Methoxypoly(ethylene glycol)-block-poly(DLlactide)(PELA) microcapsules c ontaining
bovine hemoglobin (BHb) were prepared
by a W/O/W double emulsion-solv ent diffusion process. The P 50 and Hill coeffcient were 3466 Pa and 2 4 respectively, which were near to the natural bioactivity of bovine hemoglobi n. The results suggested that polymer composition had significant influence on e ncapsulation efficiency and particle size of microcapsules. The
encapsulation ef ficiency could reach 90% and the particle size 3～5 μm when the PELA copolymer containing MPEG 2000 block was used. The encapsulation efficiency and particle s ize increased with the concentration of PELA. Increasing the concentrations of N aCl in outer aqueous solution resulted in the increase of encapsulation efficien cy and the decrease of particle size. As the concentration of stabilizer in oute r aqueous solution increased in the range of 10 g/L to 20 g/L, the particle size reduced while encapsulation efficiency was increased, further increase of the s tabilizer concentration would decrease encapsulation efficiency. Increasing of p rimary emulsion stirring rate was advantageous to the improvement of encapsulati on efficiency though it had little influence on the particle size. The influence of re-emulsion stirring rate was complicated, which was not apparent in the ca se of large volume of re-emulsion solution. When the wall polymer and primary e mulsion stirring rate were fixed, the encapsulation efficiency decreased as the particle size reduced.