BIOENCAPSULATION 

Minerva Biotecnologica 2000 December;12(4):241-8

Copyright © 2000 EDIZIONI MINERVA MEDICA

language: English

Immobilization/encapsulation of cells using electrostatic droplet generation. Experiments and theory

Pjanovic R. ¹, Goosen M. F. A. ², Nedovic V. ³, Bugarski B. ¹

¹ Department of Chemical Engineering, Faculty of Technology and Metallurgy, Belgrade University, Belgrade, Yugoslavia; ² Sultan Qaboos University, Muscat, Oman; ³ Institute of Food Technology and Biochemistry, Faculty of Agriculture, Belgrade University, Zemun, Yugoslavia

The mech­a­nism of algi­nate drop­let for­ma­tion as ­well as experi­men­tal param­e­ters for pro­duc­ing ­very ­small poly­mer micro­beads (i.e. ­less ­then 100 microns diam­e­ter) ­using an elec­tro­stat­ic drop­let gen­er­a­tor ­were inves­ti­gat­ed. It was ­found ­that micro­bead ­size was a func­tion of nee­dle diam­e­ter, ­charge arrange­ment (i.e. elec­trode geom­e­try and spac­ing) and ­strength of ­electric ­field. The pro­cess of algi­nate drop­let for­ma­tion ­under the influ­ence of elec­tro­stat­ic forc­es was ­assessed ­with an ­image anal­y­sis/vid­eo ­system and ­revealed dis­tinct stag­es; After a volt­age was ­applied the liq­uid menis­cus at the nee­dle tip was dis­tort­ed ­from a spher­i­cal ­shape ­into an invert­ed ­cone-­like ­shape. Alginate solu­tion ­flowed ­into ­this ­cone at an increas­ing ­rate caus­ing for­ma­tion of a ­neck-­like fil­a­ment. When ­this fil­a­ment ­broke ­away, pro­duc­ing ­small drop­lets, the menis­cus ­relaxed ­back to a spher­i­cal ­shape ­until ­flow of the poly­mer ­caused the pro­cess to ­start ­again. A math­e­mat­i­cal mod­el of drop­let for­ma­tion at the electri­fied nee­dle was devel­oped ­from an anal­y­sis of the forc­es act­ing on a ­charged drop­let, and ­agreed ­well ­with experi­men­tal ­results. Finally, to ­assess the ­effect of an ­electric ­field on ani­mal ­cell viabil­ity, an ­insect ­cell sus­pen­sion was sub­ject­ed to a ­high volt­age. There was no detect­able ­loss in ­cell viabil­ity ­after the volt­age was ­applied.