Welcome to my blog, enjoy reading.

Biomaterials in nano




Silica sand on the Classic Caribbean beach on the island of Martinique - Les Salines Biomineralization (e.g. silicification) is quite common in the biological world and occurs in bacteria, single-celled organisms, plants (e.g. petrified wood), and animals (invertebrates and vertebrates). Crystalline minerals formed in this type of environment often show exceptional mechanical properties (e.g. strength, hardness, fracture toughness) and tend to form hierarchical structures that exhibit microstructural order over a range of length or spatial scales. The minerals are typically crystallized from an environment that is undersaturated with respect to certain metallic elements such as silicon, calcium and phosphorous, which are readily oxidized under conditions of neutral pH and low temperature (0 - 40 degrees C). Formation of the mineral may occur either within or outside of the cell wall of an organism, and specific biochemical reactions for mineral deposition exist that include lipids, proteins and carbohydrates. The significance of the cellular machinery cannot be overemphasized, and it is with advances in experimental techniques in cellular biology and the capacity to mimic the biological environment that significant progress is currently being reported.

Sand from Pismo Beach, California including quartz, shell and rock fragments.
Examples include silicates in algae and diatoms, carbonates in invertebrates, and calciu phosphates and carbonates in vertebrates. These minerals often form structural features such as sea shells and the bone in mammals and birds Organisms have been producing mineralized skeletons for nearly 600 million years. The most common biominerals are the phosphate and carbonate salts of calcium that are used in conjunction with organic polymers such as collagen and chitin to give mechanical strength to bones and shells. Other examples include copper, iron and gold deposits involving bacteria.
Thus, most natural (or biological) materials are complex composites whose mechanical properties are often outstanding, considering the weak constituents from which they are assembled. These complex structures, which have risen from hundreds of million years of evolution, are inspiring materials scientists interested primarily in the design of novel materials with exceptional physical properties for high performance in adverse conditions. Their defining characteristics such as hierarchy, multifunctionality, and the capacity for self-healing, are currently being investigated

Electron/Photon Conductive Biopolymers and Nanotubes

Several biopolymers have well documented properties as organic electron conductors. These materials, exemplified by the cytochrome systems, have tetrapyrrole components (porphyrins) that are usually metal centered. The tetrapyrrole is a highly conjugated system that can interact with other tetrapyrroles in a face to face orientation with P bonding. Using model systems Collman and colleagues (J Amer Chem Soc 102:6027-6036 1980) has demonstrated that electron transfer is maximized when the face-to-face distances are maintained at 5-8 Angstroms. Electron transfer may be mediated both through P stacking and redox of the metal center. Phthlocyanins are biomimetics of porphyrins and these have been shown to exhibit modest electron conductivity when doped (Marks, Science 227:881-889 1985). Amperometric sensors have been constructed utilizing biotinylated polypyrroles (Cosnier et al. Analytical Chemistry 71: 3692-3697 1999) and proteins containing porphyrins (Mizutani, Sato et al. Electrochimica Acta 44: 3833-3838 1999). A challenge presented by this technology is the production of filaments of the heme or phthalocyanine entities in most efficient alignment for electron transfer. The development of biopolymer based molecular switches enable more rapid development of molecular transistors and integrated circuits.
Nucleic acids can function both as organic electron transfer materials and as templates for the deposition of electron conducting metals. The rate of electron transfer through organic conductors is approximately four orders of magnitude slower than through good metallic conductors. Double stranded deoxyribonucleic acid (dDNA) has now been demonstrated to function as an organic electron transfer material ("wire"). The electron transfer is effected through stacking and orientation of the bases (SO Kelley, JK Barton. Science 283: 375-381 1999; Wan, Fiebig et al. Proc Natl. Acad. Sci US, 96: 6-14-6019, 1999; Henderson, Jones et. al Proc. Natl. Acad Sci US, 96: 8353-8358 1999). DNA has also been shown to serve as a matrix for adsorption to gold or silver in the construction of nanowires and sensors (Elghanian, Storhoff et al. Science 277: 1078 - 1081 1997; Braun, Eichen et al. Nature 391: 775 1998). The nanowires are capable of electron conduction as metallic materials. The problems associated with this technology include the formation of uniform diameter and oriented polynucleotide fibers. Methods have yet to be developed for production of an ordered deposition of the "nanowires" (DNA or DNA gold complex with deposited metal)" on a support surface. An end product would be a nanoscale integrated circuit.
Nanotubes have been formed using organic polymers as templates (Rudolph AS, Ratna BR and Kahn B. Nature 352: 52-55 1991). The nanotubes have diameters of 1 nanometer or larger and have utility as molecular tweezers or surface probes (Gimzewski and Joachim Science 283 1683 1999). The molecular tweezers enable one to move single molecules on a solid surface for the construction of sensors and integrated molecular motor systems (Kim and Lieber Science 286: 2148-2150 1999; Baughman, Cui et al. Science 284: 1340-1344 1999). These structures may also be used to map the surface properties (i.e. uniform thickness, electrical conductivity, force required to separate two biomolecular complexes) of thin films (Gimzewski and Joachim Science 283 1683 1999). The nanoscale dimensions of the tubes, their physical strength and electronic conducting properties have utilities in a variety of industries including electronics, biomedicine, communications and QC in the manufacture of thin films. The technical issues to be addressed include mass production of uniformly thick tubules, the deposition of the tubules in an ordered manner and attachment of the tubes to larger electron conducting surfaces.

Nanotechnology, Biomolecular Electronics


In a article by Felix Hong (Sixth Newsletter of Molecular Electronics and BioComputing, 1996), he asks the question "Can a single molecule possess intelligence?" In discussing this question he suggests that because of the limited capabilities of computers, scientists are beginning to seek inspiration from biology. Living organisms operate with functional elements that are of molecular dimensions and that exploit quantum and thermal fluctuation phenomena.
Biomaterial’s had not been seriously considered for the construction of electronic devices until Nikolai Vsevolodov and his colleagues first produced an imaging device and microfilm made from biological materials called Biochrom film. The key substance was bacteriorhodopsin. Since this first study, several attempts to produce imaging and information storage devices using biological materials have been published. Many of these publications have come from the laboratory of Robert Birge at Syracuse University where he has developed a three dimensional information storage device that incorporates bacteriorhodopsin as the storage element.
With the availability of self-assembling membrane systems (SAMs) the stage has been set for the rapid development of biomolecular electronic devices and their assembly using SAM type technologies. As an example, it is obvious that a biological motor cannot be assembled in any way that could be commercially viable other then through a self-assembling process.
Biological molecules, particularly proteins and lipids have all the basic properties necessary for the assembly of nanoscale electronic devices. These biological materials conduct current, transfer molecules from one location to another, are capable of major color changes on application of current or light and can produce cascades that can be used for amplification of a optical or electronic signal. All of these properties can be applied to electronic switches, gates, storage devices, biosensors and biological transistors to name just a few.
The following white paper prepared by Dr. Steven Kornguth, University of Texas is an attempt to look at biomolecular electronics as a technology or group of technologies ready for exploitation.
After reading this document, comments and additional papers would be most welcome. Those that add to the present white paper will be added to the website for further reading and discussion. It is the hope of ATP that commercial firms and their partners both in industry, government and academia will consider the possibilities of this technology area for further research and development. ATP looks forward to further discussions of this topic and to proposals that suggest applications that will lead to commercialization. Further detailed information is available on this ATP website.

Nanoelectronics: Nanotech in Electronics

How can nanoelectronics improve the capabilities of electronic components:
Nanoelectronics holds some answers for how we might increase the capabilities of electronics devices while we reduce their weight and power consumption. Some of the nanoelectronics areas under development, which you can explore in more detail by following the links provided in the next section, include:
Improving display screens on electronics devices. This involves reducing power consumption while decreasing the weight and thickness of the screens.
Increasing the density of memory chips. Researchers are developing a type of memory chip with a projected density of one terabyte of memory per square inch or greater.
Reducing the size of transistors used in integrated circuits. One researcher believes it may be possible to "put the power of all of today's present computers in the palm of your hand".

nanotech in software

software components:
Analytical and Crystallization, to investigate, predict, and modify crystal structure and crystal growth. MorphologyPolymorph PredictorReflex, Reflex Plus, Reflex QPA, assist the interpretation of diffraction data for determination of crystalic structure, to validate the results of experiment and computation.X-Cell, indexing for medium- to high-quality powder diffraction data from X-ray, neutron, and electron radiation sources.Quantum and Catalysis Adsorption Locator, to find the most stable adsorption sites for various materials, including zeolites, carbon nanotubes, silica gel, and activated carbonCASTEP, to predict electronic, optical, and structural propertiesONETEP, to perform linear-scaling density functional theory simulationsDMol3, quantum mechanical methods to predict materials propertiesSorption, for predicting fundamental properties, such as sorption isotherms (or loading curves) and Henry’s constantsVAMP, high speed calculating many physical and chemical molecular properties, used, e.g., for quick screening in computational drug discoveryQSAR /QSAR Plus, to identify compounds with optimal physicochemical properties.Polymers and Classical Simulation, to construct and characterize models of isolated chains or bulk polymers and predict their propertiesMaterials Component CollectionMaterials Visualizer

nanotech & medicine


Nanotechnology involves manipulating properties and structures at the nanoscale, often involving dimensions that are just tiny fractions of the width of a human hair. Nanotechnology is already being used in products in its passive form, such as cosmetics and sunscreens, and it is expected that in the coming decades, new phases of products, such as better batteries and improved electronics equipment, will be developed and have far-reaching implications.
One area of nanotechnology application that holds the promise of providing great benefits for society in the future is in the realm of medicine. Nanotechnology is already being used as the basis for new, more effective drug delivery systems and is in early stage development as scaffolding in nerve regeneration research. Moreover, the National Cancer Institute has created the Alliance for Nanotechnology in Cancer in the hope that investments in this branch of nanomedicine could lead to breakthroughs in terms of detecting, diagnosing, and treating various forms of cancer.
Nanotechnology medical developments over the coming years will have a wide variety of uses and could potentially save a great number of lives. Nanotechnology is already moving from being used in passive structures to active structures, through more targeted drug therapies or “smart drugs.” These new drug therapies have already been shown to cause fewer side effects and be more effective than traditional therapies. In the future, nanotechnology will also aid in the formation of molecular systems that may be strikingly similar to living systems. These molecular structures could be the basis for the regeneration or replacement of body parts that are currently lost to infection, accident, or disease. These predictions for the future have great significance not only in encouraging nanotechnology research and development but also in determining a means of oversight. The number of products approaching the FDA approval and review process is likely to grow as time moves forward and as new nanotechnology medical applications are developed.
To better understand current and future applications of nanotechnology in various fields of medicine, the project has developed two web-based resources that track medical developments focused on cancer and drug delivery systems.

my counter

web counter html code