PH-sensitive Dioctadecylamine-501 polymeric micelles for delivery of insulin.

In this work, fluorescently labeled smart micelle copolymers which consist of Dioctadecylamine-501 (DODA-501) as the hydrophobic segment, N-isopropylacrylamide (NIPAAm) as well as acrylic acid (AAc) as the hydrophilic segments were prepared. These micelles showed both thermo- and pH-sensitive properties due to the nature properties of NIPAAm and AAc, respectively. The particle size of the prepared micelles ranged from 94 approximately 200 nm and was found to increase with DODA-501 concentration. The size of particles varied in different pH mediums or different temperatures suggesting these micelles were pH- and thermo-sensitive. The image of confocal laser scanning microscopy (CLSM) illustrates these micelles had the ability to encapsulate rhodamine solution. From CLSM observation, fluorescein isothiocyanate (FITC) expression was found on the surface of micelles indicating the target detecting ability of these micelles. In drug loading and release studies, these micelles had the ability to encapsulate insulin and its release was pH sensitive, being more rapid under intestinal fluid environment, but resisting the drug release at gastric fluid environment. Stability test indicates these micelles had good stability during storage. These results suggest the pH-sensitivity of the DODA-501 polymeric micelles may be an interesting candidate for oral drug delivery system.