Bacteriorhodopsin and its Applications in Optical Information Storage

Feng Chen1, Xun Hou1, Baofang Li2, Xing C. Li2, and Long Jiang2

1State Key Laboratory of Transient Optics and Technology, Xi´an Institute of Optics and Fine Mechanics, The Chinese Academy of Sciences, Xi´an, ShaanXi 710068, China, and 2Institute of Photographic Chemistry, The Chinese Academy of Sciences, Beijing 100101, China

e-mail: chf@optics.opt.ac.cn
 

Bacteriorhodopsin (BR) is the key protein found in the cell membrane of Halobacterium salinarium. On the absorption of light energy, BR undergoes a very complex photocycle characterized by several spectroscopically distinct. A number of investigations describing BR uses in applications were recently reported. The significant feature of this biomaterial derives from the potential of modifying the protein photochromic properties through chemical enhanced or genetic manipulation of the native protein. BR shows an exceptional stability towards chemical, thermal, and photochemical degradation. The photochromic properties of BR provide the possibility of many applications in optical information processing and storage. For permanent optical storage applications an intermediate state occurs with a lifetime of years is needed. In this paper, the characteristics of BR and its behavior of the writing, reading and erasing of the information in a bacteriorhodopsin film are investigated. A system of three-wavelength EDRAW (Erase Direct Read After Write) was setup. Optical data was written into BR film with 670 nm using the O to P photochemistry. Then the resulting data was nondestructively read out at 594 nm using differential absorption of B and P states. Finally, the information have been erased with 490 nm using the reconversion of the photoproduct state P. The result of long-term information stroage in BR films more than 1 years is obtained. And some experiments of optical storage used BR films including preliminary study by the near-field optical method were reported. It indicates BR material are suitable for long-term photochromic information storage. Especially, as a molecules device, BR film provides a possibility of superhigh-density storage for us in the future.