(153b) Multifunctional Micro- and Nanoparticles Made by Electrified Co-Jetting

Recent advances with particle designs have generated increasing enthusiasm for use of polymer particles in drug delivery or as imaging probes. Because of their controllable sizes, surface characteristics, and degradation rates, polymer particles may carry potential for mimicking biological systems, such as viruses or circulating blood cells. While a series of so-called ?multifunctional particles? has been prepared already, individual particle properties are typically convoluted and often cannot be controlled independently.

We have recently developed a disruptive technological approach to fabricate anisotropic particles with independently controllable compartments [1-4]. The fabrication process relies on electrified co-jetting, which is an off-spring of the electrospinning technology. Using co-extrusion of multiple fluid jets, manipulation in an electrical field is used to fabricate multiphasic particles. The geometry of the multi-compartment particles is induced by sustaining the interfaces between the two or more jetting solutions during the jet fragmentation and size reduction accompanying solvent evaporation. Therefore, the individual compartments can be separately loaded with biomolecules or surface-modified with reactive bioligands. Moreover, tight control of process parameters allows for controlling the size and shape of the multiphasic micro- and nanoparticles. In such nanomaterials, the anisotropic distribution of the two or more different chemical species becomes another governing rule ? in addition to size and shape. In principle, such novel particle geometries enable independent control of key parameters, such as chemical composition, surface functionalization, biological loading, shape, and size to be controlled independently for each compartment ? thereby effectively mimicking the architecture of their biological counterparts, i.e., cells or viruses.

The co-jetting technology lends itself to fabrication of diverse compartment geometries. For instance, biphasic particles with equally sized compartments can be prepared. Similarly, particles with more than two compartments can be fabricated. Modification of process parameters can yield in biphasic particles, which have core/shell geometries. At the same time, compartments can be made of different matrix materials, which enable independent surface modification, as well as independent control of extremely diverse functionalities, such as release rate, environmental responsiveness, or color, to name just a few.

[1] K. H. Roh, D. C. Martin, J. Lahann, Nat. Mater. 2005, 4, 759. [2] K. H. Roh, M. Yoshida, J. Lahann, Langmuir 2007, in press. [3] M. Yoshida, K. H. Roh, J. Lahann, Biomaterials 2007, in press. [4] K. H. Roh, D. C. Martin, J. Lahann, J. Am. Chem. Soc. 2006, 128, 6796.