Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chemists Become Sculptors of Tiny, Molecular Traps

07.12.2011
Using clever but elegant design, University at Buffalo chemists have synthesized tiny, molecular cages that can be used to capture and purify nanomaterials.

Sculpted from a special kind of molecule called a “bottle-brush molecule,” the traps consist of tiny, organic tubes whose interior walls carry a negative charge. This feature enables the tubes to selectively encapsulate only positively charged particles.


University at Buffalo
An illustrated cross-section of a nanotube UB chemists created. The green structures are negatively charged carboxylic acid groups, which help trap positively charged particles.

In addition, because UB scientists construct the tubes from scratch, they can create traps of different sizes that snare molecular prey of different sizes. The level of fine tuning possible is remarkable: In the Journal of the American Chemical Society, the researchers report that they were able to craft nanotubes that captured particles 2.8 nanometers in diameter, while leaving particles just 1.5 nanometers larger untouched.

These kinds of cages could be used, in the future, to expedite tedious tasks, such as segregating large quantum dots from small quantum dots, or separating proteins by size and charge.

Images of the bottle-brush molecule are available here: http://www.buffalo.edu/news/13057.

“The shapes and sizes of molecules and nanomaterials dictate their utility for desired applications. Our molecular cages will allow one to separate particles and molecules with pre-determined dimensions, thus creating uniform building blocks for the fabrication of advanced materials,” said Javid Rzayev, the UB assistant professor of chemistry who led the research.

“Just like a contractor wants tile squares or bricks to be the same size so they fit well together, scientists are eager to produce nanometer-size particles with the same dimensions, which can go a long way toward creating uniform and well-behaved materials,” Rzayev said.

To create the traps, Rzayev and his team first constructed a special kind of molecule called a bottle-brush molecule. These resemble a round hair brush, with molecular “bristles” protruding all the way around a molecular backbone.

After stitching the bristles together, the researchers hollowed out the center of each bottle-brush molecule, leaving behind a structure shaped like a toilet paper tube.

The carving process employed simple but clever chemistry: When building their bottlebrush molecules, the scientists constructed the heart of each molecule using molecular structures that disintegrate upon coming into contact with water. Around this core, the scientists then attached a layer of negatively charged carboxylic acid groups.

To sculpt the molecule, the scientists then immersed it water, in effect hollowing the core. The resulting structure was the trap—a nanotube whose inner walls were negatively charged due to the presence of the newly exposed carboxylic acid groups.

To test the tubes’ effectiveness as traps, Rzayev and colleagues designed a series of experiments involving a two-layered chemical cocktail.

The cocktail’s bottom layer consisted of a chloroform solution containing the nanotubes, while the top layer consisted of a water-based solution containing positively charged dyes. (As in a tequila sunrise, the thinner, water-based solution floats on top of the denser chloroform solution, with little mixing.)

When the scientists shook the cocktail for five minutes, the nanotubes collided with and trapped the dyes, bringing the dyes into the chloroform solution. (The dyes, on their own, do not dissolve in chloroform.)

In similar experiments, Rzayev and his team were able to use the nanotubes to extract positively charged molecules called dendrimers from an aqueous solution.

The nanotubes were crafted so that dendrimers with a diameter of 2.8 nanometers were trapped, while dendrimers that were 4.3 nanometers across were left in solution.

To remove the captured dendrimers from the nanotubes, the researchers simply lowered the pH of the chloroform solution, which shuts down the negative charge inside the traps and allows the captured particles to be released from their cages.

The research on nanotubes is part of a larger suite of studies Rzayev is conducting on bottle-brush molecules using a National Science Foundation CAREER award. His other work includes the fabrication of bottle-brush-based nanomembranes that could be adapted for water filtration, and the assembly of layered, bottle-brush polymers that reflect visible light like the wings of a butterfly do.

The University at Buffalo is a premier research-intensive public university, a flagship institution in the State University of New York system and its largest and most comprehensive campus. UB's more than 28,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs. Founded in 1846, the University at Buffalo is a member of the Association of American Universities.

Related Stories:
Nanomembranes Made From Bottle-Brush Molecules Could Filter Bacteria From Water: http://www.buffalo.edu/news/12288

Charlotte Hsu | Newswise Science News
Further information:
http://www.buffalo.edu

More articles from Life Sciences:

nachricht Cells communicate in a dynamic code
19.02.2018 | California Institute of Technology

nachricht Studying mitosis' structure to understand the inside of cancer cells
19.02.2018 | Biophysical Society

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Contacting the molecular world through graphene nanoribbons

19.02.2018 | Materials Sciences

When Proteins Shake Hands

19.02.2018 | Materials Sciences

Cells communicate in a dynamic code

19.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>