Conventional fabrication of microscopic spherical particles uses a “bottom-up” approach, growing the spheres from even tinier “seeds” — an approach that is only capable of producing very tiny particles. This new “top-down” method, however, can produce spheres as small as 20 nanometers (about the size of the smallest known viruses) or as large as two millimeters (about the size of a pinhead), meaning the biggest particles are 100,000 times larger than the smallest ones. But for a given batch, the size of the spheres produced can be extremely uniform — much more so than is possible with the bottom-up approach. Cheap Faucets
Yoel Fink, a professor of materials science and director of MIT’s Research Laboratory of Electronics, whose group developed the earlier method of producing multimaterial fibers, explains that the new method can also produce multimaterial spheres consisting of different layers or segments.
Even more complex structures are possible, he says, offering unprecedented control over particle architecture and composition. The most likely short-term uses of the new process would be for biomedical applications, says Ayman Abouraddy, a former postdoc in Fink’s lab who is now an assistant professor at UCF’s College of Optics and Photonics. “Typical applications of nanoparticles today are for controlled drug delivery,” he says.
But with this new process, two or more different drugs — even ones that are ordinarily incompatible — could be combined inside individual particles, and released only once they’ve reached their intended destination in the body.
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