(704b) Top-Down Fabrication of Multi-Functional Micro/Nanoparticles for Gene Delivery and Biomedical Imaging

Multifunctional micro/nanoparticles are widely used as carriers for gene delivery and as contrast enhancing agent biomedical imaging. The majority of the conventional methods for producing the particles rely on a bottom-up approach that generally suffers from poorly controlled sizes, shapes and structures. In contrast, the top-down methods such as photolithography and nanoimprint lithography are able to generate micro/nanoparticles with uniform, well-defined sizes and shapes. However, most of these methods are limited to the use of engineering materials such as photocurable resin, silicon, and thermoplastic polymers. For many of the envisioned in vivo biomedical applications, these materials are not desirable. We are developing a novel top-down method for producing micro/nanoparticles based on contact printing and layer-by-layer assembly techniques. This approach allows assembling a variety of materials including therapeutic genes for treating diseases, polyelectrolytes for condensing genes and enhancing their cellular uptake, proteins for tissue targeting, quantum dots and magnetic particles for imaging, and polymer coatings for increasing circulation time in blood stream. Particles produced by this approach are also characterized by uniform sizes, and plate-like shapes, and well-defined layered structure. This technique holds potential to produce micro/nanoparticles for simultaneous gene delivery and imaging.