title: Synthesis and characterization of biodegradable microcapsules for the controlled delivery of calcium hydroxide.
abstract: This study aimed to synthesize and characterize biodegradable microcapsules based on poly(lactic acid) (PLA) and ethylcellulose (EC) for a controlled delivery of calcium hydroxide. Phase separation technique was adopted to synthesize calcium hydroxide-loaded PLA/EC microcapsules. Four PLA/EC blends (4/1, 1/1, 1/4, pure EC) were used as shell materials and the input ratio of calcium hydroxide to shell polymer was 4:1 for all microcapsules. The morphology and composition were studied using SEM-EDS and TEM. Particle size distribution, glass-transition temperature, drug loading, and encapsulation efficiency were characterized. In vitro release of the microcapsules was evaluated using a pH microelectrode and an auto-biochemistry analyzer. SEM images of microcapsules showed uniform spherical structures with smooth surfaces. Core-shell, hetero-structures were confirmed using TEM. The presence of calcium in the microcapsules was verified with EDS. Pure calcium hydroxide was 160 nm in diameter and the particle size of the microcapsules ranged between 500 nm and 4 μm. With an increase of PLA in PLA/EC blend, the size of microcapsules increased accordingly. Encapsulation efficiency of these microcapsules was higher than 57% and drug loading was higher than 80%, which were not significantly different among four microcapsules. Pure calcium hydroxide powder was used as a control and 90% was released within 48 h, while release of calcium hydroxide from microcapsules took between 168 and 456 h, depending on the PLA/EC ratio. Compared with calcium hydroxide powder, the calcium hydroxide-loaded microcapsules showed a sustained and prolonged release, which could be controlled via the regulation of the PLA/EC ratio.
authors.affiliation: Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Han
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
authors.forename: Xuejun
authors.initials: X
authors.lastname: Gao
authors.forename: Jiguang
authors.initials: J
authors.lastname: Liu
authors.forename: Fuxin
authors.initials: F
authors.lastname: Liang
authors.forename: Xiaozhong
authors.initials: X
authors.lastname: Qu
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Yang
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002126:Calcium Hydroxide / Q000737:chemistry / Q000378:metabolism*; D002214:Capsules / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism; D002482:Cellulose / Q000031:analogs & derivatives / Q000737:chemistry; D003692:Delayed-Action Preparations / Q000737:chemistry / Q000378:metabolism; D004339:Drug Compounding / Q000379:methods; D019344:Lactic Acid / Q000737:chemistry; D008422:Materials Testing; D010316:Particle Size; D011091:Polyesters; D011108:Polymers / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D002214:Capsules; D003692:Delayed-Action Preparations; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); C013517:ethyl cellulose; D002482:Cellulose; D002126:Calcium Hydroxide; D002118:Calcium