Nature 371, 49 - 51 (01 September 2002); doi:10.1038/371049a0

Flat pearls from biofabrication of organized composites on inorganic substrates

Monika Fritz^*†§, Angela M. Belcher^*‡§, Manfred Radmacher^†, Deron A. Walters^†§, Paul K. Hansma^†§, Galen D. Stucky^‡§, Daniel E. Morse^*§ & Stephen Mann^*‡§¶

^*Marine Biotechnology Center, Marine Science Institute, University of California, Santa Barbara, California 93106, USA
^†Department of Physics University of California, Santa Barbara, California 93106, USA
^‡Department of Chemistry University of California, Santa Barbara, California 93106, USA
^§Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA
^¶School of Chemistry, University of Bath, Bath BA2 7AY, UK

THE study of biomineralization is inspiring new approaches to the controlled fabrication of synthetic materials such as nanoparticles, polymer–mineral composites and templated crystals^1–3. Although this biomimetic approach is gaining momentum, the biological mechanisms involved in biomineralization remain relatively unexplored. One major reason for this is the difficulty of analysing biomineralization processes in their native dynamic state. Here we demonstrate that a highly organized composite material—a 'flat pearl'—can be biofabricated on disks of glass, mica and MoS₂ inserted between the mantle and shell of Haliotis rufescens (red abalone). We show that the construction of this material is spatially and temporally regulated and proceeds through a developmental sequence that closely resembles that at the growth front of the natural shell. Recognition of the implanted inorganic surfaces by mantle cells apparently governs a switch, perhaps genetically controlled, from aragonite to calcite biomineralization. Once a partially oriented calcite—protein primer layer has been deposited, there is a switch back to the nucleation and assembly of columnar stacks of highly ordered aragonitic nacre. Thus the presence of an inorganic surface between the mantle and shell of the organism triggers a change in the nature of the mineral phase deposited.

References

1.	Mann, S. Nature 365, 499−505 (1993). | Article | ISI | ChemPort |
2.	Mann, S. et al. Science 261, 1286−1292 (1993). | ISI | ChemPort |
3.	Heuer, A. H. Science 255, 1098−1105 (1992). | PubMed | ISI | ChemPort |
4.	Nakahara, H., Bevlander, G. & Kakei, M. Venus 41, 33−46 (1982).
5.	Simkiss, K. & Wilbur, K. M. in Biomineralization (eds Simkiss, K. & Wilbur, K. M.) (Academic, San Diego, 1989).
6.	Addadi, L & Weiner, S. Angew. Chem. int. Edn engl. 31, 153−161 (1992).
7.	Cariolou, M. A. & Morse, D. E. J. comp. Physiol. B157, 717−729 (1988). | ChemPort |
8.	Manne, S. et al. Proc. R. Soc. B256, 17−23 (1994).
9.	Watabe, N. in Biology of the Integument 1 (eds Bereiter-Hahn, J., Matoltsy, A. G. & Richards, K. S.) 448−485 (Springer, New York, 1984).
10.	Wada, K. Bull. Natn. Pearl Res. Lab. 7, 703−827 (1961).
11.	Simkiss, K. & Wada, K. Endeavour 4, 32−37 (1980). | Article | ChemPort |
12.	Götting, K. J. Experientia 35, 756 (1979).
13.	Wada, K. Bull. Jap. Soc. Sci. Fish. 23, 302 (1957).
14.	Watabe, N. & Wilbur, K. M. Nature 198, 334 (1960).
15.	Wada, K. Bull. Jap. Soc. Sci. Fish. 26, 549−553 (1960).
16.	Rietveld, H. M. J. appl. Crystallogr. 2, 65−71 (1969). | Article | ISI | ChemPort |
17.	Morse, D. E., Cariolou, M. A., Stucky, G. D., Zaremba, C. M. & Hansma, P. K. Mater. Res. Soc. Symp. Proc. 292, 59−67 (1993). | ChemPort |
18.	Meenakshi, V. R., Blackwelder, P. L. & Wilbur, K. M. J. Zool. 171, 457−484 (1973).
19.	Meenakshi, V. R., Martin, A. W. & Wilbur, K. M. Mar. Biol. 27, 27−35 (1974). | Article |
20.	Blackwelder, P. L. & Watabe, N. Biomineralization 9, 1−10 (1977).