Control of the Domain Microstructures of PLGA and PCL Binary Systems: Importance of Morphology in Controlled Drug Release

Ratio blends of PLGA/PCL: (0:10), (1:9), (2:8), (3:7), (4:6), (5:5), (6:4), (7:3), (8:2), (9:1), and (10:0) were spin-coated to produce thin films; surface topographies were determined using interferometric microscopy. It was demonstrated that micro-wells of a defined size (150 μm) were present in all PCL dominant PLGA/PCL systems. Stratification of PLGA with PCL enabled the formation of that size of micro-well independent of the percentage of PLGA in a PCL dominant system. Perforation of the amorphous PCL solid layer with PLGA liquid introduced the conglomerates of micro-pits of PLGA with a PCL solid skin. A 20% PLGA liquid in a PCL dominant PLGA/PCL system produced the largest conglomerates and the roughest surface of film. These conglomerates of PLGA together with intact micro-well PCL framework could be considered as an ideal structure for the controlled release of proteins.