In collaborative research funded by the Macromolecular, Supramolecular and Nanochemistry program, Chong Cheng of the State University at New York at Buffalo and Honggang Cui of John Hopkins University are developing new techniques for the controlled preparation of tiny nanometer-sized polymer cages. These small structures have enormous potential for the development of new methods to deliver drugs or other substances directly to tissues and cells. The research is focused on a specific type of nanometer-sized cage, or nanocage, that is crystalline but coated with a soap-like molecule known as a surfactant. The strategy is meant to stabilize the resulting surfaces and make it possible to more closely control the size of the resulting cages. The group is also carrying out systematic studies to investigate precisely how this stabilization occurs, in order to learn more about the molecular-level events involved. This will allow application of the results of this research to other systems. The work is having a broader impact on the development of new systems for the delivery of drugs and other therapeutic agents to precise locations in the body. It is having a further broad impact through the production of a series of videos that explain the work. These videos are being distributed via YouTube, helping to bring the results of this research to members of the public.
This project focuses on the precise synthesis of polyelectrolyte nanocages via "crystal-forming" miniemulsions. A second aim of the study is to obtain a molecular level understanding of the stabilization mechanism in this template system. Systematic studies are being conducted to obtain crystallized miniemulsion nanodroplets with high surfactant efficiency and predetermined sizes. This is allowing the synthesis of a great diversity of nanocages with well-controlled dimensions and varying cross-linking densities via free-radical polymerization. The stabilization mechanism study is being performed to identify whether the surfactant monolayers are stabilized on the surface of crystallized miniemulsion nanodroplets through hydrophobic interaction or via co-crystallization of surfactant alkyl chains with oil molecules. This "crystal-forming" stabilization strategy may lead to a practical solution for the decades-long technical problem of dynamic instability of surfactant monolayers in various emulsion systems. Successful implementation of this project will lay the foundation for further optimization of monolayer systems with both enhanced stability and controlled dimensions.
