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Reactive oxygen species (ROS) generation to induce cell death is an effective strategy for cancer therapy. In particular, chemodynamic therapy (CDT), using Fenton-type reactions to generate highly cytotoxic hydroxyl radical (•OH), is a promising treatment modality. However, the therapeutic efficacy of ROS-based cancer treatment is still limited by some critical challenges, such as overexpression of enzymatic and non-enzymatic antioxidants by tumor cells, as well as the low tumor targeting efficiency of therapeutic agents. To address those problems, biomimetic CuZn protoporphyrin IX nanoscale coordination polymers have been developed, which significantly amplify oxidative stress against tumors by simultaneously inhibiting enzymatic and non-enzymatic antioxidants and initiating the CDT. In this design, cancer cell membrane camouflaged nanoparticle exhibits an excellent homotypic targeting effect. After being endocytosed into tumor cells, the nanoparticles induce depletion of the main non-enzymatic antioxidant glutathione (GSH) by undergoing a redox reaction with GSH. Afterward, the redox reaction generated cuprous ion (Cu

We developed an ultrafast one-step RT-qPCR assay for SARS-CoV-2 detection, which can be completed in only 30 mins on benchtop Bio-Rad CFX96. The assay significantly reduces the running time of conventional RT-qPCR: reduced RT step from 10 to 1 min, and reduced PCR cycle of denaturation from 10 to 1 s and extension from 30 to 1 s. A cohort of 60 nasopharyngeal swab samples testing showed that the assay had a clinical sensitivity of 100% and a clinical specificity of 100%.

Nanoscale extracellular vesicles (nEVs) have recently demonstrated potential value in cancer diagnostics and treatment monitoring, but translation has been limited by technical challenges in nEV isolation. Thus, we have developed a one-step nEV isolation platform that utilizes nEV size-matched silica nanostructures and a surface-conjugated lipid nanoprobe with an integrated microfluidic mixer. The reported platform has 28.8% capture efficiency from pancreatic cancer plasma and can sufficiently enrich nEVs for simpler positive identification of point mutations, particularly KRAS, in nEV DNA from the plasma of pancreatic cancer patients.

A novel luminescent G-quadruplex-selective iridium(iii) complex was employed in a label-free G-quadruplex-based detection assay for hepatitis C virus NS3 helicase activity., A series of luminescent Ir(iii) complexes were synthesised and evaluated for their ability to act as luminescent G-quadruplex-selective probes. The Ir(iii) complex 9, [Ir(phq)2(phen)]PF6 (where phq = 2-phenylquinoline; phen = 1,10-phenanthroline), exhibited high luminescence in the presence of G-quadruplex DNA compared to dsDNA and ssDNA, and was employed to construct a label-free G-quadruplex-based assay for hepatitis C virus NS3 helicase activity in aqueous solution. Moreover, the application of the assay for screening potential helicase inhibitors was demonstrated. To our knowledge, this is the first G-quadruplex-based assay for helicase activity.

A series of luminescent Ir(III) complexes were synthesised and evaluated for their ability to act as G-quadruplex-selective probes. A novel Ir(III) complex was found to be highly selective for G-quadruplex DNA, and was employed in a label-free G-quadruplex-based detection assay for nicking endonuclease activity in aqueous solution. A proof-of-concept of this probe has been demonstrated by using Nb·BbvCI as a model enzyme. In this assay, a DNA substrate comprised of oligonucleotides ON1 (5′-GTG3TAG3CG3T2G2CTGAG2TGA-3′) and ON2 (5′-TCAC2TCAGC2A2C2-3′) initially exists in a duplex conformation, resulting in a low luminescence signal due to the weak interaction between the Ir(III) complex and duplex DNA. Upon cleavage by Nb·BbvCI, the guanine-rich sequence is released and folds into a G-quadruplex, which greatly enhances the luminescence of the Ir(III) probe. This method was highly sensitive for Nb·BbvCI over other DNA-modifying enzymes.

A novel luminescent cyclometalated iridium(III) complex-based chemosensor (1) bearing a zinc-specific receptor, tris(2-pyridylmethyl)amine, and the 3-phenyl-1H-pyrazole ligand has been designed and synthesized. Upon the addition of Zn2+ ions to a solution of iridium(III) complex 1, a pronounced luminescence color change from blue to green can be observed, which may be attributed to the suppression of photoinduced electron transfer upon complexation of complex 1 with Zn2+ ions. The interaction of iridium(III) complex 1 with Zn2+ ions was investigated by UV–vis absorption titration, emission titration, and 1H NMR titration. Furthermore, the iridium(III) complex 1 exhibited good selectivity for Zn2+ over 13 other common metal ions, including K+, Ag+, Na+, Ni2+, Fe3+, Hg2+, Cd2+, Mg2+, Ca2+, Cu2+, Mn2+, Co2+, and Pb2+ ions. The practical application of the iridium(III) complex 1 in visualizing intracellular Zn2+ distribution in live zebrafish was also demonstrated.

A parallel G-quadruplex-selective iridium(III) complex has been synthesized and employed as a luminescent probe in a label-free G-quadruplex-based detection assay for Ca2+ ions in aqueous solution. In this assay, a guanine-rich oligonucleotide (G4, 5′-G4T4G4-3′) initially exists in an antiparallel G-quadruplex conformation, resulting in a low luminescence signal. Upon incubation with Ca2+ ions, the antiparallel G-quadruplex is induced into a parallel G-quadruplex conformation, which greatly enhances the luminescence emission of the iridium(III) probe. This method was highly sensitive for Ca2+ ions with a limit of detection in the nanomolar range, and was selective for Ca2+ over other metal ions.

A luminescent iridium(III) complex has been discovered to be selective for G-quadruplex DNA, and was employed in a label-free G-quadruplex-based detection assay for 3'→5' exonuclease activity in aqueous solution. A proof-of-concept of this assay has been demonstrated by using prokaryotic exonuclease III (ExoIII) as a model enzyme. In this assay, a G-quadruplex-forming hairpin oligonucleotide (hairpin-G4 DNA, 5'-GAG3TG4AG3TG4A2GCAGA2G2ATA2CT2C4AC3TC4AC3TC-3') initially exists in a duplex conformation, resulting in a low luminescence signal due to the weak interaction between the iridium(III) complex and duplex DNA. Upon digestion by ExoIII, the guanine-rich sequence is released and folds into a G-quadruplex, which greatly enhances the luminescence emission of the iridium(III) probe. This method was highly sensitive for 3'→5' exonuclease over other DNA-modifying enzymes.

We report herein the synthesis and application of a novel G-quadruplex-selective luminescent iridium(III) complex [Ir(ppy)2(bcp)](+) (where ppy = 2-phenylpyridine and bcp = 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) for the sensitive detection of apurinic/apyrimidinic (AP) endonuclease activity. Using endonuclease IV (Endo IV) as a model enzyme, a duplex DNA substrate containing a G-quadruplex-forming sequence is cleaved by Endo IV at the abasic site. This releases the G-quadruplex sequence, which folds into a G-quadruplex and is recognised by the G-quadruplex-selective iridium(III) complex with an enhanced luminescence response. The assay achieved high sensitivity and selectivity for Endo IV over other tested enzymes.

Transcription factors are molecules that play a fundamental role in regulating the expression of the human genome. These proteins bind to cognate sequences within the regulatory regions of genes, thereby controlling the flow of genetic information from DNA to mRNA. Due to their vital role in maintaining biological processes such as cellular specialization and growth, aberration in transcription factor signalling can lead to the pathogenesis of a number of human disorders, including cancer and inflammatory diseases. While the development of organic small molecules as modulators of transcription factor activity has gained significant momentum over the past few years, the application of transition metal complexes for the same purpose has garnered comparatively less attention. In this review, we survey recent examples in the development of transition metal complexes as inhibitors of transcription factor activity. The mechanisms of transcription factor inhibition covered include direct binding of transcription factors, binding to DNA consensus sequences, and inhibition of upstream targets. The studies presented here demonstrate that the unique properties of metal complexes can be effectively harnessed to develop promising tools for studying or modulating transcription in biological systems.

Peaceful coexistence: A double quadruplex composed of an i-motif and a G-quadruplex was constructed within one oligonucleotide strand (see picture). The defined double-quadruplex structure can serve as a NOTIF logic gate on the basis of the fluorescence of crystal violet.

The serendipitous discovery of the anticancer drug cisplatin cemented medicinal inorganic chemistry as an independent discipline in the 1960s. Luminescent metal complexes have subsequently been widely applied for sensing, bio-imaging, and in organic light-emitting diode applications. Transition-metal complexes possess a variety of advantages that make them suitable as therapeutics and as luminescent probes for biomolecules. It is thus highly desirable to develop new luminescent metal complexes that either interact with DNA through different binding modes or target alternative cellular machinery such as proteins as well as to provide a more effective means of monitoring disease progression. In this Review, we highlight recent examples of biologically active luminescent metal complexes that can target and probe a specific biomolecule, and offer insights into the future potential of these compounds for the investigation and treatment of human diseases.

Die zufallige Entdeckung des krebshemmenden Wirkstoffs Cisplatin festigte in den 1960er Jahren die Stellung der medizinischen anorganischen Chemie. In der Folge kam es zu einem weitverbreiteten Einsatz lumineszierender Metallkomplexe in der Sensorik, in der biologischen Bildgebung und in organischen Leuchtdioden. Ubergangsmetallkomplexe weisen viele Vorteile auf, aufgrund derer sie als Therapeutika und als Lumineszenzsonden fur Biomolekule geeignet sind. Daher ist die Entwicklung neuer lumineszierender Metallkomplexe wunschenswert, die uber verschiedene Bindungsmodi mit DNA wechselwirken oder auf alternative Teile der zellularen Maschinerie, z. B. auf Proteine, abzielen, um effektivere Mittel zur Uberwachung von Krankheitsverlaufen zur Verfugung zu stellen. Hier prasentieren wir aktuelle Beispiele biologisch aktiver lumineszierender Metallkomplexe, die auf ein spezifisches Biomolekul abzielen und dieses sondieren, und diskutieren das Potenzial dieser Verbindungen zur Erforschung und Behandlung menschlicher Erkrankungen.

G-quadruplexes represent a versatile sensing platform for the construction of label-free molecular detection assays owing to their diverse structures that can be selectively recognized by G-quadruplex-specific luminescent probes. In this Survey and Summary, we highlight recent examples of the application of the label-free strategy for the development of G-quadruplex-based luminescent detection platforms with a view towards the potential application of tetraplex structures in the design of DNA logic gates.

We report herein the first oligonucleotide-based luminescent method for the sensitive and selective detection of kanamycin in aqueous solution. The assay utilizes a square-planar luminescent platinum(II) complex and the kanamycin aptamer. The luminescence signal of the platinum(II) complex with the oligonucleotide is weak in the absence of kanamycin. Upon the addition of kanamycin, the aptamer changes from a random-coiled structure into a specific conformation containing a hairpin region. This facilitates intercalation of the platinum(II) complex into the bound aptamer, thereby resulting in an enhanced luminescence signal of the system in response to kanamycin. The assay is sensitive and selective towards kanamycin over other antibiotics. The assay could be used to detect trace levels of kanamycin in fish extracts with a comparable sensitivity to aqueous buffer solution.

A novel G-quadruplex-selective luminescent iridium(III) complex has been employed as a signal-transducing element for the sensitive and selective switch-on detection of sub-nanomolar human neutrophil elastase (HNE) in homogenous solution.

Luminescent metal complexes have attracted increasing attention in the literature over the last few decades. In particular, transition metal compounds have been widely studied for luminescent sensing applications in recent years due to their attractive photophysical properties. In this review, we first summarize the recent development of luminescent transition metal complexes as chemosensors for cations, anions, gas molecules and biomolecules in the years of 2010–2012. The second part of this review highlights the application of luminescent metal complexes for label-free DNA-based sensing.

Promoted by the localized surface plasmon resonance nanotechnology, a simple and sensitive plasmonic aptamer nanosensor (nanoaptasensor) on an individual Au@Ag core-shell nanocube (Au@Ag NC) has been proposed for real-time monitoring of the formation process of G-quadruplex structures and label-free analysis of potassium ions (K(+) ). In particular, the analysis of the thermodynamic parameters indicates that there are two types of binding states accompanied with a remarkable change of free energy (ΔG) in the sequential folding process of telomere DNA sequence. This nanoaptasensor has raised promising applications in monitoring the dynamic process of the structural switch of the G-quadruplex.

Many natural phenomena are associated with the presence of two or more separate variables. We report here an "OR" DNA logic gate based on a luminescent platinum(II) switch-on probe for silver nanoparticles and pH, both of which may be considered putative indicators of pollution. The modulation of metal complex/double-stranded DNA complex phosphorescence by Ag(+) and H(+) was used to construct a simple, rapid and label-free method for the label-free detection of pH and nanomolar Ag(+) ions and nanoparticles in aqueous solutions with high selectivity.

Transcription factors play a central role in cell development, differentiation and growth in biological systems due to their ability to regulate gene expression by binding to specific DNA sequences within the nucleus. The dysregulation of transcription factor signaling has been implicated in the pathogenesis of a number of cancers, developmental disorders, inflammation and autoimmunity. There is thus a high demand for convenient high-throughput methodologies able to detect sequence-specific DNA-binding proteins and monitor their DNA-binding activities. Traditional approaches for protein detection include gel mobility shift assays, DNA footprinting and enzyme-linked immunosorbent assays (ELISAs) which tend to be tedious, time-consuming, and may necessitate the use of radiographic labeling. By contrast, luminescence technologies offer the potential for rapid, sensitive and low-cost detection that are amenable to high-throughput and real-time analysis. The discoveries of molecular beacons and aptamers have spear-headed the development of new luminescent methodologies for the detection of proteins over the last decade. We survey here recent advances in the development of luminescent detection methods for DNA-binding proteins, including those based on molecular beacons, aptamer beacons, label-free techniques and exonuclease protection.

A sensitive and easy technique has been developed for the negative detection of DNA following PAGE using eosin Y. After electrophoresis, gels are fixed and stained within 40 min to provide a detection limit of 0.1-0.2 ng of single DNA band, which appears as transparent and colorless under the opaque gel matrix background. The sensitivity of the new stain is fourfold better than zinc-imidazole negative and ethidium bromide stains. Furthermore, the newly developed staining method has been successfully applied to RNA visualization in polyacrylamide gels. In addition, the inclusion of inorganic salts in staining solution was also investigated, which has great effect on the staining efficiency.

We have developed a practical, cost-effective and user-friendly protocol to meet the needs of nucleic acids research, particularly in respect of DNA detection on polyacrylamide gels. In this method, the most commonly used alkaline formaldehyde developer in DNA silver stain, which does harm to operator, is first replaced by glucose in alkaline borate buffer. In addition, the effects of six reducing sugars on the quality of DNA visualization were investigated. Consequently, the optimal protocol using glucose takes about 45 min to complete all the procedures, with a detection limit of 5 pg of single DNA band on polyacrylamide gels, was developed. The results indicate that this user-friendly and economic protocol could be a good choice for routine use in DNA visualization on polyacrylamide gels.

An improved silver-ammonia staining method for DNA on polyacrylamide gels is described. In this method, staining of DNA using silver-ammonia complex allows high sensitivity, low cost, low toxicity, and simple protocol without requiring fixation and sensitization steps. The protocol takes less than 40 min to complete, with a detection limit of 1.5 pg of single DNA band on polyacrylamide gels, approximately 30-fold higher than that of original silver-ammonia staining method. Furthermore, this novel technique not only exhibits high sensitivity for large DNA fragment, but also shows a better trend to detect low-base-pair DNA compared with other silver staining methods.

A negative detection method for proteins on SDS-PAGE is described. In this method, Eosin Y (EY) was selectively precipitated in the gel background, which is absent from those zones where proteins are located through the formation of a stable water-soluble protein-dye complex. Negative staining of proteins using EY, allows high-sensitivity, low-cost, and simple protocol. The new described method takes less than an hour to complete all the protocol, with a detection limit of 0.5 ng of single protein band. Comparing with imidazole-zinc negative stain, EY dye provides broader linear dynamic range, higher sensitivity and reproducibility, and better obvious contrast between the protein bands or spots and background. Furthermore, the novel technique developed here presented a real practical method for simultaneous processing of multiple gels, which makes it possible to perform high-throughput staining for proteome research. Additionally, we have also compared the influence of staining method on the quality of mass spectra by PMF.

A G-quadruplex-selective luminescent iridium(III) switch-on probe has been developed for the detection of cysteine (Cys) in aqueous solution. The system is highly sensitive and selective towards Cys with a tunable range of detection. The detection of glutathione (GSH) is also examined.

A novel luminescent cyclometalated iridium(III) complex-based chemosensor (1) bearing a zinc-specific receptor, tris(2-pyridylmethyl)amine, and the 3-phenyl-1H-pyrazole ligand has been designed and synthesized. Upon the addition of Zn(2+) ions to a solution of iridium(III) complex 1, a pronounced luminescence color change from blue to green can be observed, which may be attributed to the suppression of photoinduced electron transfer upon complexation of complex 1 with Zn(2+) ions. The interaction of iridium(III) complex 1 with Zn(2+) ions was investigated by UV-vis absorption titration, emission titration, and (1)H NMR titration. Furthermore, the iridium(III) complex 1 exhibited good selectivity for Zn(2+) over 13 other common metal ions, including K(+), Ag(+), Na(+), Ni(2+), Fe(3+), Hg(2+), Cd(2+), Mg(2+), Ca(2+), Cu(2+), Mn(2+), Co(2+), and Pb(2+) ions. The practical application of the iridium(III) complex 1 in visualizing intracellular Zn(2+) distribution in live zebrafish was also demonstrated.

A novel iridium(III) complex-based chemosensor bearing the 5,6-bis(salicylideneimino)-1,10-phenanthroline ligand receptor was developed, which exhibited a highly sensitive and selective color change from colorless to yellow and a visible turn-off luminescence response upon the addition of Cu(II) ions. The interactions of this iridium(III) complex with Cu2+ ions and thirteen other cations have been investigated by UV-Vis absorption titration, emission titration, and 1H NMR titration.

A label-free, oligonucleotide-based, switch-on luminescence detection method for T4 polynucleotide kinase activity has been developed using a novel G-quadruplex-selective luminescent Ir(III) complex probe. The application of the assay for screening potential T4 PNK inhibitors is also demonstrated. To our knowledge, this is the first metal-based assay for PNK activity.

DNA repair processes are responsible for upholding the integrity and stability of genomic DNA. Consequently, the development of analytical assays to monitor enzymes involved with DNA repair pathways is of great interest in a variety of disciplines, including biochemistry, cell biology and biotechnology. In this perspective, we highlight examples of the development of luminescent assays for the detection of enzymes involved with DNA repair that have been reported in the last several years.

The serendipitous discovery of the anticancer drug cisplatin cemented medicinal inorganic chemistry as an independent discipline in the 1960s. Luminescent metal complexes have subsequently been widely applied for sensing, bio-imaging, and in organic light-emitting diode applications. Transition-metal complexes possess a variety of advantages that make them suitable as therapeutics and as luminescent probes for biomolecules. It is thus highly desirable to develop new luminescent metal complexes that either interact with DNA through different binding modes or target alternative cellular machinery such as proteins as well as to provide a more effective means of monitoring disease progression. In this Review, we highlight recent examples of biologically active luminescent metal complexes that can target and probe a specific biomolecule, and offer insights into the future potential of these compounds for the investigation and treatment of human diseases.

Breakthrough advances in chemistry and biology over the last two decades have vastly expanded the repertoire of nucleic acid structure and function with potential application in multiple areas of science and technology, including sensing and analytical applications. DNA oligonucleotides represent popular tools for the development of sensing platforms due to their low cost, rich structural polymorphism, and their ability to bind to cognate ligands with sensitivity and specificity rivaling those for protein enzymes and antibodies. In this review, we give an overview of the “label-free” approach that has been a particular focus of our group and others for the construction of luminescent DNA-based sensing platforms. The label-free strategy aims to overcome some of the drawbacks associated with the use of covalently-labeled oligonucleotides prevalent in electrochemical and optical platforms. Label-free DNA-based probes harness the selective interaction between luminescent dyes and functional oligonucleotides that exhibit a “structure-switching” response upon binding to analytes. Based on the numerous examples of label-free luminescent DNA-based probes reported recently, we envisage that this field would continue to thrive and mature in the years to come.

A label-free G-quadruplex-based luminescent switch-on assay has been developed for the selective detection of micromolar histidine in aqueous solution. In this study, an iridium(III) complex was employed as a G-quadruplex-specific luminescent probe while a guanine-rich oligonucleotide (Pu27, 5′-TG 4 AG 3 TG 4 AG 3 TG 4 A 2 G 2 -3′)/cupric ion (Cu 2+ ) ensemble was employed as a recognition unit for histidine. The initial luminescence of the iridium(III) complex in the presence of G-quadruplex DNA is effectively quenched by Cu 2+ ions due to the Cu 2+ -mediated unfolding of the G-quadruplex motif. The addition of histidine sequesters Cu 2+ ions from the ensemble, thereby restoring the luminescence of the system. The assay could detect down to 1 μM of histidine in aqueous media, and also exhibited good selectivity for histidine over other amino acids with the use of the cysteine, masking agent N -ethylmaleimide. Furthermore, the application of the assay for the detection of histidine in diluted urine samples was demonstrated.

We report herein a luminescent switch-on label-free G-quadruplex-based assay for the rapid and sensitive detection of polymerase proofreading activity using a novel iridium(III) complex as a G-quadruplex-selective probe. The interaction of the iridium(III) complex with the G-quadruplex motif facilitates the highly sensitive switch-on detection of polymerase proofreading activity. Using T4 DNA polymerase (T4 pol) as a model enzyme, the assay achieved high sensitivity and selectivity for T4 pol over other tested enzymes.

Breakthrough advances in chemistry and biology over the last two decades have vastly expanded the repertoire of nucleic acid structure and function with potential application in multiple areas of science and technology, including sensing and analytical applications. DNA oligonucleotides represent popular tools for the development of sensing platforms due to their low cost, rich structural polymorphism, and their ability to bind to cognate ligands with sensitivity and specificity rivaling those for protein enzymes and antibodies. In this review, we give an overview of the “label-free” approach that has been a particular focus of our group and others for the construction of luminescent DNA-based sensing platforms. The label-free strategy aims to overcome some of the drawbacks associated with the use of covalently-labeled oligonucleotides prevalent in electrochemical and optical platforms. Label-free DNA-based probes harness the selective interaction between luminescent dyes and functional oligonucleotides that exhibit a “structure-switching” response upon binding to analytes. Based on the numerous examples of label-free luminescent DNA-based probes reported recently, we envisage that this field would continue to thrive and mature in the years to come.

The genetic information stored in DNA can be transcribed and translated into functional proteins with various biological roles, and the control of gene expression and cell division is tightly controlled under normal physiological conditions. However, genetic mutations arising during DNA replication can trigger uncontrolled cell growth, leading to the development of various types of cancers (Croce 2008). The cellular transformational events associated with cancer have been linked with mutations in particular genes, termed protooncogenes. These genes are necessary for the normal development and differentiation of cells, but when mutated into oncogenes they can lead to the overexpression of proteins involved in signal transduction and mitosis, ultimately resulting in cancer development. Blocking oncogenic translation using siRNAs has attracted intense attention in the literature (Heidenreich 2009; Ventura et al. 2009), but inhibiting oncogenic transcription through targeting DNA itself has been less explored.

There were errors in the Funding section. The correct funding information is as follows: This work is supported by Hong Kong Baptist University (FRG2/11-12/009), Environment and Conservation Fund (ECF Project 3/2010), Centre for Cancer and Inflammation Research, School of Chinese Medicine (CCIR-SCM, HKBU), the Health and Medical Research Fund (HMRF/11101212), the Research Grants Council (HKBU/201811), the University of Macau (SRG013-ICMS12-LCH, MYRG091(Y1-L2)-ICMS12-LCH and MYRG121(Y1-L2)-ICMS12-LCH), and Special Equipment Grant (SEG_PolyU01) of the University Grants Committee. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

A new cyclometallated iridium(III) complex with the 2,2'-biquinoline N-donor ligand has been synthesized and characterized. The interaction and affinity of the complex towards c-myc G-quadruplex and duplex DNA have been investigated using UV/Vis spectroscopy and gel mobility shift assay. These studies revealed that complex 1 binds to c-myc G-quadruplexes (Pu22 and Pu27) with high affinity but does not interact with duplex DNA either by intercalation or groove binding. The ability of 1 to stabilize c-myc G-quadruplex DNA in vitro has also been examined through a PCR stop assay and a cell-based luciferase reporter assay. Complex 1 displays promising cytotoxic activity against the HeLa cell line with sub-micromolar potency.

A label-free oligonucleotide-based luminescent switch-on assay has been developed for the selective detection of sub-nanomolar Pb(2+) ions in aqueous solution and real water samples. An iridium(III) complex was employed as a G-quadruplex specific luminescent probe and a guanine rich DNA (PS2.M, 5'-GTG(3)TAG(3)CG(3)T(2)G(2)-3') was employed as recognition unit for Pb(2+) ions. The PS2.M exists in a single-stranded conformation in the absence of Pb(2+) ions, and the weak binding of the iridium(III) probe to ssDNA results in a weak luminescence signal. Upon binding to Pb(2+) ions, the single-stranded DNA sequence (PS2.M) is induced into a G-quadruplex conformation, which greatly enhances the luminescence emission of the iridium(III) probe. The assay can detect Pb(2+) ions in aqueous media with a limit of detection of 600 pM. It also exhibits good selectivity for Pb(2+) ions over other heavy metal ions. Furthermore, the application of the assay for the detection of Pb(2+) ions in spiked river water samples has been demonstrated.

A G-quadruplex-based switch-on luminescence assay has been developed for the detection of gene deletion using a cyclometallated iridium(III) complex as a G-quadruplex-selective probe. Upon hybridization with the target DNA, the two split G-quadruplex-forming sequences assemble into a split G-quadruplex, which greatly enhances the luminescence emission of the iridium(III) probe. The assay is simple and highly selective.

A practical, sensitive and environment-benign protocol for the detection of DNA on polyacrylamide gels was described. In this method, the most commonly used formaldehyde-based developer in DNA silver stain, which poses potential hazards to the health of operators, is firstly replaced by vitamin C (Vc) in sodium thiosulfate solution. This allows user-friendly and efficient visualization of DNA that takes about 20 min to complete all the procedures, and provides comparable sensitivity (8 pg of single band) to the most sensitive formaldehyde-based silver staining method developed before.

The natural product-like carbamide (1) has been identified as a stabilizer of the c-myc G-quadruplex through high-throughput virtual screening. NMR and molecular modeling experiments revealed a groove-binding mode for 1. The biological activity of 1 against the c-myc G-quadruplex was confirmed by its ability to inhibit Taq polymerase-mediated DNA extension and c-myc expression in vitro, demonstrating that 1 is able to control c-myc gene expression at the transcriptional level presumably through the stabilization of the c-myc promoter G-quadruplex. Furthermore, the interaction between carbamide analogues and the c-myc G-quadruplex was also investigated by in vitro experiments in order to generate a brief structure-activity relationship (SAR) for the observed potency of carbamide 1.

NEDD8-activating enzyme (NAE) controls the specific degradation of proteins regulated by cullin-RING ubiquitin E3 ligase, and has been considered as an attractive molecular target for the development of anti-cancer drugs. We report herein the identification of the dipeptide-conjugated deoxyvasicinone derivative (1) as an inhibitor of NAE by virtual screening of over 90,000 compounds from the ZINC database of natural products. Molecular modelling results suggested that 1 may be a non-covalent competitive inhibitor of NAE by blocking the ATP-binding domain. Compound 1 was able to inhibit NAE activity in both cell-free and cell-based assay with potencies in the micromolar range and selectivity over analogous E1 enzymes UAE and SAE. We envisage that the identification and molecular docking analysis of this bioactive scaffold as an NAE inhibitor would provide the scientific community with useful information in order to generate more potent analogues.

G-quadruplexes have found increasing potential in applications such as molecular therapeutics, diagnostics, and sensing. As a consequence, small molecules capable of selectively detecting G-quadruplexes have received significant attention in recent literature. Our review here addresses representative advances in the development of luminescent G-quadruplex probes and highlights their potential applications in sensing and imaging.

We describe a visible dye-based staining method for DNA in polyacrylamide gels using ethyl violet (EV). The novel method is a background-free, sensitive, economical, and simple procedure involving only staining and washing steps that can be completed within 30 min. As little as 0.8-1.6 ng of phiX174 DNA/HaeIII can be detected by EV, which is about eightfold more sensitive than Nile blue (NB) stain and twofold less sensitive than ethidium bromide (EB) stain.