Immunoassays are the most reliable andcost-effective for the diagnosis of various diseases also the common platform that helps us identify the unknown protein in a short period of time. The market is flooded with different types of diagnostic immunoassays but it is necessary to develop more cost-effective immunoassay with increased performance. The major cost factor in this regard is the quality and amount of biomolecules that are being utilized in the product. Optimization of biomolecules can aid us in developing cost-effective products without compromising its performance. This study aims to optimize the maximum amount of antibodies that can be conjugated on commonly used 40 nm gold nanoparticles that are indicators for the conclusion of test results. The excess usage of antibody may increase unnecessary product cost as it may get eliminated during the washing steps, while the lower amount of antibody usage may reduce the product’s performance in terms of sensitivity and stability. This study helps the manufacturer and researchers to find the optimum value of antibody molecules that can be conjugated on the surface of 40 nm gold nanoparticles. According to this study, ~3.4µg of antibody molecules is sufficient to saturate the surface of 40 nm gold nanoparticles of optical density 1.0.