Optimization of biodegradable polymeric submicroparticles preparation

The influence of various surfactants and their combinations on the particle diameter and particles size distribution during their preparation from biodegradable poly(lactide acid) by the method of emulsification and solvent evaporation at reduced pressure was investigated. The attention was focused on the possibility to control the size of resultant particles by hydrophilic-lipophilic balance parameter (HLB), which is a characteristic of nonionic surfactants. First, nonionic surfactants were combined to obtain various HLB values of the system and then combinations with the biodegradable surface active polymer Gelatin A were assayed. Gelatin A proved to be a suitable emulsion stabilizer in the process of PLA submicroparticles preparation and it was found that to achieve PLA submicroparticles with the lowest diameter and narrow distribution HLB of the system has to be set up under about 16. For combinations of gelatin A and another nonionic surfactant the reduction of the aggregate HLB value of the system could better be achieved with an addition of a surfactant having HLB closer to the optimum like Tween 20 or Tween 85