AC-Electrokinetic Formation, Manipulation, and Induced Release of Lipid and Surfactant Based Vesicles

Recently, lipid based biocolloids, such as micelles and liposomes, have been of increasing interest as drug delivery systems for controlled release, specific cell targeting, and medical diagnostics via advanced electrokinetic and microfluidic techniques. In this work, complex bio-nanocolloids are synthesized via electroformation, manipulated through dielectrophoresis (DEP), and induced to release encapsulates through electromigration with the use of AC-electric fields. Developing a theoretical understanding of the polarization for complex nanocolloids is an essential stepping stone for creating a robust diagnostic device and advanced delivery techniques. In this work, AC-electric fields are applied to spin coated lipid membranes to induce membrane swelling and the creation of giant unilamellar vesicles (GUV). A formation phase diagram is experimentally determined and it is discovered the traditional range for electroformation is expanded. Additionally, the ability to manipulate and assemble lipid based particles, or liposomes, is determined by the use of DEP. The generality of DEP response of these vesicles is tested by testing plain liposomes and liposomes with surface modification: patchy coverage by nanoparticles and complete covered by a calcium phosphate layer. Finally the applicability of electrokinetic techniques is extended to the nanoscale by thorough testing of latex nanoparticles of a<50 nm and surfactant micelles of a<10 nm. Strong AC-frequency dependence of micelle concentration is observed, from which the DEP crossover frequency is determined for the first time for micelle particles. Surprisingly, an AC-field induced dissociation of the micelle structure and a resulting release of fluorescent encapsulates at a characteristic low AC-field frequency of 1-10 kHz is discovered, where the dissociation has been found to be dependent on the surface charge of the interior encapsulate. This work elucidates polarization mechanisms for complex bio-colloids and details new phenomena not previously predicted. With the fundamental development of the tools described here, advanced diagnostics and drug delivery integration is limited only by ones creativity.