The document summarizes a 1986 Nature article about an experiment using phospholipid vesicles as a model system to study biomineralization. The experiment investigated the biomineralization of iron oxide within vesicles. Iron solutions were encapsulated within vesicles and precipitation was induced by raising the pH. Transmission electron microscopy revealed the formation of magnetite crystallites within the vesicles, demonstrating that vesicles can control mineralization through an intracellular environment.

1. Midterm Presentation: Bio-mineralization
Phospholipid vesicles as a model
system for biomineralization
324, 565 (1986) Stephen Mann, John P. Hannington
& R. J. P. Williams
Course: Bioinspired Materials and Technology
Advisor: Tu Lee, Ph. D.
Department of Chemical and Materials Engineering
Reporter: Lin, Chun-Ian
Date: 11/06/2009

2. About this article...
- Originally an article from “LETTERS TO NATURE”
- An experiment on the biomineralization of iron oxide in
unilamella (Latin, thin plate pl, lamellae) phospholipid
vesicles
2

3. What will be presented,
1. The authors who contributed to this work
2. Biomineralization defined
3. Experiment design 1-2
4. Results
3

4. the authors who contributed to this work:
Source: http://www.wadham.ox.ac.uk/fellows-
Sources: http://www.chm.bris.ac.uk/inorg/mann/webpage.htm
staff/staff/professor-r.j.p.-williams.html
Professor Stephen Mann Professor R.J.P. Williams Professor John P. Hannington
School of Chemistry, Wadham College, Oxford School of Chemistry, University of Bath
University of Bristol
4

5. Biomineralization
defined
Classification:
1. Biologically induced
- little control over type and
habit of minerals
- except for the metabolism-
mediated pH, pCO2
- biological surfaces which Source: Adapted from ref.3
affects nucleation
2. Biologically controlled
(matrix-mediated)
- bones, teeth, etc.
A. Synthetic calcite
B. Coccolithophore,
Emiliania huxleyi (EHUX)
C. Aragonite layer from
Mollusk shell
D. Calcite crystal from
human inner ear
5

6. Vesicles preparation
•Phosphatidylcholine(PC) 17mM Experiment design-1
•4 , at the presence of the solutes
℃
•diameterwith vesicle
Ends up
300Å
•by sonicationencapsulated
cations (M )+
biologically-induced
crystal growth
•ion-exchange chromatography
Extravesicular ions removed by
Iron solutions
Three solutions
100mM FeCl3 pH 2.0 3
Source: Adapted from ref.4
100mM FeCl2 • 4(H2O) pH 4.0 2
50mM Fe(NO3)3 pH 2.0 3/2
50mM FeCl2
6

7. Experiment design-2
Source: Adapted from ref.3
1. NaOH(aq) is added to induce precipitation, final pH=12.0
2. Pale-yellow coloration after 30 mins, increasing in intensity for the several
days that followed
3. No precipitation after bench centrifugation <> RAPID precipitation of iron
oxide without the presence of vesicles
4. Solution centrifuged, air-dried and unstained, subjected to TEM analysis.
7

8. Source: Adapted from ref.4
Three solutions
100mM FeCl3 pH 2.0 3
100mM FeCl2 • 4(H2O) pH 4.0 2
50mM Fe(NO3)3 pH 2.0 3/2
50mM FeCl2
Results Fig.b TEM of intravesicular
magnetite particles. Bar, 15 nm
Results of precipitations:
Intravesicular/ Extravesicular
Intra: poorly-ordered spherulitic goethite
3
Extra: ferrihydrite
Intra: 20-50Å magnetite crystallites
2
Extra: acicular lepidocrocite, goethite
Intra: poorly-ordered ferrihydrite
Fig.a TEM of vesicles bound with 3/2
head group of PC. Bar, 60 nm Extra: 100-500Å magnetite
Source: Adapted from ref.4 8

9. Reference
‣Bibliography
1. Bragg WL, Claringbull GF, Taylor WH. Crystal structures of minerals. 1st ed.
LONDON: G. Bell and Sons, LTD; 1965.
2. Campbell NA, Reece JB. BIOLOGY. 6th ed. San Francisco, CA: Benjamin
Cummings; 2001.
3. Dove PM, De Yoreo JJ, Weiner S. Biomineralization. 1st ed. Washington, DC:
Mineralogical Society of America; 2003.
‣Literature
4. Mann, S., Hannington J. P., Williams R. J. P., Nature 324, pp. 565-567
(1986)
9

10. creature too tiny to be seen with
unaided eyes, yet as a resident of the
mother earth like them, I feel compelled
to introduce them to you....

11. Coccolithophore, Emiliania huxleyi
Thomas Henry Huxley (1825-1895)
• Marine phytoplankton
• Considered the most productive calcifying
organisms on earth (Plants, photosynthesis)
• Forms large blooms in favorable conditions,
sometimes the size of England
1. DMS(dimethyl sulfide), cloud formation
2. Brings carbon dioxide down to the deep ocean
3. Heat retention and radiation reflection

13. Thanks for your attention, really.

14. goethite: α-FeO(OH)
a= 4.60 (Å)
b= 9.94 (Å)
c= 3.00 (Å)
Source: Adapted from ref.1

15. Calcite: CaCO3
• Rhombohedral cells
a= 6.75 (Å)
α= 46° 5’
a’= 6.41 (Å)
α’=101° 55’
• Hexagonal cells
a= 4.99 (Å)
c= 17.06 (Å)
Source: Adapted from ref.1

16. Magnetite: FeFe2O4
a=8.42 (Å)
ρ=5.24
Source: Adapted from ref.1

17. Source: Adapted from ref.4
17