Semiquantitative assay of human chorionic gonadotropin by a simple and fast immunofiltration technique

Area of Science:

• Biochemistry
• Immunology
• Medical Diagnostics

Background:

• Human chorionic gonadotropin (hCG) is a crucial biomarker for pregnancy and certain cancers.
• Accurate and accessible detection methods for hCG are vital in clinical settings.

Purpose of the Study:

• To develop and validate a novel immunofiltration technique for the semiquantitative assay of human chorionic gonadotropin (hCG).
• To compare the specificity and utility of two antibody-based approaches within the immunofiltration assay.

Main Methods:

• An immunofiltration assay was developed using immobilized anti-beta hCG subunit antibodies on a microfibre disc.
• Two versions were tested: one using monoclonal antibodies specific for intact hCG, and another using rabbit antibodies detecting both intact hCG and its beta-chain.
• Colorimetric detection was achieved using a horse radish peroxidase conjugate and tetramethylbenzidine/hydrogen peroxide solution.

Main Results:

• The assay demonstrated a concentration-dependent colorimetric response, with blue bar formation indicating hCG presence.
• The monoclonal antibody version was specific for intact hCG, while the rabbit antibody version detected both intact hCG and its beta-chain.
• Negligible cross-reactivity with human lutropin and thyrotropin was observed, and common substances like hemoglobin, urea, and drugs did not interfere.
• Results correlated well with established ELISA and commercial kit methods when tested on urine from pregnant women and sera from patients with trophoblastic diseases.

Conclusions:

• The developed immunofiltration technique offers a reliable and specific method for semiquantitative hCG detection.
• This assay is suitable for clinical applications, including pregnancy testing and monitoring trophoblastic diseases.
• The assay's performance is comparable to existing gold-standard methods, suggesting its potential for widespread adoption.