Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Purdue researchers align nanotubes to improve artificial joints

24.11.2004


Researchers at Purdue University have shown that artificial joints might be improved by making the implants out of tiny carbon tubes and filaments that are all aligned in the same direction, mimicking the alignment of collagen fibers and natural ceramic crystals in real bones.

The researchers already have shown in a series of experiments that bone cells in Petri dishes attach better to materials that possess smaller surface bumps than are found on conventional materials used to make artificial joints. The smaller features also stimulate the growth of more new bone tissue, which is critical for the proper attachment of artificial joints once they are implanted. Now, the Purdue researchers have shown even more enhanced cell adhesion and growth when so-called "nanotubes" and nanofibers are aligned in the same direction. This orientation is similar to the way collagen and natural ceramic crystals, called hydroxyapatite, are aligned in bone, said Thomas Webster, an assistant professor of biomedical engineering at Purdue.

Findings were presented at two recent scientific conferences in research papers written by Webster; Purdue physics doctoral student Dongwoo Khang; and three researchers from the Seoul National University in South Korea, physics doctoral students Minbaek Lee and Sun Namkung, and physics professor Seunghun Hong. Previous experiments in the Purdue lab have shown that about one-third more bone-forming cells, or osteoblasts, attach to carbon nanotubes that possess surface bumps about as wide as 100 nanometers, or billionths of a meter. Fewer bone cells stick to conventional titanium, which has surface features on the scale of microns, or millionths of a meter.



The nanometer-scale bumps mimic surface features of proteins and natural tissues, prompting cells to stick better and promoting the growth of new cells, Webster said. The findings also suggest that using such nanometer-scale materials might cause less of a rejection response from the body. Rejection eventually weakens the attachment of implants and causes them to become loose and painful, requiring replacement surgery. Aligning the nanotubes to further mimic natural bone also might provide more strength, Webster said.

Researchers used two methods to align the tiny nanotube structures, which have diameters of about 60 nanometers. One nanometer is roughly the length of 10 hydrogen atoms strung together. A human hair is more than 1,000 times wider than the nanotubes used in the study. In one method, researchers mixed the nanotubes in a polymer, or plastic, and passed an electric current through the mixture. Because nanotubes have the same natural electrical charge, they react to electricity by orienting themselves in the same direction. Once the polymer solidifies, the nanotubes are fixed in the aligned position.

The research team also aligned the nanotubes using another method in which the nanotubes are poured into grids of tiny channels. Because the channels are so narrow, the tubes can only fit lengthwise, causing them to become aligned. The grids can then be removed, leaving behind the aligned nanotubes.

The researchers then added the aligned nanotubes to a suspension of dyed bone cells in a small container. After one hour, the nanotubes were washed and a microscope was used to count how many of the dyed osteoblasts adhered to the material. Out of 3,000 bone cells per square centimeter of surface area, about 80 percent specifically stuck to and aligned with the carbon nanotubes – or about twice as many as those that adhered to non-aligned nanotubes in previous work. "So, in a very short period of time, one hour, we’re already seeing a big improvement in how well the cells stick to the nanotubes," Webster said.

Future research may focus on combining the two methods for aligning nanotubes. Using the grid technique creates a greater number of aligned nanotubes on the surface, which helps to increase bone-cell adhesion and alignment, whereas using electricity could better stimulate the growth of new bone tissue.

The research has been funded by the National Science Foundation though the NSF Nanoscale Exploratory Research program.

Findings were presented in October during the Biomedical Engineering Society’s annual meeting and a conference by the Society for Biomaterials entitled Biomaterials in Regenerative Medicine: The Advent of Combination Products. Both meetings were in Philadelphia.
Writer: Emil Venere, (765) 494-4709, venere@purdue.edu

Source: Thomas Webster, (765) 496-7516, twebster@purdue.edu

Purdue News Service: (765) 494-2096; purduenews@purdue.edu

Thomas Webster | EurekAlert!
Further information:
http://www.purdue.edu

More articles from Health and Medicine:

nachricht Researchers release the brakes on the immune system
18.10.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht Norovirus evades immune system by hiding out in rare gut cells
12.10.2017 | University of Pennsylvania School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>