PRODUCTION OF BCG ALGINATE-PLL MICROCAPSULES BY EMULSIFICATION INTERNAL GELATION

A biocompatible emulsification method for microencapsulation of live c ells and enzymes within a calcium alginate matrix applied to Bacillus Calmetre-Guerin (BCG) has been developed. Small-diameter alginate bead s (microcapsules) were formed via internal gelation of an alginate sol ution emulsified within vegetable oil. Five different oils (sesame, sw eet almond, perhydrosqualene, camomile and jojoba) were used. The rheo logical analysis of the oils showed a Newtonian behaviour, with viscos ities=30.0, 37.7, 51.2, 59.3 and 67.1 mPa.s for perhydrosqualene, jojo ba, camomile, sesame and sweet almond oil respectively. The particle s ize of the microcapsules obtained ranged from 30.3 mu m for the microc apsules prepared with sweet almond oil to 57.0 mu m for those made wit h perhydrosqualene. The mean particle diameter obtained was found to b e dependent on the viscosity of the oil employed, according to the equ ation: empty set (mu m) = 76.6-0.628 eta (mPa.s) (r(2) = 0.943). The e ncapsulated BCG was identified by the Difco TB stain set K, followed b y observation under optical microscopy. Freeze-drying of the microcaps ules was carried out to ensure their stability during storage. Two bat ches of microcapsules (those prepared with sesame and jojoba oil) and four types of cryoprotectors (glucose, trehalose, mannitol and sorbito l), at three concentration levels (5, 10 and 20% w/v) were studied. Th e parameters evaluated were particle size, physical appearance, recons titution of lyophilizates and microscopical evaluation. For both batch es of microcapsules the best results were obtained with trehalose 5%, showing particle sizes of 42.1 mu m in the case of the microcapsules p repared with sesame oil, and of 45.3 mu m for those prepared with jojo ba.