3-p-hydroxyphenylpropionic acid--a sensitive fluorogenic substrate for automated fluorometric enzyme immunoassays

Area of Science:

• Biochemistry
• Immunology
• Analytical Chemistry

Background:

• Horseradish peroxidase (HRP) is a key enzyme in immunoassays.
• Fluorogenic substrates offer sensitive detection methods.
• Automated microplate assays enhance efficiency and reproducibility.

Purpose of the Study:

• To describe the application of 3-p-hydroxyphenylpropionic acid (HPPA) as a fluorogenic substrate in automated microplate enzyme immunoassays.
• To evaluate the performance of a fluorometric enzyme immunoassay (FEIA) using HPPA compared to a colorimetric assay.
• To assess the quantitative detection capabilities and clinical correlation of the FEIA.

Main Methods:

• Utilized 3-p-hydroxyphenylpropionic acid (HPPA), a fluorogenic substrate for HRP.
• Developed an automated microplate fluorometric enzyme immunoassay (FEIA).
• Compared FEIA with HPPA to a colorimetric enzyme immunoassay using tetramethylbenzidine (TMB) for detecting human thyrotropin (TSH) and recombinant hepatitis B surface antigen (rHBsAg).

Main Results:

• Fluorescence intensity was dependent on buffer pH and substrate mixture concentrations.
• The FEIA sensitivity was comparable to the colorimetric assay.
• The FEIA demonstrated a wide dynamic range for quantitative analyte detection.
• Clinical evaluation showed good correlation between the FEIA and conventional methods.

Conclusions:

• HPPA is a suitable fluorogenic substrate for automated HRP-based immunoassays.
• FEIA offers sensitive and quantitative detection with a broad dynamic range.
• The developed FEIA is a viable alternative to conventional immunoassay methods.