title: Cationic conjugated polyelectrolytes-triggered conformational change of molecular beacon aptamer for highly sensitive and selective potassium ion detection.
abstract: We demonstrate highly sensitive and selective potassium ion detection against excess sodium ions in water, by modulating the interaction between the G-quadruplex-forming molecular beacon aptamer (MBA) and cationic conjugated polyelectrolyte (CPE). The K(+)-specific aptamer sequence in MBA is used as the molecular recognition element, and the high binding specificity of MBA for potassium ions offers selectivity against a range of metal ions. The hairpin-type MBA labeled with a fluorophore and quencher at both termini undergoes a conformational change (by complexation with CPEs) to either an open-chain form or a G-quadruplex in the absence or presence of K(+) ions. Conformational changes of MBA as well as fluorescence (of the fluorophore in MBA) quenching or amplification via fluorescence resonance energy transfer from CPEs provide clear signal turn-off and -on in the presence or absence of K(+). The detection limit of the K(+) assays is determined to be ~1.5 nM in the presence of 100 mM Na(+) ions, which is ~3 orders of magnitude lower than those reported previously. The successful detection of 5'-adenosine triphosphate (ATP) with the MBA containing an ATP-specific aptamer sequence is also demonstrated using the same sensor scheme. The scheme reported herein is applicable to the detection of other kinds of G-rich aptamer-binding chemicals and biomolecules.
authors.affiliation: Department of Nano Fusion Technology, Pusan National University, Miryang 627-706, Republic of Korea.
authors.forename: Boram
authors.initials: B
authors.lastname: Kim
authors.forename: In Hwan
authors.initials: IH
authors.lastname: Jung
authors.forename: Mijeong
authors.initials: M
authors.lastname: Kang
authors.forename: Hong-Ku
authors.initials: HK
authors.lastname: Shim
authors.forename: Han Young
authors.initials: HY
authors.lastname: Woo
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry*; D054856:G-Quadruplexes; D006860:Hydrogen Bonding; D007477:Ions; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008956:Models, Chemical; D008968:Molecular Conformation; D011188:Potassium / Q000737:chemistry*; D012680:Sensitivity and Specificity; D015398:Signal Transduction; D012964:Sodium / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D055672:Static Electricity; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D004573:Electrolytes; D007477:Ions; D000255:Adenosine Triphosphate; D012964:Sodium; D011188:Potassium