The document discusses functionalizing inorganic silica nanoparticles for drug delivery across the blood-brain barrier (BBB). It notes two general approaches: 1) Coating hydrophilic silica surfaces with hydrophobic organically modified silica (ORMOSIL) to allow crossing of the BBB; and 2) Conjugating monoclonal antibodies like OX26 to the silica nanoparticle surface to target receptors on brain endothelial cells and facilitate transport across the BBB. The conjugation process involves dissolving the antibody in phosphate buffer and adding the crosslinker MBS to attach the antibody to the silica nanoparticle surface.