This research project, supported in the Analytical and Surface Chemistry Program, targets the development of direct amperometric affinity electrodes for application as immunosensors and DNA probes. These devices will expand the newly created class of biosensors based on "wired" redox macromolecules. In these amperometric sensors, substrates selectively undergo electron transfer with redox proteins which in turn undergo electron exchange with amperometric electrodes. "Wiring" of redox processes is accomplished through immobilization of enzymes at electrodes in an imidazole-substituted polyacrylamide hydrogel containing coordinated osmium wherein substrate analytes are afforded easy access to enzyme sites, and electron exchange between enzyme and electrode is mediated by the redox polymer. Increased analytical sensitivity derives from the use of both high-turnover enzymes and highly efficient mediation of electron exchange between enzyme and electrode. Specific goals to be pursued by Professor Heller and his students during the tenure of this three-year grant include bringing electrochemical DNA sensing to a level of sensitivity that will obviate the need for polymerase chain reaction (PCR) amplification of the probed sequence, and surpassing the speed of present PCR methodology through enhanced mass transport in the hydrogel of the amperometric biosensor. The development of more rapid, sensitive, and selective techniques for detecting and quantifying biomolecules is broadly important to fundamental disciplinary and technological advances. Through synergistic combination of fundamentals of biochemistry, biophysics, materials chemistry, inorganic chemistry, and electrochemistry, new biosensors will be developed which have selectivity and sensitivity characteristics that exceed current methodology.
