A Protein Coated Piezoelectric Crystal Detector

The purpose of this project was to develop a protein coated, portable piezoelectric crystal detector for organophosphorus compounds. The performance of acetylcholinesterase, GD-1 anti-soman, anti-DMMP antibody, and bovine serum albumin BSA coatings was evaluated. Different immobilization methods were also tested. The responses obtained with the protein coatings immobilized via cross- linking with glutaraldehyde were acceptable, provided that the reference crystal was coated with dextran. The proposed coatings showed good stability and reasonable lifetimes that ranged from approximately three weeks in the case of the antibody coatings to several months in the case of BSA. Although moisture, gasoline, and sulfur are potential interferents, their effects on the sensor were eliminated by using a sodium sulfate scrubber which did not affect the performance of the detector towards organophosphates. A small, battery operated portable instrument capable of real time measurements with alarm function was produced. The instrument can be used in a wide range of applications, depending on the coatings applied to the crystals. Keywords Piezoelectric crystal, Organophosphorus compounds, Enzyme, Immobilization, Antibody, Biosensors, Biomedical instrumentation, Protein coatings.