Passerini N, Craig D Q
The School of Pharmacy, The Queen's University of Belfast, Biomedical Centre, 97 Lisburn Road, BT9 7BL, Belfast, UK.
J Control Release. 2001 May 18;73(1):111-5. doi: 10.1016/s0168-3659(01)00245-0.
The objective of the study was to ascertain residual water levels in polylactide and polylactide-co-glycolide microspheres prepared using the solvent evaporation technique and to investigate the effects of that water on the glass transitional behaviour of the microspheres. Microspheres were prepared from polylactic acid (PLA) and polylactide-co-glycolide (PLGA) 50:50 and 75:25 using a standard solvent evaporation technique. The glass transition was measured as a function of drying conditions using modulated temperature DSC. The microspheres were found to contain very low levels of dichloromethane, while residual water levels of up to circa 3% w/w were noted after freeze or oven drying, these levels being higher for microspheres containing higher glycolic acid levels. The residual water was found to lower the T(g) following the Gordon-Taylor relationship. The data indicate that the microparticles may retain significant water levels following standard preparation and drying protocols and that this drying may markedly lower the T(g) of the spheres.
本研究的目的是确定采用溶剂蒸发技术制备的聚乳酸和聚乳酸-乙醇酸共聚物微球中的残留水分水平，并研究该水分对微球玻璃化转变行为的影响。使用标准溶剂蒸发技术，由聚乳酸（PLA）以及50:50和75:25的聚乳酸-乙醇酸共聚物（PLGA）制备微球。使用调制温度DSC测量玻璃化转变与干燥条件的函数关系。发现微球中含有极低水平的二氯甲烷，而冷冻或烘箱干燥后，残留水分水平高达约3%（w/w），对于含有较高乙醇酸水平的微球，这些水平更高。发现残留水分根据戈登-泰勒关系降低玻璃化转变温度（Tg）。数据表明，按照标准制备和干燥方案，微粒可能保留显著的水分水平，并且这种干燥可能会显著降低微球的Tg。
