Enhanced Resonance Light Scattering of Antibody Covalently Conjugated Gold Nanoparticles Due to Antigen-Antibody Interaction Induced Aggregation

Antibody coated nanoparticles have been used extensively in optical immunoassay for detecting various proteins. However, in most cases, the strategies for preparing antibody attached nanoparticles were based on physical adsorption, which is adverse to promote the detection limit and sensitivity of optical immunoassay. In this paper, antibody was covalently conjugated to gold nanospheres using a long chain alkanethiol: 16-mercaptohexadecanoic acid (16-MHDA). 16-MHDA modified gold nanoparticles were more stable and easier to conjugate antibody. Characterized results confirmed that antibody was covalently coated on the surface of gold nanoparticles. Owing to antigen-antibody interaction, the fabricated gold nanoparticles/antibody bioconjugates produced specific aggregation in the presence of antigen, which enhanced the resonance light scattering intensity. The enhanced intensity was highly sensitive to the concentration of antigen. The results suggested that such bioconjugates had great potential in detecting proteins using resonance light scattering with high sensitivity.