Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tokyo Tech researchers produce new photoactive micelles

31.01.2013
Researchers at Tokyo Institute of Technology have produced a new form of photoactive micelles with potential applications in photofunctional dyes and sensors. The research was published in Angewandte Chemie recently.

A new form of micelle, which is composed of detergents with bent aromatic panels, has been created by Michito Yoshizawa and his colleagues at Tokyo Institute of Technology. Unlike traditional micelles, the new ‘aromatic micelles’ are photoactive, and capable of encapsulating dye molecules and showing unusual fluorescence in aqueous solutions.


Figure 1: Schematic representation of spherical assemblies. a) A standard micelle composed of string-like detergents. b) An aromatic micelle composed of new detergents with bent aromatic panels.


Figure 2: a) Encapsulation of dye molecules (NR and DCM) by the aromatic micelle in aqueous solution. b) Molecular modeling of the aromatic micelle. c) Fluorescence spectra of the micelle, micelle-NR, and micelle-DCM complexes upon irradiation at 370 nm.

“The present micelles might be suitable for potential applications in the fields of photofunctional dyes, sensors, and materials owing to their ability to accommodate dye molecules and their efficient host-guest energy transfer in aqueous media,” explain the researchers. They also emphasise the straightforward synthesis, aqueous green chemistry and high stability of the aromatic micelles.

Micelles are used in a range of dissolution, separation, and preservation applications and form the basis of soap detergents. They assemble from string-like molecules in aqueous solutions as a result of different chemical components (hydrophobic and hydrophilic moieties) at either end of the strings. Michito Yoshizawa and Kei Kondo et al. replaced the hydrophobic part of the string with large aromatic panels, which are known to be photochemically active.

The new aromatic micelles form two nanometer-sized capsules that have a cavity surrounded by large aromatic panels. The selective encapsulation of fluorescent dye molecules to form photoactive guest-host complexes is the first demonstration of efficient fluorescence energy transfer from the host framework to dye ‘guest molecules’.
Background

The micelles
Micelles are typically made of string-like molecules, where one end of the string attracts water molecules (hydrophilic) and the other end repels them (hydrophobic). In aqueous solution these strings form spherical assembles like spoke on a dandelion puffball with the hydrophobic ends at the centre. These typical micelles are not photoactive, which places limitations on their potential applications.

Aromatic molecules
Aromatic molecules are carbon-based molecules with six-membered rings that have a particular type of electronic configuration, which leads to a number of specific properties. Large aromatic molecules are planar and photo- and electrochemically active, which may make them useful in applications such as liquid crystal displays. However they do not readily form discrete micelle-like assemblies.
Producing aromatic micelles
To create the aromatic micelles, the researchers made new detergents with bent aromatic panels, comprising two anthracene moieties with a spacer to connect them. The spacer was functionalized with two hydrophilic groups. The steric repulsion between the anthracene and spacer moieties gives the molecule its bent shape. With the hydrophobic bent panels and the hydrophilic groups, the detergent molecules form spherical assemblies in aqueous solution. The assembly is driven by stacking of the hydrophobic aromatic panels.
Aromatic micelle properties
The aromatic micelles had a cavity surrounded by anthracene shells with a diameter of approximately one nanometer. The shell emitted blue-green fluorescence (~500 nm). The aromatic micelles were also extremely robust. Atomic force microscopy (AFM) images showed the spherical structures persisted even after complete evaporation of water.

Dye encapsulation
The researchers demonstrated the encapsulation of two well known hydrophobic dyes, Nile red (NR) and DCM by the aromatic micelles. Stirring a suspension of the dyes in an aqueous solution of the aromatic micelles for an hour produced a clear solution. Spectroscopic observations revealed changes to the light absorption and emission properties of the micelle following encapsulation of the dyes. Strong red emission (~640 nm) from the encapsulated DCM was observed upon irradiation of the micelle-DCM complex at 370 nm. In contrast, the irradiation of DCM in the absence of the micelle at 370 nm showed almost no emission. Measurements of the fluorescence quenching profile of the anthracene panels in the micelles indicated the energy transfer efficiency as high as 97%. The work is the first demonstration of efficient fluorescent resonance energy transfer from discrete self-assembled hosts.
Next steps
The authors expect that the functionalization of the aromatic shells as well as the use of other aromatic panels will lead to new aromatic micelles with a wide range of fluorescent properties. Studies along these lines are currently in progress in their research group.

Further information
Yukiko Tokida, Miwako Kato
Center for Public Information, Tokyo Institute of Technology
2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
E-mail: kouhou@jim.titech.ac.jp
URL: http://www.titech.ac.jp/english/
Tel: +81-3-5734-2975 Fax: +81-3-5734-3661

About Tokyo Institute of Technology
As one of Japan’s top universities, Tokyo Institute of Technology seeks to contribute to civilization, peace and prosperity in the world, and aims at developing global human capabilities par excellence through pioneering research and education in science and technology, including industrial and social management. To achieve this mission, we have an eye on educating highly moral students to acquire not only scientific expertise but also expertise in the liberal arts, and a balanced knowledge of the social sciences and humanities, all while researching deeply from basics to practice with academic mastery. Through these activities, we wish to contribute to global sustainability of the natural world and the support of human life.
Website: http://www.titech.ac.jp/english/

Journal information
Reference
K. Kondo, A. Suzuki, M. Akita, and M. Yoshizawa, “Micelle-like Molecular Capsules with Anthracene Shells as Photoactive Hosts” Angewandte Chemie International Edition, 2013, DOI: 10.1002/anie.201208643 (Article first published online: 23 Jan 2013).

Funding information

Support
This research was supported by the Japan Society for the Promotion of Science (JSPS) through the “Funding Program for Next-Generation World-Leading Researchers” and by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) through a Grant-in-Aid for Scientific Research on Innovative Areas (“Coordination Programming”).

Adarsh Sandhu | Research asia research news
Further information:
http://www.titech.ac.jp/english/
http://www.researchsea.com

More articles from Life Sciences:

nachricht New switch decides between genome repair and death of cells
27.09.2016 | University of Cologne - Universität zu Köln

nachricht A blue stoplight to prevent runaway photosynthesis
27.09.2016 | National Institute for Basic Biology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

 
Latest News

New imaging technique in Alzheimer’s disease - opens up possibilities for new drug development

28.09.2016 | Medical Engineering

Innovate coating extends the life of materials for industrial use

28.09.2016 | Materials Sciences

Blockchain Set to Transform the Financial Services Market

28.09.2016 | Business and Finance

VideoLinks
B2B-VideoLinks
More VideoLinks >>>