Featured Research

from universities, journals, and other organizations

DNA brings materials to life: DNA-coated colloids help create novel self-assembling materials

Date:
June 13, 2013
Source:
Ecole Polytechnique Fédérale de Lausanne
Summary:
A colloid is a substance spread out evenly inside another substance. Everyday examples include milk, styrofoam, hair sprays, paints, shaving foam, gels and even dust, mud and fog. One of the most interesting properties of colloids is their ability to self-assemble -- to aggregate spontaneously into well-defined structures, driven by nothing but local interactions between the colloid's particles. Self-assembly has been of major interest in industry, since controlling it would open up a whole host of new technologies, such as smart drug-delivery patches or novel paints that change with light. Scientists have now discovered a technique to control and direct the self-assembly of two different colloids.

This shows two colloids interacting over time in relation to temperature.
Credit: Giuseppe Foffi, EPFL

A colloid is a substance spread out evenly inside another substance. Everyday examples include milk, styrofoam, hair sprays, paints, shaving foam, gels and even dust, mud and fog. One of the most interesting properties of colloids is their ability to self-assemble -- to aggregate spontaneously into well-defined structures, driven by nothing but local interactions between the colloid's particles. Self-assembly has been of major interest in industry, since controlling it would open up a whole host of new technologies, such as smart drug-delivery patches or novel paints that change with light. In a recent Nature Communications publication, scientists from EPFL and the University of Cambridge have discovered a technique to control and direct the self-assembly of two different colloids.

Related Articles


Contrary to solutions that are made up of discrete molecules, colloidal solutions are made up of large particles, dispersed in a liquid solvent. This unusual structure gives colloids unique properties such as Brownian motion (the random zig-zag movement of particles as they collide with the molecules of the dispersion medium), electrophoresis (the unidirectional movement of particles under and electric current) and optical properties such as the Tyndall effect (light entering a colloid scatters and exits as a different color). It is because of such properties that colloids are so commonplace in everyday life; but one particular property holds special interest: self-assembly.

Self-assembly refers to the ability of a colloid's particles to spontaneously form a kind of stable structural arrangement as a result of the shape and direction of the colloid's particles as they interact with the dispersal medium. Although no external force is required, self-assembly generally takes place as a response to a change in an environmental factor such as temperature, light, etc. In biological colloids like DNA, proteins and other macromolecules, self-assembly is usually the first step to self-organization, which underlies many cellular structures. But in terms of technology, self-assembling colloids could have a wide range of applications, fuelling much research in the field.

But what about self-assembly of two -- or more -- species of different colloids? This is the question addressed by Giuseppe Foffi's group at EPFL, working in collaboration with Erika Eiser's group at the University of Cambridge. The scientists showed that when the interactions between the particles of two different colloids are carefully designed, they result in the formation of new structures. Specifically, they have discovered a ways to obtain self-assembled structures that depend strongly on temperature changes. Giuseppe Foffi says: "In a sense, the new structures have a 'memory' of their preparation history."

Using DNA-coated colloids, the group of Erika Eiser was able to control the self-assembling progress between two different colloidal species. Fluorescent polystyrene spheres were coated with different DNA strands (giving them a 'hairy' appearance) that acted as means of particle interaction and can be used to characterize the different species. The advantage of using DNA strands was that the interactions between the particles could be programed using the compatibility of the DNA sequences. Another very interesting property is their responsiveness to sharp changes in temperature, offering a high degree in specificity and programmability. The two species of colloids were mixed together in a 'binary mixture' where one could aggregate faster, therefore creating a structural 'scaffold' for the other to assemble upon.

By exploiting the selectivity of DNA base-pairing, supported by simulation studies by the EPFL group, the scientists found that they could achieve an unprecedented control of the morphology of the interacting colloids. By gathering data about the system's morphology and the dynamics of particle interactions, the authors concluded that this approach is not restricted to nano-scale objects like other methods, but can be applied to the entire range of colloidal sizes. In addition, they foresee that this method can have a number of applications, for example light-reacting paints or smart patches that respond to changes in the body's temperature or pH by releasing particles filled with a drug like an antibiotic or antipyretic.


Story Source:

The above story is based on materials provided by Ecole Polytechnique Fédérale de Lausanne. Note: Materials may be edited for content and length.


Journal Reference:

  1. Lorenzo Di Michele, Francesco Varrato, Jurij Kotar, Simon H. Nathan, Giuseppe Foffi, Erika Eiser. Multistep kinetic self-assembly of DNA-coated colloids. Nature Communications, 2013; 4 DOI: 10.1038/ncomms3007

Cite This Page:

Ecole Polytechnique Fédérale de Lausanne. "DNA brings materials to life: DNA-coated colloids help create novel self-assembling materials." ScienceDaily. ScienceDaily, 13 June 2013. <www.sciencedaily.com/releases/2013/06/130613104426.htm>.
Ecole Polytechnique Fédérale de Lausanne. (2013, June 13). DNA brings materials to life: DNA-coated colloids help create novel self-assembling materials. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2013/06/130613104426.htm
Ecole Polytechnique Fédérale de Lausanne. "DNA brings materials to life: DNA-coated colloids help create novel self-assembling materials." ScienceDaily. www.sciencedaily.com/releases/2013/06/130613104426.htm (accessed October 24, 2014).

Share This



More Matter & Energy News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Police Testing New Gunfire Tracking Technology

Police Testing New Gunfire Tracking Technology

AP (Oct. 24, 2014) — A California-based startup has designed new law enforcement technology that aims to automatically alert dispatch when an officer's gun is unholstered and fired. Two law enforcement agencies are currently testing the technology. (Oct. 24) Video provided by AP
Powered by NewsLook.com
3D Printed Instruments Make Sweet Music in Sweden

3D Printed Instruments Make Sweet Music in Sweden

Reuters - Innovations Video Online (Oct. 23, 2014) — Students from Lund University's Malmo Academy of Music are believed to be the world's first band to all use 3D printed instruments. The guitar, bass guitar, keyboard and drums were built by Olaf Diegel, professor of product development, who says 3D printing allows musicians to design an instrument to their exact specifications. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) — Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) — Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins