Recently, a dual-functionalized nanoparticle has been described
that combines histidine-tagged protein purification with site-specific
fluorophore labeling46. The particles are tetramethylrhodamine-doped
nickel chelate silica nanoparticles surface modified with nitrilotriacetic
acid. When exposed to a bacterial lysate containing the estrogen
receptor alpha ligand binding domain (ERalpha) as a minor component,
these beads show very high specificity binding, enabling protein
purification in one step. The particles also exhibit good activity for
ligand binding and ligand-induced binding to co-activators in solution
FRET experiments and protein microarray fluorometric and FRET
assays46.