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In this work, three kinds of antibacterial ingredients were loaded into the hydroxyapatite (HA) coating: antibiotic (ampicillin sodium salt), silver ions and water soluble chitosan. Two different kinds of HA coatings with dense and porous structures were prepared by the air plasma spraying (APS) and liquid precursor plasma spraying (LPPS) processes, respectively, for loading the antibacterial ingredients. The effects of different antibacterial ingredients and different coating microstructures on the antibacterial behaviors of HA coatings have been systematically studied. The antibiotic loaded HA coatings showed the best antibacterial activity, while the silver ion loaded HA coatings showed the worst bacterial inhibitory effects among the three kinds of antibacterial materials. The LPPS porous coating loaded with chitosan demonstrated the same excellent antibacterial effect as the antibiotic loaded coatings, while the APS dense coatings loaded with chitosan showed almost no antibacterial effect at 24 h. Overall, the HA coating with porous structure showed increased loading of antibacterial materials and enhanced antibacterial properties. Such observations suggest that both antibacterial material and coating structure have strong influences on the antibacterial properties of the HA coatings.

Three types of triblock copolymers, ABA, ABC and ACB, where A, B and C are poly (ϵ-caprolactone) (PCL), pply- dl -lactide (PLA) and polyglycolide (PGA), respectively, were synthesized by living polymerization of the purified monomers, ϵ-caprolactone (ϵ-CL), dl -lactide (LA) and glycolide (GA), in dry toluene at 90 °C in the presence of an Al/Zn bimetallic alkoxide complex. The composition of each block copolymer was determined by NMR spectrometry and corresponded to the monomer ratio. Microspheres containing levonorgestrel (LNG) were prepared from the triblock copolymers by the solvent evaporation process and possessed a non-porous surface and an appropriate size for injection. In vitro release of LNG from the copolymer matrices with different compositions and molecular weights was measured in deionized water at 37°C; a constant rate of release of LNG of about 0.4-1.0 /gmg/day/ mg of microspheres was maintained for 3 to 6 months. The release profiles depended on the block length and molecular weight of the block copolymer. It may be attributed to the increase of erosion-controlled release associated with PLA and PGA segments in the copolymer, which effectively compensated for the declining diffusional release from the PCL phase.

Antifibrinolytic agents are being investigated to reduce menstrual blood loss for IUD users. In this study pentamidine isethionate (PI) was selected as an antifibrinolytic agent with a copolymer of ethylene-vinyl acetate (EVA) as its carrier. Matrices of EVA with different vinyl acetate (VA) contents incorporated with different amounts of PI have been prepared and their release rates were tested in vitro. The data revealed that the release of PI from the EVA was directly dependent upon VA content and drug loading. The release rate increased with the VA content. The structure of the films was changed by raising the drug loading thus causing a strong increase in PI release rate.