Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Problem: Implant Infection. Solution: Nanotech Surfaces

10.07.2006
For the first time, engineers have created surfaces for orthopaedic implants that reduce the presence of bacteria. The research, led by Brown University engineer Thomas Webster, may lead to a new class of artificial joints. That is a big market: More than 750,000 Americans undergo knee, hip or shoulder replacement surgery each year.

Orthopaedic implants help millions of Americans stay active. But these medical devices are prone to infection, forcing patients back to surgery for repair or replacement. Now, for the first time, a team of engineers has shown that zinc or titanium oxide nanosurfaces can reduce the presence of bacteria, a technique that can be applied to implants to reduce the number of these costly and debilitating infections.


Microcraters and nanosurfaces

A rougher terrain engineered on the nanoscale (top) promoted bone adhesion and inhibited bacterial growth much better than the smoother surface engineered on the microscale (bottom). Units are in microns. Image: T.J. Webster

Thomas Webster, an associate professor of engineering at Brown, led the research. Results are published in the Journal of Biomedical Materials Research.

“We’ve found a method of coating implants that discourages bacteria growth,” Webster said, “and it does so significantly. The hope is that this technique will lead to safer, longer-lasting implants.”

According to the American Academy of Orthopaedic Surgeons, 766,100 Americans underwent surgery for hip, knee and shoulder replacements in 2002. During typical procedures, surgeons remove an arthritic or damaged joint and replace it with an artificial one. In about 1 to 2 percent of cases, the implant gets infected. The most common culprit: Staphylococcus epidermidis. Found on skin or in mucous membrane, S. epidermidis can enter a surgical wound and adhere to an implant. The bacteria multiply, causing a slimy layer, or biofilm, to form around the implant. The slime is tough stuff, acting as a physical and chemical barrier that resists antibiotics. The result is additional surgery to clean the implant or replace it outright.

Webster, along with former Purdue University colleagues Gabriel Colon and Brian Ward, knew that abrading or coating implants to produce microscopic bumps, which create a sand-papery surface, aid in bone growth. This helps anchor the implant in the body and extends its life. Some artificial joints now sport these microstructured surfaces.

But the team wondered if smaller peaks and craters – ones that measure on the nanometer scale – would work even better. And how would bacteria react? So they experimented.

The engineers chose zinc and titanium oxides as their materials. Zinc oxide is a well-known antimicrobial agent. Titanium oxide, strong and light, is a commonly used in implants. Engineers took nanoparticles of these ceramics and pressed them into dime-sized discs. They took microparticles of these same materials and made more discs. Discs with nanostructured surfaces had bumps that measured only .023 microns in diameter. Discs with microstructured surfaces had bumps that measured about 5 microns in diameter. Under a microscope, the surface differences are extreme; the nanostructured discs look like saw-toothed mountains, the microstructured discs look like smooth plateaus.

The engineers put S. epidermidis on the discs and waited an hour. Then they counted the bacteria. The results were dramatic. Microstructured zinc oxide discs were host to 1,000 times more bacteria than the nanostructured zinc oxide discs. Similar, but less striking, results were duplicated on titanium oxide discs.

The engineers conducted similar experiments with bone-forming cells and found that twice as many of these cells grew and formed bone on nanostructured discs. Other indicators of healthy bone growth, such as collagen synthesis, were also stronger with nanostructured discs.

“Surface area seems to be key,” Webster said. “With the nanostructured surfaces we created, surface area increased by 25 to 35 percent. We think that this additional area, along with the unique surface energetics of these nanomaterials, gave bone-forming cells more places to adhere. But with bacteria, increased surface area may work the other way, exposing the bugs to more of the germ-fighting properties of the zinc oxide.”

The National Science Foundation funded the work.

Wendy Lawton | EurekAlert!
Further information:
http://www.brown.edu

More articles from Materials Sciences:

nachricht Using a simple, scalable method, a material that can be used as a sensor is developed
15.02.2017 | University of the Basque Country

nachricht New mechanical metamaterials can block symmetry of motion, findings suggest
14.02.2017 | University of Texas at Austin

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>