A coordination polymer for the site-specific integration of semiconducting sequences into DNA-based materials
- Authors: Al-Mahamad, Lamia , El-Zubir, Osama , Smith, David , Horrocks, Benjamin , Houlton, Andrew
- Date: 2017
- Type: Text , Journal article
- Relation: Nature Communications Vol. 8, no. 1 (2017), p. 720-27
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- Description: Advances in bottom-up material design have been significantly progressed through DNA-based approaches. However, the routine integration of semiconducting properties, particularly long-range electrical conduction, into the basic topological motif of DNA remains challenging. Here, we demonstrate this with a coordination polymer derived from 6-thioguanosine (6-TG-H), a sulfur-containing analog of a natural nucleoside. The complexation reaction with Au(I) ions spontaneously assembles luminescent one-dimensional helical chains, characterized as {Au (μ-6-TG)} , extending many μm in length that are structurally analogous to natural DNA. Uniquely, for such a material, this gold-thiolate can be transformed into a wire-like conducting form by oxidative doping. We also show that this self-assembly reaction is compatible with a 6-TG-modified DNA duplex and provides a straightforward method by which to integrate semiconducting sequences, site-specifically, into the framework of DNA materials, transforming their properties in a fundamental and technologically useful manner.Integration of semiconducting properties into the basic topological motif of DNA remains challenging. Here, the authors show a coordination polymer derived from 6-thioguanosine that complexes with Au(I) ions to form a wire-like material that can also integrate semiconducting sequences into the framework of DNA materials.
A reversible fluorescent probe for monitoring Ag(I) ions
- Authors: Lim, Zelong , Smith, David , Kolanowski, Jacek , Mattison, Rebecca , Knowles, Jonathan , Baek, Song-Yi , Chrzanowski, Wojciech , New, Elizabeth
- Date: 2018
- Type: Text , Journal article
- Relation: Journal of the Royal Society Interface Vol. 15, no. 144 (2018), p. 20180346-20180346
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- Description: Silver-containing nanomaterials are of interest for their antibiotic properties, for a wide range of applications from medicine to consumer products. However, much remains to be learnt about the degradation of such materials and their effects on human health. While most analyses involve measurement of total silver levels, it is important also to be able to measure concentrations of active free Ag(I) ions. We report here the preparation of a coumarin-based probe, thiocoumarin silver sensor 1 ( ), that responds reversibly to the addition of silver ions through the appearance of a new fluorescence emission peak at 565 nm. Importantly, this peak is not observed in the presence of Hg(II), a common interferent in Ag(I) sensing. To establish the utility of this sensor, we prepared silver-doped phosphate glasses with demonstrated bactericidal properties, and observed the Ag(I) release from these glasses in solutions of different ionic strength. is therefore a useful tool for the study of the environmental and medical effects of silver-containing materials.
Are two better than one? Comparing intermolecular and intramolecular indicator displacement assays in pyrophosphate sensors
- Authors: Liu, Xuejian , Smith, David , Jolliffe, Katrina
- Date: 2016
- Type: Text , Journal article
- Relation: Chemical Communications Vol. 52, no. 54 (2016), p. 8463-8466
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- Description: Peptide receptors with Zn(ii)-DPA units and a covalently bound fluorescent coumarin indicator on an oxazole-containing scaffold are shown to function as more selective pyrophosphate sensors than the analogous chemosensing ensembles in indicator displacement assays.
Deltamides and croconamides: Expanding the range of dual h‐bond donors for selective anion recognition
- Authors: Zwicker, Vincent , Yuen, Karen , Smith, David , Ho, Junming , Qin, Lei , Turner, Peter , Jolliffe, Katrina
- Date: 2018
- Type: Text , Journal article
- Relation: Chemistry : a European journal Vol. 24, no. 5 (2018), p. 1140-1150
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- Description: Dual H‐bond donors are widely used as recognition motifs in anion receptors. We report the synthesis of a library of dual H‐bond receptors, incorporating the deltic and croconic acid derivatives, termed deltamides and croconamides, respectively, and a comparison of their anion binding affinities (for monovalent species) and Brønsted acidities to those of the well‐established urea and squaramide dual H‐bond donor motifs. For dual H‐bonding cores with identical substituents, the trend in Brønsted acidity is croconamides>squaramides>deltamides>ureas, with the croconamides found to be 10–15 pKa units more acidic than the corresponding ureas. In contrast to the trends displayed by ureas, deltamides and squaramides, N,N′‐dialkyl croconamides displayed higher binding affinity to chloride than the N,N′‐diaryl derivatives, which was attributed to partial deprotonation of the N,N′‐diaryl derivatives at neutral pH. A number of differences in anion binding selectivity were observed upon comparison of the dual H‐bond cores. Whereas the squaramides display similar affinity for both chloride and acetate ions, the ureas have significantly higher affinity for acetate than chloride ions and the deltamides display higher affinity for dihydrogenphosphate ions than other oxoanions or halides. These inherent differences in binding affinity could be exploited in the design of anion receptors with improved ability to discriminate between monovalent anions. Croconamides spotted in the delta! Bite‐angle and Brønsted acidity control anion binding affinity and selectivity by amides from the oxo‐carbon family.
Fluorescent sensing arrays for cations and anions
- Authors: Smith, David , Topolnicki, Inga , Zwicker, Vincent , Jolliffe, Katrina , New, Elizabeth
- Date: 2017
- Type: Text , Journal article
- Relation: Analyst Vol. 142, no. 19 (2017), p. 3549-3563
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- Description: Array-based sensing methods can be used to distinguish sets of similar analytes, by using a number of non-specific or cross-reactive probes. Following subsequent statistical analysis, patterns or components can be isolated that can be used to unambiguously identify the specific analyte(s) present. Over the past two decades, various arrays for the identification of cations and anions have been reported. These often employ fluorescence methods, owing to good sensitivity and a versatile, easy to read output. The past few years have seen an increase in the number of such studies reported in the literature. This critical review will summarise this recent work, and identify the criteria required for a successful array system. In particular, it will focus on the different types of molecular structures that can be used, the breadth of ions that can be distinguished in a single array, the sensitivity and dynamic range to which they can be identified, and how successfully these aims have been met. A review of fluorescent sensing arrays for anions and cations, highlighting promising strategies and directions for future research.
Pattern recognition of toxic metal ions using a single-probe thiocoumarin array
- Authors: Smith, David , Mitchell, Linda , New, Elizabeth
- Date: 2018
- Type: Text , Journal article
- Relation: Analyst Vol. 144, no. 1 (2018), p. 230-236
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- Description: Pattern recognition methods such as linear discriminant analysis and principal component analysis are useful tools for the identification of analytes such as metal ions. These typically use a number of distinct molecular probes that exhibit cross-reactivity. Here we report a single molecule that demonstrates varying response in different solvents, therefore enabling the combination of probe and solvent to generate the required array diversity. Seven toxic metal ions were introduced as aqueous samples, and PCA and LDA techniques applied. The array could correctly identify all metals in pure water samples, all metals in doped lake-water samples. Further, we have explored the limit of detection of the system for two metal ions, Cu(ii) and Hg(ii), confirming the promise of the system as a candidate to identify toxic metals in environmental water sources.
Respiratory viral pathogens associated with lower respiratory tract disease among young children in the highlands of Papua New Guinea
- Authors: Chidlow, Glenys , Laing, Ingrid , Harnett, Gerald , Greenhill, Andrew , Phuanukoonnon, Suparat , Siba, Peter , Pomat, William , Shellam, Geoffrey , Smith, David , Lehmann, Deborah
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Clinical Virology Vol. 54, no. 3 (2012), p. 235-239
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- Description: Background: Acute lower respiratory tract infections (ALRI) commonly result in fatal outcomes in the young children of Papua New Guinea (PNG). However, comprehensive studies of the viral aetiology of ALRI have not been conducted in PNG for almost 30 years. Objectives: To determine the viruses associated with ALRI among children living in the PNG highlands using sensitive molecular detection techniques. Study design: Pernasal swabs were collected routinely between 1 week and 18 months of age and also during episodes of ALRI, as part of a neonatal pneumococcal conjugate vaccine trial. A tandem multiplex real-time PCR assay was used to test for a comprehensive range of respiratory viruses in samples collected from 221 young children. Picornavirus typing was supported by DNA sequence analysis. Results: Recognized pathogenic respiratory viruses were detected in 198/273 (73%) samples collected from children with no evidence of ALRI and 69/80 (86%) samples collected during ALRI episodes. Human rhinoviruses (HRV) species A, B and C were detected in 152 (56%) samples from non-ALRI children and 50 (63%) samples collected during ALRI episodes. Partial structural region sequences for two new species C rhinoviruses were added to the GenBank database. ALRI was associated with detection of adenovirus species B (p< 0.01) or C (p< 0.05), influenza A (p< 0.0001) or respiratory syncytial virus (p< 0.0001). Multiple viruses were detected more often during ALRI episodes (49%) than when children displayed no symptoms of ALRI (18%) (p< 0.0001). Conclusions: The burden of infection with respiratory viruses remains significant in young children living in the PNG highlands.
tele-substitution reactions in the synthesis of a promising class of 1,2,4-Triazolo[4,3- a]pyrazine-based antimalarials
- Authors: Korsik, Marat , Tse, Edwin , Smith, David , Lewis, William , Rutledge, Peter , Todd, Matthew
- Date: 2020
- Type: Text , Journal article
- Relation: Journal of Organic Chemistry Vol. 85, no. 21 (2020), p. 13438-13452
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- Description: We have discovered and studied a tele-substitution reaction in a biologically important heterocyclic ring system. Conditions that favor the tele-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base or the use of softer nucleophiles, less polar solvents, and larger halogens on the electrophile. Using results from X-ray crystallographic and isotope labeling experiments, a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the in vivo active antiplasmodium compounds of Series 4 of the Open Source Malaria consortium. © 2020 American Chemical Society. All rights reserved.