the effect of glucose concentration on D, seems to indicate that D, increased with decreasing glucose concentration at very low concentrations (i.e., < -100 mM) and increased with increasing glucose concentrations at high concentrations (i.e., > -200 mM). Increasing the concentration of either the calcium chloride or sodium alginate component used in calcium alginate formation substantially decreased D,, but the effect of sodium alginate was the greater of the two.

Calcium alginate beads as a slow‐release system for delivering angiogenic molecules In Vivo and In Vitro

“…Tanaka et al (1980) measured diffusion from calcium alginate beads in stirred solution of small molecules such as L-tryptophan and glucose, and of large proteins such as IgG and fibrinogen. Measurements of diffusion of insulin from zinc alginate or zinckalcium alginate beads (Gray and Dowsett, 1988), IgG from calcium alginate beads (Chevalier et al, 1987), and glucose from calcium alginate discs (Itamunoala, 1987) showed that increasing the concentration of alginate in the mixture decreased the rate of diffusion of the molecules in solution. In addition, cell entrapment procedures similar to those used in this laboratory have been applied to hybridoma cells producing IgG in culture (Nilsson et al, 1983;Sinacore et al.…”

An intensified degradation of phenanthrene with macroporous alginate–lignin beads immobilized Phanerochaete chrysosporium

“…The immobilized culture is more effective in shielding environmental perturbations such as pH and toxic chemicals in comparison to suspension culture [5]. In practice, calcium alginate has been extensively tested to encapsulate enzymes and living cells [6,7] used for the treatment of metal ions [8,9], dyes [10,11] and phenol [12]. One major problem with this matrix is its high resistance to mass transfer within the dense gel layer [13].…”

Diffusivity measurement in calcium alginate gel by holographic interferometry

“…However, the accuracy is higher than when conventional techniques are used (Itamunoala, 1987). Furthermore, the diffusional process can almost be visualized with holographic interferometry, whereas with conventional techniques, the diffusion coefficient has to be measured by means of indirect methods.…”

“…In the same paper (Itamunoala, 1987), the author also uses another method that he calls cylinder type. As in the thin-disc type, the gel is initially free from solute, but in the cylinder type, the concentration of source and sink remain constant and the gel, being cylindrical in shape, has a much greater thickness.…”