Speaker: Tatiana Bronich, University of Nebraska Medical Center
Date & Time: January 29, 2008 - 11:00am
Polymer micelles as nanocarriers for drugs and imaging agents
Chemistry and Chemical Biology
Tatiana Bronich, University of Nebraska Medical Center
11:00 AM, WL-Aud
Self-assembled block copolymer micelles have attracted great attention as nanoscale carriers for delivery of low molecular mass drugs, proteins, genes, and imaging agents. The advantages of polymer micelles for development of novel therapeutic and diagnostic modalities include the small size and core-shell architecture leading to protection of an active agent in the core by a hydrophilic polymer shell. After administration in the body the micelles circumvent renal excretion, display long circulation times, and extravasate into the disease sites with enhanced vascular permeability. Recently, nanofabrication of polymer micelles was significantly advanced by using block copolymers containing ionic and nonionic blocks (block ionomers�). Such block copolymers react with oppositely charged species forming block ionomer complexes, which self-assemble into core-shell micelles. They are unique because they allow encapsulation of charged molecules into the micelle core. However, all polymer micelles have a drawback as a delivery system because they disintegrate after dilution in the body fluids, resulting in premature drug release. Herein, we will discuss the design of novel polymer micelles with cross-linked ionic cores that display high stability. Such micelles represent hydrophilic nanospheres of core-shell morphology. A highly hydrated porous multifunctional ionic core can efficiently immobilize various metal-based therapeutic and imaging agents while hydrophilic shell chains provide increased solubility and prevent interactions of plasma components with the nanosphere. These micelles displayed the pH- and ionic strength-responsive hydrogel-like behavior due to the effect of the cross-linked ionic core. Such behavior is instrumental for the design of drug carriers with controlled loading and release characteristics.