A Suspension Array Immunoassay for the Toxin Simulant Ovalbumin

Abstract

A microsphere-based suspension array (SA) system was used for the development and characterization of an immunoassay for the toxin simulant ovalbumin. Results obtained by SA immunoassay were compared with those obtained by enzyme-linked immunosorbent assay (ELISA) using the same immunoreagents. The limit of detection (LOD) for the SA ovalbumin assay was 4.9 ng/mL, compared to a LOD of 0.01 ng/mL for the ovalbumin ELISA. Although the ELISA LOD exceeded that of the SA assay, the SA assay was simple and rapid to perform, with assays being completed in half the time of the traditional ELISA. The well-to-well reproducibility (coefficient of variation (CV)) of the ELISA and the SA assay was 4.9% and 5.1%, respectively. The ELISA and SA assay plate-to-plate reproducibility was 14.8% and 6.1%, respectively. The protocols used to develop the SA assay for ovalbumin may be used as a template for development of other SA assays for toxins, bacteria, and viruses.

Keywords:

• ELISA
• Immunoassay
• Microsphere
• Multiplex
• Ovalbumin
• Suspension array

Notes

Standard conditions for SA assay: 5 µg/mL CAb, 10 µg/mL ovalbumin, 5 µg/mL DAb, 0.25 µg/mL IAb. Four replicate wells per plate. %CV = SD/mean FI.

Standard conditions for ELISA: 15 µg/mL CAb, 10 µg/mL ovalbumin, 3 µg/mL DAb, 80 ng/mL IAb. Three replicate wells per plate. %CV = SD/mean absorbance.

Standard conditions for SA assay: 5 µg/mL CAb, 10 µg/mL ovalbumin, 5 µg/mL DAb, 0.25 µg/mL IAb. Standard conditions for ELISA: 15 µg/mL CAb, 10 µg/mL ovalbumin, 3 µg/mL DAb, 80 ng/mL IAb. %CV = SD/mean.