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Substrate
Enhancement
In order to coax liver cells into growing on silicon chips,
the exposed surface of the chip must be specially prepared.
First, it is finely etched with a texture of microscopic pores.
Then, the surface is chemically treated to mimic the structural
elements of the liver's natural environment. The result is
an artificial scaffolding on which liver cells adhere and
function.
In
this activity, you'll have the opportunity to test how the
surface coating of a substrate affects the success of a biofilm.
A biofilm is a sticky, slimy coating made from carbohydrates.
It is produced by colonies of bacteria and algal cells.
This
activity page will offer:
-
Insight into factors that affect cell adhesion.
- An
opportunity to observe the production of a biofilm.
- An
opportunity to test the effects of surface coatings on the
production of biofilms
MATERIALS
- Plastic
2-liter container (with top half removed)
- Spring
water
- Cup
of water from an aquarium overgrown with algae
- Plastic
slides
- Cup
- Waterproof
clay (from florist supply store or craft store)
- Plastic
wrap
- Petroleum
jelly
- Suntan
lotion
PROCEDURE
- Obtain
a plastic 2-liter container that has been prepared by your
instructor.
- Fill
the container 3/4 full with spring water.
- "Inoculate"
the container by adding a cup of water that has been taken
from an aquarium environment overgrown with algae.
- Coat
both sides of a plastic microscope slide with a thick layer
of petroleum jelly.
- Place
one end of the coated slide into a marble-sized lump of
waterproof clay, then place the coated slide into the container,
clay-side down. Make sure that the clay offers a stable
base to keep the slide supported upright in the water column.
- Repeat
step 5 using a slide that has been coated with suntan lotion.
- Repeat
step 5 using a slide that has not been coated with any material.
- Cover
the top with plastic wrap to prevent the evaporation of
water.
- Place
the covered container with its three upright slides in a
location where the setup will not be disturbed.
- Wait
about ten days. Carefully remove the slides. Do not disturb
any film that may have grown on the surface of the slides.
- Closely
examine the surface of each slide by holding it up to a
light. Which slide appears the least transparent, having
the most dense bioflim coverage? Now touch each surface.
Compare and contrast their appearances and feel.
Questions
- Where
did the slime-producing microorganisms come from?
- In
step 7, a slide that was not coated with any materials was
placed into the container. Explain.
- How
did the biofilm coverage compare? What factors seemed to
promote the growth of a biofilm?
- How
can you apply what you've learned in this activity to the
content of this segment of SAF?
EXTENSIONS
3D Sculpture
Remember
how the liver chip looked in the program? Think about its
pitted surface and the network of pores that transported nutrients
and waste to and from the liver cells. Then, use a variety
of art materials to construct a sculpture that represents
the liver chip. Your sculpture can either be a scientific
model that accurately portrays this liver chip or it can be
a creative, artistic representation.
Science
Fiction Writing
Imagine being inside a microscopic submarine whose mission
is to explore the liver chip. Using this unique perspective,
create a fictional log that describes what you observe as
you navigate in and around the chip structure.
WEB
CONNECTION
Liver
Cell
http://ilil.essortment.com/liverscellsstr_ricl.htm
This site offers an overview of liver cell structure and function.
CNEWS
Science
http://www.canoe.ca/CNEWSScience0104/23_liver-ap.html
An online article for the general public that describes the
success in culturing liver cells on a silicon chip.
Artificial
Liver Trial
http://www.uchospitals.edu/news/ELAD.html
This site describes the use of liver cell cultures in assembling
an artificial liver.
The
activities in this guide were contributed by Michael DiSpezio,
a Massachusetts-based science writer and author of "Critical
Thinking Puzzles" and "Awesome Experiments in Light & Sound"
(Sterling Publishing Co., NY).
Academic Advisors for this Guide:
Corrine Lowen, Science Department, Wayland Public Schools,
Wayland, MA
Suzanne
Panico, Science Teacher Mentor, Cambridge Public Schools,
Cambridge, MA
Anne E. Jones, Science Department, Wayland Middle School,
Wayland, MA
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