Selection by size and substance
Separating molecules is an important part of many manufacturing and testing processes, including pharmaceutical production and some biomedical tests. One way of carrying out such separation is by using nanofilters — materials with holes of a precisely controlled tiny diameter, to allow molecules up to that size to pass through while blocking any that are larger. But a new system devised by researchers at MIT could add an important new capability: a way to selectively filter out molecules of the same size that have different chemical properties.Karen Gleason, an MIT professor of chemical engineering and associate dean of engineering for research, and postdoctoral fellow Ayse Asatekin described the process in a paper published this month in the journal Nano Letters.This is “a fundamentally different way” of separating molecules, Gleason says. “People usually think of size as being the defining factor,” but by making the pores in the filter small enough...