Molecular Engineering of Amperometric Biosensors

ChEMS Seminar

Featuring Dr. Harold G. Monbouquette
Chemical & Biomolecular Engineering Department
of California, Los Angeles

Location: Computer Science (CS) 174
*Refreshments will be served after seminar

Amperometric biosensors consist of a biological element (e.g., enzyme, antibody, receptor) for molecular recognition and a transduction scheme to produce an electrical current in response to selective biomolecular interaction events.  Such an approach is achieved most readily with an enzyme catalyzing an oxidation or reduction reaction that is coupled electronically to an electrode via an electron transfer mediator, a relatively small molecule that shuttles electrons between enzyme and electrode. 

In any case, optimal amperometric biosensor construction requires attention to molecular-scale design issues including, for example, electrode surface modification, enzyme immobilization, and electronic coupling.  Two very different amperometric biosensor designs will be presented: a highly selective glutamate biosensor based on an oxidase immobilized atop a permselective, electropolymerized film on a platinum black electrode; and an amperometric sensing system for estradiol, and related man-made compounds, based on a hydrolytic reporter enzyme that catalyzes production of an electroactive molecule from a sacrificial substrate.  The glutamate microbiosensor is produced using high-throughput micromachining technology and is being used to detect the excitory neurotransmitter, glutamate, in the brains of mice and rats.  In contrast, the estradiol biosensor essentially consists of a molecular switch that enables detection, at low concentration, of a class of endocrine disrupting chemicals (EDCs) that mimic estradiol.