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ABSTRACT: A choline labeled pyrene probe (Py-Ch) was designed and synthesized. Poly(vinylsulfonate) (PVS) could induce Py-Ch aggregation. The aggregation and deaggregation process could be finely controlled by the acetylcholinesterase (AChE) enzymatic hydrolysis of Py-Ch. The resulting excimer-monomer transition provided a facile way for real-time AChE activity fluorometric assay and inhibitor screening.
Organic Letters 04/2013; · 5.86 Impact Factor
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ABSTRACT: Highly fluorescent papain stabilized gold nanoclusters (NCs) have been synthesized through a simple wet chemical route. Papain was used for the first time as an effective capping and reducing agent for these clusters. The optimal conditions for the synthesis of the gold nanoclusters, including the concentrations of papain and NaOH, reaction time and temperature, were investigated. The as-prepared Au clusters show intense red emission at ∼660nm (QY ∼4.3%) and are uniform in size. The clusters are quite stable and the intense red emission remained unchanged at a buffer pH range of 6-12. The fluorescent Au NCs were then used as a label-free probe for the sensitive detection of Cu. A limit of detection of 3nM was obtained. The sensing strategy is also highly selective against the various potential interference ions.
Journal of Colloid and Interface Science 04/2013; 396:63-8. · 3.07 Impact Factor
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ABSTRACT: A highly sensitive and convenient chemiluminescence (CL) turn-on assay for protease without any label and synthesis has been developed. Cytochrome c was digested by a protease, and heme was released as a peptide-heme conjugate, which greatly enhanced the luminol-H2O2 CL reaction.
Chemical Communications 03/2013; · 6.17 Impact Factor
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ABSTRACT: A novel method for the sensing of acetylcholinesterase (AChE) activity and inhibitor screening based on the formation of metal coordination polymer has been developed. Acetylthiocholine (ATCh) was selected as the substrate. In the presence of AChE, ATCh was hydrolyzed to thiocholine and acetate. Thiocholine interacted with Ag(I) to form a metal coordination polymer. A positively charged perylene probe (probe 1) was employed. The fluorescence of probe 1 was very efficiently quenched by a polyanion [PVS, poly(vinyl sulfonate)]. In the presence of acetylcholinesterase, the positively charged metal coordination polymer newly formed in situ would interact with PVS, probe 1 monomer molecules were released, and a turn on fluorescence signal was detected. The assay is highly sensitive, a limit of detection of 0.04 mU/mL AChE was obtained. The assay is also highly selective, a number of potential interference proteins (enzymes) were tested, and none of them show noticeable interference. Sensing of AChE inhibitor was also demonstrated. Our assay is fairly simple and inexpensive. We envision that it could be used for the sensitive detection of other hydrolytic enzyme activities with properly selected substrates, and for the screening of potential inhibitor drugs.
Analytical Chemistry 02/2013; · 5.86 Impact Factor
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ABSTRACT: A tetracationic perylene probe (probe 1) was designed and synthesized. Probe 1 was used for the real-time fluorescence turn-on assay of alkaline phosphatase (ALP) activity and inhibitor screening. Probe 1 monomer fluorescence could be very efficiently quenched by ATP through the formation of an ATP/probe 1 complex. ALP triggered the degradation of ATP, the breakdown of the ATP/probe 1 complex, and the recovery of the probe 1 monomer fluorescence. In the presence of an ALP inhibitor, a decrease in fluorescence recovery was observed.
Chemistry - An Asian Journal 11/2012; · 4.50 Impact Factor
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ABSTRACT: A label free continuous assay for protease activity and inhibitor screening has been developed. A protease (trypsin) could digest hemoglobin. Free heme molecules were released. Strong π-π stacking and hydrophobic interactions with the perylene probe resulted in efficient quenching of the probe's monomer fluorescence.
Chemical Communications 09/2012; 48(81):10123-5. · 6.17 Impact Factor
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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: This paper presents a study of the synthesis of a polymer monolith column and its application to the analysis of PAHs in smoked meat products. A poly(butyl methacrylate-co-ethylene glycol dimethacrylate) monolith capillary has been successfully prepared with in situ polymerization method. The polymer monolith microextraction combined with HPLC determinations is employed for the analysis of naphthalene, biphenyl, phenanthrene, and anthracene. Various parameters affecting the extraction efficiency have been investigated and optimized. Under the optimum experimental conditions, the method provides an acceptable linearity (2-10,000 μg/L), low limits of detection (1.4-2.0 μg/L), and good precision (intraday relative standard deviations<4.1%, interday relative standard deviations<5.7%). When applied to the determination of the four PAHs in smoked meat samples, recoveries are obtained in the range of 86.6-101.5%.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 09/2011; 879(28):3012-6. · 2.78 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: A new approach has been developed for the highly sensitive and selective sensing of a protein. Lysozyme binding to its aptamer prevents SSB protein binding, and the subsequent binding of the free SSB protein to a molecular beacon results in a turn-on fluorescence signal, which can be used for lysozyme quantification.
Chemical Communications 05/2011; 47(19):5485-7. · 6.17 Impact Factor
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ABSTRACT: The pyrene probe and pyrene-labeled oligonucleotides (ODNs) probe are expected to be candidates as fluorescent probe for DNA assay. In particular, label-free detection is a very hot because of its simpleness, speediness and cheapness. Herein, we have investigated the use of a pyrenylakylammonium salt, a novel fluorescent probe for the detection of one single nucleotide polymorphism (SNP) in double stranded DNA. After S1 nuclease digestion, the pyrene probes bind electrostatically to the perfect complement DNA and emit a strong excimer emission. However, treatment of the non-complementary DNA with S1 nuclease caused nucleotide fragments of less than 5 bases, which could not induce excimer emission. By comparing ratio of excimer to monomer fluorescence between normal and mutant DNA after S1 nuclease digestion, One-base mutation in DNA was detected easily. This new method may be applied to the detection of SNP.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2011; 78(2):747-52. · 2.10 Impact Factor
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ABSTRACT: We report a label-free fluorescence turn-on approach for the selective sensing of potassium. A properly selected G-rich oligonucleotide (oligo-Y) folded into stable quadruplex structure when mixed with potassium in an aqueous solution. Single-stranded nucleic acid specific nuclease was subsequently added. Since an oligonucleotide in quadruplex structure is markedly more resistant to nuclease digestion than in its random coil conformation, oligo-Y digestion by nuclease was considerably slow. On the other hand, oligo-Y mixed with other common mono- or divalent ions was completely digested in 5 min under our experimental conditions because no quadruplex or less stable quadruplex was formed. Oligo-Y in potassium was subsequently mixed with a positively charged pyrene probe. Electrostatic interactions between oligo-Y (a polyanion) and the probe induced aggregation of the probe, which in turn induced strong pyrene excimer emission. The intensity of the induced excimer emission was directly proportional to the amount of potassium added. Our method shows good sensitivity, and good selectivity against other common interference ions.
The Analyst 08/2010; 135(8):2074-8. · 4.23 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
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ABSTRACT: Nucleic acid was found to induce the aggregation of the positively charged pyrene probe (compound 1); as a result, strong pyrene excimer emission was observed. The intensity of the excimer emission was dependent on the concentration of the pyrene probe and the oligonucleotide length, sequence, and concentration. These results suggest a new strategy for label-free nucleic acid-based biosensing applications.
Organic Letters 10/2009; 11(19):4302-5. · 5.86 Impact Factor
