Until now, DeSimone said, most current techniques for particle formation were incompatible with organic materials. That was because they involved baking, etching or processing robust metals and such with solvents that would have destroyed far more fragile organic matter such as genes or drugs.
The new method avoids harsh treatment but also allows formation of uniform particles in any shape designers choose ?spheres, rods, cones, trapezoidal solids, etc. -- and essentially any composition, he said. The relatively simple process, which he and colleagues are calling Particle Replication in Nonwetting Templates, or PRINT, also avoids creating films or "scum layers" that would clump particles together rather than allowing them to be harvested independent of one another."This is in contrast to traditional imprint lithography with silicon, glass or quartz molds where it is difficult to eliminate this residual material between objects," DeSimone said.
Particles injected into the body can be designed to be biodegradable, he said. Some are made from the same material used to make surgical sutures. They will incorporate as "cargo" whatever biological material designers want to get into patients' bloodstreams for more efficient uptake by cells for diagnostic testing or therapy.Studies with various organic compounds have been very successful, the chemist said. New studies with mice have recently begun at the UNC School of Medicine, which DeSimone joined as professor of pharmacology.
"The process starts off when we make a master template in a clean room at places like the Triangle National Lithography Center at N.C. State University," DeSimone said. "From that we make impressions with what we call liquid Teflon, and the resulting molds look something like ice cube trays with tiny cavities in them. After that, we mold the carrier and fragile functional materials into w
Source:University of North Carolina at Chapel Hill