Composite microcapsules of poly amino acids for Hb controlled release

The spheral and smooth calcium alginate beads whose average size was around 290  μm were obtained through the electronic droplet generator. With poly-L-arginine and poly-L-histidine,  the novel ALG/(PLA-PLH) composite microcapsules were prepared by incubating the beads into the mixed solution of PLA and PLH for the polymeric membrane forming. In vitro release characteristics of the microcapsules were investigated and the feasibility of application as an oral protein delivery carrier was evaluated by choosing Hb as the protein drug model.The results show that during the first half hour,  the cumulative amount of Hb release from the composite microcapsules is lower than 40% and then reaches more than 80% in the end. The ALG/(PLA-PLH) group and the ALG/PLH group possesses a slower release rate compared with the ALG/PLA group. Due to the highest drug loading and encapsulation ratio,  the 10 min group is considered as the optimal one. The microcapsules made from the pH 4.6 HAc-NaAc buffer has an obvious capacity of longtime release and low amount of leftover compared with the ones made from distilled water. The cumulative release of Hb is less than 10% when the microcapsules are immersed in the pH 1.2 HCl at the end of the first two hours,  while most Hb is released in the pH 6.8 PBS buffer. The release time could be prolonged to some extent through the introduction of chitosan. The composite microcapsules of poly amino acids are likely to become a potential carrier of oral drug delivery system due to their excellent performance.