title: Complementary base-pair-facilitated electron tunneling for electrically pinpointing complementary nucleobases.
abstract: Molecular tips in scanning tunneling microscopy can directly detect intermolecular electron tunneling between sample and tip molecules and reveal the tunneling facilitation through chemical interactions that provide overlap of respective electronic wave functions, that is, hydrogen-bond, metal-coordination-bond, and charge-transfer interactions. Nucleobase molecular tips were prepared by chemical modification of underlying metal tips with thiol derivatives of adenine, guanine, cytosine, and uracil and the outmost single nucleobase adsorbate probes intermolecular electron tunneling to or from a sample nucleobase molecule. We found that the electron tunneling between a sample nucleobase and its complementary nucleobase molecular tip was much facilitated compared with its noncomplementary counterpart. The complementary nucleobase tip was thereby capable of electrically pinpointing each nucleobase. Chemically selective imaging using molecular tips may be coined "intermolecular tunneling microscopy" as its principle goes and is of general significance for novel molecular imaging of chemical identities at the membrane and solid surfaces.
authors.affiliation: Department of Chemistry, School of Science, University of Tokyo, and Japan Science and Technology Agency, Hongo, Bunkyo-Ku, Tokyo 133-0033, Japan.
authors.forename: Takahito
authors.initials: T
authors.lastname: Ohshiro
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Umezawa
mesh_terms: D020029:Base Pairing / Q000235:genetics*; D001483:Base Sequence; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D004583:Electrons; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D009838:Oligodeoxyribonucleotides; D013438:Sulfhydryl Compounds