Production of 5-15 microns diameter alginate-polylysine microcapsules by an air-atomization technique

A novel method of preparing small-sized microcapsules using a Turbotak air-atomizer is reported. Alginate-polylysine microcapsules containing Bacillus Calmette Guérin vaccine have been prepared by an adaptation of the method of Lim (1) which allows the manufacture of small-sized microcapsules. A Turbotak is used to spray sodium alginate solution into calcium chloride solution to form temporary calcium alginate microgel capsules. These temporary microgel droplets are subsequently cross-linked with polylysine to form permanent membranes. Microcapules in the size range of 5-15 microns have been produced which can be compared to an average diameter of greater than or equal to 300 microns obtained by the method reported by Lim. The microcapsule size is dependent on the conditions of operation of the Turbotak and the concentration of the sodium alginate solution. Particles within the size range 5-15 microns can be reproducibly manufactured using the conditions of operation reported here. Other size ranges below the minimum of 300 microns reported by Lim are also feasible using this technique.