title: Phenylene-ethynylene trication as an efficient fluorescent signal transducer in an aptasensor for potassium ion.
abstract: A tricationic phenylene-ethynylene (N(3+)) fluorophore is investigated as a fluorescent transducer in homogeneous aptasensing system for potassium ion (K(+)) assay in aqueous media. The enhancement of the fluorescent signal of N(3+) by three K(+) aptamers consisting of 12, 15, and 21 nucleotides are observed and used for the determination of N(3+)-aptamer binding affinities. The binding affinities increase with the length of the aptameric oligonucleotides and are proven to be important to the sensitivity and selectivity of the aptasensors. The enhanced fluorescent signal of each N(3+)-aptamer solution is selectively quenched by K(+) due to the ability of K(+) in stabilizing the G-quadruplex structure of the aptamer. Among three aptamers, the 15-base aptamer provides optimal sensitivity and selectivity over other ions such as Li(+), Na(+), NH(4)(+), Mg(2+), Ca(2+) and Sr(2+). The sensing system shows the detection limit of 1 μM of K(+) in clean buffered solution and 30 μM of K(+) in the solution containing 4800-fold excess of Na(+), with wide linear dynamic ranges of micro- to millimolar concentration. This label-free fluorescence aptasensor is conveniently and effectively applicable for analysis of K(+) in urine samples.
authors.affiliation: Center for Petroleum, Petrochemicals and Advanced Materials, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Wannapa
authors.initials: W
authors.lastname: Yuanboonlim
authors.forename: Warathip
authors.initials: W
authors.lastname: Siripornnoppakhun
authors.forename: Nakorn
authors.initials: N
authors.lastname: Niamnont
authors.forename: Paitoon
authors.initials: P
authors.lastname: Rashatasakhon
authors.forename: Tirayut
authors.initials: T
authors.lastname: Vilaivan
authors.forename: Mongkol
authors.initials: M
authors.lastname: Sukwattanasinitt
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002942:Circular Dichroism; D004987:Ethers / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D054856:G-Quadruplexes; D006801:Humans; D011188:Potassium / Q000032:analysis* / Q000652:urine
chemical_list: D000480:Alkynes; D052157:Aptamers, Nucleotide; D004987:Ethers; D005456:Fluorescent Dyes; C436384:phenyleneethynylene; D011188:Potassium