title: Non-covalent monolayer-piercing anchoring of lipophilic nucleic acids: preparation, characterization, and sensing applications.
abstract: Functional interfaces of biomolecules and inorganic substrates like semiconductor materials are of utmost importance for the development of highly sensitive biosensors and microarray technology. However, there is still a lot of room for improving the techniques for immobilization of biomolecules, in particular nucleic acids and proteins. Conventional anchoring strategies rely on attaching biomacromolecules via complementary functional groups, appropriate bifunctional linker molecules, or non-covalent immobilization via electrostatic interactions. In this work, we demonstrate a facile, new, and general method for the reversible non-covalent attachment of amphiphilic DNA probes containing hydrophobic units attached to the nucleobases (lipid-DNA) onto SAM-modified gold electrodes, silicon semiconductor surfaces, and glass substrates. We show the anchoring of well-defined amounts of lipid-DNA onto the surface by insertion of their lipid tails into the hydrophobic monolayer structure. The surface coverage of DNA molecules can be conveniently controlled by modulating the initial concentration and incubation time. Further control over the DNA layer is afforded by the additional external stimulus of temperature. Heating the DNA-modified surfaces at temperatures >80 °C leads to the release of the lipid-DNA structures from the surface without harming the integrity of the hydrophobic SAMs. These supramolecular DNA layers can be further tuned by anchoring onto a mixed SAM containing hydrophobic molecules of different lengths, rather than a homogeneous SAM. Immobilization of lipid-DNA on such SAMs has revealed that the surface density of DNA probes is highly dependent on the composition of the surface layer and the structure of the lipid-DNA. The formation of the lipid-DNA sensing layers was monitored and characterized by numerous techniques including X-ray photoelectron spectroscopy, quartz crystal microbalance, ellipsometry, contact angle measurements, atomic force microscopy, and confocal fluorescence imaging. Finally, this new DNA modification strategy was applied for the sensing of target DNAs using silicon-nanowire field-effect transistor device arrays, showing a high degree of specificity toward the complementary DNA target, as well as single-base mismatch selectivity.
authors.affiliation: School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Moria
authors.initials: M
authors.lastname: Kwiat
authors.forename: Roey
authors.initials: R
authors.lastname: Elnathan
authors.forename: Minseok
authors.initials: M
authors.lastname: Kwak
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: de Vries
authors.forename: Alexander
authors.initials: A
authors.lastname: Pevzner
authors.forename: Yoni
authors.initials: Y
authors.lastname: Engel
authors.forename: Larisa
authors.initials: L
authors.lastname: Burstein
authors.forename: Artium
authors.initials: A
authors.lastname: Khatchtourints
authors.forename: Amir
authors.initials: A
authors.lastname: Lichtenstein
authors.forename: Eli
authors.initials: E
authors.lastname: Flaxer
authors.forename: Andreas
authors.initials: A
authors.lastname: Herrmann
authors.forename: Fernando
authors.initials: F
authors.lastname: Patolsky
mesh_terms: D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004566:Electrodes; D005898:Glass / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000235:genetics; D012666:Semiconductors; D012825:Silicon / Q000737:chemistry; D013499:Surface Properties
chemical_list: D009838:Oligodeoxyribonucleotides; D006046:Gold; D004247:DNA; D012825:Silicon