Biophysics of green algae:
Euglena gracilis investigated
by atomic force microscopy
C. Gruenberger, R. Ritter, I.C. Gebeshuber
Institut fuer Allgemeine Physik, Vienna University of Technology, Wien, Austria
Austrian Center of Competence for Tribology AC2T, Wiener Neustadt, Austria
http://www.ille.com
Overview
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Some properties of biological materials
Motivation to study algae
Introduction to Euglena gracilis
AFM of whole cells
AFM of cell parts
Conclusions
Outlook (algae, biomaterials)
Properties of biological material
• The hydrodynamic, aerodynamic, wetting and
adhesive properties of natural materials are
remarkable.
• The results of evolution often converge on
limited constituents or principles.
• For example, the same material component will
be found just slightly but effectively varied to
obey different functions in the same organism
(e.g. collagen occurs in bones, skin, tendons and
the cornea).
Properties of biological material
• One smart feature of natural materials concerns their
beautiful organization in which structure and
function are optimized at different length scales.
• Natural systems also show a high level of
integration: miniaturization whose object is to
accommodate a maximum of elementary functions in
a small volume, hybridization between inorganic and
organic components optimizing complementary
possibilities and functions and hierarchy.
Properties of biological material
• Some biomolecules such as amino acids and
thereby also proteins are defined in their structure
down to the atomic level. They are materials built with
molecular precision.
• In principle, each and every cell, plant, animal and
person can be called a nanotechnological wonder.
• Nowadays, materials scientists have just started to
make man-made materials of such precision.
Motivation for studying algae
• interesting material properties of E. gracilis
• many TEM and SEM and optical microscopy
images available, AFM only sparsely (yields
information not only on topography but also
mechanical properties)
• AFM of photoreceptor ultimate goal
Introduction to E. gracilis
• green alga, length 20mm-100mm
• single celled organism
• typical model organism for plant researchers and
simple animal researchers
• high pressure
resistant natural
containers (200 bar)
Flagellar swelling:
Euglena gracilis photoreceptor
Scale bar 100nm, © CNR Pisa
• photoreceptor with single photon sensitivity at
room temperature
• simple two state photocycle  promising
building block in biocomputers
AFM of whole cells
AFM of whole cells
flagellum
reservoir
paramylon
grain
Euglena pellicle
TEM
© Peter v. Sengbusch
SEM
© http://www.biol.tsukuba.ac.jp/~inouye/ino/e
• mechanical stability
• flexible
• interlocking ridges
• slide against each other
• biogenic lubricants
AFM of whole cells
© Barsanti et al., 1993, Vision Res. 33(15), 2043-2050
AFM of cell parts:
paramylon grain
AFM tapping mode, 2.5mm*2.5mm,
height scale 353nm
AFM of cell parts:
crystalline lipid body
Conclusion
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development of preparation method
AFM of cell walls
AFM of mucus excretion pellicle pores
AFM of new surface features
AFM of crystalline cell parts
Outlook I: Towards AFM
of the photoreceptor
• The soluton of crystalline parts contains only few
photoreceptors.
• Lipid bodies, paramylon grains and not
completely dissolved cell tissue amount for a
large portion of the solution.
• Combination with fluorescence microscopy is
needed.
Outlook II: Biomaterials in
material science
• Relating structure to function in biomaterials can
only be the beginning of promising developments.
• The thermal and hydrolytic sensitivities of
biological materials limit their applicability in many
important synthetic materials applications.
• A real breakthrough requires an understanding
of the basic building principles of living
organisms and a study of the chemical and
physical properties at the interfaces, to control the
form, size and compaction of objects.