Abstract:

BACKGROUND: How to make growth factor plays a role persistently and efficiently is a key in constructing bone tissue engineered bone. Currently, varied microspheres or scaffolds were used as release carriers, however, the delayed release effects needs elevating.
OBJECTIVE: To prepare chitosan microspheres/nano-hydroxyapatite/poly (lactic-co-glycolic acid) (CMs/nHA/PLGA) scaffolds, and to measure its characteristics of delayed release of bovine serum albumin (BSA).
METHODS: CMs were prepared by an emulsifying cross linking method with BSA as a model protein. Using ice particulates as porogen, composite CMs/nHA/PLGA scaffolds were prepared by freeze-drying. The characteristic and morphology of the composite were observed by scanning electron microscope, later particle size analyzer, mercury porosimeter and universal testing machine, and the release behavior of BSA was investigated in vitro.
RESULTS AND CONCLUSION: The CMs were spherical shape with a regular surface, with diameters of 20-40 μm. The encapsulation efficiency of the CMs was 86.5%, and the loading capacity was 0.8%. With the increase of initial BSA dosage, the loading capacity increased to 2.6%, while the encapsulation efficiency decreased to 74.1%. The CMs can be uniformly distributed in PLGA scaffolds to form CMs/nHA/PLGA scaffolds, which had 100-400 μm pore diameter and over 80% porosity, with 1.1-2.3 μMPa compressive strength, and 26.5% cumulative degradation at 10 weeks. The cumulative release of BSA from nHA/PLGA scaffolds was above 85% at 36 hours, which from CMs was 33.6% at 10 days, and that from CMs/nHA/PLGA scaffolds was 81.5% at 40 days. The results demonstrated that CMs/nHA/PLGA scaffolds have an excellent releasing efficiency for protein drugs with suitable compressive strength and degradation, which would be used as delivery system and tissue engineering scaffolds.