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Stimuli-responsive assemblies have generated a lot of interest in recent years especially in view of their biological applications.  Enzyme-responsive assemblies for controlled drug release have gained particular interest as this offers potentially selective and targeted delivery of therapeutics.

A team of scientists from Nankai University (China) led by Yu Liu have fabricated a supramolecular assembly based on the host-guest complexation of amphiphillic calixarene with adenosine triphosphate (ATP).  Complextion of the calixarene with ATP markedly lowers it’s critical aggregation concentration, forming hollow spherical nanoparticles.  The nanospheres were shown to be responsive to phosphatase – an enzyme over-expressed in many tumor cells - and thus may have applications in drug delivery and cancer therapy.

Read the full article for free until the 24th May 2013:

Phosphatase-responsive amphiphilic calixarene assembly, Yi-Xuan Wang, Dong-Sheng Guo, Yu Caoa and Yu Liu, RSC Adv., 2013, DOI: 10.1039/C3RA40453F

Scientists from the University of Chinese Academy of Sciences (Beijing, China) led by Kebin Zhou investigated the interaction between nanorods of Ce(OH)₃ and CeO₂ and the redox protein hemoglobin.

The nano-bio interfaces, such as those between inorganic nanomaterials and biological systems, are gaining a significant amount of interest due to their importance in biomedical applications, but also out of concerns over the bio-safety of nano-engineered particles.  In the case of ceria-based nanomaterials, some studies have found they were able to prevent the increase of reactive oxygen species (ROS) in vitro and in vivo due to the existence of Ce³⁺.  However, others have found that some of these materials could actually generate ROS and cause toxicity to cells as Ce⁴⁺ is reduced to Ce³⁺.

In this work, Zhou and co-workers hydrothermally prepared Ce(OH)₃ and CeO₂ nanorods and studied their interaction with a typical redox protein hemoglobin through an electrochemical method combined with Electron Paramagnetic Resonance spectroscopy.  Ce(OH)₃ was found to be more efficient in enhancing the direct electron-transfer of hemoglobin which may be due to the strong electron-conjugation interaction.

Read the full article for free until the 7th May 2013.

Strong electron-conjugation interaction facilitates electron transfer of hemoglobin by Ce(OH)₃nanorods, Lei Wang, Qingfen Luan, Dan Yang, Xin Yao and Kebin Zhou, RSC Adv., 2013, DOI: 10.1039/C3RA40336J

Shobhana Menon and colleagues from Gujarat University, India, have designed a new series of lower rim azocalix[4]arene basket-type mesogens.  Along with their rigid core, calix[4]arenes are easy to functionalize with various linkages and flexible aliphatic chains at the hydrophilic hydroxyl groups.  They are therefore promising candidates for liquid crystal applications.

The new basket-shaped scaffolds were fully characterised, and the proposed supramolecular organisation displays needle shaped, focal conic, rod like and schlieren textures (see image). 

Read the full article for free until the 25th March 2013!

Synthesis, mesomorphism and dielectric behaviour of novel basket shaped scaffolds constructed on lower rim azocalix[4]arenes, Pinkesh G. Sutariya, Nishith R. Modi, Alok Pandya, V. A. Rana and Shobhana K. Menon, RSC Adv., 2013, DOI: 10.1039/C3RA22422H

If asked to name a promising element to contribute to highly efficient, clean energy, few chemists would immediately think of lead.

Nevertheless Xiao Zhao and colleagues at the Chinese Academy of Sciences, in Changchun, Jilin, China, have used an alloy of this metal with platinum, which is much better known  for its catalytic properties, to create a more efficient catalyst for the direct electrooxidaton of formic acid, useful for direct formic acid fuel cells (DFAFC). These have the potential to provide clean, efficient energy conversion devices. The group used a self-sacrifice templating method to tune the structure and composition of Pt-Pb catalysts, which show enhanced kinetics due to reduced poisoning by carbon monoxide.

Meanwhile Yuan-Yuan Feng and colleagues, at Tsinghua University in Beijing, China, have worked with a more conventional catalyst combination in the form of palladium and gold for the same reaction. They found that controlled deposition of Pd on Au nanoparticles could tune the Pd dispersion and produce higher catalytic activity for the electrooxidation of formic acid. They have also characterised in detail the interaction of Pd with the reactive species.

To find out more, read about the work in RSC Advances for free until the 14th March 2013:

Pt–Pb hollow sphere networks: self-sacrifice-templating method and enhanced activity for formic acid electrooxidation, Xiao Zhao, Jianbing Zhu, Weiwei Cai, Meiling Xiao, Liang Liang, Changpeng Liu and Wei Xing, RSC Adv., 2013, 3, 1763–1767

Catalytic Pd-on-Au nanostructures with improved Pd activity for formic acid electro-oxidation, Yuan-Yuan Feng, Gui-Rong Zhang and Bo-Qing Xu, RSC Adv., 2013, 3, 1748–1752

By Sara Coles

Ice recrystallization inhibitors (IRIs) are very important when it comes to preventing cell damage which can occur during cryopreservation.  This is particularly crucial for the cryopreservation of progenitor cells (such as certain types of stem cells) where the clinical outcome in regenerative therapies to treat acute injuries, is directly linked to an increased supply and quality of cells.  Therefore there has been considerable interest in designing effective IRIs.

In this work, Robert Ben and colleagues from the University of Ottawa, Canada, investigated whether lysine-based surfactants/gelators and anti-ice nucleating agents could also possess IRI activity.  The authors found that long alkyl chains were very important for potent IRI activity and that the position of these chains is critical.  Although the exact mechanisms which would explain the role of these long alkyl chains in this process are still unclear, the results from this study will facilitate the design of IRIs for medical, commercial and industrial uses.

Read the full article for free until the 7th March 2013!

The importance of hydrophobic moieties in ice recrystallization inhibitors, Anna K. Balcerzak, Michela Febbraro and Robert N. Ben, RSC Adv., 2013, DOI: 10.1039/C3RA23220D

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One goal of nanoparticle synthesis is to produce the lowest possible polydispersity – in other words, the best possible average size distribution. ‘Greener’ routes to achieve this without harmful solvents and capping agents often come from the natural world. In this case Graham Hutchings at Cardiff University, UK, plus collaborators in Bristol, UK, and Niigata, Japan, have used chitosan, a derivative of natural chitin found in crab and shrimp shells, to template the formation of supported gold-palladium nanoparticles.

These precious alloys are used as catalysts in the solventless aerobic oxidation of benzyl alcohol to benzaldehyde, an important class of reactions in the fine chemicals industry.

Hutchings and co-workers have previously found supported gold-palladium catalysts to be most active and stable for a range of other reactions including direct synthesis of hydrogen peroxide from H₂ and O₂, and for the oxidation of polyols such as glycerol. It is to be hoped that the new chitosan-templated synthesis will pave the way for new, greener routes to commercial scale production of fine chemical intermediates, for example allowing the replacement of traditional oxygen donors like chromate or permanganate.

To find out more, read about the work in RSC Advances for free:

Biotemplated synthesis of catalytic Au–Pd nanoparticles, Simon R. Hall, Andrew M. Collins, Natalie J. Wood, Wataru Ogasawara, Moataz Morad, Peter J. Miedziak, Meenakshisundaram Sankar, David W. Knight and Graham J. Hutchings, RSC Adv., 2012, 2, 2217–2220

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By Sara Coles