Navigation Links
Why carbon nanotubes spell trouble for cells
Date:9/18/2011

PROVIDENCE, R.I. [Brown University] It's been long known that asbestos spells trouble for human cells. Scientists have seen cells stabbed with spiky, long asbestos fibers, and the image is gory: Part of the fiber is protruding from the cell, like a quivering arrow that's found its mark.

But scientists had been unable to understand why cells would be interested in asbestos fibers and other materials at the nanoscale that are too long to be fully ingested. Now a group of researchers at Brown University explains what happens. Through molecular simulations and experiments, the team reports in Nature Nanotechnology that certain nanomaterials, such as carbon nanotubes, enter cells tip-first and almost always at a 90-degree angle. The orientation ends up fooling the cell; by taking in the rounded tip first, the cell mistakes the particle for a sphere, rather than a long cylinder. By the time the cell realizes the material is too long to be fully ingested, it's too late.

"It's as if we would eat a lollipop that's longer than us," said Huajian Gao, professor of engineering at Brown and the paper's corresponding author. "It would get stuck."

The research is important because nanomaterials like carbon nanotubes have promise in medicine, such as acting as vehicles to transport drugs to specific cells or to specific locations in the human body. If scientists can fully understand how nanomaterials interact with cells, then they can conceivably design products that help cells rather than harm them.

"If we can fully understand (nanomaterial-cell dynamics), we can make other tubes that can control how cells interact with nanomaterials and not be toxic," Gao said. "We ultimately want to stop the attraction between the nanotip and the cell."

Like asbestos fibers, commercially available carbon nanotubes and gold nanowires have rounded tips that often range from 10 to 100 nanometers in diameter. Size is important here; the diameter fits well within the cell's parameters for what it can handle. Brushing up against the nanotube, special proteins called receptors on the cell spring into action, clustering and bending the membrane wall to wrap the cell around the nanotube tip in a sequence that the authors call "tip recognition." As this occurs, the nanotube is tipped to a 90-degree angle, which reduces the amount of energy needed for the cell to engulf the particle.

Once the engulfing endocytosis begins, there is no turning back. Within minutes, the cell senses it can't fully engulf the nanostructure and essentially dials 911. "At this stage, it's too late," Gao said. "It's in trouble and calls for help, triggering an immune response that can cause repeated inflammation."

The team hypothesized the interaction using coarse-grained molecular dynamic simulations and capped multiwalled carbon nanotubes. In experiments involving nanotubes and gold nanowires and mouse liver cells and human mesothelial cells, the nanomaterials entered the cells tip-first and at a 90-degree angle about 90 percent of the time, the researchers report.

"We thought the tube was going to lie on the cell membrane to obtain more binding sites. However, our simulations revealed the tube steadily rotating to a high-entry degree, with its tip being fully wrapped," said Xinghua Shi, first author on the paper who earned his doctorate at Brown and is at the Chinese Academy of Sciences in Beijing. "It is counter-intuitive and is mainly due to the bending energy release as the membrane is wrapping the tube."

The team would like to study whether nanotubes without rounded tips or less rigid nanomaterials such as nanoribbons pose the same dilemma for cells.

"Interestingly, if the rounded tip of a carbon nanotube is cut off (meaning the tube is open and hollow), the tube lies on the cell membrane, instead of entering the cell at a high-degree-angle," Shi said.


'/>"/>

Contact: Richard Lewis
Richard_Lewis@brown.edu
401-863-3766
Brown University
Source:Eurekalert  

Related biology news :

1. Carbon nanoparticles break barriers -- and that may not be good
2. NJIT professor working with graphene, carbon nanotubes to receive honor
3. Up from the depths: How bacteria capture carbon in the twilight zone
4. Irrigations impacts on global carbon uptake
5. Increased tropical forest growth could release carbon from the soil
6. To avoid carbon debt, CRP beats fields of corn, soybeans
7. Carbon hitches a ride from field to market
8. USDA scientists study effects of rising carbon dioxide on rangelands
9. Organic carbon suggests Swedish lakes were less acidified
10. Scientists report dramatic carbon loss from massive Arctic wildfire
11. Northwest Forest Plan has unintended benefit - carbon sequestration
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Why carbon nanotubes spell trouble for cells
(Date:3/22/2016)... PUNE, India , March 22, 2016 ... new market research report "Electronic Sensors Market for ... Fingerprint, Proximity, & Others), Application (Communication & ... and Geography - Global Forecast to 2022", ... consumer industry is expected to reach USD ...
(Date:3/21/2016)... Massachusetts , March 22, 2016 ... facial recognition with passcodes for superior security   ... ), a leading provider of secure digital communications services, ... their biometric technology and offer enterprise customers, particularly those ... secure facial recognition and voice authentication within a mobile ...
(Date:3/17/2016)... ABI Research, the leader in transformative ... market will reach more than $30 billion by ... Consumer electronics, particularly smartphones, continue to boost the ... reach two billion shipments by 2021 at a ... Research Analyst at ABI Research. "Surveillance is also ...
Breaking Biology News(10 mins):
(Date:5/3/2016)... ... ... In a list published by the Boston Business Journal, iLab Solutions ... percentage of the state's 615,000+ small businesses. The list examined companies based in the ... to 2015. , As this award comes on the heels of iLab’s ...
(Date:5/3/2016)... ... 03, 2016 , ... Flagship Biosciences, the leader in ... Board of Directors. Dr. Gillett recently retired from Charles River Laboratories (CRL), where, ... Scientific Officer. A board-certified veterinary pathologist, Dr. Gillett joined Charles River in 1999 ...
(Date:5/3/2016)... ... May 03, 2016 , ... ... the sensor and data driven conferences, will take place on June 7-8, 2016, at the New ... Vidya Raman-Tangella on incorporating technology -- including AR/VR, machine learning, apps, robotics and AI ...
(Date:5/3/2016)... , May 3, 2016  Dr. Thomas ... surgeon in The Woodlands, Texas , ... 24 percent of treated fat cells in just 25-minutes, ... Close to 90 percent of Americans report feeling bothered ... Nonsurgical fat reduction procedures are a growing industry. This ...
Breaking Biology Technology: