title: Resonance energy-transfer studies of the conformational change on the adsorption of oligonucleotides to a silica interface.
abstract: Time-resolved evanescent wave-induced fluorescence studies have been carried out on a series of fluorescently labeled oligonucleotide sequences adsorbed to a silica surface from solution. The fluorescence decay profiles of a fluorescent energy donor group undergoing resonance energy transfer to a nonemissive energy-acceptor molecule have been analyzed in terms of a distribution of donor-acceptor distances to reveal the conformational changes that occur in these oligonucleotides upon adsorption. Evanescent wave-induced time-resolved Förster resonance energy-transfer (EW-TRFRET) measurements indicate that at a high electrolyte concentration, there is localized separation of the oligonucleotide strands, and the helical structure adopts an "unraveled" conformation as a result of adsorption. This is attributed to the flexibility within the oligonucleotide at high electrolyte concentration allowing multiple segments of the oligonucleotide to have direct surface interaction. In contrast, the EW-TRFRET measurements at a lower electrolyte concentration reveal that the oligonucleotide retains its helical conformation in a localized extended state. This behavior implies that the rigidity of the oligonucleotide at this electrolyte concentration restricts direct interaction with the silica to a few segments, which correspondingly introduces kinks in the double helix conformation and results in significant oligonucleotide segmental extension into solution.
authors.affiliation: School of Chemistry, University of Melbourne, Victoria 3010, Australia.
authors.forename: Colin A
authors.initials: CA
authors.lastname: Scholes
authors.forename: David P
authors.initials: DP
authors.lastname: Millar
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Gee
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Smith
mesh_terms: D000327:Adsorption; D004573:Electrolytes / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D004573:Electrolytes; D009841:Oligonucleotides; D012822:Silicon Dioxide