Nanoscale & Nanoscale Advances Blog

Tooth and claw

Biological structures such as teeth and bone are produced by a process called biomineralisation. The shape and structure of biominerals are controlled in an extremely precise way, from the nanoscale right up to the macroscopic level. The spontaneous formation of a tooth, claw, spine or shell is a truly amazing piece of chemistry, and unlocking the secrets of this could prove vital for materials scientists in their quest to engineer ever more complex nanostructures.

Biomineralisation of calcium carbonate

In  Nanoscale, we have recently published some papers on the formation of crystalline calcium carbonate (calcite) by biomineralisation. Yang et al., in their paper entitled ‘Biomineral nanoparticles are space filling’, present a study of biomineralisation in sea urchins, which contain spicules, spines and teeth (pictured left) all composed of calcium carbonate. They discuss the formation of crystalline biominerals through amorphous precursors, where one can imagine hydrated amorphous calcium carbonate nanoparticulate building blocks being able to flow and morph into the intricate shape of the final biomineral, followed by a period of dehydration and crystallization which forms the solid product. This process of dehydration and crystallization is discussed further by Rodriguez-Blanco et al., who used time-resolved X-ray diffraction in order to study the changes in crystal structure which occur when amorphous calcium carbonate crystallizes. They discovered that, under certain conditions, crystallization from the amorphous form to calcite occurs via another crystalline form, known as vaterite.

In November’s themed issue of Nanoscale, entitled Crystallization and Formation Mechanisms of Nanostructures, we published some other work on calcium biominarlisation, including studies of the formation and stability of amorphous calcium carbonate by Jiang et al. and Sommerdijk et al., and of calcium phosphate crystals by Mann et al., Taubert et al., Zhai et al., and Ibsen and Birkedal, which discussed the use of structure directing agents and organic additives to control crystal growth and morphology.

Papers like these are prime examples of how the study of natural processes can provide vital insight into the synthetic mechanisms which scientists are developing to produce new nanomaterials.

Can street lights be replaced by trees? Taiwanese scientists believe that they can using gold nanoparticles to induce luminescence in leaves.

Yen Hsun Su and coworkers at Academia Sinica and the National Cheng Kung University in Taipei and Tainan have tackled this problem by synthesising gold nanoparticles shaped like sea urchins and diffusing them into plant leaves to create bio-LEDs.

Yuandi Li

Read this exciting Nanoscale paper today:
Influence of surface plasmon resonance on the emission intermittency of photoluminescence from gold nano-sea-urchins
Y. H. Su, S.-L. Tu, S.-W. Tseng, Y.-C. Chang, S.-H. Chang and W.-M. Zhang, Nanoscale, 2010
DOI: 10.1039/C0NR00330A

Nanoscale’s new Publishing Editor Philip Howes, talks about a recent article on conjugated polymer nanoparticles published in the journal…

This month, a Nanoscale Feature Article presents a very interesting account of recent investigations into a novel type of fluorescent nanoparticles.

Read the Feature Article now for free:
Amplified energy transfer in conjugated polymer nanoparticle tags and sensors
Zhiyuan Tian, Jiangbo Yu, Changfeng Wu, Craig Szymanski and Jason McNeill
Nanoscale, 2010, 2, 1999-2011

Conjugated polymers are a fascinating class of material which combine the electrical behaviour of metals with the ease of processing of plastics. These organic molecules exhibit semiconducting behaviour as they possess a band structure similar to traditional inorganic semiconductors, like silicon, which allows the formation of excitons. For this reason, conjugated polymers are being used for the production of optoelectronic devices, such as LEDs and photovoltaics.

However, the use of conjugated polymers is not confined to device applications. As the polymers exhibit extremely high fluorescence brightness under UV excitation, they have been used to make fluorescent nanoparticles for use in biological imaging. The physical properties of conjugated polymer nanoparticles compare very well with the best known alternatives, such as quantum dots or dye-doped silica, and as they are relatively benign they appear to be promising for uses in biological fluorescence imaging studies where nanoparticle toxicity may be a concern. Furthermore, tuning of the colour of these nanoparticles is easily achieved by changing the type of polymer used, and as there is a vast range of conjugated polymers commercially available, emission across the visible spectrum is easily obtainable.

In this Feature Article, the authors review recent investigations into conjugated polymer nanoparticles with particular reference to optical and energy transfer phenomena, and applications in fluorescence based imaging and sensing applications. The underlying science of how fluorescent conjugated polymers behave in nanoparticle form is both fascinating and complex, and this is dealt with extremely well in this paper. As the authors explain, the development of conjugated polymer nanoparticles is still in its infancy and some important advances need to be made, such as reliable encapsulation and bioconjugation. However, the paper lays out many positive arguments as to why this type of particle should have a bright future in the development of fluorescent nanoparticles for biological imaging studies.

Philip Howes
Publishing Editor, Nanoscale

Can street lights be replaced by trees? Scientists report in Nanoscale they believe they can by using gold nanoparticles.

Light emitting diodes are used in street and bicycle lights and have a higher efficiency than traditional light bulbs. Now Yen Hsun Su has synthesised gold nanoparticles shaped like sea urchins and diffused them into Bacopa caroliniana chloroplast which creates a bio-LED.

Chlorophyll shows bioluminescence upon high wavelength (400 nm) ultra violet excitation. In contrast, the gold nanoparticles are excited at shorter wavelengths and emit at 400 nm. By implanting the nanoparticles in the plants, the chlorophyll in the leaves can be induced to produce a red emission.

In addition, the nanoparticles were able to suppress emission blinking – a known problem for gold nanoparticles –as they have a strong surface plasmon resonance. Su says that this bio-LED could be used to make roadside trees luminescent at night once the efficiency is improved and are also planning to apply the same strategy to other plant biomolecules.

Read this exciting paper today for free:
Influence of surface plasmon resonance on the emission intermittency of photoluminescence from gold nano-sea-urchins
Y. H. Su, S.-L. Tu, S.-W. Tseng, Y.-C. Chang, S.-H. Chang and W.-M. Zhang, Nanoscale, 2010
DOI: 10.1039/C0NR00330A

Nanoscale Issue 10, just published

Cover Article
Polyelectrolyte and carbon nanotube multilayers made from ionic liquid solutions
Takuya Nakashima, Jian Zhu, Ming Qin, Szushen Ho and Nicholas A. Kotov
Nanoscale, 2010, 2, 2084-2090

Highlight
Amplified energy transfer in conjugated polymer nanoparticle tags and sensors
Zhiyuan Tian, Jiangbo Yu, Changfeng Wu, Craig Szymanski and Jason McNeill
Nanoscale, 2010, 2, 1999-2011

Read the issue now