Ultrasensitive Detection of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] Using a Microcantilever Sensor

Microcantilevers modified with a self-assembled monolayer respond sensitively to specific ion concentrations. Here, we report the detection of trace amounts of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] using microcantilevers modified with a self-assembled monolayer of triethyl-12-mercaptododecylammonium bromide. The self-assembled monolayer was prepared on a silicon microcantilever coated with a thin layer of gold on one side. The microcantilever undergoes bending due to sorption of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] ions on the monolayer-modified side. It was found that a concentration of [10.sup.-9] M [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] call be detected using this technology in a flow cell. Other anions, such as [Cl.sup.-], [Br.sup.-], [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], have minimal effect on the deflection of this cantilever. The mechanics of the bending and the chemistry of cantilever modification are discussed.