Bacteriorhodopsin is a two-dimensional crystalline photochromic protein which is astonishingly stable towards chemical and thermal degradation. This is one of the reasons why this is one of the very few proteins which may be used as a biological pigment in printing inks. Variants of the naturally occurring bacteriorhodopsin have been developed which show a distinguished color change even with low light intensities and without the requirement of UV-light. Several pigments with different color changes are available right now. In addition to this visual detectable feature, the photochromism, the proteins amino acid sequence can be genetically altered in order to code and identify specific production lots. For advanced applications the data storage capability of bacteriorhodopsin will be useful. Write-once-read-many (WORM) recording of digital data is accomplished by laser excitation of printed bacteriorhodopsin inks. A density of 1 MBit per square inch is currently achieved. Several application examples for this biological molecule are described where low and high level features are used in combination. Bacteriorhodopsin-based inks are a new class of optical security pigments.

Date Published: 19 April 2002
PDF: 8 pages
Proc. SPIE 4677, Optical Security and Counterfeit Deterrence Techniques IV, (19 April 2002); doi: 10.1117/12.462703

Published in SPIE Proceedings Vol. 4677:
Optical Security and Counterfeit Deterrence Techniques IV
Rudolf L. van Renesse, Editor(s)