(33b) Amphiphilic Block Copolymer Inverse Micelles For Delivery Of Hydrophilic Drugs
Amphiphilic block copolymers have been the subject of significant recent research due to their ability to self-assemble on the nanometer length scale into a variety of morphologies, enabling a diverse range of applications. For many biological applications these systems are assembled in water, however, in our work we are studying inverse micelles assembled in an oil phase resulting in a hydrophobic corona and a hydrophilic core. Our work has focused on the bioresorbable polymer, poly(epsilon-caprolactone)-block-poly(2-vinylpyridine), as well as nonresorbable poly(styrene-b-2-vinylpyridine) and poly(styrene-b-polyacrylic acid). We have previously shown the ability cast these micelles on substrates to form quasi-hexagonal micellar arrays. These films undergo a rearrangement driven by the swelling of hydrophilic core domains when exposed to aqueous solution that opens (?cavitates') the micelles and exposes the hydrophilic domains to the solution. We have demonstrated the ability to load hydrophilic small molecules, polysaccharides, and proteins into the hydrophilic core of these micellar systems. When cast into films, the micelles release their contents upon exposure to aqueous solutions, giving them the potential to be used for film-based drug delivery. Alternatively, the oil phase containing the micelles can be placed in contact with an aqueous phase and the drug will be released into the aqueous phase. We have investigated the assembly of these polymer systems in biocompatible oil phases of interest for transdermal drug delivery; due to their hydrophobic exterior and the ability to encapsulate hydrophilic drugs, oil suspensions of these inverse micelle materials may provide improved transcutaneous delivery of compounds through the stratum corneum of skin.