From 112 polyarylate compounds in his library, Kohn has already found several promising leads. These include polymers that appear to promote cell growth, migration and attachment: critical processes for tissue replacement. In addition to helping Kohn beat the odds of finding such molecules, studying the compounds in his library may allow him to identify structure-function relationships that would enable him to design-rather than simply screen for-improved biomaterials.
Introducing "Click Chemistry"
Another speaker, K. Barry Sharpless of the Scripps Research Institute, studies the synthetic methods used to create combinatorial libraries, as well as to manufacture the promising compounds they yield. With a technique he calls "Click Chemistry," Sharpless says he hopes to greatly increase the rate by which new compounds can be made. Click Chemistry involves assembling compounds in a single step-rather than a series of reactions-from several reactive components that "click" together easily. "We're looking for unknown, easy-to-make structures that act in new ways," he states.
"This is not conventional combinatorial chemistry," Sharpless adds. "We want to make drugs and other useful materials from much simpler building blocks [than are currently used]." Nature, he says, teaches us that the most efficient way to build molecules is by assembling them from smaller molecules that already contain carbon-carbon bonds, rather than by making new bonds between carbons. Click Chemistry reactions generate so-called heteroatom bonds between carbon atoms and non-carbon atoms such as nitrogen or oxygen--bonds that are much easier to make than those between carbons.
Chemicals called olefins, which are easily derived from crude oil and natural
plant oils, provide a cheap source of building blocks for Click Chemistry,
Contact: Ginger Pinholster
University of Delaware