Design and application of switchable micelles comprised of redox-active biocompatible surfactants

ORGN 265

Yan-Yeung Luk, yluk@syr.edu, Yanmei Lan, ylan@mailbox.syr.edu, and Kejun Cheng, c_kj@yahoo.com. Department of Chemistry; Department of Biomedical and Chemical Engineering, Syracuse University, 1-014 CST 111 College Place, Syracuse, NY 13244
We report the design and characterization of the reversible switching between two different micelle morphologies via the disassembly and re-assembly of redox-active surfactants by electrochemical means. The redox-active surfactant is comprised of an aliphatic chain tethered to a ferrocene group covalently caged in the annular void of beta cyclodextrin (bCD). While beta-cyclodextrin by itself has a water solubility too low for consideration as a hydrophilic head group, our covalent modification renders this molecule amphiphilic, and thus surface active. Using bCD as the hydrophilic head group, this surfactant is bio-friendly in that protein denaturation is minimal or non-existent. Under electrochemical control, the surfactant switches between non-ionic and cationic with gross conformational difference, which results in different micelle formation. Employing a wide range of measurements such as 2-dimensional NMR spectroscopy, circular dichroism and electrochemistry, we characterize this micelle assembly and disassembly, and discuss its potential applications in sequestering membrane proteins and controlled drug release.