Presentation of a nano-based tag for immunoassay, based on amine-modified bovine serum albumin nanoparticles

The aim of this study was to evaluate four immunoassays, based on amine-modified bovine serum albumin nanoparticles (AMBSANPs). First, the capability of nitrate absorption by AMBSANPs under different conditions was evaluated. Then, serial concentrations of pure ßHCG were added to wells coated with ßHCG antibody for immunoassays 1 and 2, and wells coated with ßHCG aptamer for immunoassays 3 and 4. Next, AMBSANPs conjugated with ßHCG antibody was added for immunoassays 1 and 3, and AMBSANPs conjugated with ßHCG aptamer were added for immunoassays 2 and 4. Finally, the optical density (OD) of each well was read at 340 nm, and compared with controls. Moreover, the concentration of ßHCG in the clinical samples was quantified by immunoassays 1, 2, 3, 4 and ELISA, and then compared. The effect of some serum interferences on these immunoassay methods was evaluated. The authors observed that the amount of nitrate absorption by AMBSANPs increased with an increase in H+ ion concentration and temperature, and decreased with an increase in ion strength. The correlation (R2) between ELISA and immunoassays 1, 2, 3 and 4 were 0.97, 0.97, 0.98, 0.99, respectively. It was found that the increase in the serum interferences led to a decrease in the measured ßHCG concentration.