Submitted to: Biosensors World Congress
Publication Type: Abstract Only
Publication Acceptance Date: July 24, 1997
Publication Date: N/A
Whole-cell microbial biosensors are reliable and rugged in field applications and can provide real-time assays of a variety of substances. Potential applications include clinical analyses, environmental monitoring, and measurements in the food and fermentation industries. The most common configuration of whole-cell biosensors (first generation biosensors) involves immobilized microorganisms coupled with an oxygen (Clark-type) electrode. In this case, the catabolism of analytes results in changes in dissolved oxygen concentration that are registered at the receptor element. The depletion of oxygen can reduce the rate of these reactions, and sensor responses are thus limited by the oxygen available in a base solution. Completely fluorinated organic substances (CFOS or perfluorocarbons) have the capacity to accumulate oxygen and transfer it to water or an electrolyte solution when it is in contact with it. CFOS are also biologically inert and insoluble in aqueous media. CFOS have never before been tested in conjunction with microbial biosensors. We used perfluorodecaline to hyperoxygenate the base medium of amperometric sensors containing immobilized cells of Gluconobacter oxydans. Glucose was used as the test analyte. Oxygen-saturated perfluorodecaline increased the base medium oxygen content from 9.2 to 41.0 mg/l, resulting in improved biosensor sensitivity and extended response range. Using a bioreceptor cell load of 0.025 mg/mm**2, sensor responses to 3.0 mM glucose were 250% higher in oxygenated buffers than in control buffers. Results suggest that hyperoxygenation may be a new general approach for modulating biosensor responses.