This is the tale of two biological substances-cells from mammals and bacteria. It's a
story about the havoc these microscopic entities can wreak on all manner of surfaces,
from mighty ships to teeth and medical devices, and how two Syracuse University
researchers are discovering new ways to prevent the damage.
Under moist conditions, bacteria form what scientists call biofilms-a sticky, slimy
buildup on almost any kind of surface. Biofilms can corrode the hulls of ships,
produce green slime on rocks, pollute drinking water systems, form plaque on teeth
and stick to medical devices implanted in humans, resulting in infection or rejection.
It's critically important, therefore, for scientists to gain a better understanding of how
biofilms are formed and use that knowledge to develop surfaces that will resist such
biofouling. In an unusual, interdisciplinary collaboration, SU researchers have found
that if you can prevent protein from sticking to a surface, you can prevent both
bacteria and mammalian cells from doing likewise. In the process, they developed a
novel surface technology that scientists can use to study biofilms in ways that were
not previously possible.
In a series of experiments, Yan-Yeung Luk, assistant professor of chemistry in SU's
College of Arts and Sciences, and
Dacheng Ren, assistant professor of biomedical
engineering in SU's L.C. Smith College of Engineering and Computer Science,
created a surface material on which they could manipulate and confine biofilm
growth four times longer than current technologies. By further manipulating the
chemical makeup of the surface, the scientists uncovered how mammalian cells and
bacteria adhere to surfaces.
Their work, which is supported by grants from the National Science Foundation, was
reported in the Feb. 4 online version of "ChemComm," the journal of the Royal
Society of Chemistry (forthcoming in print) and in the Jan. 9 online version of
"Langmuir," published by the American Chemical Society (forthcoming in print).
Luk and Ren began collaborating about three years ago, when they discovered a
common thread in their individual research efforts-the desire to chemically modify
surfaces to prevent biofouling. They went on to create a surface that seems to repel
both bacteria and mammalian cells when the molecule is chemically applied to a
surface. The surface used in the laboratory is a thin film of gold coated on a glass
slide.
They explain their research in terms of land, soil and plants. "You start with a glass
surface (the land); apply a thin film of gold to that surface, about 20 nanometers or
five atoms thick (the soil); then top the gold with the molecules we created in the
laboratory (the trees)," Luk says. "The goal is to see if the special molecules (trees)
can resist or prevent protein from sticking to the overall surface. Put another way, do
the trees provide an inhospitable environment for birds (the biofilm) and therefore
prevent them from roosting en masse?"
The surface the researchers created in the laboratory was able to confine the growth
of bacteria to surface patterns of desired, two-dimensional shapes. In other words, the
researchers were able to control the growth of the biofilm with the surface material,
allowing the biofilm to form in some places and restricting its growth in others.
Additionally, the scientists found that when confined in two dimensions, the biofilm
grew in a vertical direction.
In other experiments, the scientists discovered important differences in the way
mammalian cells and bacteria attach to a surface. "Our surfaces are able to reveal
that mammalian cell adhesion requires the existence of an anchor, while bacteria can
adhere to almost any sticky surface," Luk says.
The researchers' discoveries and the surface technology they developed can be used to
answer critical questions that previously eluded scientists and may lead to the
development of improved medical implants and to new ways to prevent biofouling.
"This level of surface control has never before been achieved," Ren says. "We hope
that what we have learned in the laboratory will help answer other fundamental
questions in surface materials research and lead to the production of new materials
for use in medicine and industry."
