Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Penn Team Uses Self-Assembly to Make Tiny Particles With Patches of Charge

Dennis Discher
Dennis Discher

Abstract:
Physicists, chemists and engineers at the University of Pennsylvania have demonstrated a novel method for the controlled formation of patchy particles, using charged, self-assembling molecules that may one day serve as drug-delivery vehicles to combat disease and perhaps be used in small batteries that store and release charge.

Penn Team Uses Self-Assembly to Make Tiny Particles With Patches of Charge

Philadelphia, PA | Posted on October 20th, 2009

Researchers demonstrated that the positive electrical charges of calcium ions just like the calcium in teeth and bone can form bridges between negatively charged polymers that would normally repel each other. The polymers, similar to the lipids that make the membranes surrounding living cells, have both a water-loving part linked to a water-repelling part. On the surfaces of these cell-sized polymer sacks, the calcium ions create calcium-rich islands or patches on top of negatively-charged polymer. Copper ions also work, and the patches can be made to coalesce and cover half of the particle. This polarized structure is the basic arrangement needed to set up, for example, the two electrodes of a microscopic battery. They could also one day be functionalized into docking sites to enhance targeted delivery of drug-laden particles to cells.

While the concept seems simple, that opposite charges attract, the creation and control of patches on one small particle has been a challenge. Scientists like Dennis E. Discher, principal investigator of the study and a professor of chemical and biomolecular engineering at Penn, are designing materials at the nanoscale because future technologies will increasingly rely on structures with distinct and controlled surfaces. Physicians, for example, will improve medical therapies by wrapping drugs within the bioengineered polymer sacks, or by creating tiny biomedical sensors. Green energy production and storage will also require structures with scales no longer measured by inches, but by micrometers and nanometers.

The collaboration involved faculty from Penn's School of Engineering and Applied Science, the School of Medicine and the School of Arts and Sciences, and demonstrated, more specifically, the selective binding of multivalent cationic ligands within a mixture of both polyanionic and non-ionic amphiphiles that all co-assemble into either patchy sacks called vesicles or molecular cylinders called worm-like micelles. Similar principles have been explored with lipids in the field of membrane biophysics because calcium is key to many cellular signaling processes. The trick is that the energy of attraction of opposite charges must be adjusted to find a balance with the large entropic price for localization into spots. If the attractions are too large, the ions precipitate, just like adding too much sugar to tea or coffee.

Using a little bit of acid or a little of base, the patchy polymer vesicles and cylinders can be made with tunable sizes, shapes and spacings. Assemblies with single large patches are called Janus assemblies, named after the double-faced Roman god, and the assemblies generally last for years because these are polymer-based structures.

"The key advance we present in this study is the restricted range of conditions that are required for self assembly in these solutions," Discher said. "We show that, in addition to polymers, negatively-charged cell lipids which are involved in all sorts of cell-signaling processes like cell motion and cancer mechanics, can also make domains or islands with calcium."

The work is representative of national research into soft matter, materials constructed from organic molecules like lipids, peptides and nucleic acids. A properly designed molecular system can produce a wide array of nanostructures and microstructures, emulating and extending what is found in nature.

The study, published as the cover article in the journal Nature Materials, was conducted by members of Penn's Laboratory for Research on the Structure of Matter, including David A. Christian, Aiwei Tian and Karthikan Rajagopal of the Department of Chemical and Biomolecular Engineering; Wouter G. Ellenbroek and Andrea J. Liu of the Department of Physics and Astronomy; Ilya Levental of the Bioengineering Graduate Group; Paul A. Janmey of the Department of Physiology; Tobias Baumgart of the Department of Chemistry; and Discher.

The study was funded by the National Science Foundation, the National Institutes of Health, the National Science Foundation and the Department of Defense.

####

About University of Pennsylvania
Today Penn is home to a diverse undergraduate student body of nearly 10,000, hailing from every state in the union and all around the globe. Admissions are among the most selective in the country and Penn consistently ranks among the top 10 universities in the annual U.S. News & World Report survey. Another 10,000 students are enrolled in Penn's 12 graduate and professional schools, which are national leaders in their fields. The Wharton School is consistently one of the nation's top three business schools. The School of Nursing is one of the two best in the U.S. The School of Arts and Sciences, Graduate School of Education, Law School, School of Medicine, School of Veterinary Medicine, and Annenberg School for Communication all rank among the top 10 schools in their fields.

For more information, please click here

Contacts:
Jordan Reese
215-573-6604

Copyright © University of Pennsylvania

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

Making nanowires from protein and DNA September 3rd, 2015

Making fuel from light: Argonne research sheds light on photosynthesis and creation of solar fuel September 3rd, 2015

Reversible Writing with Light: Self-assembling nanoparticles take their cues from their surroundings September 3rd, 2015

Phagraphene, a 'relative' of graphene, discovered September 2nd, 2015

Govt.-Legislation/Regulation/Funding/Policy

Making nanowires from protein and DNA September 3rd, 2015

Making fuel from light: Argonne research sheds light on photosynthesis and creation of solar fuel September 3rd, 2015

Reversible Writing with Light: Self-assembling nanoparticles take their cues from their surroundings September 3rd, 2015

Silk bio-ink could help advance tissue engineering with 3-D printers September 2nd, 2015

Possible Futures

Silk bio-ink could help advance tissue engineering with 3-D printers September 2nd, 2015

Sediment dwelling creatures at risk from nanoparticles in common household products August 13th, 2015

Harris & Harris Group Reports Financial Statements as of June 30, 2015, and Announces a Stock Repurchase Program August 10th, 2015

Molecular trick alters rules of attraction for non-magnetic metals August 5th, 2015

Self Assembly

Making nanowires from protein and DNA September 3rd, 2015

Reversible Writing with Light: Self-assembling nanoparticles take their cues from their surroundings September 3rd, 2015

Using DNA origami to build nanodevices of the future September 1st, 2015

Louisiana Tech University researchers discover synthesis of a new nanomaterial: Interdisciplinary team creates biocomposite for first time using physiological conditions August 24th, 2015

Nanomedicine

Making nanowires from protein and DNA September 3rd, 2015

Reversible Writing with Light: Self-assembling nanoparticles take their cues from their surroundings September 3rd, 2015

Silk bio-ink could help advance tissue engineering with 3-D printers September 2nd, 2015

Using DNA origami to build nanodevices of the future September 1st, 2015

Announcements

Making nanowires from protein and DNA September 3rd, 2015

Making fuel from light: Argonne research sheds light on photosynthesis and creation of solar fuel September 3rd, 2015

Reversible Writing with Light: Self-assembling nanoparticles take their cues from their surroundings September 3rd, 2015

A marine creature's magic trick explained: Crystal structures on the sea sapphire's back appear differently depending on the angle of reflection September 2nd, 2015

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

Artificial leaf harnesses sunlight for efficient fuel production August 30th, 2015

CWRU researchers efficiently charge a lithium-ion battery with solar cell: Coupling with perovskite solar cell holds potential for cleaner cars and more August 27th, 2015

'Diamonds from the sky' approach turns CO2 into valuable products August 19th, 2015

Drexel engineers 'sandwich' atomic layers to make new materials for energy storage August 15th, 2015

Nanobiotechnology

Making nanowires from protein and DNA September 3rd, 2015

A marine creature's magic trick explained: Crystal structures on the sea sapphire's back appear differently depending on the angle of reflection September 2nd, 2015

Using DNA origami to build nanodevices of the future September 1st, 2015

Researchers use DNA 'clews' to shuttle CRISPR-Cas9 gene-editing tool into cells August 30th, 2015

Alliances/Trade associations/Partnerships/Distributorships

TCL and QD Vision Demonstrate the Future of Wide Color Gamut Television at IFA: Color IQ Based Display is the First Commercially-Branded Television to Present Over 90% of ITU Rec. 2020 Color Gamut September 2nd, 2015

National Space Society Welcomes Janet Ivey As New NSS Governor: Janet Ivey of Janet's Planet is NOW IN ORBIT as a member of the Board of Governors of the National Space Society August 27th, 2015

National Space Society Welcomes Geoff Notkin As New NSS Governor August 26th, 2015

XEI Scientific appoints EM Resolutions as Distributor for the UK & Irish markets August 11th, 2015

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic