A one-step immunoassay for carbohydrate antigen 19-9 by biosensor based on imaging ellipsometry

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Immunotechnology

Background:

• Accurate cancer marker detection is crucial for early diagnosis and management.
• Existing methods for cancer biomarkers like carbohydrate antigen 19-9 (CA19-9) can be time-consuming.
• Development of simple, rapid, and reliable diagnostic assays is essential for clinical settings.

Purpose of the Study:

• To develop and evaluate a one-step immunoassay for CA19-9 using biosensor-based imaging ellipsometry (BIE).
• To assess the analytical performance, including sensitivity, specificity, reproducibility, and accuracy, of the developed BIE immunoassay.
• To investigate the potential clinical applicability of the BIE immunoassay for CA19-9 detection.

Main Methods:

• Immobilization of anti-CA19-9 monoclonal antibody on a carboxyl-modified silicon substrate.
• Blocking of the sensing layer with bovine serum albumin (BSA).
• Detection of CA19-9 using biosensor-based imaging ellipsometry (BIE).

Main Results:

• The BIE immunoassay demonstrated a linear detection range of 15.0–120.0 U/mL with a limit of detection of 10.0 U/mL (S/N=3).
• High reproducibility was observed with intra-slide and inter-slide coefficients of variation (CV%) below 10%.
• Accuracy ranged from 95.1-106.7%, specificity was high (cross-reaction rate <5.8%), and results correlated strongly with ECLIA (R²=0.997) in clinical samples.

Conclusions:

• The developed one-step BIE immunoassay provides a sensitive, specific, and reproducible method for CA19-9 detection.
• The assay exhibits excellent accuracy and strong correlation with established methods, suggesting clinical utility.
• Biosensor-based imaging ellipsometry offers a promising platform for rapid and efficient cancer biomarker analysis in clinical diagnostics.