Controlled release of dexamethasone from porous PLGA scaffolds under cyclic loading

Poly(L-lactide)-b-poly(ethylene glycol) (PLLA-PEG) microspheres containing dexamethasone (Dex) have been fabricated using a spray-drying technique. Porous poly(lactic-co-glycolic acid) (PLGA) scaffolds were prepared using a method combining thermally induced phase separation and porogen leaching. A post-seeding technique was used to immobilize Dex-containing PLLA-PEG microspheres on porous PLGA scaffolds, and drug-containing microspheres- scaffolds (MS-S) were obtained. Simple Dex-containing scaffolds (D-S) were also made as the control by directly dissolving Dex in the PLGA solution during scaffold fabrication. The morphologies of microspheres and scaffolds were studied by scanning electron microscopy. Drug release profiles of both MS-S and D-S were determined under cyclic loading and shaking water bath, respectively. The cumulative release of Dex was measured using an ultraviolet visible spectrophotometer. The results show that the incorporation of Dex and microspheres had little effect on the overall morphology of the porous PLGA scaffolds. Cyclic loading significantly accelerated the release of Dex from the drug-containing scaffolds. Compared with D-S, MS-S reduced the drug release rate. The controlled drug delivery of tissue engineering scaffolds under cyclic loading is a key factor to mimic the in vivo mechanical environments and achieve optical clinical efficacy.