Nanoscale Curvature Enhances Mixing of Otherwise Immiscible Polymer Brush Chains You-Yeon Won, Purdue University, DMR 0906567.
The evolving demands of modern technologies utilizing nanoparticles now necessitate the incorporation of multi-functionality into a nano-sized particle. In this project, we explore the implications of confining multiple, chemically-distinct macromolecules to a nanoparticle surface. We found that incompatible polymer brush mixtures favor a phase-separated state at flat interfaces, while the same mixed brushes tend to exist in a mixed state when grafted to highly-curved surfaces of nanoparticles [Macromolecules, 41, 2735 (2008)]. This concept enabled us to develop a novel polymer micelle-based multidrug/siRNA carrier (“micelleplex”) [ACS Nano, 5, 3493 (2011)]. A mixed brush in the corona layer formed by two incompatible polymers was an essential enabling component of this micelleplex design.
A cartoon explaining the concept of a “micelleplex” drug carrier (upper). The size of the micelleplexes ( 50 nm, as shown in the lower left AFM image) provides for effective accumulation and retention in tumor tissue (lower right).
In Summer 2010, Kimberly Ohn (who was then a finishing junior at Purdue University) was involved in this project through the Summer Undergraduate Research Fellowship Program. Kimberly conducted a study of the surface pressure-area isotherm behavior of air-water interfacial films of PEO-PnBA and PDMAEMA-PnBA diblock copolymers. Her contribution was essential in developing a model mixed brush system for investigation of the conformational properties of the mixed brush by neutron and X-ray reflectivity measurements (currently under progress).
The work highlighted in the previous slide was mainly conducted by an outstanding African-American graduate student, Dana Gary. Dana graduated with PhD under the mentorship of the PI in August 2010. The PI continues to serve as an active member of the Purdue AGEP Program which aims to enhance the recruitment, retention and mentoring of under-represented minority students in science and engineering graduate programs.