Microparticles for cell encapsulation and colonic delivery produced by membrane emulsification

Membrane Emulsification was used to encapsulate yeast cells and form microparticles. W/O emulsions were produced using a Dispersion Cell; the aqueous phase consisted of gelatin/chitosan, or pure gelatin solution, containing yeast cells, the continuous phase was 2 wt% of SPAN 80 in kerosene. Varying the dispersed phase flux (from 70 to 350 L h- m-2) and the shear stress (from 17 to 1 Pa) applied on the membrane surface droplet sizes of between 60 and 340 µm were produced, with a coefficient of variation of 17% under the best operating conditions. The liquid drops were loaded with increasing amount of yeast (3.14×107 to 3.14×108 cells/mL). The stability and uniformity of the emulsions was independent of the cell concentration. PTFE coated hydrophobic membrane produced smaller W/O drops compared to FAS coated membranes. The liquid polymeric droplets were solidified in solid particles using thermal gelation and/or ionic crosslinking, obtaining yeast encapsulated particles sized ~100 µm. The pH sensitive polymer, Eudragit S100, was used as a coating to create gastro resistant particles suitable for intestinal-colonic targeted release. Viability of the released yeast cells was demonstrated using fluorescence probes and checking cell glucose metabolism with time.