Competitive immunosorbent assays for biotin using bifunctional unilamellar vesicles

Area of Science:

• Biochemistry
• Immunology
• Nanotechnology

Background:

• Competitive immunosorbent assays (CIAs) are vital for detecting analytes.
• Enzyme-labeled antigens are commonly used in CIAs, but their performance can vary.
• Optimizing antibody surface density is crucial for assay sensitivity.

Purpose of the Study:

• To compare the performance of vesicle-based and commercially available enzyme-labeled antigens in biotin CIAs.
• To investigate the impact of antibody surface density on assay sensitivity and detection limits.
• To determine the optimal configuration for sensitive and efficient biotin detection.

Main Methods:

• Competitive immunosorbent assays were conducted using biotinylated unilamellar vesicles (HBVs) and biotin-labeled horseradish peroxidase (B-HRP).
• Anti-biotin antibody (ABA) surface densities were varied from low to full monolayer coverage.
• Assay sensitivity, least detectable dose, and signal response were measured and compared.

Main Results:

• Vesicle-based assays (HBVs) showed strong dependence on antibody surface density, unlike B-HRP assays.
• HBVs achieved a lower detectable antigen concentration (10(-9) M) than B-HRP (10(-8) M).
• HBVs allowed for comparable signals at significantly lower antibody concentrations, indicating higher efficiency.

Conclusions:

• Unilamellar vesicles offer enhanced sensitivity and efficiency in competitive immunoassays for biotin detection.
• Vesicle-based assays are more adaptable to varying antibody surface densities, providing greater flexibility.
• The findings suggest that vesicle-based systems represent a promising advancement for sensitive immunosorbent assays.