Size Matters: Influence of the Size of Nanoparticles on Their Interactions with Ligands Immobilized on the Solid Surface

The correlation between the size of biotinylated nanoparticles and their affinity in relation to interactions with the solid surface was investigated. The silica particles with a diameter of 50−200 nm containing amino groups on the surface were labeled with different quantities of biotin. The affinity properties of biotinylated nanoparticles were studied using a Biacore 3000 instrument equipped with a streptavidin-coated sensor chip (SA chip). It was shown that the increase in the particle size from 50 to 200 nm reduced the affinity (K_D) of biotin−streptavidin interactions from 1.2 × 10⁻¹² to 1.2 × 10⁻¹⁰ M. It was found that the particles with higher concentrations of immobilized biotin on particle surfaces demonstrated stronger binding with streptavidin.