title: Structure and electronic properties of "DNA-gold-nanotube" systems: a quantum chemical analysis.
abstract: The development of novel DNA sensors is a crucial issue in the diagnosis of pathogenic and genetic diseases. We have used density functional theory (DFT) to investigate the performance of hybrid DNA sensors consisting of a gold atom (Au) deposited on two types of single-walled carbon nanotubes: armchair SWCNT(8,0)/Au and zigzag SWCNT(5,5)/Au and compared these with bare Au. We also chose adenine:thymine (A:T) as a Watson-Crick base pair of the DNA double helix. In the recognition probe, SWCNT/Au/A, adenine is immobilized on the SWCNT/Au supporter via its active N7 anchor point. After thymine hybridization (SWCNT/Au/A:T), the overall modulations compared with the original systems. Due to the complimentary functions of gold, which acts as a powerful electron withdrawing and transmitting group and of the SWNCTs, which act as electron collecting centers, respectively, the hybrid systems, "SWNCTs/Au", were found to exhibit more stability and sensitivity than the Au center alone. The changes in the HOMO-LUMO band gaps and in the atomic partial charges upon binding of thymine were rather small, but the change of the overall dipole moment was considerably larger in SWCNT/Au/A than it was in Au/A alone. The overall results suggest that the "SWCNTs/gold" system is a potential candidate for a nanostructure-based DNA sensor.
authors.affiliation: Physical Chemistry Division, Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Pannopard
authors.forename: P
authors.initials: P
authors.lastname: Khongpracha
authors.forename: M
authors.initials: M
authors.lastname: Probst
authors.forename: J
authors.initials: J
authors.lastname: Limtrakul
mesh_terms: D000225:Adenine / Q000737:chemistry; D020029:Base Pairing; D015374:Biosensing Techniques; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004583:Electrons; D006046:Gold / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D011789:Quantum Theory; D013941:Thymine / Q000737:chemistry
chemical_list: D037742:Nanotubes, Carbon; D006046:Gold; D004247:DNA; D000225:Adenine; D013941:Thymine