NJC Blog

Scientists in the UK have made metal-containing thin films that can be incorporated into wound dressings or on surfaces to kill microbes and bacteria in hospitals.

Andrew Johnson, at the University of Bath, and colleagues created the antimicrobial films from zinc and copper Schiff-base complexes incorporating ligands made by reacting aldehydes with primary amines, which they then deposited onto polypropylene fabric commonly used in nappies and bandages.

The team found that the copper and zinc complexes were good at killing microbes, and when tested against Staphylococcus aureus (which, amongst other things, causes impetigo – a bacterial skin infection – and toxic shock syndrome) and Pseudomonas aeruginosa (causes inflammation and sepsis), they were found to be highly effective, limiting bacterial growth for up to 16 hours. Techniques to reduce the prevalence of these particular bacteria are needed as they are known for their antibiotic resistance.

The zinc complex was found to be particularly successful, but the reason for this is not yet known. Johnson and his team speculate that it may be due to the toxicity of the Zn2+ ion and at higher levels may be due to transmetallation, in which the complex exchanges zinc for other vital metals in bacterial cells.

Antimicrobial zinc-based Schiff complexes could be deposited onto polypropylene fabric commonly used in nappies

Silver is a commonly used antimicrobial metal, but it is expensive so Johnson has spotted an advantage for his zinc and copper-based materials: ‘As only a small amount of the zinc monomer is required to deposit the films, it should be easy to scale up for industry and, most importantly, it will be cheap.’ Another advantage is that the ‘coatings are a post production treatment, so from a commercial perspective, we are not changing the manufacturing process for commodity bulk items such as bandages,’ he adds.

Ivan Parkin, an expert in antimicrobial coatings from University College London, UK, comments that: ‘The ability to inhibit bacterial growth on surfaces is very important.’ He adds that the work provides an indication of a new possible route to achieving this goal. However, he says: ‘It should be noted that on the treated sample, bacterial growth to the level of 106 was still seen, so complete kill has not been achieved.’

Johnson’s team now hopes to improve their films to apply them to medical devices such as catheters, wound dressings and personal care items. In particular, they are working with the paediatrics burns unit for the south-west of England at Frenchay Hospital, Bristol, to further develop their materials into advanced wound dressings for burn victims.

Holly Sheahan

Plasma deposited metal Schiff-base compounds as antimicrobials
Neil Poulter, Matthew Donaldson, Geraldine Mulley, Luis Duque, Nicholas Waterfield, Alex G. Shard, Steve Spencer, A. Tobias A. Jenkins and Andrew L. Johnson, New J. Chem., 2011
DOI: 10.1039/c1nj20091g

In this NJC ‘Hot Article’, Prof. Helen Hailes and co-workers at University College London, UK, highlight the synthesis and self-assembly of a novel two donors (D) and two acceptors (A) (DDAA) quadruple-hydrogen bonded dimer. The newly disclosed system uses a ureidocytosine module, the advantage being that it can readily be functionalised at N-1 and N-9, enabling the introduction of alternative moieties such as polymers or fluorescent groups at different positions in the arrays.

Researchers in synthetic, supramolecular, materials chemistry … this article will be of interest to you!
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Quadruple hydrogen bonded cytosine modules: N-1 functionalised arrays, Valerie G. H. Lafitte, Abil E. Aliev, Elisabetta Greco, Kason Bala, Peter Golding and Helen C. Hailes
New J. Chem., 2011, Advance Article
DOI: 10.1039/C1NJ20162J

Selective sensing of phosphates derivatives, including nucleotides and inorganic phosphates, is high on the targets list due to their pivotal role in biological systems. In this NJC paper, Kumaresh Ghosh et al. (University of Kalyani, India) have designed a simple pincer-like receptor that selectively recognises tetra- butylammonium dihydrogenphosphate in CH3CN over a series of other anions by exhibiting characteristic excimer emission in fluorescence. Also the simple receptor 1 fluoro- metrically distinguishes ATP from ADP and AMP in aqueous CH3CN.

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A new ortho-phenylenediamine-based cleft for selective sensing of H2PO4− and ATP, Kumaresh Ghosh and Indrajit Saha
New J. Chem., 2011, Advance Article
DOI: 10.1039/C1NJ20116F

Continuing on their pioneering studies, the Roses and co-workers show in this NJC Letter how phosphino and thienyl substituents are incorporated to (cyclohexadienyl)Mn(CO)3 systems, ultimately forming arenes or chiral cyclohexenones.
‘The new eta-5 complexes are particularly attractive, knowing that planar chiral ligands based on tricarbonyl-metal complexes are beginning to play important roles in enantioselective catalysis, with a “spectator” metal distinct from the catalytically active metal’, says Francoise Rose-Munch

So far, most of the previous examples relied on a planar chiral (η6-arene)Cr(CO)3 scaffold and more scarcely on (η5-Cp)Mn(CO)3. The latter compounds containing a cyclopentadienyl platform are the only tricarbonylmanganese complexes used as catalysts and up to now, complexes such as (η5-cyclohexadienyl)Mn(CO)3 had never been employed for the design of planar chiral ligands.

This NJC letter has been selected as a ‘Hot’, and will be of interest to organometallic chemists and the synthetic organic community alike, in the search of new routes to chiral systems.

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• This article will be included in the NJC special issue in the Honour of Didier Astruc, on the occasion of his 65th birthday – Coming soon.

Phosphino-substituted (η5-cyclohexadienyl)tricarbonylmanganese complexes: synthesis and structure
Françoise Rose-Munch, Derya Cetiner, Murielle Chavarot-Kerlidou and Eric Rose
New J. Chem., 2011, Advance Article
DOI: 10.1039/C1NJ20152B, Letter

Crooks and co-workers (University of Texas, USA) report the synthesis and characterization of Pt and Pd dendrimer-encapsulated nanoparticles (DENs) using the method of galvanic exchange. In the presence of either PtCl₄²⁻ or PdCl₄²⁻, the less noble Cu DENs oxidize to Cu²⁺ leaving behind an equal-sized DEN of Pt or Pd, respectively. This methodology is shown to be much faster and giving higher yields than using the common synthetic route i.e. direct reduction with BH₄⁻.Equally important, the detailed characterization presented demonstrates that the structure and composition of Pt and Pd DENs synthesized by direct BH₄⁻ reduction and galvanic exchange are indistinguishable.



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Synthesis, characterization, and electrocatalysis using Pt and Pd dendrimer-encapsulated nanoparticles prepared by galvanic exchange
Surojit Pande, Michael G. Weir, Brian A. Zaccheo and Richard M. Crooks
New J. Chem., 2011, Advance Article DOI: 10.1039/C1NJ20083F, Paper.

Scientists from the Universities of Rennes and Nancy in France have developed dual-role biphotonic chromophores for photodynamic therapy (PDT) applications that retain fluorescence properties, thus enabling their 3-D localization and the selective irradiation of cancer cells when combined with targeting.

In their paper selected as ‘Hot Article’, the collaboration led by Mireille Blanchard-Desce presents the synthesis and photophysical study of “banana-shaped” chromophores where the nature of the conjugated backbone is modified by playing with the aromatic units (a complementary approach to that based on the incorporation of heavy atom substituents).

By optimizing the chromophore structure of a series of fluorene derivatives, the researchers were able to design photosensitizers exhibiting large two-photon adsorption (TPA) cross section in the biologically useful spectral region combined with singlet oxygen production.

‘This route allows to combine in a single biphotonic chromophore several features highly desirable for two-photon PDT: fluorescence (for localisation and subsequent localized irradiation), large and broad TPA responses in the spectral range of interest for bio-oriented applications (700-1000 nm), as well reasonable singlet oxygen sensitization ability’, says Mireille Blanchard-Desce.

The team is now working on developing nano-objects with very high TPA, that incorporate the biphotonic sensitizers.

Banana-shaped biphotonic quadrupolar chromophores: from fluorophores to biphotonic photosensitizers
Cédric Rouxel, Marina Charlot, Youssef Mir, Céline Frochot, Olivier Mongin and Mireille Blanchard-Desce
New J. Chem., 2011, Advance Article
DOI: 10.1039/C1NJ20073A, Paper

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In this NJC Hot Article, Richard Compton and co-workers at the University of Oxford highlight novel electro-synthetic applications of ionic liquids.

The team has decorated carbon nanotubes with Palladium nanoparticles and used the composite material for the efficient electrochemical deprotection of common functional groups in ionic liquids (IL), thus demonstrating that Pd nanoparticles can be used for clean, efficient, safe electro- chemical hydrogenolysis in IL media.

This NJC article will be of interest to synthetic organic and inorganic chemists, electrochemists, material chemists, pharmaceutical chemists and process chemists alike.

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Palladium nanoparticle-modified carbon nanotubes for electrochemical hydrogenolysis in ionic liquids
Yao Meng, Leigh Aldous, Ben S. Pilgrim, Timothy J. Donohoe and Richard G. Compton
New J. Chem., 2011, Advance Article
DOI: 10.1039/C1NJ20070D, Paper