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ABSTRACT: A single stranded oligonucleotide could induce aggregation of a perylene probe, the probe's monomer fluorescence was efficiently quenched. However, when the oligonucleotide was 5'-phosphorylated by polynucleotide kinase, it could be very efficiently degraded by lambda exonuclease, probe monomers were released, and a turn on fluorescence signal was detected.
Chemical Communications 08/2012; 48(63):7862-4. · 6.17 Impact Factor
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ABSTRACT: In the current work, we report a label-free fluorescence turn-on approach for the sensitive and selective sensing of Ag(+). A cationic perylene derivative, compound A, was used as the fluorescence probe. Compound A monomer is strongly fluorescent, and the fluorescence can be efficiently quenched through self-aggregation (self-assembly). A cytosine (C)-rich oligonucleotide, oligo-C, was employed. In the absence of Ag(+), oligo-C induced strong compound A aggregation due to electrostatic interactions in aqueous media, and very weak fluorescence signal was detected. However, in the presence of Ag(+), the specific interactions between oligo-C and Ag(+) induced hairpin structure formation of oligo-C through C-Ag(+)-C bonding interactions. Oligo-C binding to compound A aggregates was weakened; therefore, compound A monomer could be released and detected. The intensity of the fluorescence signal was directly related to the amount of Ag(+) added to the assay solution. Our method is highly sensitive-a limit of detection of 5nM was obtained-and also very selective. Ag(+) detection in complex sample mixtures was also demonstrated.
Analytical Biochemistry 07/2012; 430(1):48-52. · 3.00 Impact Factor
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ABSTRACT: We have developed a simple, inexpensive, and label-free method for the selective detection of adenosine. Klenow fragment polymerase (KF polymerase) is a commonly-used 5' to 3' DNA polymerase, it also has 3' to 5' exonuclease activity that can digest single-stranded DNA. An adenosine binding DNA aptamer was employed, the aptamer was split into two pieces of single-stranded DNA (aptamer-A1 + aptamer-A2). Without the addition of adenosine, aptamer-A1 and aptamer-A2 existed as single-stranded DNA which could be efficiently degraded by the exonuclease activity of KF polymerase. Much reduced background fluorescence was obtained when SYBR Green dye was added. However, in the presence of adenosine, aptamer-A1 and aptamer-A2 bound to adenosine, and hybridization of the complementary sequences resulted in the formation of a duplex DNA structure, which could initiate DNA polymerization. The addition of SYBR Green dye resulted in a very high fluorescence enhancement, which could be used for the quantification of adenosine.
The Analyst 12/2011; 137(4):978-82. · 4.23 Impact Factor
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ABSTRACT: A fluorophore labeled oligonucleotide could induce aggregation of a positively charged perylene probe. The perylene aggregate could very efficiently quench the fluorescence of the labeled fluorophore. Based on this observation, a new method for the highly sensitive and selective detection of a protein has been developed.
Chemical Communications 08/2011; 47(37):10269-71. · 6.17 Impact Factor
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ABSTRACT: In the present work, we report a fluorescence turn-on approach for the sensitive and selective detection of Hg(2+). A cationic perylene derivative (compound 1) was used as the fluorescence probe, and a thymine-rich oligonucleotide (oligo-M) was employed for the specific interaction with Hg(2+). Compound 1 shows strong tendency to self-aggregate into linear chain structures in aqueous media because of the pi-pi stacking interactions of its planar aromatic ring structure. The compound 1 free monomer is strongly fluorescent, whereas its aggregates are not fluorescent. When oligo-M and compound 1 were mixed, oligo-M induced strong compound 1 aggregation and resulted in significant fluorescence quenching. In the presence of Hg(2+), the specific interactions between oligo-M and Hg(2+) induced hairpin structure formation of oligo-M and thus weakened its binding to compound 1 aggregates. As a result, free probe monomers were released, and increased fluorescence was observed. The fluorescence intensity increase was in direct proportion to the concentration of Hg(2+) added. Our method provides a simple, fast, and efficient means for Hg(2+) quantification, it is highly sensitive with a limit of detection of 1 nM, and is also highly selective against other common metal ions.
The Analyst 08/2010; 135(8):1986-91. · 4.23 Impact Factor
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Angewandte Chemie International Edition 02/2010; 49(8):1485-8. · 13.45 Impact Factor
