Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Insect wings inspire antibacterial surfaces for corneal transplants, other medical devices

15.03.2016

Someday, cicadas and dragonflies might save your sight. The key to this power lies in their wings, which are coated with a forest of tiny pointed pillars that impale and kill bacterial cells unlucky enough to land on them. Now, scientists report they have replicated these antibacterial nanopillars on synthetic polymers that are being developed to restore vision.

The researchers present their work today at the 251st National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world's largest scientific society, is holding the meeting here through Thursday. It features more than 12,500 presentations on a wide range of science topics.


The center of an artificial cornea (on glove) is coated with tiny pillars that impale and kill bacterial cells (inset).

Credit: Jonathan Pegan (cornea) and Mary Nora Dickson (inset)

"Other research groups have also created antibacterial nanopillar surfaces, but none of their approaches can be used on ordinary polymer surfaces or be scaled up easily," according to Albert F. Yee, Ph.D., who leads a team working on the topic. By contrast, the production method his group is adapting overcomes these hurdles.

"Our method is based on one developed in the early 2000s for the semiconductor industry," says Mary Nora Dickson, a graduate student in Yee's lab. "It is robust, inexpensive and can be used in industrial production. So it can now be applied to medical devices that could improve people's quality of life."

One such application is an artificial cornea that Yee's group aims to construct from poly(methyl methacrylate) (PMMA), familiar to many by trade names such as Plexiglas® and Lucite®. The material is already commonly used in medical devices including implantable intraocular lenses and traditional hard contact lenses. By building nanopillars into the surfaces of these types of devices, the researchers hope to make them bactericidal without the need for a separate biocidal coating or antibiotic drugs.

In earlier work, Yee, Dickson, Elena Liang, and colleagues at the University of California, Irvine, showed that their nanopillars, like those on cicada wings, can kill bacteria referred to as "gram-negative." This group of microorganisms includes E. coli. But cicada nanopillars are unable to kill another type of bacteria known as "gram-positive" because these microbes have thicker cell walls. Wiping out these bacteria, which include MRSA (methicillin-resistant Staphylococcus aureus) and Streptococcus (known as "strep"), is important because they cause infections on medical devices and in hospitals.

Compared to cicada nanopillars, the ones on dragonfly wings are taller and skinnier, and they can kill gram-positive bacteria. Now Dickson is trying to form these types of nanopillars on PMMA. However, she is finding that these structures are harder to replicate than the cicadas' stubby pillars. She is currently modifying the production process in several different ways to overcome these challenges.

For example, one version of the process uses commercial molds that contain billions of tiny pits in an area that covers just a few square inches. Pressing the mold onto a heated polymer film reshapes the film, leaving it decorated with nanopillars once the mold is removed. That method works just fine for the stubbier cicada-like pillars, but the finer dragonfly-like pillars tend to break apart when the mold is removed, much like over-cooked cupcakes sticking to the inside of an ungreased muffin tin.

So Dickson is experimenting with fluorinated silane coatings for the mold; these coatings could help free the pillars when it's time to remove the polymer film. She's also testing different chemical compositions for the mold itself.

Yee, Liang and Dickson are now applying their technique to curved surfaces such as an artificial cornea. For this application, Dickson created a flexible mold for the cicada-like pillars. She recently showed that the nanopillared PMMA surface produced with this curved mold retains the ability to kill bacteria without harming other kinds of cells in the eye. The team is currently developing a mold for the taller, dragonfly-type pillars.

The group has filed for patents on the bactericidal surface and artificial cornea application and hopes to begin animal trials this year.

###

A press conference on this topic will be held Tuesday, March 15, at 9:30 a.m. Pacific time in the San Diego Convention Center. Reporters may check-in at Room 16B (Mezzanine) in person, or watch live on YouTube http://bit.ly/ACSliveSanDiego. To ask questions online, sign in with a Google account.

Yee acknowledges funding from the University of California, Irvine, and from the Allergan Foundation.

The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 158,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.

Note to journalists: Please report that this research is being presented at a meeting of the American Chemical Society.

Follow us: Twitter | Facebook

Title

Towards a Scalable, Biomimetic Antibacterial Polymer Surface

Abstract

Nanopillars on cicada wings are inherently antibacterial, irrespective of surface chemistry. Application of nanopillars to polymer surfaces would result in inherently antibacterial surfaces without use of antibiotic drugs or biocide chemicals. Nano- and microstructured antibacterial surfaces have been previously proposed; none of these approaches can be used on ordinary polymer surfaces or easily scaled up. Thus, we applied industrial polymer nanostructuring techniques to generate biomimetic antibacterial nanostructures at the surfaces of poly(methylmethacrylate) (PMMA), a material commonly used in medical devices. We employed nanoimprint lithography, an industrially viable fabrication process, to produce our nanostructures. We utilized several molds for our process: a nano-holed (negative) mold, a commercially available nickel antireflective nanopillar (positive) mold, and a black silicon nanopillar (positive) mold fabricated with reactive ion etching. We treated these oxide surfaces with a fluorinated silane release coating (perflurodecyltrichlorosilane) using molecular vapor deposition. These molds were used to fabricate PMMA nanopillar arrays or to generate polydimethylsiloxane nanohole arrays to be used for subsequent PMMA nanopillar molding. The replication processes resulted in large, flat PMMA nanopillar arrays. Compared to flat films, PMMA nanopillar arrays 1) exhibited reduced surface adhesion of live E. coli determined by a standard fluorescence based viability assay, and 2) killed these bacteria, as evidenced AFM and SEM showing punctured bacterial cells on nanopillar arrays. Recent efforts have focused on optimizing the bactericidal performance of pillars to assess effectiveness against gram-positive bacteria. Our surfaces could be used for a wide variety of environmental and medical applications.

Media Contact

619-525-6215 (San Diego Press Center, March 13-16)

Michael Bernstein
202-872-6042 (D.C. Office)
301-275-3221 (Cell)
m_bernstein@acs.org

Katie Cottingham, Ph.D.
301-775-8455 (Cell)
k_cottingham@acs.org

@ACSpressroom
http://www.acs.org

Michael Bernstein | EurekAlert!

More articles from Life Sciences:

nachricht New photocatalyst speeds up the conversion of carbon dioxide into chemical resources
29.05.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

nachricht Copper hydroxide nanoparticles provide protection against toxic oxygen radicals in cigarette smoke
29.05.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

New drug reduces transplant and mortality rates significantly in patients with hepatitis C

29.05.2017 | Statistics

VideoLinks
B2B-VideoLinks
More VideoLinks >>>