Materials – Page 10 – Chemical Communications Blog

Archive for the ‘Materials’ Category

Fullerene ‘hide and seek’ in lipid membranes

05 Oct 2011

Japanese researchers have experimentally proven that fullerenes reside in the hydrophobic core of liposome membranes.

Liposomes are vesicular structures made up of a phospholipid bilayer. Due to their ability to encapsulate a range of different substances and target numerous cell types, they have great potential as drug delivery agents. Recently, liposomes have been modified with fullerene for a number of uses such as DNA photocleavage, anti-bacterial agents, and photodynamic therapy. Although theoretical simulations have been performed to characterise these fullerene–liposomes, up until now there has been no experimental proof of where the fullerene units end up in the lipid membranes.

Using differential scanning calorimetry and ¹³C NMR spectroscopy, Atsushi Ikeda and colleagues have determined that the fullerenes self-aggregate in the core of the bilayer, separating themselves from the alkyl chains. The fullerene units are expected to be located in a similar fashion in a cell membrane, say the team. This new insight means efforts can commence on bringing the fullerenes up to the surface of the lipid which may help improve the photoactivity of the fullerenes whilst reducing any deleterious effects they may have.

Download Ikeda’s ChemComm article to find out more…

Comments Off on Fullerene ‘hide and seek’ in lipid membranes

Ionic Liquids web theme issue – welcoming submissions

03 Oct 2011

ChemComm is delighted to announce a high-profile web themed issue on Ionic Liquids.

Guest editors: Robin D. Rogers (University of Alabama), Doug MacFarlane (Monash University) and Suojiang Zhang (Institute of Process Engineering)

Picture courtesy of Photodisc

This issue will consist of a series of Communications and Feature Articles from prominent scientists working on all aspects of ionic liquid chemistry. The scope will range from new fundamental knowledge about ionic liquids to novel applications of ionic liquids which take advantage of their unique attributes. Follow on studies or those of routine interest will not be considered.

The level of quality of this issue will be extremely high, and all manuscripts will undergo strict peer review. You are therefore encouraged to report work that you consider to be very important and conceptually significant in accord with the ChemComm mandate. Please note that inclusion in the issue is subject to the discretion of the guest editors.

Publication of the peer-reviewed articles will occur without delay to ensure the timely dissemination of the work. The articles will then be assembled on the ChemComm website as a web-based thematic issue.

Submit your work before 29^th February 2012. Please add “ionic liquids” in the comments to the editor section.

Comments Off on Ionic Liquids web theme issue – welcoming submissions

Bendy Crystals

26 Sep 2011

Scientists are trying to create molecular systems that mimic machinery components. The idea is for these molecular machines to exhibit mechanical movement once an external stimulus is applied.

With this in mind, Japanese researchers have grown crystals that bend upon shining UV light on them. The crystals are of a salicylideneaniline compound which changes its structure depending on the wavelength of light.

The molecular transformation from the enol to the trans-keto form causes the crystals to bend on the macroscopic scale, which is also accompanied by a colour change from pale yellow to reddish-orange. When the UV light is blocked, the crystals resume their initial straight form and colour. This reversible bending can be repeated for over 200 cycles.

To find out more, download Koshima’s ChemComm article.

Comments Off on Bendy Crystals

Yeast cell wall particles for multi-modal imaging

23 Sep 2011

Scientists based in Italy and Portugal have developed a new carrier system for Magnetic Resonance Imaging (MRI) based on yeast cell wall particles (YCWPs).

YCWPs are well tolerated in vivo because they have a cell wall based on a glucan polymer. However, previous attempts at using it as a carrier of hydrophilic and amphiphilic chemicals have failed due to the porous and hydrophilic nature of the membrane.

In this work the team, led by Enzo Terreno at the University of Turin, realised that they could use the YCWPs as microreactors. Once loaded with an imaging agent the particles were exposed to a sudden change in solvent polarity therefore forming a micro-emulsion inside the particles. Importantly this traps the imaging agent in the particle core.

When loaded with gadolinium, the particles were found to have an increased paramagnetic density and also enhanced relaxivity per paramagnetic centre. In all, this should lead to better contrast when used for imaging. In the future Terreno envisages potential applications in cell tracking experiments and particularly for cells found in the immune system.

Want to find out more? Then download the full ChemComm article for free today.

Comments Off on Yeast cell wall particles for multi-modal imaging

Meet our author… Weiping Wang

30 Aug 2011

Weiping Wang is now a Ph.D. student under the supervision of Professor Ying Chau at the Hong Kong University of Science and Technology. He has just passed his Ph.D. thesis defense and has been accepted into a postdoctoral position in Boston area. Weiping took some time out from his work to talk to ChemComm…

Chau and Wang’s recent ChemComm article, Efficient and facile formation of two-component nanoparticles via aromatic moiety directed self-assembly, presents a self assembling system based around Fmoc groups for the construction of nanoparticles.

What initially inspired you to become a scientist?

I grew up in a family of teachers and was influenced by my parents. I became interested in the natural sciences from a very young age. I spent my childhood making simple circuits, performing oil combustion, observing ant behavior. Becoming a scientist was a very natural path for me. After I started my Ph.D. my desire to become a scientist was consolidated. For me, scientific research is the best career in the world. You can accelerate societal development and bring benefits to the human race by investigating topics that interest you.

What was your motivation behind the research described in your ChemComm communication?

Aromatic groups conjugated with small molecules can engage in specific interactions to facilitate self-assembly. However, most synthetic small aromatic molecules self-assemble into nanofibrous structures, which are not suitable as drug delivery carriers. Inspired from the natural protein clathrin, we envisioned that a simple trigonal core molecule conjugated with three aromatic groups may achieve a rapid and efficient assembly into nanoparticles. Moreover, as drug delivery carriers, nanoparticles need to be well-dispersed at physiological conditions. This further motivated us to design this two-component self-assembling system employing aromatic interactions.

Where do you see your research heading next?

The two-step aromatic-directed self-assembling process allows us to introduce biofunctional peptides on the surface of nanoparticles. We have successfully prepared two-component nanoparticles functionalized by Fmoc-modified targeting peptides. The nanoparticles have shown attractive physicochemical and biofunctional properties for drug delivery application. Now the nanoparticles are being evaluated for encapsulating poorly soluble anticancer drugs and in vitro cytotoxicity. The idea of the self-assembling system may also inspire the construction of functional nanomaterials using other aromatic moieties. Other aromatic groups or even aromatic drug molecules may be formulated into a promising drug delivery system using a similar approach.

What advice would you have for young scientists considering a career in science research?

Passion is the most important factor to consider.

What do enjoy doing in your spare time?

Travelling, hiking, swimming and photography

If you could not be a scientist, but could be anything else, what would you be?

I think I would be an entrepreneur and start up a company with friends. I would like to know whether I can run a company well.

Comments Off on Meet our author… Weiping Wang

Two for one – cleaning water and generating energy

18 Aug 2011

A fuel cell system that can generate electricity from organic compounds and clean up wastewater at the same time has been developed by scientists in China.

Yanbiao Liu from Shanghai Jiao Tong University and colleagues made a photocatalytic fuel cell comprising a TiO₂-nanotube-array (TNA) anode and a platinum-based cathode. The cell uses light energy to degrade organic compounds in wastewater, generating electrons that pass through to the cathode, which converts the chemical energy into electrical energy.

Interested in learning more? Read the full news story in Chemistry World and download the team’s ChemComm communication.

Comments Off on Two for one – cleaning water and generating energy

Meet our author… Daniela Iacopino

05 Aug 2011

Daniela Iacopino, a chemist working on organic nanostructures at the Tyndall National Institute, in the Republic of Ireland, takes some time away from her research to speak with us…

Iacopino’s recent communication in ChemComm reports an advance in the field of photoswitchable nanomaterials and in particular polymer nanotubes: Reversible modulation of photoluminescence from conjugated polymer nanotubes by incorporation of photochromic spirooxazine molecules.

What initially inspired you to become a scientist?

I was inspired by my chemistry teacher in school.

What was your motivation behind the research described in your ChemComm communication?

When we started working on the photoswitiching paper we had been working on polymer nanostructures for a while, exploring their photophysical characteristics. We were then interested in observing different functionalities and also studying possible energy transfer processes in novel doped systems.

Where do you see your research heading next?

At the moment we are investigating the manipulation and functionalisation of metal nanorods. We are also working on dark field spectroscopy of single metal nanostructures for sensing applications.

What advice do you have for young scientists considering a career in science research?

Be curious and be patient, I haven’t always been patient but I have always been curious.

What do enjoy doing in your spare time?

I read, run, swim and practise yoga.

If you could not be a scientist, but could be anything else, what would you be?

I’d seriously consider becoming a midwife.

Comments Off on Meet our author… Daniela Iacopino

Metal organic frameworks for hydrogen storage

23 Jun 2011

Hydrogen is seen by many as the energy to fuel the future of the automotive industry. But its low polluting profile and high energy efficiency are currently overshadowed by the technical difficulties in developing safe and efficient storage strategies for mobile applications.

Alternatives to the common high pressure tanks have been looked for over the years and some promising results came from the use of metal hydrides, formic acid, carbon nanotubes, metal organic frameworks (MOFs) as storage supports.

MOF research for hydrogen storage is a young field, established in the early 2000s when reports of the application of these porous materials started to appear in journals such as Science (Science, 2003, 300 (5622), 1127-1129 DOI: 10.1126/science.1083440). After the first proofs of concept, research has moved on increasing the hydrogen absorption capabilities of these materials by screening different metals, organic linkers and fabrication techniques.

The group lead by Champness and Schröder at the University of Nottingham, not new to the field (Angew. Chem. Int. Ed. 2006, 45, 7358 –7364, DOI: 10.1002/anie.200601991; Nature Chemistry 1, 487 – 493 (2009), DOI:10.1038/nchem.333), has recently focused on the development of two new scandium(III)-based MOFs that exhibit promising hydrogen absorption qualities. The novel materials, based on the general formula [M₂(μ₂-OH)(OCR)₄)], were characterised and their performance as storage supports tested.

Graphical abstract: Highly porous and robust scandium-based metal–organic frameworks for hydrogen storage The novel MOFs, NOTT-400 and NOTT-401, share the same metal-based fragment as building block and differ from each other by the organic linker employed (H₄BPTC and H₂TDA). They retained high crystallinity up to 500 °C and 350 °C respectively and were successfully reacted with acetone and degassed to afford the fully desolvated material ready for use.

The hydrogen absorption capabilities were tested at 77 and 87 K at hydrogen pressures ranging up to 20 bar with a maximum absorption of 4.44 wt% at 20 bar for NOTT-401. The absorption kinetics showed a very fast intake, reaching equilibrium in about 3 minutes, and good reversibility. No hysteresis was observed.

For the original communication see:
Highly porous and robust scandium-based metal–organic frameworks for hydrogen storage
Ilich A. Ibarra, Sihai Yang, Xiang Lin, Alexander J. Blake, Pierre J. Rizkallah, Harriott Nowell, David R. Allan, Neil R. Champness, Peter Hubberstey and Martin Schröder
Chem. Commun., 2011, DOI: 10.1039/C1CC11168J

Posted on behalf of Dr. Giorgio De Faveri, Web Writer for Catalysis Science & Technology.

Comments Off on Metal organic frameworks for hydrogen storage

Magnetic nanoparticles detect low levels of cyanide

22 Jun 2011

Chinese scientists have reported dumbbell-shaped nanoparticles capable of detecting cyanide concentrations as low as 4 x 10^-7 M in drinking water. This low detection limit, which is below the acceptable limit advised by the World Health Organization, is attributed to a combination of fluorescence detection with a filtering process called ‘magnetic concentration-washing’.

The toxicity of cyanide and its potential prevalence in drinking water has made easy detection of cyanide an active area of research. Gold nanoparticles have attracted attention as cyanide sensors due to their selectivity for cyanide over other anions. Now, Shaojun Dong and colleagues at the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, have adapted a bifunctional nanoparticle made up of Au and magnetic Fe₃O₄ nanoparticles for sensitive detection of cyanide, even in the presence of interfering species.

Schematic depiction of the turn-on fluorescent detection of cyanide based on the dual-functional Au–Fe3O4 dumbbell nanoparticles.

The group detected cyanide by relying on what is known as the ‘inner filter effect’, observed when two molecules present in a solution have overlapping absorption and emission wavelengths. The fluorescence emission from a fluorophore is blocked, or reabsorbed, by the second molecule, reducing or even quenching the overall fluorescence of the solution. In the present system, the excitation and emission energy for the fluorophore Rhodamine B is quenched by the Au-Fe₃O₄ nanoparticles. However, addition of cyanide to the sample reduces the gold component of the nanoparticles by forming an Au(CN)₂^– complex. This change in the structure alters the nanoparticles’ absorbance spectra and the Rhodamine B emissions are no longer fully absorbed. The team calculated the amount of cyanide present in a sample by monitoring the change in fluorescence.

To extend this detection method for use with environmental samples, which may contain dyes or other contaminants that absorb or emit at a similar wavelength to Rhodamine B, Dong and colleagues implemented a ‘magnetic concentration-washing process’. In it, the Au-Fe₃O₄ nanoparticles are magnetically separated from the sample solution after they have reacted with any cyanide present in the sample. This magnetic separation retains the bifunctional nanoparticles and leaves any interfering species behind. Pure buffered water containing additional Rhodamine B is added and the fluorescence is monitored. The authors showed that two cycles of this process were enough to remove any interfering species and accurately detect cyanide levels.

To find out more, read the full article:

Dual-Functonal Au-Fe₃O₄ Dumbbell Nanoparticles for Sensitive and Selective Turn-on Fluorescent Detection of Cyanide Based on the Inner Filter Effect
Yueming Zhai, Lihua Jin, Ping Wang and Shaojun Dong, Chem. Commun., 2011, DOI: 10.1039/C1CC13149D

Posted on behalf of Patricia Pantoș, web writer for ChemComm.

Comments Off on Magnetic nanoparticles detect low levels of cyanide

New template has potential for bone tissue engineering

10 Jun 2011

British scientists at working at Imperial College, London have synthesised a macroporous hydroxyapatite bioceramic with potential uses in bone regeneration.

Porous hydroxyapatite (HA) bioceramics are widely studied for their potential use in bone regeneration. These materials are biocompatible and have a structure that contains many connected pores. This allows fluid to flow through the material and provides nucleation points for bone growth. The best results are obtained when the the pores are smaller than 1 μm and therefore synthetic methods that give good control over the pore size and material structure are highly desirable.

Prof. Molly Stevens and her team have now demonstrated a way of making an HA bioceramic with a 3D ordered (DOM) macroporous structure. They used an ordered macroporous carbon template (OMC) in combination with a sol-gel method to form the desired bioceramic. They found that the DOM HA, when compared with HA material made without the OMC template, allowed the nucleation of calcium phosphate on the surface of the pores, thus demonstrating that the template method used affects the crystallisation of material.

hydroxyapatite bioceramics

The team hopes that these materials will find applications not only in the generation of bone but also in the generation of other materials. Want to find out more? Then download the ChemComm article for free today and leave a comment below to let us know what you think.

Comments Off on New template has potential for bone tissue engineering

Chemical Communications Blog