Nanotechnology Now







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

Self-assembling biomaterial forms nanostructure templates for human tissue formation April 27th, 2015

International research team discovers new mechanism behind malaria progression: Findings provide a new avenue for research in malaria treatment April 27th, 2015

More is less in novel electronic material: Adding electrons actually shrinks the system April 27th, 2015

Sensor Designed in Iran Able to Remove Formaldehyde Gas from Environment April 27th, 2015

Govt.-Legislation/Regulation/Funding/Policy

International research team discovers new mechanism behind malaria progression: Findings provide a new avenue for research in malaria treatment April 27th, 2015

More is less in novel electronic material: Adding electrons actually shrinks the system April 27th, 2015

Two-dimensional semiconductor comes clean April 27th, 2015

Scientists join forces to reveal the mass and shape of single molecules April 27th, 2015

Possible Futures

Printing Silicon on Paper, with Lasers April 21st, 2015

A glass fiber that brings light to a standstill: By coupling photons to atoms, light in a glass fiber can be slowed down to the speed of an express train; for a short while it can even be brought to a complete stop April 9th, 2015

Nanotechnology in Medical Devices Market is expected to reach $8.5 Billion by 2019 March 25th, 2015

Nanotechnology Enabled Drug Delivery to Influence Future Diagnosis and Treatments of Diseases March 21st, 2015

Self Assembly

Scientists Use Nanoscale Building Blocks and DNA 'Glue' to Shape 3D Superlattices: New approach to designing ordered composite materials for possible energy applications April 23rd, 2015

Advances in molecular electronics: Lights on -- molecule on: Researchers from Dresden and Konstanz succeed in light-controlled molecule switching April 20th, 2015

Carnegie Mellon chemists create tiny gold nanoparticles that reflect nature's patterns April 9th, 2015

DWI scientists program the lifetime of self-assembled nanostructures April 9th, 2015

Nanomedicine

Self-assembling biomaterial forms nanostructure templates for human tissue formation April 27th, 2015

International research team discovers new mechanism behind malaria progression: Findings provide a new avenue for research in malaria treatment April 27th, 2015

Scientists join forces to reveal the mass and shape of single molecules April 27th, 2015

Northwestern scientists develop first liquid nanolaser: Technology could lead to new way of doing 'lab on a chip' medical diagnostics April 25th, 2015

Announcements

Scientists join forces to reveal the mass and shape of single molecules April 27th, 2015

The 16th Trends in Nanotechnology International Conference (TNT 2015) unveils 25 Keynote Speakers: Call for abstracts open April 27th, 2015

Graphenea celebrates fifth anniversary April 27th, 2015

Sensor Designed in Iran Able to Remove Formaldehyde Gas from Environment April 27th, 2015

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

Phonons, arise! Small electric voltage alters conductivity in key materials April 22nd, 2015

New class of 3D-printed aerogels improve energy storage April 22nd, 2015

'Holey' graphene for energy storage: Charged holes in graphene increase energy storage capacity April 22nd, 2015

‘Oxford Instruments Young Nanoscientist India Award 2015’ to Prof. Arindam Ghosh April 20th, 2015

Nanobiotechnology

Self-assembling biomaterial forms nanostructure templates for human tissue formation April 27th, 2015

Scientists join forces to reveal the mass and shape of single molecules April 27th, 2015

A silver lining: UCSB researchers cradle silver nanoclusters inside synthetic DNA to create a programmed, tunable fluorescent array April 23rd, 2015

Scientists Use Nanoscale Building Blocks and DNA 'Glue' to Shape 3D Superlattices: New approach to designing ordered composite materials for possible energy applications April 23rd, 2015

Alliances/Partnerships/Distributorships

How can you see an atom? (video) April 10th, 2015

FibeRio and VF Corporation Form Strategic Partnership to Lead the Apparel and Footwear Markets in Nanofiber Technology April 8th, 2015

UK National Graphene Institute Selects Bruker as Official Partner: World-Leading Graphene Research Facility Purchases Multiple Bruker AFMs April 7th, 2015

NXP and GLOBALFOUNDRIES Announce Production of 40nm Embedded Non-Volatile Memory Technology: Co-developed technology to leverage GLOBALFOUNDRIES 40nm process technology platform March 24th, 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