Tatyana V. Dyukova

Retinal—protein complexes as optoelectronic components

Naturally occurring retinal-protein complexes (RPCs) have recently received much attention with regard to their potential use as light-sensitive elements for optical recording. The best-known RPC is bacteriorhodopsin (BR), a photosensitive protein from the membrane of extreme halophilic bacteria, which has been studied in great detail. The remarkably robust nature of BR, coupled with its ability to reversibly change color upon illumination and its high cyclicity of ground-to-photoinduced state transitions, makes BR a promising material for optical information processing.

Optical and electrical characterization of bacteriorhodopsin films.

The lifetime of the M-state of bacteriorhodopsin (BR) is increased by genetic and chemical modifications and by solubilizing purple membranes (PMs) with detergent. Chemically modified D96E films as well as D96N films, possess close to 100% bleaching efficiency which makes them attractive for use as image storage media. The mutant S35C has spectral and kinetic properties identical to the WT, both in aqueous suspensions and in films. This indicates that substitution of Ser-35 with Cys has an insignificant effect on the photocycling activity of BR. This substitution provides an attachment site that does not interfere with the function of BR. The magnitude of photocurrent transients generated by mutant BR proteins is used to measure the efficiency of the ground-to-M-state transitions.

Dehydration effects on D96N bacteriorhodopsin films

Abstract Dehydration effects on gelatin films of the D96N mutant bacteriordopsin (BR) and wild-type BR were studied. Unlike the wild-type BR films, wherein dehydration to 12% humidity results in an approximate 200-fold increase in the lifetime of the M state. D96N BR films dehydrated to the same extent have been shown to exhibit only a 17- to 20-fold increase in the lifetime of the M state. Chemically-enhanced D96N BR films possessa total bleaching efficiency of the initial-to-M-state transition that is close to theoretical maximum (1.0) over a wide range of relative humidity (35 to 85%). This provides an additional benefit to the D96N BR films as a material for storage and retrieval of optical information.

Optical properties of Triton X-100-treated purple membranes embedded in gelatin films☆

Abstract The purple membrane (PM) of the microorganism Halobacterium salinarium contains a hexagonally packed monolayer of the light-sensitive protein, bacteriorhodopsin (BR). The optical characteristics of gelatin-immobilized PMs depend strongly on the chemical environment of the PMs in the matrix. Here we present photoinduced absorptive and holographic characteristics of gelatin-embedded PMs solubilized with the non-ionic detergent, Triton X-100. The BR/detergent interaction was shown to slow the M-to-initial state transition of the photocycle and to increase the photosensitivity of the BR films. The lifetime of the holographic grating in Triton X-100-treated BR films was 2–3 times greater, when compared to the unmodified sample. Holographic grating growth times in BR films were shown to change depending on the extent of solubilization. The measured holographic sensitivity appeared to maximize in the range of Triton X-100/BR molar ratios from 15:1 to 25:1. The possible advantages of solubilized PM films as they are applied to optoelectronic devices are discussed.

Holographic properties of Triton X-100-treated bacteriorhodopsin embedded in gelatin films

Bacteriorhodopsin (b) thin films have been fabricated with varying amounts of the detergent Triton X-100 to measure the effect of this additive on the holographic performance of these thin films. Holographic spectroscopy is used to measure the effect of these detergents on the overall diffraction efficiency as well as on the phase and amplitude components of the overall signal. The diffracted rise and decay kinetics of these materials will also be presented as a function of varying detergent concentration. This research also studied the effect of this additive on the absorptive properties of bR-based thin films. Comparisons of the two complimentary sets of data are drawn.

Nonlinear polarization interaction in bacteriorhodopsin films with anisotropically saturating absorption

The effect of protein and matrix modifications on the photoanisotropic properties is studied for developing the concept of impact upon the main optical properties of the dynamic optical material based on bacteriorhodopsin (BR) both interaction of transmembrane protein--chromophore complex BR with matrix and interaction of protein opsin with chromophore retinal. Also possibility of the application of BR-films for the light polarization modulator is proposed.

High-capacity optical spatial switch based on reversible holograms

This paper discusses the architecture of an N X N optical spatial switch in which independent and arbitrary switching is realized using diffraction of light beams by a microhologram array (MA) programmed by two 1 X N acousto-optical elements. It is shown that a bacteriorhodopsin film can be used as a recording medium for MA. The throughput of each channel, being up to several Gbit/s the capacity of such a switch, can reach 104 X 104 channels, the time of an arbitrary switching being not more than 100 ms. Experimental results are given proving the possibility of implementing a switch having said characteristics.

Real-Time Probing the Biological Processes by Holographic Recording in Polarization-Sensitive Bacteriorhodopsin Films

Bacteriorhodopsin is a photosensitive protein similar to visual rhodopsin. We propose to apply photoinduced anisotropy and holographic recording in bacteriorhodopsin films for real-time analysis of the biological tissue image and study of retina dark adaptation. Article not available.

B-M-type anisotropy in bacteriorhodopsin films for nonlinear spatial light modulation

Bacteriorhodopsin (BR), a photoreceptor protein possesses a photochemical cycle of several distinct intermediates; all of them are photoactive. The BR molecules both in the initial form of the photocycle, BR570 (absorption maximum around 570 nm) and longest-lived (in films) intermediate M412 (absorption maximum at 412 nm) possess anisotropic absorption. Under the action of linearly polarized light, the reversible anisotropic photoselection of BR molecules takes place. So far only the method of photoinduced anisotropy based on anisotropic properties of BR570 was applied to realtime optical processing. In the present work, the potentialities for the use of photoinduced anisotropy in the BR-films based on both BR570 and M412 for the spatial light modulation are demonstrated. The overall blocking of highintensity features from an image is shown. Mixed B-M-type anisotropy in the chemically modified BR films, as applied to the edge enhancement, can provide a contrast ratio as high as 250:1. Low saturation intensity of the BR-films allows for the blocking of any intensity feature from an image that is carried out by choosing an appropriate intensity level of a controlling He-Ne laser beam without analyzer rotation. The photoanisotropic incoherent-to-coherent optical conversion with concurrent spatial-intensity modulation is also performed on the BR-films.