Rapid detection and identification of biological and chemical agents by immunoassay, gene probe assay and enzyme inhibition using a silicon-based biosensor

A rapid biosensor assay procedure that utilizes biotin-streptavidin mediate d filtration capture onto nitrocellulose membrane, in conjunction with a si licon-based light-addressable potentiometric sensor (LAPS) was developed fo r detection and identification of biological and chemical threat agents. Sa ndwich immunoassays, nucleic acid hybridization assays and enzyme inhibitio n assays are described. For immunoassays, the lower limits of detection (LO D) per 100-mu l sample were approximately 5 pg/ml for protein (Staphylococc al enterotoxin B), 2 ng/ml for virus (Newcastle disease virus), and 20 ng/m l for vegetative bacteria (Brucella melitensis). In a dual gene probe assay format, the LOD was 0.30 fmol (1.8 x 10(8) copies per 60-mu l) of single s tranded target DNA. Enzyme inhibition assays on the LAPS using acetylcholin esterase were able to detect soman and sarin in aqueous samples at 2 and 8 pg (100 and 600 pM), respectively. The assays were easy to perform and requ ired a total time equal to the reaction period plus about 15 min for filter ing, washing and sensing. The assay format is suitable for detection of a w ide range of infectious and toxic substances. New assays can be developed a nd optimized readily, often within 1 or 2 days. (C) 2000 Elsevier Science S .A. All rights reserved.