The self-organizing properties of squid reflectin protein

Abstract

Reflectins, a recently identified protein family that is enriched in aromatic and sulphur-containing amino acids, are used by certain cephalopods to manage and manipulate incident light in their environment. These proteins are the predominant constituent of nanoscaled photonic structures that function in static and adaptive colouration, extending visual performance and intra-species communication. Our investigation into recombinantly expressed reflectin has revealed unanticipated self-assembling and behavioural properties, and we demonstrate that reflectin can be easily processed into thin films, photonic grating structures and fibres. Our findings represent a key step in our understanding of the property–function relationships of this unique family of reflective proteins.

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Figure 1: Light-organ platelets and native self-assembly of reflectin 1a protein from an insoluble precursor.
Figure 2: Solution casting of recombinant reflectin thin films.
Figure 3: Reflectin films exhibit shifts in the spectral interference peaks due to film swelling.
Figure 4: Surface diffraction gratings produced from reflectin/ionic liquid thin films.
Figure 5: Reflectin 1a fibres pulled from bulk precipitated protein.

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Acknowledgements

This work has been financially supported by DARPA (DSO) and AFOSR. We acknowledge M. McFall-Ngai (NIH AI50611) and E.G. Ruby (NIH RR 12294) for providing us with squid tissue. We thank M. Gupta for assistance with white-light interferometry imaging and D. Morse, R. Hanlon and M. Yustak for helpful discussions.

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Correspondence to Rajesh R. Naik.

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Kramer, R., Crookes-Goodson, W. & Naik, R. The self-organizing properties of squid reflectin protein. Nature Mater 6, 533–538 (2007). https://doi.org/10.1038/nmat1930

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