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

onic Present breakthrough in CMOS-based Transceivers for mm-Wave Radar Systems March 1st, 2015

Graphene Shows Promise In Eradication Of Stem Cancer Cells March 1st, 2015

Novel Method to Determine Optical Purity of Drug Components March 1st, 2015

Scientific breakthrough in rechargeable batteries: Researchers from Singapore and Québec Team Up to Develop Next-Generation Materials to Power Electronic Devices and Electric Vehicles February 28th, 2015

Govt.-Legislation/Regulation/Funding/Policy

First detailed microscopy evidence of bacteria at the lower size limit of life: Berkeley Lab research provides comprehensive description of ultra-small bacteria February 28th, 2015

Warming up the world of superconductors: Clusters of aluminum metal atoms become superconductive at surprisingly high temperatures February 25th, 2015

SUNY Poly CNSE Researchers and Corporate Partners to Present Forty Papers at Globally Recognized Lithography Conference: SUNY Poly CNSE Research Group Awarded Both ‘Best Research Paper’ and ‘Best Research Poster’ at SPIE Advanced Lithography 2015 forum February 25th, 2015

European roadmap for graphene science and technology published February 25th, 2015

Possible Futures

European roadmap for graphene science and technology published February 25th, 2015

Quantum research past, present and future for discussion at AAAS February 16th, 2015

World’s first compact rotary 3D printer-cum-scanner unveiled at AAAS by NTU Singapore start-up: With production funded by crowdsourcing, the first unit will be delivered to the United States in March February 16th, 2015

Nanotechnology Electric Vehicle (EV) Market Analysis Report 2015: According to Radiant Insights, Inc February 13th, 2015

Self Assembly

Nanotubes self-organize and wiggle: Evolution of a nonequilibrium system demonstrates MEPP February 10th, 2015

Engineering self-assembling amyloid fibers January 26th, 2015

Revealed: How bacteria drill into our cells and kill them December 2nd, 2014

Live Images from the Nano-cosmos: Researchers watch layers of football molecules grow November 5th, 2014

Nanomedicine

Graphene Shows Promise In Eradication Of Stem Cancer Cells March 1st, 2015

Novel Method to Determine Optical Purity of Drug Components March 1st, 2015

Untangling DNA with a droplet of water, a pipet and a polymer: With the 'rolling droplet technique,' a DNA-injected water droplet rolls like a ball over a platelet, sticking the DNA to the plate surface February 27th, 2015

Graphene shows potential as novel anti-cancer therapeutic strategy: University of Manchester scientists have used graphene to target and neutralise cancer stem cells while not harming other cells February 26th, 2015

Announcements

onic Present breakthrough in CMOS-based Transceivers for mm-Wave Radar Systems March 1st, 2015

Graphene Shows Promise In Eradication Of Stem Cancer Cells March 1st, 2015

Novel Method to Determine Optical Purity of Drug Components March 1st, 2015

Scientific breakthrough in rechargeable batteries: Researchers from Singapore and Québec Team Up to Develop Next-Generation Materials to Power Electronic Devices and Electric Vehicles February 28th, 2015

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

Scientific breakthrough in rechargeable batteries: Researchers from Singapore and Québec Team Up to Develop Next-Generation Materials to Power Electronic Devices and Electric Vehicles February 28th, 2015

In quest for better lithium-air batteries, chemists boost carbon's stability: Nanoparticle coatings improve stability, cyclability of '3DOm' carbon February 25th, 2015

Dendrite eraser: New electrolyte rids batteries of short-circuiting fibers: Solution enables a battery with both high efficiency & current density February 24th, 2015

New Paper-like Material Could Boost Electric Vehicle Batteries: Researchers create silicon nanofibers 100 times thinner than human hair for potential applications in batteries for electric cars and personal electronics February 20th, 2015

Nanobiotechnology

Untangling DNA with a droplet of water, a pipet and a polymer: With the 'rolling droplet technique,' a DNA-injected water droplet rolls like a ball over a platelet, sticking the DNA to the plate surface February 27th, 2015

Bacteria network for food: Bacteria connect to each other and exchange nutrients February 23rd, 2015

Building tailor-made DNA nanotubes step by step: New, block-by-block assembly method could pave way for applications in opto-electronics, drug delivery February 23rd, 2015

Better batteries inspired by lowly snail shells: Biological molecules can latch onto nanoscale components and lock them into position to make high performing Li-ion battery electrodes, according to new research presented at the 59th annual meeting of the Biophysical Society February 12th, 2015

Alliances/Partnerships/Distributorships

onic Present breakthrough in CMOS-based Transceivers for mm-Wave Radar Systems March 1st, 2015

National Space Society and Space Frontier Foundation announce the formation of the Alliance for Space Development February 25th, 2015

European roadmap for graphene science and technology published February 25th, 2015

Silicon Catalyst Announces Partnership With imec to Support Semiconductor Start-Ups February 23rd, 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







© Copyright 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE