A novel aggregation-induced emission fluorescent probe for nucleic acid detection and its applications in cell imaging.

A new kind of aggregation-induced emission compound was synthesized and used as the probe of nucleic acid. The characterization of this compound was studied. Both the RNA and DNA were detected by using this probe. And the detection scope of DNA and RNA was different. We researched the selectivity of our probe in double and single strand DNA sequences. The visualization of gel electrophoresis and the cell nucleus imaging were researched as well. Compared with the traditional nucleus dye Hoechst 33258, our probe also has the potential to be nucleus dye. And the cell toxicity was well performed by MTT assays.

Symmetric cyanovinyl-pyridinium triphenylamine: a novel fluorescent switch-on probe for an antiparallel G-quadruplex.

In this study, we present a fluorescent switch-on probe based on a cyanovinyl-pyridinium triphenylamine (CPT) derivative that exhibited a 190-fold increase in fluorescence upon binding to G-quadruplex-forming oligonucleotide 22AG. This probe showed specificity and selectivity towards an antiparallel G-quadruplex, indicating its promising potential in G-quadruplex imaging.

Selective detection of 5-formyl-2'-deoxycytidine in DNA using a fluorogenic hydroxylamine reagent.

Fluorogenic hydroxylamine reagents were used for detecting 5-fC through a labeling pathway. Chemical synthesis, HPLC, denaturing PAGE, and DNA MS were applied to testify that the probe reacted with 5-fC with oligodeoxynucleotide selectivity to achieve 5-fC detection conveniently and quantificationally with the method of fluorescence. The feasibility of fluorescently detecting 5-fC in a genome was also investigated.

Existence of G-quadruplex structures in promoter region of oncogenes confirmed by G-quadruplex DNA cross-linking strategy.

Existence of G-quadruplex DNA in vivo always attract widespread interest in the field of biology and biological chemistry. We reported our findings for the existence of G-quadruplex structures in promoter region of oncogenes confirmed by G-quadruplex DNA cross-linking strategy. Probes for selective G-quadruplex cross-linking was designed and synthesized that show high selectivity for G-quadruplex cross-linking. Further biological studies demonstrated its good inhibition activity against murine melanoma cells. To further investigate if G-quadruplex DNA was formed in vivo and as the target, a derivative was synthesized and pull-down process toward chromosome DNAs combined with circular dichroism and high throughput deep sequencing were performed. Several simulated intracellular conditions, including X. laevis oocytes, Ficoll 70 and PEG, was used to investigate the compound's pure cross-linking ability upon preformed G-quadruplex. Thus, as a potent G-quadruplex cross-linking agent, our strategy provided both valuable evidence of G-quadruplex structures in vivo and intense potential in anti-cancer therapy.

A turn-on fluorescent probe for detection of tyrosinase activity.

We have presented a fluorescent probe that exhibits a fluorescence turn-on signal upon reaction with tyrosinase, and we show that it can be readily employed for the assessment of tyrosinase activity and tyrosinase inhibitor activities in buffered aqueous solution.

A novel fluorescent "Turn-Off/Turn-On" system for the detection of acid phosphatase activity.

Acid phosphatase (ACP) can be sensitively, conveniently and efficiently detected via a new fluorescent "Turn-Off/Turn-On" system. Inexpensive (NaPO(3))(6) is carefully introduced into this system as a quencher of the aggregation-caused quenching (ACQ) probe. In our method, the limit of detection (LOD) is quite low for detecting ACP, which is an important biomarker and indication of several diseases.

Selective chemical labelling of 5-formylcytosine in DNA by fluorescent dyes.

Direct labelling: 5-Formylcytosine in DNA can be selectively labelled by fluorescent dyes containing an active amino group. The labelled DNA shows strong fluorescence and can be detected by polyacrylamide gel electrophoresis (PAGE) and fluorescence measurements (see scheme). This method can distinguish 5-formylcytosine from other methylation forms of cytosine in DNA.

Synthesis and spectroscopic properties of fluorescent 5-benzimidazolyl-2'-deoxyuridines 5-fdU probes obtained from o-phenylenediamine derivatives.

Fluorescent nucleosides (dU(bmz)) with desirable fluorescence quantum yield (Φ) are synthesized from almost non-fluorescent 5-fdU and o-phenylenediamine derivatives. The fluorescence of these nucleosides is quite sensitive to pH and organic solvents. 4-Methoxybenzene-1,2-diamine was used for the detection of 5-fdU among natural nucleosides.

A two-photon fluorescent probe for intracellular detection of tyrosinase activity.

AAN effective sensor: The two-photon turn-on fluorescent probe NHU was synthesized to optically detect tyrosinase activity in vitro and in melanoma cells. NHU is composed of a 4-aminophenol moiety and a naphthylamine unit, both of which are connected through a urea linkage. Upon exposure to tyrosinase, the 4-aminophenol site is gradually oxidized to the corresponding orthoquinone, ultimately releasing the highly fluorescent product 6-acyl-N-methyl-2-naphthylamine (AAN).

Development of a pH-activatable fluorescent probe and its application for visualizing cellular pH change.

Novel pH-activatable fluorescent probes with various pK(a) values have been developed utilizing 4-nitro-benzo[1,2,5]oxadiazole derivatives (NBD) as fluorophores and piperazine moieties as proton receptors. Under acidic conditions, probe FoPz displayed significant fluorescent enhancement of about 30 fold with a pK(a) value of 5.70 and it responds rapidly and sensitively to intracellular pH distributions and cellular pH fluctuations.

Site-specific recognition of guanosine by manganese(III) corroles in DNA non-duplex regions through active oxygen transfer.

DNA damage plays an important role in cellular processes. Besides natural protein nucleases, different types of efficient agents for DNA damage have been developed over recent decades in the search for new anticancer and antiviral drugs. In addition to the double-stranded configuration, DNA structures also include some non-duplex regions, which are considered to be from spontaneous errors in DNA replication, thus playing an important role for cells. Herein, we focused on these non-duplex regions of DNA and generated manganese(III) corroles, which exhibit a highly selective cleavage ability for guanosine units located at non-duplex portions, such as loops and bulges. The cleavage mechanism was demonstrated to be a manganese-induced oxidation process. The results given herein show a molecular approach that could specifically probe the guanosine units in DNA non-duplex structures, thus representing a promising step in the construction of tools to target non-duplex structures in chromosomes.

Quinazolines with intra-molecular hydrogen bonding scaffold (iMHBS) as PI3K/mTOR dual inhibitors.

Intra-molecular hydrogen bonding was introduced to the quinazoline motif to form a pseudo ring (intra-molecular H-bond scaffold, iMHBS) to mimic our previous published core structures, pyrido[2.3-D]pyrimidin-7-one and pteridinone, as PI3K/mTOR dual inhibitors. This design results in potent PI3K/mTOR dual inhibitors and the purposed intra-molecular hydrogen bonding structure is well supported by co-crystal structure in PI3Kγ enzyme. In addition, a novel synthetic route was developed for these analogs.

A novel cationic triazatetrabenzcorrole: selective detection of mercury(II) by nucleic acid-induced aggregation.

In the present work, a novel water-soluble cationic triazatetrabenzcorrole compound was synthesised. Its aggregation and fluorescence quenching properties are demonstrated by serval methods, such as UV-vis and fluorescence spectroscopic studies and naked-eye visualization. Unlike the traditional Hg(2+) sensor based on thymine-Hg(2+)-thymine, we use a novel approach, exploiting the high affinity of Hg(2+) for sulfur in phosphorothioate DNA. Based on the S-Hg(2+)-S pairs, we designed the phosphorothioate DNA T4G4-S3 as an Hg(2+) sensor, which can detect Hg(2+) sensitively and selectively in aqueous solution. And this sensing system is fairly fast and convenient.

Aptamer-based turn-on fluorescent four-branched quaternary ammonium pyrazine probe for selective thrombin detection.

In this thrombin detection system, the bright fluorescence of TASPI is almost eliminated by the DNA aptamer TBA (turn-off); however, in the presence of thrombin, it specifically binds to TBA by folding unrestricted TBA into an anti-parallel G-quadruplex structure and then releasing TASPI molecules, resulting in vivid and facile fluorescence recovery (turn-on).