Avidin decorated core-shell nanoparticles for biorecognition studies by elastic light scattering

A straightforward method based on elastic light scattering is shown to provide a sensitive and reliable tool for the quantitative determination of protein-ligand interactions occurring at the surface of suitably designed core-shell nanoparticles. The assay makes use of monodisperse nanocolloids having minimal optical contrast with the aqueous environment. By properly coating the particles with avidin and oligoethylene glycol based amphiphiles, we developed an hybrid system combining the availability of standard ligands with the necessary bioinvisibility towards accidental adsorption of non-specific macromolecules. This probe was employed to detect interactions with choices from different kinds of biotinylated proteins, revealing high specificity and affinities in the low nanomolar range. In particular, we obtained an efficient avidin anchorage of biotinylated protein A on the surface of the nanoparticles, which we exploited as a functional probe for the rapid, quantitative picomolar detection of human IgG antibodies. Overall, these light scattering-based nanosensors appear as a simple and highly informative tool for proteomics studies.