Curcumin-Loading-Dependent Stability of PEGMEMA-Based Micelles Affects Endocytosis and Exocytosis in Colon Carcinoma Cells

Polymeric micelles were formed from poly(poly(ethylene glycol) methyl ether methacrylate)-block-poly(styrene) (P-(PEGMEMA)-b-PS) block copolymer of two different chain lengths. The micelles formed were approximately 16 and 46 nm in diameter and used to encapsulate curcumin. Upon loading of the curcumin into the micelles, their size increased to approximately 34 and 80 nm in diameter, respectively, with a loading efficiency of 58%. The unloaded micelles were not cytotoxic to human colon carcinoma cells, whereas only the smaller loaded micelles were cytotoxic after 72 h of exposure. The micelles were rapidly internalized by the cells within minutes of exposure, with the loaded micelles internalized to a greater extent owing to their enhanced stability compared to that of the unloaded micelles. The larger micelles were more rapidly internalized and exocytosed than the smaller micelles, demonstrating the effect of micelle size and drug loading drug delivery and cytotoxicity.