DNA-directed assembly on dual-functionalized microspheres

The bottom-up assembly of functional devices requires novel building blocks to facilitate the incorporation of functional and structural hierarchy. Anisotropic building blocks can substantially broaden the creation of self-assembled devices With unique properties because of their morphological and/or chemical asymmetry. In this regard. we have created microspheres with one hemispherical face exposing silica and the other exposing gold. These microspheres were formed by the shadow deposition of gold onto silica microspheres. The two different surfaces allowed the use of different surface chemistries - silane chemistry for the silica side and thiol chemistry for the bold side - to immobilize different oligo sequences on the two faces. These dual-functionalized microspheres were used for the selective orthogonal assembly of fluorophore-tagged target oligonucleotides. This DNA-directed assembly was confirmed by confocal microscopy of the microspheres.