Technologies that permit fast chemical measurement have myriad applications in medicine, the environment and food safety monitoring. However, methods that rely on heat or changes in optical properties often require long sampling times and equipment not suitable for use in the field. Additionally, optical methods can only be used when the testing solution is clear, precluding their use on blood and any other opaque solution.
Did you know? To detect the interactions between individual molecules, atomic force microscopes must accurately measure forces as small as a few piconewtons (trillionths of a newton). Professors Robert Clark and Piotr Marszalek, of the mechanical engineering and materials sciences department, in collaboration with chemistry Professor Eric Toone, have devised a promising new atomic force microscopy (AFM)-based method that could make the detection of virtually any molecule in solution as easy as fishing in a barrel. They reported a demonstration of the technique in Proceedings of the National Academy of Sciences. The researchers use the AFM's cantilever as a fishing rod, which they bait with a sample of the chemical to be measured in order to catch "fish," actually proteins known to specifically bind the target chemical. Because the fish are easier to catch with the baited cantilever when there are fewer free "worms" to compete with, the researchers can quantify the amount of chemical in solution by tallying the number of successful catches. The method eventually could be incorporated into devices similar to hand-held personal digital assistants that might test for different chemicals by simply switching out a chip.