Drug Release Properties of Poly(lactic-co-glycolic acid) Coatings

Poly(lactic-co-glycolic acid) (PLGA) rapamycin (Rap) solutions were prepared using ethyl acetate as solvent, and then PLGA coatings loading Rap were prepared through drop-coating method on the surface of 316L stainless in a shaking bath. The Rap release kinetics of PLGA coatings was studied in phosphate buffer solution (PBS) at 37 ℃ while oscillating. The mass of Rap released was measured by ultraviolet and visible spectrophotometer. Results showed that a smaller molecular weight of PLGA and a higher ratio of glycolic acid (GA) in PLGA led to a higher release rate of Rap from the coating. Rap release mass depended linearly on the volume of drop-coating solution, and the relationship between Rap release ratio and reciprocal of the volume of drop-coating solution also showed linear. With the increasing of Rap loading, Rap release mass increased non-linearly, however Rap release ratio initially increased and then decreased.