3. Results and discussion
3.1. Preparation of antibody–gold nanoparticle conjugate
Gold nanoparticles were synthesized by chemical condensation,
where HAuCl4 was reduced to neutral gold atoms by sodium
citrate. The solution became supersaturated, and the gold gradually
started to precipitate in the form of gold nanoparticles. The
color of the solution changed from yellow of HAuCl4 to red of
gold nanoparticles