温敏型智能化靶向式药物载体研究(II)——具有温敏开关的微囊

Study on Thermo-sensitive Intelligent Targeting Type Drug Carriers(II) Microcapsules with Grafted Thermo-sensitive Gates

采用环境感应式微囊作为智能化靶向式药物载体 ,可以实现药物的定点、定时、定量控制释放。本文研究了膜孔内接枝聚异丙基丙烯酰胺 (PNIPAM)“开关”的温敏型控制释放微囊载体的制备 ,并对其进行了温度感应控释性能实验。实验中采用界面聚合法制备聚酰胺多孔微囊 ,然后利用等离子体接枝填孔聚合法将PNIPAM接枝在微囊壁的膜孔中。研究结果表明 ,这种接枝了PNIPAM“开关”的微囊具有温度感应特性 ,其利用膜孔内PNI PAM接枝链的膨胀 收缩特性实现了感温性控制释放。当环境温度低于PNIPAM的低临界溶解温度 (LCST)时 ,膜孔内PNIPAM分子链膨胀而使膜孔呈“关闭”状态 ,从而限制囊内溶质分子通过 ,于是释放速率慢 ;而当环境温度高于LCST时 ,PNIPAM分子链变为收缩状态而使膜孔“开启” ,为微囊内溶质分子的释放敞开通道 ,于是释放速率快。

Environmental stimuli-responsive microcapsules are gett ing more and m ore interests because of their potential applications in site-specific and time - and rate-programmed controlled-release. In this study, thermo-responsive mic roc apsules with linear grafted poly(N-isopropylacrylamide) (PNIPAM) gates on the i n ner pore surface were prepared, and the thermo-responsive controlled-release e xp eriments were carried out. Interfacial polymerization was introduced to prepare polyamide porous microcapsules, and plasma-graft pore-filling polymerization w as used to graft PNIPAM into the pore of the microcapsule membranes. The experimen tal results showed that PNIPAM-grafted microcapsules were featured with thermo -r esponsiveness due to the thermo-responsive swollen-shrunken property of PNIPAM c hains grafted on the inner pore surface of the microcapsule membrane. At tempera tures below the lower critical solution temperature (LCST), the linear grafted P NIPAM chains on the inner pore surface were in the swollen state, and the pores in the membrane were closed and the solute molecules were restrained to pass, as a result the release rate was low. In contrast, the grafted PNIPAM chains were in the shrunken state at temperatures above the LCST, and therefore the pores in the membrane were open, and a high release rate was the result.