Having found that whether bacteria stick to surfaces depends partly on how stiff those surfaces are, MIT engineers have created ultrathin films made of polymers that could be applied to medical devices and other surfaces to control microbe accumulation.
The inexpensive, easy-to-produce films could provide a valuable layer of protection for the health care industry by helping to reduce the spread of hospital-acquired infections, which take the lives of 100,000 people and cost the United States an estimated $4.5 billion annually.
The researchers, who describe their work in an upcoming issue of the journal Biomacromolecules, found they could control the extent of bacterial adhesion to surfaces by manipulating the mechanical stiffness of polymer films called polyelectrolyte multilayers. Thus, the films could be designed to prevent accumulation of hazardous bacteria or promote growth of desirable bacteria.
“All other factors being equal, mechanical stiffness of material surfaces increases bacterial adhesion,” said Krystyn Van Vliet, the Thomas Lord Assistant Professor of Materials Science and Engineering and the paper's anchor author.
Van Vliet and her colleagues found the same trend in experiments with three strains of bacteria: Staphylococcus epidermidis, commonly found on skin, and two types of Escherichia coli.
Stiffness has usually been overlooked in studies of how bacteria adhere to surfaces in favor of other traits such as surface charge, roughness, and attraction to or repulsion from water. The new work shows that stiffness should also be taken into account, said Van Vliet.
The new films could be combined with current methods of repelling bacteria to boost their effectiveness, said Michael Rubner, an author of the paper and director of MIT's Center for Materials Science and Engineering.
Those methods include coating surfaces with antimicrobial chemicals or embedding metal nanoparticles into the surface, which disrupt the bacterial cell walls.
“For those bacteria that readily form biofilms, we have no delusions that we can prevent bacterial films from starting to form. However, if we can limit how much growth occurs, these existing methods can become much more effective,” Rubner said.Jenny Lichter, graduate student in materials science and engineering, and Todd Thompson, a graduate student in the Harvard-MIT Division of Health Sciences and Technology, are joint lead authors of the paper.
They note that the films could also be used on medical devices that go inside the body, such as stents and other cardiac implants.
“Once a foreign object enters into the body, if you can limit the number of bacteria going in with it, this may increase the chances that the immune system can defend against that infection,” said Thompson.
Another possible application for the films is to promote growth of so- called “good bugs” by tuning the mechanical stiffness of the material on which these bacteria are cultured. These films could stimulate growth of bacteria needed for scientific study, medical testing, or industrial uses such as making ethanol.
The researchers built their films, which are about 50 nanometers (billionths of a meter) thick, with layers of polyelectrolytes (a class of charged polymer). Alternating layers are added at different pH (acidity) levels, which determines how stiff the material is when hydrated at near-neutral pH, such as water. Polymer films assembled at higher pH (up to 6) are stiffer because the polymer chains crosslink readily and the polymers do not swell too much; those added at lower, more acidic pH (down to 2.5) are more compliant.
Van Vliet says the team's results could be explained by the relationship between surfaces and tiny projections from the bacterial cell walls, known as pili. Stiffer surfaces may reinforce stronger, more stable bonds with the bacterial pili. The researchers are now working on figuring out this mechanism.
The research was funded by the National Science Foundation, National Institutes of Health and the Arnold and Mabel Beckman Foundation Young Investigator Program.
Maricela Delgadillo, a senior in materials science and engineering, and Takehiro Nishikawa, a former postdoctoral researcher at MIT, now at the Advanced Medical Engineering Center in Osaka, Japan, are also authors of the paper.
Written by Anne Trafton, MIT News Office
Elizabeth A. Thomson | MIT News Office
Transport of molecular motors into cilia
28.03.2017 | Aarhus University
Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy