Protein polarization in isotropic membrane hollow-fiber bioreactors

Adsorptive and Membrane-Type Separations: A Bibliographical Update (1994)

This paper provides a bibliography of the 1994 journal literature for adsorptive and membrane-type separations. The references are taken from the 45 most important chemical engineering journals. This paper provides an update to the literature as provide in previous bibliographic papers (Ray 1990a, 1991, 1994, 1995). A bibliography of the chemical engineering journal literature from 1967–88 has been published by the author (Ray 1990b), and can provide access to a wider range of topics. A complete bibliographic listing of the chemical engineering journal literature from 1989 to 1995 (with subsequent six-monthly updates) is available on a CD-ROM database and full details can be obtained from the author.

The papers included here have been divided into the following subject groups: theory; design data; adsorbents; PSA and cyclic systems, and applications; liquid-phase adsorption; ion exchange, chromatography, etc.; membranes; and membrane-type separations.

Bioreactors for tissue mass culture: Design, characterization, and recent advances

This paper reviews reports on three-dimensional mammalian tissue growth in bioreactors and the corresponding mammalian tissue growth requirements. The needs for nutrient and waste removal of several mammalian tissues are reviewed and compared with the environment of many reactors currently in use such as the continuous stirred tank, the hollow fiber, the Couette-Taylor, the airlift, and the rotating-wall reactors developed by NASA. Many studies conclude that oxygen supply appears to be one of the most important factors limiting tissue growth. Various correlations to describe oxygen mass transfer are presented and discussed with the aim to provide some guidance to design, construct, and test reactors for tissue mass culture. To obtain tissue thickness clinically valuable, dimensionless and other types of analysis tend to point out that diffusive transport will have to be matched with an important convection to bring sufficient oxygen molecular flux to the growing cells located within a tissue mass. As learned from solid-state fermentation and hairy root culture, during the growth of large biomass, heterogeneity (i.e., channeling, temperature gradients, non-uniform cell growth, transfer gradients, etc.) can cause some important problems and these should be addressed in tissue engineering as well. Reactors (along with the scaffolds) should be designed to minimize these issues. The role of the uterus, the reactor built by Nature, is examined, and the environment provided to a growing embryo is reported, yielding possible paths for further reactor developments. Finally, the importance of cell seeding methods is also addressed.

Effect of harvesting protocol on performance of a hollow fiber bioreactor

In this study, a bioreactor subject to Starling flow in closed shell batch harvest mode was compared to two forms of additional forced extracapillary (EC) space convection including EC circulation and EC cycling. Despite the presence of Starling flow as the dominant EC convection mechanism in the batch harvest system, the bioreactor start up was fairly good. However, the antibody productivity of the batch harvest system fell off rapidly after day 20 resulting in only 4.5 g of antibody produced. EC circulation with flow parallel to the fibers had a slightly better start up than the batch harvest. However, the antibody productivity also dropped after day 20 with EC circulation, resulting in only 7.5 g of antibody produced. EC cycling with flow both parallel and perpendicular to the fibers resulted in a start up similar to that of EC circulation. However, in contrast to the other two systems, antibody productivity in the EC cycling system was stable over the 60-day experiment resulting in the production of 23 g of antibody. These results demonstrate the importance of inducing the proper flow distribution in the EC space to allow consistent and stable production in hollow fiber bioreactors.