Experimental and modeling studies of mass transfer in microencapsulated cell systems

Abstract

Gaining a better understanding of mass transfer problems in encapsulated cell systems and in tissue engineering requires both experimental investigations and mathematical modelling. Specific mass transfer studies are reviewed including oxygen transfer in immobilised animal cell culture systems, modelling of electrostatic polymer droplet formation, and growth of plant somatic tissue encapsulated in alginate using electrostatics.

Hydrocolloid Gel Particles: Formation, Characterization, and Application

“…The electrostatic technique is a modified version of the smallscale extrusion technique where the syringe and the solution have opposite charges, which can affect gel particle size (Goosen, 2003;Klokk and Melvik, 2002;Zvitov and Nussinovitch, 2001;Zvitov and Nussinovitch, 2003). The rate at which the droplets form, and droplet size, is needle diameter, charge arrangement (electrode geometry and spacing), and strength of electric field (Bugarski et al, 1994), although hydrocolloid solution and hardening solution (if present) properties can also have an effect.…”

“…If a positive charge is always on the needle, this ensures that the smallest gel particle size is produced at the lowest applied potential (Goosen, 2003). Particle sizes ranging from 40-2500 µm can be achieved using this method (Bugarski et al, 1994;Goosen, 2003;Zvitov and Nussinovitch, 2003).…”

“…The most effective electrode and charge arrangement for producing small droplets is a positively charged needle and a grounded plate. Two other arrangements are also possible; positively charged plate attached to needle, and a positively charged collecting solution (Goosen, 2003). If a positive charge is always on the needle, this ensures that the smallest gel particle size is produced at the lowest applied potential (Goosen, 2003).…”

Electrospray in the dripping mode for cell microencapsulation

“…Two guluronate blocks of adjacent polymer chains can be cross-linked with multivalent cations (Ca 2+ , Cu 2+ , Ba 2+ ) through interactions with the carboxylic groups in the sugars, which lead to the formation of a gel network for use in cell microencapsulation by many researchers [2,4,[24][25][26][27]. Commonly, alginates with high guluronic acid content generate hard porous gels which can retain their integrity for long term.…”

“…studied the effect of electrode spacing, applied voltage and electrode geometry on the microbead size [22,23]. Subsequently, the effect of diameter of nozzle, viscosity of alginate solution, and flow rate of polymer solution on the microbead size and growth of plant callus cells encapsulated in alginate were investigated [24][25][26][27]. Watanabe et al studied the immobilized enzyme gel particles using electrostatic atomization technique and the corresponding catalytic performance of immobilized enzyme [28].…”