Rational assembly and dual functionalization of Au@MnO heteroparticles on TiO2 nanowires

Abstract

Au–MnO heteroparticles were immobilized on the surface of TiO₂ nanowires and tagged subsequently with a fluorescent ligand. The immobilization of the Au@MnO heteroparticles was achieved by functionalizing the TiO₂ nanowire support with a polymer containing catechol anchor groups for binding to the metal oxide surface and amine groups for conjugation to the Au domains of the Au@MnO heteroparticles. The Au domain of the resulting TiO₂@Au–MnO nanocomposite could be functionalized selectively with a thiol-tagged 24 mer oligomer containing Texas red (SH-ODN-TXS red), whereas a green dye (NBD–Cl) could be anchored selectively to the TiO₂ “support” using the free amine groups of the polymeric ligand. The binding of the NBD and the Texas red fluorophors was monitored by confocal microscopy and the functionalization of the metal oxide nanoparticles was monitored by UV-Vis spectroscopy. All composite products were characterized by transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDX), confocal laser scanning microscopy (CLSM) and UV-Vis spectroscopy.