Trikur I. Preparation film structures based on bacteriorhodopsin and study the influence of humidity and ammonia on their optical characteristics

The dissertation is aimed on improvement of techniques for obtaining bacteriorhodopsin and film structures based on it. Work also describe the process of films synthesis as well as results of a comprehensive evaluation of the films, study of their characteristics and effect of the environmental parameters during their exposure. Efficiency of the bacteriorhodopsin synthesis as well as its quality are increased by optimizing the spectral characteristics of light illumination during cultivation and optimal selection of strain Dependence of the bacteriorhodopsin characteristics from the time of treatment of lysate by deoxyribonuclease was studied and optimum parameters of the process were determined. To improve the optical quality of films, method of ultrasonic treatment of film-forming mixture has been developed. Comprehensive studies of the cross-section and surface morphology of films, obtained by different methods with different matrices, using AFM and SEM showed that the methods used for film deposition provide uniform distribution of bacteriorhodopsin in film volume. Introducing purple membrane leads to an increase of surface roughness compared to films without bacteriorhodopsin for all types of matrices. Study of the films porosity have shown that total volume of open pores for inorganic sol-gel films is more than 2.5 orders higher than for polymer matrices. It is shown that humidity has effect on the spectral characteristics and holographic properties of bacteriorhodopsin films in case of both, sol-gel and gelatin matrices. The observed changes are explained by differences in the photo-cycle of bacteriorhodopsin due to varying degrees of hydration of key amino acid residues at different values of humidity. It is established that film adsorb ammonia which interacts with bacteriorhodopsin in both, vapour-gas mixtures and aqueous solutions, that leads to an increase of the life-time of the M412 intermediate and changes the optical characteristics of the films. The proposed mechanism of interaction of ammonia with bacteriorhodopsin molecules, whereby ammonia is temporary binding free protons, creates a local deficiency of hydrogen ions and complicates the protonation of key amino acid residues. The method of creating nanocomposite film structures of type inorganic sol-gel matrix - bacteriorhodopsin - quantum dots is developed. It is shown that the fluorescent emission of quantum dots can initiate bacteriorhodopsin photo-cycle. Investigation of influence of moisture and ammonia on the characteristics of film structures showed that the intensity of the fluorescent radiation of quantum dots significantly varies depending on the environment.