A label free Ag sensing method via in situ formation of metal coordination polymer.

Metal ions sensing play critical roles in environmental monitoring and in biology. In this assay, we report the development of a facile fluorometric method for the sensing of Ag ions via the in situ formation of metal coordination polymer, based on the selective interactions of GSH with Ag. The formation of coordination polymer with net multiple negative charges in an aqueous buffer solution (Tris-HAc, pH 9.

Sensing of a nucleic acid binding protein via a label-free perylene probe fluorescence recovery assay.

A novel label-free fluorescence recovery assay for the sensing of a DNA binding protein has been developed. A transcription factor c-Jun protein, and a 21 base pair duplex DNA containing the c-Jun protein binding site (J-DNA) were selected. J-DNA was mixed with a cationic fluorescent perylene probe (compound 1), and induced aggregation of the probe.

Fluorescence turn-on detection of a protein using cytochrome c as a quencher.

A new approach for the sensitive and selective sensing of a protein has been developed. Cytochrome c could quench the fluorescence of a fluorophore labeled aptamer efficiently. The specific binding between the aptamer and the target protein resulted in a turn-on emission signal, which could be used for protein quantification.

A fluorescence turn-on method for real-time monitoring of protease activity based on the electron transfer between a fluorophore labeled oligonucleotide and cytochrome c.

A new continuous fluorescence turn-on assay for protease activity and inhibitor screening has been developed. A fluorophore labeled single stranded DNA (FAM-DNA) and cytochrome c (cyt c) were employed. The fluorescence of the FAM-DNA was efficiently quenched when binding to cyt c, through the electron transfer between the FAM fluorophore and the heme cofactor of cyt c.

Real-time fluorometric assay for acetylcholinesterase activity and inhibitor screening through the pyrene probe monomer-excimer transition.

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.

In situ formation of metal coordination polymer: a strategy for fluorescence turn-on assay of acetylcholinesterase activity and inhibitor screening.

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.

Real-time fluorescence turn-on detection of alkaline phosphatase activity with a novel perylene probe.

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.

Label free fluorescence turn-on detection of polynucleotide kinase activity with a perylene probe.

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.

KF polymerase-based fluorescence aptasensor for the label-free adenosine detection.

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).

Superquencher formation via nucleic acid induced noncovalent perylene probe self-assembly.

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.

Fluorescence turn-on detection of a protein through the displaced single-stranded DNA binding protein binding to a molecular beacon.

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.

Label-free detection of polynucleotide single-base mismatch via pyrene probe excimer emission.

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.

Nucleic acid-induced aggregation and pyrene excimer formation.

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.