Main description:

The properties of materials depend on the nature of the macromolecules, small molecules and inorganic components and the interfaces and interactions between them. Polymer chemistry and physics, and inorganic phase structure and density are major factors that influence the performance of materials. In addition, molecular recognition, organic-inorganic interfaces and many other types of interactions among components are key issues in determining the properties of materials for a wide range of applications. Materials require­ ments are becoming more and more specialized to meet increasingly demand­ ing needs, from specific environmental stresses to high performance or biomedical applications such as matrices for controlled release tissue scaf­ folds. One approach to meet these performance criteria is to achieve better control over the tailoring of the components and their interactions that govern the material properties. This goal is driving a great deal of ongoing research in material science laboratories. In addition, control at the molecular level of interactions between these components is a key in many instances in order to reach this goal since traditional approaches used to glue, stitch or fasten parts together can no longer suffice at these new levels of manipulation to achieve higher performance. In many cases, molecular recognition and self-assembly must begin to drive these processes to achieve the levels of control desired. This same need for improved performance has driven Nature over millenia to attain higher and higher complexity.

Contents:

1. Introduction.- A. Biophotonic Processes.- B. Bioelectric Phenomena.- C. Molecular Electronics.- D. Biomolecular Electronics.- E. Biomolecular Computing: An Overview of What Needs to Be Done.- 2. The Distinguished Family of Rhodopsins..- A. Visual Rhodopsin (VR) in Vertebrates.- 1. General Structure of Rhodopsins.- 2. The Photochemical Process in VR is Irreversible.- 3. Photoinduced VR Intermediates.- 4. Electrogenic VR Intermediates.- 5. Electrical Signals from the Retina.- 6. A Brief Look at Visual Pathways and Mechanisms.- 7. Measurement of Early and Late Receptor Potentials.- 8. VR Response to an Electric Field (Electrochromism).- 9. The Boundary Between Photochromism and Photoisomerism in Rhodopsins.- 10. The Influence of Ions on VR Spectra (Ionochromism).- 11. Rhodopsin in Fish Eyes.- B. Rhodopsins in Invertebrates and Microorganisms.- 1. Some Natural Examples of Rhodopsin-based Photopigments.- 2. Retinochrome: A Photoisomerizing Enzyme.- 3. Retinal-binding Proteins.- 4. Rhodopsins for Use in Detecting UV Light.- 5. Chlamyrhodopsin: A Recently Discovered Photopigment.- C. Bacterial Rhodopsin Isolated from Halobacteria.- 1. Discovery of a New Proton Pump.- 2. The Story of Discovery Unfolds.- 3. Biosynthesis of Purple Membranes.- 4. Purple Membranes: Two-dimensional Crystals.- 5. Halobacteria: A Riddle for Biological Evolution.- D. Modification of Rhodopsins.- 3. The Unique Properties of Bacteriorhodopdins (BR) as Energy Converters.- A. Wild-type Bacteriorhodopsin (BR).- 1. Chemical and Physical Properties of BR.- 2. The Photochemical Process of BR is Reversible!.- 3. Photocycle Intermediates.- 4. The Effects of Various Parameters on the BR Photocycle.- 5. Photochromic Properties.- 6. Photoelectric Properties.- 7. Electrochromic Properties.- 8. BR Viewed as a “Black Box” Energy Converter.- B. BR Variants.- 1. Random Mutagenesis.- 2. Site-specific Mutagenesis.- 3. How Many Strains of Halobacteria Have Been Found?.- 4. Photochromic Properties of BR Variants.- C. BR Analogs.- 1. Apomembranes.- 2. Artificial Retinal-Proteins.- 3. Photochemistry of BR Analogs.- 4. Analogs with Infrared Absorption.- 5. Analogs with Ultraviolet Absorption.- D. BR Monolayers and BR Films.- 1. BR Solubilization.- 2. BR Films.- 3. BR Aggregates.- 4. The Possibility of a Three Dimensional BR Crystal.- E. Halorhodopsin Acting as a Chloride Ion Pump.- F. The Discovery of Sensory Rhodopsins (SR).- 1. SR-I- An Attractant Receptor for Orange-red Light.- 2. SR-II- A Repellent Receptor for Blue-green Light.- G. Phototaxis of Phoborhodopsins.- 1. Phoborhodopsins Isolated from Halobacteria.- 2. Pharaonis Phoborhodopsin.- H. Yellow Protein Isolated from a Halophile.- I. A Summary of Properties of BR and BR Variants.- J. From Electronics to Bioelectronics.- 4. Photosensitive Materials for Use as Optical Memory.- A. Photographic Films.- 1. 150 Years of Photography.- 2. The End of Halogen-Silver Films?.- B. Photochromic Materials.- 1. 35 Years of Photochromic Materials Research.- 2. The Physics and Chemistry of Photochromic Processes.- 3. Organic and Inorganic Photochromic Materials.- 4. Is There a Future for Photochromic Materials?.- C. Construction of Layered Purple Membranes.- 1. Air-dried Layers on Supports.- 2. Layers with Oriented Purple Membrane.- 3. Purple Membranes in a Polymeric Matrix.- D. Biochrome: A BR-based Photochromic Film.- 1. The Discovery of Biochromic Films.- 2. Optical Characteristics.- 3. Holographic Properties.- E. BR Analogs for New Photochromic Films.- 1. Properties of BR Analogs.- 2. 4-keto BR Films.- 3. 4-keto BR: A Potentially Useful Anomaly.- F. More Photosensitive Materials.- 1. Chlorophyll Photographic Films.- 2. Visual Rhodopsin Photographic Films.- 3. Photographic Films with Enzymes.- 4. Other Types of Photochromic Materials in Nature.- 5. BR as Optolectronic Materials.- A. Molecular Computing Elements.- B. Ultrafast Electro-optical Detectors.- C. Biosensors.- D. Photosensitive Hybrids of Purple Membrane with Mitochondria and Nonphotosynthetic Bacteria.- E. Position-sensitive Detectors.- F. Photovoltaic Devices.- G. 3-D memory in BR.- 6. Applications of Biochrome and Similar Films.- A. Optical Memory.- B. Can Bacteriorhodopsin-based Compact Disks Exist?.- C. The Generation of the Second Harmonic of Laser Radiation.- D. Increasing the Contrast of a Photostat copy.- E. Polarization Holography.- F. Real Time Holography.- G. Holographic Connections for Optical Communication.- H. Biomedical Applications.- I. Military Use.- J. Light Testers.- K. From Toys to Computers.- 7. Conclusion.- A. Proteins in Bioelectronics.- B. The Truth and Science Fiction of Biocomputers.- 8. References.- 9. Glossary and abbreviations.- 10. Appendix.