passages.id: 436
passages.type: title and abstract
passages.text: Enzyme-responsive surface erosion of poly(ethylene carbonate) for controlled drug release.
  Cholesterol esterase (CE) induced surface erosion of poly(ethylene carbonate) (PEC) and drug release from PEC under mild physiological environment was investigated. The degradation process was monitored by changes of mass and molecular weight (MW) and surface morphology of polymer films. During the whole period of degradation, MW of PEC was unchanged. Water uptake of the polymer was only 2.8 and 0.2% for PEC with the MW of 200 kDa (PEC200) and PEC with the MW of 41 kDa (PEC41), respectively. Degradation of less hydrophilic PEC41 with higher density was slower than that of PEC200. By this mechanism, CE-responsive drug in vitro release from PEC in situ forming depots (ISFD) was conducted successfully. As expected, less bovine serum albumin (BSA) was released from PEC41 compared with that of PEC200 in the same time period. In conclusion, this work enabled the in vitro drug release evaluation of existing PEC devices and implied a new candidate for the development of enzyme-responsive systems.