Polyelectrolyte Complex Micelles

Coacervate Core Micelle

Schematic formation of a coacervate-core micelle from the electrostatic complexation of a negatively-charged homopolymer with a block copolymer composed of a positively-charged polyelectrolyte block and a neutral water soluble polymer block.

Electrostatically driven micellization is a useful way of assembling functional nanostructures because of the ability to tune intermolecular interactions using pH and salt. Using molecular design, the macroscopic phenomenon of complex coacervation can be achieved at the nanoscale by coupling the polyelectrolyte to a neutral yet hydrophilic block, forming micelles with a coacervate core and a hydrophilic corona. However, micellization occurs when the core is a precipitate as well. Our lab explores the differences between complex coacervate core micelles and precipitate core micelles using characterization techniques such as static light scattering, dynamic light scattering, small angle X-ray scattering and transmission electron microscopy.

Additionally, we create polyelectrolyte complex micelles that contain therapeutically relevant charged molecules such as miRNA and peptides, specifically for the treatment of atherosclerotic lesions and cancer. To increase the efficacy of delivering miRNA, we use triblock copolymers consisting of a polyelectrolyte block, a polyethylene oxide block, and a targeting ligand, creating polyelectrolyte complex micelles with a targeting ligand outside the corona of the micelle. We are also creating thermoresponsive polyelectrolyte complex micelles by incorporating polymers that exhibit lower critical solution temperature behavior as the corona-forming segment.