Homogeneous fluorescent immunoassay with dry reagents

Area of Science:

• Analytical Chemistry
• Biochemistry

Background:

• Theophylline is a critical drug for managing respiratory diseases, necessitating accurate and accessible serum concentration monitoring.
• Traditional assays for theophylline can be time-consuming and require specialized laboratory equipment.

Purpose of the Study:

• To develop and validate a novel, rapid, and convenient paper strip-based assay for theophylline quantification in serum.
• To compare the performance of the new strip assay against established analytical methods.

Main Methods:

• Development of two paper strip assay formats: dilution-into-conjugate and integral strip assays.
• Utilized dry reagents in a paper matrix for substrate-labeled fluorescent immunoassay.
• Compared results with solution assay, high-performance liquid chromatography, and enzyme immunoassay.

Main Results:

• The dilution-into-conjugate strip assay showed excellent correlation with solution assay (r=0.975) and HPLC (r=0.980).
• The integral strip assay demonstrated high agreement with enzyme immunoassay (r=0.990).
• Both strip assay formats require only a single dilution step, enhancing user convenience.

Conclusions:

• Paper strip assays offer a rapid, convenient, and accurate alternative for serum theophylline measurement.
• The developed assay formats are suitable for point-of-care or resource-limited settings.
• This approach simplifies theophylline monitoring, potentially improving patient management.