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Making light work of hydrogel formation

14 Aug 2012

UK scientists have developed a new way to make hydrogels using light. The hydrogels could be used in a range of applications from cell culture to biosensors.

Graphical abstract: Dipeptide hydrogelation triggered via ultraviolet light Dave Adams, at the University of Liverpool, and colleagues made the hydrogels from dipeptide conjugates using UV light to trigger the gelation. Unlike previous light-activated gelations, the team used a photoacid generator (a molecule that is photolysed by light to produce an acid) to lower the pH of the gelator solution below the apparent pKa of the gelators, resulting in gelation.

The team showed that they could pattern the hydrogel using a photomask. The patterned channels of gels could be used in microfluidics, biosensors and synthetic biomaterials, the team suggest.

Read more about this research in Adams’ ChemComm communication, free to access for a limited period.

Also of interest:
Chem Soc Rev critical review: Supramolecular gels formed from multi-component low molecular weight species

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Yong-Qiang Tu joins the ChemComm Editorial Board

30 Jul 2012

On behalf of the ChemComm Editorial Board, I am delighted to welcome Professor Yong-Qiang Tu as the new ChemComm Associate Editor for organic chemistry.

Professor Tu is a council member of Chinese Chemistry Society and the president of Gansu Chemistry Society. His current research interests centre on tandem rearrangement reactions and their application to the total syntheses of bioactive alkaloids, synthetic studies of biologically active natural products, and the construction of C-C and C-N bonds via C-H functionalisations.

Professor Tu’s editorial office is now open for submissions, welcoming urgent communications highlighting the latest advances in organic chemistry.

Find out more about Professor Tu’s research by reading these exciting articles:

Total synthesis of (±)-maistemonine and (±)-stemonamide
Zhi-Hua Chen, Yong-Qiang Zhang, Zhi-Min Chen, Yong-Qiang Tu and Fu-Min Zhang
Chem. Commun., 2011,47, 1836-1838, DOI: 10.1039/C0CC02612C, Communication

Enantioselective bromination/semipinacol rearrangement for the synthesis of β-bromoketones containing an all-α-carbon quaternary center
Hui Li , Fu-Min Zhang , Yong-Qiang Tu , Qing-Wei Zhang , Zhi-Min Chen , Zhi-Hua Chen and Jian Li
Chem. Sci., 2011,2, 1839-1841, DOI: 10.1039/C1SC00295C

Are you an organic chemist based in North America? Submit your research to Michael Krische, ChemComm North American Associate Editor for organic chemistry.

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Quick and clean way to make intermediates for dyes and pharmaceuticals

30 Jul 2012

Scientists in China have developed a quick and clean way to reduce nitroarenes to aminoarenes, which are common intermediates for making dyestuffs, pharmaceuticals and agricultural chemicals.

Sodium borohydride and molecular hydrogen are commonly used for this reaction but their hydrogen elements cannot reduce nitroarenes under mild reaction conditions. Usually, expensive noble-metal catalysts are necessary to activate the hydrogen elements in the reductants.

Here, the researchers have used a vanadium-doped porous TiO₂ with highly active hydrogen, which can instantly (<10s) and selectively reduce nitroarenes to aminoarenes under ambient conditions without catalysts. After being consumed by nitroarenes, the active hydrogen species can be regenerated by irradiating the V-doped TiO₂ with UV light.

Link to journal article
Porous vanadium-doped titania with active hydrogen: a renewable reductant for chemoselective hydrogenation of nitroarenes at ambient condition
J Su et al
Chem. Commun., 2012, DOI: 10.1039/c2cc33969b

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Silica sheets to deliver DNA into cells for disease prevention and treatment

17 Jul 2012

Scientists in Japan have made a new DNA delivery substrate based on networks of bio-friendly upright silica sheets. The network of sheets forms a porous film on to which they can immobilise DNA, ready for delivery (transfection) into cells. The transfection efficiency of the silica film is approximately double that of solution-based transfection. Gene transfection is a potential method for preventing and treating diseases and analysing cell functions.

Link to journal article
Silica-based Gene Reverse Transfection: Upright Nanosheet Network for Promoted DNA Delivery to Cell
Q Ji et al
Chem. Commun., 2012, DOI: 10.1039/c2cc34289h

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Bendy non-volatile flash memory data storage device

11 Jul 2012

Scientists in Taiwan have made a flexible memory device, which they say could open up a new design approach for high performance flexible non-volatile resistive memory devices. Non-volatile devices are computer memory devices that can retain stored information even when not powered, for example read-only memory, flash memory, hard drives and floppy disks.

The team’s device consists of a single-layer donor-acceptor conjugated polymer fabricated on plastic polyethylene naphthalene. It displayed a low threshold voltage (±2V), low switching power (~100µW cm^-2), large on/off memory window (10⁴), good retention (>10⁴s) and excellent endurance against electrical and mechanical stimuli, they say.

Link to journal article
Poly(fluorene-thiophene) Donor Tethered Phenanthro[9,10-d]imidazole Acceptor for Flexible Nonvolatile Flash Resistive Memory Devices
H-C Wu et al
Chem. Commun., 2012, DOI: 10.1039/c2cc34257j

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A new type of conducting polymer

05 Jul 2012

Scientists in the US have reported a new type of conducting polymer, generated by a ROMP (ring opening metathesis polymerisation) reaction. The new polymers could have potentially useful properties, they say.

They reacted the complex (η⁵-C₅H₅)Ir(η⁴-C₆H₆) with Grubbs’ catalyst to give a polyacetylene consisting of cyclopentadienyliridium bound s-cis butadiene moieties separated by C=C linkages, a previously unavailable polyacetylene type.

Link to journal article
Ring Opening Metathesis Polymerization of an η⁴-Benzene Complex: A Direct Synthesis of a Polyacetylene with a Regular Pattern of Π Bound Metal Fragments
P D Zeits, T Fiedler and J A Gladysz
Chem. Commun., 2012, DOI: 10.1039/c2cc32150e

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Film to aid drug metabolism study

05 Jul 2012

A way to study drug metabolism using cytochrome P450 enzymes (which are involved in the metabolism of over 60% of clinically used drugs) has been developed by scientists in China.

The team made a film of indium tin oxide nanoparticles (they have good conductivity) and cytochrome P450s encapsulated by chitosan (which are biocompatible) on a carbon electrode. They were able to bioelectronically initiate cytochrome P450 catalysis by replacing electron donation from expensive nicotinamide adenine dinucleotide phosphate with electrodes.

The system has potential for applications in drug discovery and development by monitoring substrate metabolism and enzyme inhibition. Other applications include biosensors for toxicity analysis and bioreactors for chemical synthesis.

Link to journal article
Electrochemically Driven Drug Metabolism via Cytochrome P450 2C9 Isozyme Microsomes with Cytochrome P450 Reductase and Indium Tin Oxide Nanoparticle Composites
X Xu et al
Chem. Commun., 2012, DOI: 10.1039/c2cc33575a

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Macrocycle insulation for molecular wires

05 Jul 2012

Researchers in Texas are using rotaxane formation to sterically protect or “insulate” molecular wires.

Molecular wires, in which an unsaturated linker separates two or more redox active metal sites, are of great research interest. These structures allow phenomena such as electron delocalisation or transport between the two redox sites. John Gladysz’s group at Texas A&M University have an ongoing interest in dimetallic polyynediyl complexes, in which two metal centres are linked by conjugated polyynediyl linkers that they now hope to “insulate” to reduce interactions between wires and the external environment. A previous approach used long alkyl bis-phosphine, which wrapped around the wire in a double helix to complex both metal centres. However, this gave two enantiomers, which interconverted rapidly in solution via uncoiling of the protective ligands.

The Gladysz group are now reporting a straightforward solution to this problem. They found that by synthesising their bis-platinum wire in the presence of a 33-membered macrocycle, they could incorporate the wire as the thread of a rotaxane complex. This provides a more robust protection for the wire which is unaffected by dynamic processes.

space filling representation of the rotaxane

This work shows a fantastic application of rotaxane chemistry for protection of a molecular wire. What’s more, the synthesis of this rotaxane is adaptable, and the Gladysz group are working on exciting new and improved systems including longer polyynediyl linkers and redox inactive macrocycles to improve the properties of the insulated wires.

The full communication can be downloaded here.

Cally Haynes

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Why some metal hip replacements fail

04 Jul 2012

Hundreds of thousands of patients have been fitted with metal-on-metal hip joints

An investigation into why metal-on-metal hip joints fail long before other types of joints, such as metal-on-polyethylene and ceramic-on-ceramic, has revealed how the metal particles shed by the joints grinding against each other damage surrounding cells. The work, carried out by scientists in the UK, Canada, the Netherlands and the US, could lead to ways to predict which patients will have problems with these joints.

One theory why metal-on-metal hip implants fail points to the debris that is generated as the joints wear. It is thought that the debris is not compatible with human tissue, which causes the metal hip joints to fail, but it’s not known why.

Read the full article in Chemistry World

Link to journal article
Chemical Speciation of Nanoparticles Surrounding Metal-on-Metal Hips
A E Goode et al
Chem. Commun., 2012, DOI: 10.1039/c2cc33016d

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Kitchen nanodot chemistry

02 Jul 2012

For carbon nanodots, simply heat soy milk for three hours. The milk undergoes carbonisation, surface functionalisation and doping

Water-soluble, nitrogen-doped fluorescent carbon nanodots (FCNs) have been made by simply heating soy milk. This cheap and green approach produces a carbon nanomaterial suitable for bioimaging applications, and has already shown promise as an electrocatalyst, say scientists in China.

There have already been several successful demonstrations using natural biomass as a precursor for producing nanomaterials. Inspired by these endeavours, Shaojun Dong and colleagues at the Chinese Academy of Sciences have developed a simpler, time-saving method for preparing bifunctional nanomaterials, in just three hours, using soy beans.

Read the full article in Chemistry World

Link to journal article
Bifunctional fluorescent carbon nanodots: green synthesis via soy milk and as metal-free electrocatalysts for oxygen reduction
C Zhu, J Zhai and S Dong
Chem. Commun., 2012, DOI: 10.1039/c2cc33844k

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Chemical Communications Blog

Archive for the ‘News’ Category

Making light work of hydrogel formation

Yong-Qiang Tu joins the ChemComm Editorial Board

Quick and clean way to make intermediates for dyes and pharmaceuticals

Silica sheets to deliver DNA into cells for disease prevention and treatment

Bendy non-volatile flash memory data storage device

A new type of conducting polymer

Film to aid drug metabolism study

Macrocycle insulation for molecular wires

Why some metal hip replacements fail

Kitchen nanodot chemistry

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