Page 128 - Nanotechnology an introduction

Figure 11.5 An optically switched optical switch. The basic construction is a slab of bacteriorhodopsin-containing purple membrane fragments sandwiched between two optical waveguides. Initially, let us suppose that an optical wave
introduced at the input I is guided through the structure to emerge at output O 2 . If a grating (indicated by the stripes) is holographically generated in the bacteriorhodopsin slab by illuminating with light of 570 nm (from G, the “gate”), light
will be coupled out from the lower waveguide and coupled into the upper waveguide, emerging at output O 1 . Destroying the grating by illuminating with light of 410 nm will cause the output to revert to O 2 .
11.7. Summary
Bionanotechnology is defined as the incorporation of biological molecules into nanoartifacts. The highly refined molecular binding specificity is
particularly valued, and used to facilitate the assembly of unique structures from a solution of precursors and for capturing chemicals from the
environment prior to registering their presence via a transducer (biosensors). A further application involves using the widely encountered ability of
biomolecules to easily accomplish actions associated with difficult and extreme conditions in the artificial realm, such as the catalysis of many
chemical reactions, and optical nonlinearity with single photons, a feature which can be exploited to construct optical computers. One might also
mention the kidneys as a marvellous example of biological nanoengineering that functions to extract certain substances from highly dilute solutions,
an operation which may become of increasing importance as conventionally processable ores become depleted [161].

11.8 Further Reading
Armstrong, F.A.; Hill, H.A.O.; Walton, N.J., Reactions of electron-transfer proteins at electrodes, Q. Rev. Biophys. 18 (1986) 261–322.
Blumenfeld, L.A., Problems of Biological Physics. (1981) Springer, Berlin.
In: (Editors: Chen, J.; Jonoska, N.; Rozenberg, G.) Nanotechnology: Science and Computation (2006) Springer, Berlin.
In: (Editors: Dér, A.; Keszthelyi, L.) Bioelectronic Applications of Photochromic Pigments (2001) IOS Press, Amsterdam.
Scheller, F.; Schubert, F., Biosensoren. (1989) Akademie-Verlag, Berlin.
Valleton, J.-M., Information processing in biomolecule-based biomimetic systems, From macroscopic to nanoscopic scale, React. Polym. 12
(1990) 109–131.
Yoshida, M.; Muneyuki, E.; Hisabori, T., ATP synthase—a marvellous rotary engine of the cell, Nature Rev. Mol. Cell Biol. 2 (2001) 669–677.