Enzyme immunochromatography--a quantitative immunoassay requiring no instrumentation

Area of Science:

• Analytical Chemistry
• Biotechnology

Background:

• Accurate quantification of drugs in biological fluids is crucial for therapeutic drug monitoring.
• Existing instrumental methods can be time-consuming and require specialized laboratory settings.

Purpose of the Study:

• To develop a novel, rapid, and non-instrumental immunoassay for quantifying theophylline.
• To provide a cost-effective and accessible method for on-site drug testing.

Main Methods:

• Development of an enzyme immunochromatographic assay (immunograph) combining enzyme-channeling immunoassay and immunochromatography.
• Utilizing capillary migration on a paper strip with immobilized antibodies for a non-separation assay.
• Quantification based on the spatial distribution of enzyme label, not enzyme activity.

Main Results:

• The immunograph assay provides accurate quantification of theophylline in whole blood or plasma.
• The method is insensitive to sample matrix effects, enzyme instability, temperature, and incubation timing.
• Results correlate well with established instrumental methods, with a rapid 15-minute protocol.

Conclusions:

• The novel enzyme immunochromatographic assay is a simple, rapid, and reliable method for theophylline quantification.
• Its non-instrumental nature and robustness make it suitable for on-site testing in non-laboratory environments.
• This assay offers a practical alternative for therapeutic drug monitoring and point-of-care diagnostics.