Disposable Micromachined Flow Immunoassay for Field Detection of Contaminants

The use of enzyme-linked immunosorbent assay (ELISA) to detect contaminants such as solvents, fuels, and pesticides in soil and water samples is now well established. Although ELISA and related methods can facilitate analysis of samples, several washing and separation steps are involved that require 30 to 120 minutes per sample to reach equilibrium. Recently, near infrared fluorescence immunoassays have been shown to exhibit unparalleled sensitivity to solvents, fuels, and pesticides in a laboratory setting. However, there remains a need to develop a reliable, highly sensitive, lightweight instrument capable of performing automated immunoassays of contaminants for field applications. This proposal suggests the development of a compact, fluorescent flow immunosensor having near-infrared emitting diode laser excitation that can be used in soil and water analysis. The innovation of the proposed system is the combination of microelectromechanical methods of sample introduction and preparation with sensitive diode laser-based near-infrared fluorescence-tagged immunological probes to provide a low-cost sensor having high sensitivity to a range of hazardous materials in field operations. The Phase I technical objectives include design and fabrication of a flow cell and modular probe for use in diode laser-based immunoassay, coupling of near-infrared fluorophores to contaminant-specific antibodies, and calibration of the flow immunosensor using nanoMolar hydrocarbon and pesticide samples for acquisition of families of test data to be used in the optimization of a proof-of-concept prototype system.