title: Stepwise functionalization of ZnO nanotips with DNA.
abstract: A surface functionalization methodology for the development of ZnO nanotips biosensors that can be integrated with microelectronics was developed. Two types of long chain carboxylic acids linkers were employed for the functionalization of 0.5 mum thick MOCVD-grown ZnO nanotip films with single-stranded DNA (ssDNA), followed by hybridization with complementary ssDNA tagged with fluorescein. The ZnO functionalization strategy was developed for the fabrication of ZnO nanotips-linker-biomolecule films integrated with bulk acoustic wave (BAW) biosensors, and it involved three main steps. First, 16-(2-pyridyldithiol)hexadecanoic acid or N-(15-carboxypentadecanoyloxy)succinimide, both bifunctional C16 carboxylic acids, were bound to ZnO nanotip films through the COOH group, leaving at the opposite end of the alkyl chain a thiol group protected as a 2-pyridyl disulfide, or a carboxylic group protected as a N-succinimide, respectively. In the second step, ssDNA was covalently linked to each type of ZnO-linker film: the 2-pyridyl disulfide end group was substituted with 16 bases 5'-thiol-modified DNA (SH-ssDNA), and the N-succinimide ester end group was substituted with 16 bases 5'-amino-modified DNA (NH(2)-ssDNA). In the third step, the DNA-functionalized ZnO nanotip films were hybridized with complementary 5'-fluorescein ssDNA. The surface-modified ZnO nanotip films were characterized after each step by FT-IR-ATR, fluorescence emission spectroscopy, and fluorescence microscopy. This functionalization approach allows sequential reactions on the surface and, in principle, can be extended to numerous other molecules and biomolecules.
authors.affiliation: Department of Chemistry, Rutgers, The State University of New Jersey, 73 Warren Street, Newark, New Jersey 07102, USA.
authors.forename: Olena
authors.initials: O
authors.lastname: Taratula
authors.forename: Elena
authors.initials: E
authors.lastname: Galoppini
authors.forename: Richard
authors.initials: R
authors.lastname: Mendelsohn
authors.forename: Pavel Ivanoff
authors.initials: PI
authors.lastname: Reyes
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Ziqing
authors.initials: Z
authors.lastname: Duan
authors.forename: Jian
authors.initials: J
authors.lastname: Zhong
authors.forename: Yicheng
authors.initials: Y
authors.lastname: Lu
mesh_terms: D004247:DNA / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D019308:Palmitic Acid / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D019308:Palmitic Acid; D004247:DNA; D015034:Zinc Oxide