Molecular Molds; November 1996; Scientific American Magazine; by Wallich; 2 Page(s)

While some biochemists have struggled to synthesize complex macromolecules to mimic natural compounds, others have been taking a simpler road--to cast the desired molecule in plastic. Many polymers consist of molecular building blocks that are small enough to be linked together to approximate the crannies and bulges of a drug, enzyme, antibody or other biologically active structure.

For the better part of 20 years, researchers have been attempting to realize this elegant approach, which suffers from a number of difficulties: the molecule from which the cast is being taken must be removed safely from the polymer after the process is finished, and it also must not be distorted unduly while the cast is being made. But in the past two years investigators have begun to meet with success. This summer Klaus Mosbach of the University of Lund cast holes in the shape of corticosteroids (antiinflammatory drugs that typically contain several dozen atoms) and discovered that the resulting plastic could bind the steroids from a solution containing a mixture of similar compounds. Mosbach also imprinted polymers to recognize diazepam (the active ingredient in Valium). Because the plastic¿s properties change when its cavities are filled, it can serve as a highly specific biosensor.