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 Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously
17.01.2017 | Sonderforschungsbereich 668

nachricht Manchester scientists tie the tightest knot ever achieved
13.01.2017 | University of Manchester

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>