Studies On Photochromic Properties Of Bacteriorhodopsin And Its Applications

Bacteriorhodopsin (BR), a biomolecular material, has the unique photochromic properties. This photosensitive protein holds the all-around advantage compared with other organic photochromic materials. Recently, the incorporation of genetic technology infuses new vigor into the application research based on bacteriorhodopsin. Focusing on the photochromic properties and applications of bacteriorhodopsin film, the author mainly completed the following works:1. A theory of first-order kinetic approximation on the potochromic film was established. It provides a theoretical method for analyzing the photochromic properties of bacteriorhodopsin.2. With simplified two-level model of BR photocycle (B and M states), the rate equations and Lambert-Beer equation were numerically calculated. The kinetic and static absorption response of BR film at 570nm single beam and under 570nm and 412nm double beams were theoretically calculated.3. By fitting and analyzing the variation of the absorption spectra of genetic variant BR-D96N, which has a long lifetime of M state, the absorption spectra of B state, M state and D state were extracted from the experimental data. The spectra at various time were fitted with the least square method, therefore the variation of population percentages of the three states were obtained and the lifetimes of M state and B state were estimated. In another way, by measuring the absorption dynamics at 407nm and 568nm, the lifetimes of M state and B state were also obtained by two exponential data fitting.4. The absorption kinetic curve, saturation absorption curve and the double beams complementary suppression curve of BR-D96N film were experimentally measured, which were compared with numerical calculation. The parameters such as and M state lifetime were obtained by fitting with the first-order approximation formulae. Based on the property of double beams complementarysuppression between yellow and blue light, applications in suppressing brighter background and intensity reversion were carried out.5. The principle of measuring the photoinduced anisotropy of bacteriorhodopsin by pump-probe method was elucidated. The dependence of photoinduced anisotropy on the excitation intensity as well as the time decay of the photoinduced anisotropy in BR-WT film were experimentally studied. Two images were written on the same area of BR film with different polarizations, and they could be selectively readout.6. The photoinduced permanent polarization of bacteriorhodopsin was experimentally investigated. The parameters of anisotropy were measured and calculated. Polarization coloring was observed and qualitatively analyzed. Security application was studied based on the photoinduced permanent polarization.7. The properties of holographic recording of BR-D96N film were theoretically and experimentally studied. Polarization holographic recording and diffraction efficiency were theoretically analyzed. By using phase conjugated beam of reference beam as reconstruction wave, aberration of object could be effectively corrected. By using orthogonal polarization holographic recording, the signal-to-noise ratio of diffraction image could be greatly improved.