Sustained releasable chitosan scaffolds embedded with PLGA microspheres

In order to solve the problem of nutrition insufficiency in the tissue engineering scaffolds, the microspheres containing sustained releasable nutrition were incorporated into the chitosan-based scaffolds to make that a stable nutrition concentration can be maintained within the scaffolds by the sustained release of the nutrition in the microspheres. The PLGA microspheres containing BSA used as model protein were prepared by double emulsion method, then through the processes of mixing them with chitosan solution and freeze-drying, the chitosan scaffolds were formed. The BSA release profiles of the microspheres before and after incorporated into the chitosan scaffolds were monitored by ELIASA (enzyme linked immunosobent assay) with BCA protein assay. The configuration of PLGA microspheres and the configuration changes of the microspheres and chitosan scaffolds after the microspheres were incorporated into the scaffolds were observed by scanning electron microscope. The results show that the PLGA microspheres can be uniformly embedded into the scaffolds without any morphology change and they have a size range of 27~55 μm and the chitosan scaffolds present the construction with uniform porous. It was found that the porosity, water content and degradation ratios of the chitosan scaffolds are (92.99±2.51)%, (89.66±0.66)% and (73.77±3.21)%, respectively. The in vitro BSA release tests of the microspheres show that the BSA release is sustained and the bursting release is very few. The cumulative release amount of BSA from PLGA microspheres within 168 h is (20.24±0.83)%, and the protein concentration in the chitosan scaffolds after 168 h is (11.44±1.81)×10 -2 mg·mL -1 . Comparing with the traditional nutrition supply method of providing the nutrition to cells locating inside the scaffolds by free diffusion of the external culture medium, the proposed method of using the novel chitosan-based scaffolds embedded with nutrition containing PLGA microspheres is better, for it has the sustained release ability and can maintain a homogeneous concentration of the cells growth factors inside the scaffolds for a long time. In other words, the proposed method provides the promising ideal scaffolds for the tissue engineering.