his laboratory at the Department of Agriculture and Biosystems
Engineering, Mark Riley is working on producing devices that
can sense toxins and pathogens in the environment. With the
uncommon mixture of scientific curiosity and the problem solving
tenacity of an engineer, he is interested not only in detecting
them, but in understanding how cells respond to their presence.
The sensors that Mark is engineering began as relatively simple
devices and have evolved in complexity and sensitivity over the
years. The focus of his research, airborne particulate matter,
is a complex mixture of chemicals, some of them more toxic, some
less. Mark hopes to use the sensors he develops to help determine
what the “bad actors” in particulate contaminants are.
He is also interested in finding out how these components of particulate
matter work together as toxins. Do bad actors work independently,
represented in the equation 1 + 1 = 2, or do some bad actors work
together to produce a really awful “show”, as in 1
+ 1 = 3? Perhaps there are good actors present too. Maybe some
chemicals can cancel out the bad effects of others, as in 1 + 1
Mark’s sensors use live human cells, lung epithelial cells
and macrophages, grown outside the body, as detectors of toxins
in particulate matter. His aim is to use non-invasive methods of
gauging the cells’ reaction to the presence of particulate
matter. This means that he is developing techniques that do not
interfere with the cell function as you read their reaction. To
do this Mark uses a technique called spectroscopy, which measures
how light interacts with the molecules it passes through. Mark
can grow the human cells on the outside of a thin fiber-optic cable.
At one end of the sensor, light is sent into the cable, where it
interacts with the cells on the surface of the cable. Cellular
material, such as proteins and lipids, absorb certain portions
of the light spectrum, and the wavelength of the absorbed light
can be measured as the light exits the cable at the other end.
This technique gives Mark a characteristic graph that can be used
to get some idea of the health of the cells on the fiber-optic
cable. If air containing particulate matter, say from an interstate
highway, is passed over the cells, toxins in the particulate matter
will begin to affect the cells. Two of the changes that will occur
in the cells are a change in the lipid composition in the cell
membrane near the fiber-optic cable and a change in the shape of
proteins in or near the cell membrane. Each of theses changes in
the cells will cause a change in the pattern of absorbance that
is measured in the light. By comparing absorbance patterns from
healthy cells to cells that have been exposed to particulate matter,
Mark hopes to build up a profile of what happens to a cell when
it is exposed to toxins. Further, by studying the absorbance spectrum
carefully, Mark hopes to be able to determine exactly which toxin
is present in the sample that the cells are exposed to.
Most of Mark’s projects are collaborations with other laboratories.
He feels that his role is as a mediator between the biologists
and the engineers of the project. He has worked hard to encourage
interdisciplinary work, bringing together ideas and techniques
from widely differing fields of study. This type of work is becoming
popular at universities and research organizations around the world,
as a way to stimulate innovation and discovery. However, Mark and
others know that collaboration is a difficult process. As an example,
say an experiment fails. Mark is then faced with engineers on one
side of his team saying, “This is terrible, another thing
we have to fix”. The scientists on the other side will, however
say, “Great here is something we don’t understand,
what a lucky opportunity to learn more”.
Of course there are benefits that offset the difficulties of such
collaborations. The public has a much better understanding of the
process of engineering than they do the process of science. To
engineers the goals of a project are tangible outcomes, applications
or devices that benefit people and society. However the goals of
a scientific research project are often intangible knowledge, information
that is added to the existing knowledge-base and while it will
be important to help explain our world, it may not benefit it.
Knowledge for knowledge’s sake appeals to scientists, but
not necessarily voters and politicians. Thus a collaboration that
combines the best of both goals moves closer to satisfying everyone.