Abstract:

In the present study we aimed to control insulin release from the reverse hexagonal (H-II) mesophase using Thermomyces lanuginosa lipase (TLL) in the environment (outer TLL) or within the H-II cylinders (inner TLL). Two insulin-loaded systems differing by the presence (or absence) of phosphatidylcholine (PC) were examined. In general, incorporation of PC into the H-II interface (without TLL) increased insulin release, as a more cooperative system was formed. Addition of TLL to the systems' environments resulted in lipolysis of the H-II structure. In the absence of PC, the lipolysis was more dominant and led to a significant increase in insulin release (50% after 8 h). However, the presence of PC stabilized the interface, hindering the lipolysis, and therefore no impact on the release profile was detected during the first 8 h. Entrapment of TLL within the H-II cylinders (with and without PC) drastically increased insulin release in both systems up to 100%. In the presence of PC insulin released faster and the structure was more stable. Consequently, the presence of lipases (inner or outer) both enhanced the destruction of the carrier, and provided sustained release of the entrapped insulin. (C) 2017 Elsevier B.V. All rights reserved.