Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

’Smart’ Bio-nanotubes Developed; May Help in Drug Delivery

04.08.2005


"Smart" bionanotubes. Lipid protein nanotubes made of microtuble protein (made of tubulin protein subunits shown as red-blue-yellow-green objects) that is coated by a lipid bilayer (drawn with yellow tails and green and white spherical heads) which in turn is coated by tubulin protein rings or spirals. By controlling the relative amount of lipid and protein it is possible to switch between two states of nanotubes with either open ends (shown in the center) or closed ends with lipid caps (shown on the left), a process which forms the basis for controlled chemical and drug encapsulation and release. A top view of the nanotubes and a magnified region is shown on the right. The image was created by Peter Allen.


Materials scientists working with biologists at the University of California, Santa Barbara have developed "smart" bio-nanotubes — with open or closed ends — that could be developed for drug or gene delivery applications.

The nanotubes are "smart" because in the future they could be designed to encapsulate and then open up to deliver a drug or gene in a particular location in the body. The scientists found that by manipulating the electrical charges of lipid bilayer membranes and microtubules from cells, they could create open or closed bio-nanotubes, or nanoscale capsules. The news is reported in an article to be published in the August 9 issue of the Proceedings of the National Academy of Sciences. It is currently available on-line in the PNAS Early Edition.

The findings resulted from a collaboration between the laboratories of Cyrus R. Safinya, professor of materials and physics and faculty member of the Molecular, Cellular, and Developmental Biology Department, and Leslie Wilson, professor of biochemistry in the Department of Molecular, Cellular and Developmental Biology and the Biomolecular Science and Engineering Program. The first author of the article is Uri Raviv, a post-doctoral researcher in Safinya’s lab and a fellow of the International Human Frontier Science Program Organization. The other co-authors are Daniel J. Needleman, formerly Safinya’s graduate student who is now a postdoctoral fellow at Harvard Medical School; Youli Li, researcher in the Materials Research Laboratory; and Herbert P. Miller, staff research associate in the Department of Molecular, Cellular and Developmental Biology.



The scientists used microtubules purified from the brain tissue of a cow for their experiments. Microtubules are nanometer-scale hollow cylinders derived from the cell cytoskeleton. In an organism, microtubules and their assembled structures are critical components in a broad range of cell functions –– from providing tracks for the transport of cargo to forming the spindle structure in cell division. Their functions include the transport of neurotransmitter precursors in neurons.

"In our paper, we report on a new paradigm for lipid self-assembly leading to nanotubule formation in mixed charged systems," said Safinya.

Raviv explained, "We looked at the interaction between microtubules –– negatively charged nanometer-scale hollow cylinders derived from cell cytoskeleton –– and cationic (positively charged) lipid membranes. We discovered that, under the right conditions, spontaneous lipid protein nanotubules will form."

They used the example of water beading up or coating a car, depending on whether or not the car has been waxed. Likewise the lipid will either bead up on the surface of the microtubule, or flatten out and coat the whole cylindrical surface of the microtubule, depending on the charge.

The new type of self-assembly arises because of an extreme mismatch between the charge densities of microtubules and cationic lipid, explained Raviv. "This is a novel finding in equilibrium self-assembly," he said.

The nanotubule consisting of a three-layer wall appears to be the way the system compensates for this charge density mismatch, according to the authors.

"Very interestingly, we have found that controlling the degree of overcharging of the lipid-protein nanotube enables us to switch between two states of nanotubes," said Safinya. "With either open ends (negative overcharged), or closed ends (positive overcharged with lipid caps), these nanotubes could form the basis for controlled chemical and drug encapsulation and release."

The inner space of the nanotube in these experiments measures about 16 nanometers in diameter. (A nanometer is a billionth of a meter.) The whole capsule is about 40 nanometers in diameter.

Raviv explained that the chemotherapy drug Taxol is one type of drug that could be delivered with these nanotubes. The scientists are already using Taxol in their experiments to stabilize and lengthen the lipid-protein nanotubes.

The work was performed using state-of-the-art synchrotron x-ray scattering techniques at the Stanford Synchrotron Radiation Laboratory (SSRL), combined with sophisticated electron microscopy at UCSB. The work was funded by the National Institutes of Health and the National Science Foundation. SSRL is supported by the U.S. Department of Energy. Raviv was also supported by the International Human Frontier Science Program and the European Molecular Biology Organization.

Gail Gallessich | EurekAlert!
Further information:
http://www.pnas.org/cgi/content/abstract/0502183102v1
http://www.ucsb.edu

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>