Journal of Materials Chemistry Blog

Thin films are a part of everyday life; if you looked in a mirror today you experienced the advantages of a thin film at work. Crystalline thin films can be made of a range of functional materials and are essential to achieve the desired functionality of various devices including micromachines (not the miniature racing cars but micro-electronic-mechanical systems or MEMS). Crystal films can offer characteristics such as ferroelectricity and piezoelectricity, however these properties are strongly dependent on crystal orientation, degree of orientation and film crystallinity.

Epitaxial growth has become a highly important method for growing crystalline films as it allows for tailoring of properties in order to control electronic, optical and magnetic qualities. Unfortunately as described in this paper by Shibata et al, one of the basic requirements for attaining a good epitaxy is a close structural matching between a substrate and a growing crystal epilayer. This restriction causes a major obstacle for its wide application. In order to overcome this problem these researchers, led by Takayoshi Sasaki, have used 2D inorganic nanosheets of either Ca₂Nb₃O₁₀^–, Ti_0.87O₂^0.52- or MoO₂^δ- as highly organised layers depositied onto amorphous glass. These different surfaces allow for the deposition of SrTiO₃ on to the glass with precise and selective control of crystallographic orientation.

This novel technique has already grabbed press attention because of its cost-effective and universal nature that comes from the possibility to use conventional substrates such as glass and plastic that wasn’t possible before. Whilst some development is still required this technique is already being seen as a huge leap forward in the growth of crystal films that will bring significant technological innovation in the future.

Versatile van der Waals epitaxy-like growth of crystal films using two-dimensional nanosheets as a seed layer: orientation tuning of SrTiO₃ films along three important axes on glass substrates

Tatsuo Shibata, Hikaru Takano, Yasuo Ebina, Dae Sung Kim, Tadashi C. Ozawa, Kosho Akatsuka, Tsuyoshi Ohnishi, Kazunori Takada, Toshihiro Kogure and Takayoshi Sasaki

J. Mater. Chem. C, 2014, 2, 441-449 C3TC31787K

H. L. Parker is a guest web writer for the Journal of Materials Chemistry blog. She currently works at the Green Chemistry Centre of Excellence, the University of York.

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Abdelmohsen et al write in the first line of this review “biological motors are one of the most remarkable products of evolution” and I couldn’t agree more. Nanoscale biomotors are common in nature and these tiny machines have inspired scientists to copy nature and attempt to develop man-made micro- and nano-motors themselves. Incredibly, machines that are as small as one 60,000th of a human hair have already been made.

Micro-machines show remarkable promise for use in a wide range of biomedical applications; including drug delivery, sensing and isolation, nanosurgery and imaging that would enable targeted or non-invasive medicine to be carried out. Although as this review points out there is still a considerable amount of work to take micro- and nano-machines for in vivo applications from concept into reality.

This paper covers topics including micro-motor design, potential fuel and fuel free machines and new developments for their use in biomedical applications and gives an interesting and balanced insight into the work of micro-machines highlighting the opportunities and challenges currently facing this field.

Micro- and nano-motors for biomedical applications

Loai K. E. A. Abdelmohsen, Fei Peng, Yingfeng Tu and Daniela A. Wilson,

 J. Mater. Chem. B, 2014. C3TB21451F

H. L. Parker is a guest web writer for the Journal of Materials Chemistry blog. She currently works at the Green Chemistry Centre of Excellence, the University of York.

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Glycoproteins are abundant in living organisms and appear in nearly every biological process studied. There are also many clinical biomarkers and therapeutic targets that are glycoproteins. The diverse function of glycoproteins is due to their structure – they consist of a polypeptide covalently bonded to a carbohydrate moiety.

The recognition and analysis of glycoproteins can be tricky. Mass spectrometry has proven a powerful tool; however when glycoproteins are in low abundance an enrichment process is required in order to see the proteins. In order to improve glycoprotein recognition Lin et al have developed a novel imprinting strategy using reversible covalent complexation of glycoprotein to create glycoprotein-specific recognition cavities on 3-acrylamidophenylboronic acid-immobilized silica nanoparticles (SiO2@AAPBA).

When tested the materials exhibited high glycoprotein adsorption capacity and excellent recognition selectivity not just between glycoproteins and non-glycoproteins but also between specific glycoproteins themselves.

Synthesis of boronic acid-functionalized molecularly imprinted silica nanoparticles for glycoprotein recognition and enrichment

Zian Lin, Lixiang Sun, Wei Lui, Zhiwei Xia, Huanghao Yang and Guonan Chen,
J. Mater. Chem. B, 2014, 2, 637-643. C3TB21520B

H. L. Parker is a guest web writer for the Journal of Materials Chemistry blog. She currently works at the Green Chemistry Centre of Excellence, the University of York.

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Writing this blog I am currently experiencing the uncomfortable outcome of not having a desk at home: scorched knees from my overworked laptop giving off enough heat to penetrate two substantial layers of clothing.

It is well known and, as I am experiencing, easily demonstrated that machines generate heat when they operate. This waste heat is an unfortunate trade off in order for it to produce enough power to perform its intended task. However, this heat whilst unavoidable does not have to be wasted. Through the use of thermoelectric materials this heat could be captured and used to generate emission-free renewable power.

This paper by Peng et al presents results of the enhancement of promising thermoelectric Yb-filled COSb₃ skutterudite bulk materials, by incorporating nanoparticles into the bulk material lattice, in order to improve thermoelectric performance. By inclusion of AgSbTe₂ nanoparticles the electrical resistivity of the composites is decreased and the ability of the material to convert heat to electricity is also improved. Overall this leads to a remarkable boost of the power factor that can be achieved.

A Study of Yb0.2Co4Sb12-AgSbTe2 nanocomposites: simultaneous enhancement of all three thermoelectric properties

Jiangying Peng, Liangwei Fu, Qiongzhen Lui, Ming Liu, Junyou Yang, Dale Hitchcock, Menghan, Zhou and Jian He
J. Mater. Chem. A, 2014, 2, 73-79. C3TA13729E

H. L. Parker is a guest web writer for the Journal of Materials Chemistry blog. She currently works at the Green Chemistry Centre of Excellence, the University of York.

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In addition to making the study of chemistry more complicated than it needs to be, three-centre-two-electron bonds also provide carboranes with many useful properties. The inclusion of carborane clusters allows the thermal and chemical stability of polymers to be improved, glass transition temperatures to be increased and the propensity for unwanted aggregation to be reduced.

Recent work by Marshall et al. has focused on the incorporation of ortho­-carborane into conjugated polymers for use in organic electronics. Carboranes are of particular interest in this area due to the possibility that their electron deficiency will allow them to fulfil the role of the electron acceptor in a donor-acceptor polymer. By preparing a novel monomer based on benzocarborane, it was possible to carry out a Stille polymerisation with an electron donating monomer and prepare polymers with molecular weights of the order of 10 kDa.

In comparison to analogous materials that contained no carborane, both novel polymers showed a decrease in band gap. One polymer was found to behave as a p-type semiconductor in a field effect transistor (FET) – the first time that a carborane-containing polymer has been used in such a device.

Incorporation of benzocarborane into conjugated polymer systems: synthesis, characterisation and optoelectronic properties
Jonathan Marshall, Zhuping Fei, Chin Pang Yau, Nir Yaacobi-Gross, Stephan Rossbauer, Thomas D. Anthopoulos, Scott E. Watkins, Peter Beavis and Martin Heeney
J. Mater. Chem. C, 2014, 2, 232.  DOI:10.1039/C3TC31663g

James Serginson is a guest web writer for the Journal of Materials Chemistry blog. He currently works at Imperial College London carrying out research into nanocomposites.

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Although the chemistry of life is usually considered to be organic, living organisms also need to carry out inorganic synthesis. The formation of bones, teeth and shells all depend on the ability of cellular machinery to efficiently prepare inorganic materials with the correct morphology. This machinery is complex and involves the concerted action of small molecules, enzymes and high concentrations of macromolecules.

It is the role of the macromolecules that is the focus of a recent paper by David N. Carace and Christine D. Keating. They aimed to mimic the formation of CaCO₃ by conducting a mineralization reaction in an aqueous two-phase system (ATPS). This system consisted of two immiscible polymer solutions: a poly(ethylene glycol) (PEG) solution floating on a solution of dextran. The mineralisation reaction involved the urease–mediated conversion of urea to carbonate ions and their subsequent reaction with calcium. It was found that biomineralization occurred predominantly in the dextran layer due to the localization of urease. It was also found that decreasing the relative volume of the dextran phase increased the rate of CaCO₃ formation.

This work has demonstrated a fascinating method of biological reaction compartmentalization that does not rely on membranes.

Biocatalysed mineralization in an aqueous two-phase system: effect of background polymers and enzyme partitioning
David N. Cacace and Christine D. Keating
J. Mater. Chem. B, 2013, 1, 1794.  DOI:10.1039/C3TB00550j

James Serginson is a guest web writer for the Journal of Materials Chemistry blog. He currently works at Imperial College London carrying out research into nanocomposites.

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