91福利

Hydrogels are an important class of materials and find use accross a wide range of disciplines. Think of for example soft contact lenses, vodka jellies, and applications in medicine for example as matrixes for regenerative tissue engineering. They can be made from watersoluble polymer molecules and form a gel through crosslinking a phenonomenon that interconnects the polymer chains creating a network. When we shrink the dimensions of the hydrogel object down and disperse them as particles in water we speak of a microgel dispersion. When we decrease the size of the hydrogel particles further, down to approximately 100 nm or less, we speak of a nanogel.

Hydrogels can be crosslinked by covalent chemical bonds or through physical crosslinking. The latter process is often found in hydrogels formed from natural polymers, such as agarose and gelatine which upon cooling in water aggregate through formation of double helices. Alginate gels can be formed by ionic crosslinking with calcium ions. Synthetic hydrogels on the other hand are conveniently formed mostly through covalent crosslinking, an important class being thermoresponsive gels (often in micro- or nanogel format) made from poly(N-isopropyl acrylamide).

Stefan Bon and his team () now for the first time show that thermoresponsive synthetic nanogels can be made using multiple hydrogen bond arrays as non-covalent crosslinks. They replaced the covalent crosslinking monomers traditionally used in the synthesis of the nanogel dispersions with a 2-ureido-4[1H] pyrimidinone (UPy) functionalized comonomer. In their work they show that the UPy groups are capable of forming strong self-complimentary quadruple hydrogen bonds, hereby linking all the polymer chains together to form a network, creating the nanogel particle.

Stefan Bon says "we are very excited about these results as it opens up a different way of thinking in how hydrogels and nanogel dispersions can be made using the traditional synthetic route of free radical polymerization. The reversibility of the hydrogen bond formation means that these materials will have exciting physical and mechanical characteristics which potentially differ from the hydrogel materials made through covalent crosslinking"

Their findings are published in Polymer Chemistry ( to the paper), a journal by the Royal Society of Chemistry.

Ada Della Pia and Giovanni Costantini publish the Scanning Tunneling Microscopy entry for the Springer Encyclopedia of Nanotechnology, Bharat Bhushan (ed).

The O’Connor group has developed a computation which simultaneously doubles the resolution, sensitivity and mass accuracy of Fourier Transform Mass Spectrometry at no extra cost.

In their Angewandte Communication P. R. Unwin, J. V. Macpherson, et al. combined high-resolution electrochemical imaging, micro-Raman, and electron-microscopy data to demonstrate that spatially heterogeneous electron-transfer kinetics correlates directly with the local density of electronic states of polycrystalline boron-doped diamond (pBDD). A Multi-Microscopy Approach allowed electrochemical reaction rates to be linked to the corresponding dopant levels in pBDD. See for more details.

Establishing an independent academic career is an exciting and challenging process. The data available for UK chemistry suggests that more women than men find the process not exciting enough or too challenging. A key aspect of success in any career path is finding role models, establishing networks, and being tapped into good sources of information. Our aim is therefore to create opportunities for all of these in the first (and subsequent) Irène Joliot-Curie conference.

Prof. Greg Challis and Dr Lijiang Song, in collaboration with researchers at the University of Paris, report in Angewandte Chemie a hitherto unanticipated pathway for the biosynthesis of pyrroles from sugars. Using a combination of genetic engineering, isolation, structure elucidation, synthesis and feeding of biosynthetic intermediates, and incorporation of stable isotope-labelled precursors, the researchers showed that a carbohydrate, most likely N-acetylglucosamine-1-phosphate, is elaborated to the 4-acetamidopyrrole-2-carboxylate building blocks of the DNA-binding antibiotic congocidine (also known as netropsin). The assembly of pyrroles from carbohydrates is unprecedented in Nature and raises several intriguing questions regarding the mechanisms of the reactions involved. See for further details.

Nanodiamonds have been found to help loosen crystallized fat from surfaces in a project led by Dr Andrew Marsh at 91福利. The tiny carbon particles transform the ability of surfactants to shift dirt in cold water, findings that could bring eco friendly low temperature laundry cycles.

The research is published in ACS Applied Materials and Interfaces and highlighted in the and Daily Telegraph, 26 June.

Nanodiamond Promotes Surfactant-Mediated Triglyceride Removal from a Hydrophobic Surface at or below Room Temperature Xianjin Cui, Xianping Liu, Andrew S. Tatton, Steven P. Brown, Haitao Ye, and Andrew Marsh ACS Applied Materials and Interfaces 2012,

The Gibson group report in Angewandte Chemie: Here they probe the accessibility of carbohydrate binding sites in bacterial toxins, exemplified with the toxin produced by Vibrio cholerae, the causative agent of cholera.

Two members of the Gibson group have won poster prizes. Robert Deller won 1st Place at the RSC younger Members symposium (at Uni. Nottingham) for his work on Peptidomimetic Cryopreservation Agents. Lucienne Otten won 3rd place at the Systems Biology Annual Conference for her work on Label Free Analysis of Protein-Carbohydrate Interactions.

The Challis group and collaborators at the John Innes Centre report in the journal Chemical Science on the genomics-driven discovery of a novel polyketide alkaloid with an unprecedented structure. Incorporation experiments with stable isotope-labelled precursors combined with bioinformatics analyses were used to deduce the likely biosynthetic pathway for the natural product. See for further details.

Costantini and collaborators have reported in a special themed issue of Chemical Communications about a novel chemical pathway observed only in the presence of a metal substrate. In solution chemistry, assuming no kinetic limitations, the thermodynamic product is formed independently of the absolute reactant concentration. However, inclusion of a metallic substrate introduces a further variable which ultimately defines the chemistry observed. In their recent work, terephthalic acid was deposited onto a Cu(110) substrate, where, at low surface coverages, 2-dimensional metal-organic structures form. However, with increasing coverage, the interaction between molecule and metal induces the formation of a denser, less energetically-favoured hydrogen-bonded network.

The article can be read .

Costantini and collaborators report on the importance of metallic atoms in Si surface alloys for their use as effective substrates for 2D supramolecular self-assembly.
Scanning tunnelling microscopy is used to compare the assembly properties of terephthalic acid on two Bi-Si surface alloys with different metallic surface density. Results published in Surface Science show that, besides the absence of semiconductor dangling bonds, also a high density of Bi surface atoms is essential to smoothen the energy landscape experienced by adsorbed molecules and therefore promote their diffusion and assembly. More at