Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Tiny pump builds polyrotaxanes with precision: Artificial molecular pump gives precise control for materials design

Fraser Stoddart
Board of Trustees Professor of Chemistry
Director of the Center for Chemistry of Integrated Systems
Fraser Stoddart Board of Trustees Professor of Chemistry Director of the Center for Chemistry of Integrated Systems

Abstract:
Northwestern University researchers have developed the most precise way to build polyrotaxanes, a mechanically locked polymer for slide-ring gels, battery electrode materials and drug-delivery platforms.

Tiny pump builds polyrotaxanes with precision: Artificial molecular pump gives precise control for materials design

Evanston, IL | Posted on June 12th, 2020

A necklace-like molecule made with rings threaded onto a polymer string, polyrotaxanes are notoriously difficult to construct. A new method from the laboratory of Nobel Prize-winning chemist Sir Fraser Stoddart uses two artificial molecular pumps to install rings onto each end of a polymer string. The tiny pumps allow researchers to control precisely how many rings pass onto the polymer.



“These polyrotaxanes have never before been made with such precision,” Stoddart said. “Without the ability to define accurately the polymer’s structure, you cannot fine-tune the material’s overall properties.”



The paper will be published on Friday, June 12 in the journal Science.



Stoddart is the Board of Trustees Professor in Northwestern’s Weinberg College of Arts and Sciences. Yunyan Qiu, a postdoctoral fellow in Stoddart’s lab, is the paper’s first author.



Researchers have studied polyrotaxanes for years, fascinated by their stretchy mechanical properties and potential of materials containing them to self-heal. But, until now, it was impossible to build these promising polymers with a precise number of rings.



“Traditionally, researchers mix the rings and polymers together, and they form inclusion complexes by noncovalent interactions,” Qiu said. “But you couldn’t know how many rings were threaded until you analyzed it later using nuclear magnetic resonance microscopy. People could roughly control the percentage of rings to some extent, but it was still an estimate.”



To overcome this challenge, the Northwestern researchers used an artificial molecular pump, which was developed in Stoddart’s laboratory in 2015. The first of its kind, the pump draws power from redox reactions, driving molecules from a low-energy state to a high-energy state.



To build polyrotaxanes, the pump employs repetitive redox reactions either chemically or electrochemically, in which a molecule gains or loses electrons. Initially, the pump — situated at both ends of the polymer string — and the rings are both positively charged and, thus, repel each other.



Upon injecting electrons, units in both pumps and rings change from dicationic to radical cationic states. Suddenly, the rings are attracted to the pump heads and thread onto both ends of the polymer string. Subsequent oxidation removes the electrons, restoring the positive charges. The rings try to escape but cannot due to the positively charged units at both end of the polymer string. Mild heating allows the ring to pass over a speed bump onto the polymer chain. The pump repeats this process to recruit rings in pairs onto the polymer string.



“We can recruit up to 10 rings onto the thread,” Qiu said. “But we believe we’re only limited by the length of the chosen polymer chain. If we double the length of the polymer, we can double the number of rings.”



The team also believes that, with this method, they could use many different types of polymers to create untraditional polyrotaxanes with unusual properties.



“I’m very excited about this research,” Stoddart said. “I put it up there with some of the best papers I’ve been associated with during the past 50 years.”



Stoddart is a member of the International Institute of Nanotechnology and the Robert H. Lurie Comprehensive Cancer Center of Northwestern University,



The study, “A precises polyrotaxane synthesizer,” was supported by the National Institutes of Health (grant number R01GM128037).

####

For more information, please click here

Contacts:
Amanda Morris


Fraser Stoddart

Copyright © Northwestern University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Drawing data in nanometer scale September 30th, 2022

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Synthesis of air-stable room-temperature van der Waals magnetic thin flakes September 30th, 2022

ACM Research Launches New Furnace Tool for Thermal Atomic Layer Deposition to Support Advanced Semiconductor Manufacturing Requirements: Ultra Fn A Furnace Tool Shipped to China-Based Foundry Customer September 30th, 2022

Videos/Movies

Solvent study solves solar cell durability puzzle: Rice-led project could make perovskite cells ready for prime time September 23rd, 2022

Scientists prepare for the world’s smallest race: Nanocar Race II March 18th, 2022

Visualizing the invisible: New fluorescent DNA label reveals nanoscopic cancer features March 4th, 2022

OCSiAl receives the green light for Luxembourg graphene nanotube facility project to power the next generation of electric vehicles in Europe March 4th, 2022

Possible Futures

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Synthesis of air-stable room-temperature van der Waals magnetic thin flakes September 30th, 2022

Layer Hall effect and hidden Berry curvature in antiferromagnetic insulators September 30th, 2022

ACM Research Launches New Furnace Tool for Thermal Atomic Layer Deposition to Support Advanced Semiconductor Manufacturing Requirements: Ultra Fn A Furnace Tool Shipped to China-Based Foundry Customer September 30th, 2022

Nanomedicine

Cleveland researchers reveal new strategy to prevent blood clots without increasing the risk of bleeding: University Hospitals and Case Western Reserve University findings may be especially impactful for cancer patients who experience blood clot complications September 30th, 2022

Georgia State researchers discover novel way to treat IBD with lipid nanoparticles August 26th, 2022

Engineers fabricate a chip-free, wireless electronic “skin”: The device senses and wirelessly transmits signals related to pulse, sweat, and ultraviolet exposure, without bulky chips or batteries August 19th, 2022

Immune system: First image of antigen-bound T-cell receptor at atomic resolution: Antigen binding does not trigger any structural changes in T-cell receptors – Signal transduction probably occurs after receptor enrichment August 19th, 2022

Discoveries

Surface microstructures of lunar soil returned by Chang’e-5 mission reveal an intermediate stage in space weathering process September 30th, 2022

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Synthesis of air-stable room-temperature van der Waals magnetic thin flakes September 30th, 2022

Layer Hall effect and hidden Berry curvature in antiferromagnetic insulators September 30th, 2022

Announcements

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Synthesis of air-stable room-temperature van der Waals magnetic thin flakes September 30th, 2022

Layer Hall effect and hidden Berry curvature in antiferromagnetic insulators September 30th, 2022

ACM Research Launches New Furnace Tool for Thermal Atomic Layer Deposition to Support Advanced Semiconductor Manufacturing Requirements: Ultra Fn A Furnace Tool Shipped to China-Based Foundry Customer September 30th, 2022

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Conformal optical black hole for cavity September 30th, 2022

Cleveland researchers reveal new strategy to prevent blood clots without increasing the risk of bleeding: University Hospitals and Case Western Reserve University findings may be especially impactful for cancer patients who experience blood clot complications September 30th, 2022

Ultrasmall VN/Co heterostructure with optimized N active sites anchored in N-doped graphitic nanocarbons for boosting hydrogen evolution September 30th, 2022

Layer Hall effect and hidden Berry curvature in antiferromagnetic insulators September 30th, 2022

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

Conformal optical black hole for cavity September 30th, 2022

Researchers unveil mystery inside Li- o2 batteries September 30th, 2022

Modulating MoSe2 functional plane via doping-defect engineering strategy to develop conductive and electrocatalytic mediators in Li-S batteries September 23rd, 2022

Heat-resistant nanophotonic material could help turn heat into electricity: The key to beating the heat is degrading the materials in advance September 23rd, 2022

Nanobiotechnology

Cleveland researchers reveal new strategy to prevent blood clots without increasing the risk of bleeding: University Hospitals and Case Western Reserve University findings may be especially impactful for cancer patients who experience blood clot complications September 30th, 2022

Georgia State researchers discover novel way to treat IBD with lipid nanoparticles August 26th, 2022

Rice team eyes cells for sophisticated data storage: National Science Foundation backs effort to turn living cells into equivalent of computer RAM August 19th, 2022

Engineers fabricate a chip-free, wireless electronic “skin”: The device senses and wirelessly transmits signals related to pulse, sweat, and ultraviolet exposure, without bulky chips or batteries August 19th, 2022

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project