Biosensors using enzyme inhibition principles for in vivo, environmental, and defense applications

In this study, biosensor concepts using biomolecular recognition principles are being explored, potential applications for such devices in biomedical, environmental, and military/antiterrorism fields are being identified, and critical factors for the development of catalytic and affinity biosensors based on these concepts are being addressed. Such biosensors are capable, in principle, of detecting small analyte concentrations even when faced with substantial interferences from extraneous molecules. Two parallel studies were conducted here. In the first, nerve agent-surrogates malathion (MA) and pirimiphos-methyl (PM) were detected based on their inhibition of the enzyme butyrylcholinesterase (BuChE). In the second study, numerous metal ions of biomedical interest were detected based on inhibition of the enzyme urease (Ur). The biosensors were constructed by immobilizing the enzymes on nylon membranes. Tests with BuChE sensors have yielded detected levels in the part-per-million (ppm) range for MA and PM. Tests with Ur sensors have yielded detected levels in the part-per-billion (ppb) to ppm range for several metallic ions including Ag⁺, Hg²⁺, and Cu²⁺. Assay optimization procedures for lowering detection limits and producing more repeatable data have been developed. Nylon-based biosensors will serve as effective benchmarks for further hydrogel-based biosensor studies that we hope to conduct. The optimization study findings for nylon-based sensors should all be transferable to hydrogel-based sensors, and could greatly improve the efficacy of this technology. The BuChE sensor may eventually have promise for antiterrorism efforts, and a Ur-based biosensor could have many potential biomedical applications.