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Nanostructured thin films obtained by electrodeposition over a colloidal crystal template: applications in electrochemical devices

GONÇALES, Vinicius R.; MASSAFERA, Mariana P.; BENEDETTI, Tânia M.; MOORE, David G.; TORRESI, Susana I. Córdoba de; TORRESI, Roberto M.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
38.026619%
Colloidal particles have been used to template the electrosynthesis of several materials, such as semiconductors, metals and alloys. The method allows good control over the thickness of the resulting material by choosing the appropriate charge applied to the system, and it is able to produce high density deposited materials without shrinkage. These materials are a true model of the template structure and, due to the high surface areas obtained, are very promising for use in electrochemical applications. In the present work, the assembly of monodisperse polystyrene templates was conduced over gold, platinum and glassy carbon substrates in order to show the electrodeposition of an oxide, a conducting polymer and a hybrid inorganic-organic material with applications in the supercapacitor and sensor fields. The performances of the resulting nanostructured films have been compared with the analogue bulk material and the results achieved are depicted in this paper.; Partículas coloidais têm sido empregadas na síntese dirigida por molde de diversos materiais, tais como semicondutores, metais e ligas. Esse método permite um controle da espessura do material resultante através da escolha adequada da carga aplicada no sistema e é possível produzir materiais densamente depositados...

On the template synthesis of nanostructured inorganic/organic hybrid films

GONCALES, V. R.; SALVADOR, R. P.; ALCANTARA, M. R.; TORRESI, S. I. Cordoba de
Fonte: ELECTROCHEMICAL SOC INC Publicador: ELECTROCHEMICAL SOC INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.441345%
Prussian Blue has been introduced as a mediator to achieve stable, sensitive, reproducible, and interference-free biosensors. However, Na(+), Li(+), H(+), and all group II cations are capable to block the activity of Prussian Blue and, because Na(+) can be found in most human fluids, Prussian Blue analogs have already been developed to overcome this problem. These analogs, such as copper hexacyanoferrate, have also been introduced in a conducting polypyrrole matrix to create hybrid materials (copper hexacyanoferrate/polypyrrole, CuHCNFe/Ppy) with improved mechanical and electrochemical characteristics. Nowadays, the challenges in amperometric enzymatic biosensors consist of improving the enzyme immobilization and in making the chemical signal transduction more efficient. The incorporation of nanostructured materials in biosensors can optimize both steps and a nanostructured hybrid CuHCNFe/Ppy mediator has been developed using a template of colloidal polystyrene particles. The nanostructured material has achieved sensitivities 7.6 times higher than the bulk film during H(2)O(2) detection and it has also presented better results in other analytical parameters such as time response and detection limit. Besides, the nanostructured mediator was successfully applied at glucose biosensing in electrolytes containing Prussian Blue blocking cations. (C) 2008 The Electrochemical Society.

Nanostructured thin films obtained by electrodeposition over a colloidal crystal template: applications in electrochemical devices

Gonçales,Vinicius R.; Massafera,Mariana P.; Benedetti,Tânia M.; Moore,David G.; Torresi,Susana I. Córdoba de; Torresi,Roberto M.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
38.026619%
Colloidal particles have been used to template the electrosynthesis of several materials, such as semiconductors, metals and alloys. The method allows good control over the thickness of the resulting material by choosing the appropriate charge applied to the system, and it is able to produce high density deposited materials without shrinkage. These materials are a true model of the template structure and, due to the high surface areas obtained, are very promising for use in electrochemical applications. In the present work, the assembly of monodisperse polystyrene templates was conduced over gold, platinum and glassy carbon substrates in order to show the electrodeposition of an oxide, a conducting polymer and a hybrid inorganic-organic material with applications in the supercapacitor and sensor fields. The performances of the resulting nanostructured films have been compared with the analogue bulk material and the results achieved are depicted in this paper.

Charge Stabilized Crystalline Colloidal Arrays As Templates For Fabrication of Non-Close-Packed Inverted Photonic Crystals

Bohn, Justin J.; Ben-Moshe, Matti; Tikhonov, Alexander; Qu, Dan; Lamont, Daniel N.; Asher, Sanford A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.769624%
We developed a straightforward method to form non close-packed highly ordered fcc direct and inverse opal silica photonic crystals. We utilize an electrostatically self assembled crystalline colloidal array (CCA) template formed by monodisperse, highly charged polystyrene particles. We then polymerize a hydrogel around the CCA (PCCA) and condense the silica to form a highly ordered silica impregnated (siPCCA) photonic crystal. Heating at 450 °C removes the organic polymer leaving a silica inverse opal structure. By altering the colloidal particle concentration we independently control the particle spacing and the wall thickness of the inverse opal photonic crystals. This allows us to control the optical dielectric constant modulation in order to optimize the diffraction; the dielectric constant modulation is controlled independently of the photonic crystal periodicity. These fcc photonic crystals are better ordered than typical close-packed photonic crystals because their self assembly utilizes soft electrostatic repulsive potentials. We show that colloidal particle size and charge polydispersity has modest impact on ordering, in contrast to that for close-packed crystals.

Scalable, Shape-specific, Top-down Fabrication Methods for the Synthesis of Engineered Colloidal Particles

Merkel, Timothy J.; Herlihy, Kevin P.; Nunes, Janine; Orgel, Ryan M.; Rolland, Jason P.; DeSimone, Joseph M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 17/08/2010 EN
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27.441345%
The search for a method to fabricate non-spherical colloidal particles from a variety of materials is of growing interest. As the commercialization of nanotechnology continues to expand, the ability to translate particle fabrication methods from a laboratory to an industrial scale is of increasing significance. In this article, we examine several of the most readily scalable top-down methods for the fabrication of such shape specific particles and compare their capabilities with respect to particle composition, size, shape and complexity as well as the scalability of the method. We offer an extensive examination of Particle Replication In Non-wetting Templates (PRINT®) with regards to the versatility and scalability of this technique. We also detail the specific methods used in PRINT particle fabrication, including harvesting, purification and surface modification techniques, with examination of both past and current methods.

New Colloidal Lithographic Nanopatterns Fabricated by Combining Pre-Heating and Reactive Ion Etching

Cong, Chunxiao; Junus, WilliamChandra; Shen, Zexiang; Yu, Ting
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 28/07/2009 EN
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28.151675%
We report a low-cost and simple method for fabrication of nonspherical colloidal lithographic nanopatterns with a long-range order by preheating and oxygen reactive ion etching of monolayer and double-layer polystyrene spheres. This strategy allows excellent control of size and morphology of the colloidal particles and expands the applications of the colloidal patterns as templates for preparing ordered functional nanostructure arrays. For the first time, various unique nanostructures with long-range order, including network structures with tunable neck length and width, hexagonal-shaped, and rectangular-shaped arrays as well as size tunable nanohole arrays, were fabricated by this route. Promising potentials of such unique periodic nanostructures in various fields, such as photonic crystals, catalysts, templates for deposition, and masks for etching, are naturally expected.

Fabricating colloidal crystals and construction of ordered nanostructures

Sun, Zhiqiang; Yang, Bai
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 28/07/2006 EN
Relevância na Pesquisa
28.027095%
Colloidal crystals of polymeric or inorganic microspheres are of extensive interest due to their potential applications in such as sensing, optics, photonic bandgap and surface patterning. The article highlights a set of approaches developed in our group, which are efficient to prepare colloidal crystals with ordered voids, patterned colloidal crystals on non-planar surfaces, heterogeneous colloidal crystals of different building blocks, colloidal crystals composed of non-spherical polyhedrons, and colloidal crystals of non-close-packed colloidal microspheres in particular. The use of these colloidal crystals as templates for different microstructures range from nanoscale to micron-scale is also summarized.

Colloidal lithography for fabricating patterned polymer-brush microstructures

Chen, Tao; Chang, Debby P; Jordan, Rainer; Zauscher, Stefan
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 15/05/2012 EN
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27.644565%
We exploit a series of robust, but simple and convenient colloidal lithography (CL) approaches, using a microsphere array as a mask or as a guiding template, and combine this with surface-initiated atom-transfer radical polymerization (SI-ATRP) to fabricate patterned polymer-brush microstructures. The advantages of the CL technique over other lithographic approaches for the fabrication of patterned polymer brushes are (i) that it can be carried out with commercially available colloidal particles at a relatively low cost, (ii) that no complex equipment is required to create the patterned templates with micro- and nanoscale features, and (iii) that polymer brush features are controlled simply by changing the size or chemical functionality of the microspheres or the substrate.

Multilayer Lactate Oxidase Shells on Colloidal Carriers as Engines for Nanosensors

Stein, Erich W.; McShane, Michael J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/2003 EN
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37.441345%
Self-assembly methods are being studied for construction of nanoscale chemical sensors employing coimmobilized enzymes and indicator dyes. This paper describes the assembly of the catalytic enzyme lactate oxidase in multilayer films on colloidal templates via layer-by-layer self-assembly, which is a step toward achieving nanoengineered biosensors. The architecture of the resulting films was characterized using quartz crystal microbalance and zeta potential analysis, and catalytic activity was characterized colorimetrically. The tailored activity of the functional nanofilms was proportional to the number of enzyme layers deposited during assembly, which provides a basis for designing sensors with specific interactions.

Reconfigurable multi-scale colloidal assembly on excluded volume patterns

Edwards, Tara D.; Yang, Yuguang; Everett, W. Neil; Bevan, Michael A.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 02/09/2015 EN
Relevância na Pesquisa
27.915525%
The ability to create multi-scale, periodic colloidal assemblies with unique properties is important to emerging applications. Dynamically manipulating colloidal structures via tunable kT-scale attraction can provide the opportunity to create particle-based nano- and microstructured materials that are reconfigurable. Here, we report a novel tactic to obtain reconfigurable, multi-scale, periodic colloidal assemblies by combining thermoresponsive depletant particles and patterned topographical features that, together, reversibly mediate local kT-scale depletion interactions. This method is demonstrated in optical microscopy experiments to produce colloidal microstructures that reconfigure between well-defined ordered structures and disordered fluid states as a function of temperature and pattern feature depth. These results are well described by Monte Carlo simulations using theoretical depletion potentials that include patterned excluded volume. Ultimately, the approach reported here can be extended to control the size, shape, orientation, and microstructure of colloidal assemblies on multiple lengths scales and on arbitrary pre-defined pattern templates.

Defects in Hard-Sphere Colloidal Crystals

Persson Gulda, Maria Christina Margareta
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Relevância na Pesquisa
27.441345%
Colloidal crystals of (1.55 mu m) diameter silica particles were grown on {100} and flat templates by sedimentation and centrifugation. The particles interact as hard spheres. The vacancies and divacancies in these crystals are not in equilibrium, since no movement of single vacancies is observed. The lack of mobility is consistent with the extrapolation of earlier simulations at lower densities. The volume of relaxation of the vacancy has a plausible value for these densities as the volume of formation is approaching the volume in a close-packed crystal. The volume of relaxation for the divacancy is smaller than that of two vacancies, so that the association of two vacancies into a divacancy requires extra volume, and hence extra entropy. The mean square displacement of the nearest neighbors of the vacancies is an order of magnitude larger than that of the nearest neighbors of particles. The mobility of the divacancies is consistent with the extrapolation of older simulations and is similar to that associated with the annihilation of the vacancy-interstitial pair. The volume of motion of the divacancies is (Delta V_m = 0.19V_o (V_o): close-packed volume) and the entropy of motion is (Delta S_m = 0.49k_BT). Dislocation-twin boundary interactions can be observed by introducing strain via a misfit template. The dislocations formed are Shockley partials. When a dislocation goes through the boundary...

Structure and Defects of Hard-Sphere Colloidal Crystals and Glasses

Jensen, Katharine Estelle
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
EN_US
Relevância na Pesquisa
28.609272%
Colloidal particles provide convenient and useful building blocks for creating ordered and disordered structures with length scales on the order of a micrometer. These structures are useful materials in their own right, and also serve as excellent scale models for exploring properties of atomic materials that would otherwise be inaccessible to direct experiment. In this dissertation, we explore structure formation in hard-sphere colloidal systems using templated sedimentation techniques, and then use colloidal crystals and glasses formed in this way to study the development of extended defects in single crystals and shear defects in glasses. We find that it is possible to form large, defect-free colloidal single crystals extremely rapidly by centrifugation onto a deterministic template. On non-deterministic templates, we find a critical deposition flux above which the material always crosses over to forming a glass. With this understanding of the effects of template and deposition flux, we designed and tested amorphous templates that allow us to make colloidal glasses by sedimentation under gravity, as well as more complex structures. In face-centered cubic colloidal single crystals grown on (100) templates, extended defects (dislocations and stacking faults) can nucleate and grow if the crystal exceeds a critical thickness that depends on the lattice misfit with the template spacing. We account for the experimental observations of the density of misfit dislocations using the Frank-van der Merwe theory...

Stiffness of the Crystal-Liquid Interface in a Hard-Sphere Colloidal System Measured from Capillary Fluctuations

Ramsteiner, I. B.; Weitz, David A.; Spaepen, Frans A.
Fonte: American Physical Society (APS) Publicador: American Physical Society (APS)
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
27.441345%
Face-centered cubic single crystals of (σ=1.55 μm) diameter hard-sphere silica colloidal particles were prepared by sedimentation onto (100) and (110) oriented templates. The crystals had a wide interface with the overlaying liquid that was parallel to the template. The location of the interface was determined by confocal microscopic location of the particles, followed by identification of the crystalline and liquid phases by a bond-orientation order parameter. Fluctuations in the height of the interface about its average position were recorded for several hundred configurations. The interfacial stiffness (γ̃) was determined from the slope of the inverse squared Fourier components of the height profile vs the square of the wave number, according to the continuum capillary fluctuation method. The offset of the fit from the origin could quantitatively be accounted for by gravitational damping of the fluctuations. For the (100) interface, (γ̃ =(1.3±0.3)k_{B}T/σ^{2}); for the (110) interface, (γ̃ =(1.0±0.2)k_{B}T/σ^{2}). The interfacial stiffness of both interfaces was found to be isotropic in the plane. This is surprising for the (110), where crystallography predicts twofold symmetry. Sedimentation onto a (111) template yielded a randomly stacked hexagonal crystal with isotropic (γ̃ =0.66k_{B}T/σ^{2}). This value...

Chemistry directed assembly of multilayered polymer thin films and colloidal particles

Jiang, Xueping, 1971-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 246 p.; 22612814 bytes; 22612572 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
28.026619%
In this thesis, multilayered polymer thin films have been directed to different regions of a surface based on both electrostatic and secondary interactions between the polymer and the surface. This concept of adsorption directed by surface chemistry is universal, in that the same sets of rules derived for polymeric systems can also be applied to molecule and meso-scale systems, including dye molecules, colloidal particles, proteins and cells. An approach of "surface sorting" was proposed to direct two or more objects with varying functionalities to deposit on predetermined regions of a surface based on specific surface interactions. Specifically, on the surface patterned with alternating charged carboxylic acid (COOH) surface groups and neutral oligoethylene glycol (EG) surface groups, linear polyethyleneimine (LPEI) based multilayers predominately adsorb on the COOH surface, with maximal selectivity at the moderate pH level of 4.8; in contrast, polyallylamine hydrochloride (PAH) based multilayers are attracted to the EG surface under certain pH conditions, with maximal selectivity on EG also at a pH of 4.8. Chemical force microscopy was used to directly examine the intermolecular interactions between polyamines and functional surfaces. The driving forces were identified to be primarily an electrostatic interaction for LPEI adsorption on the COOH surface...

2D and 3D periodic templates through holographic interference lithography : photonic and phononic crystals and biomimetic microlens arrays; Two-dimensional and three-dimensional periodic templates through holographic interference lithography

Ullal, Chaitanya K. (Chaitanya Kishore)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 133 leaves; 6752048 bytes; 6757595 bytes; application/pdf; application/pdf
ENG
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27.435435%
In this thesis a simple technique for controlling structure via holographic interference lithography was established and implemented. Access to various space groups including such important structures as the level set approximations to the Diamond, the Schwartz P structure, the FCC, and the non centrosymmetric Gyroid structures were demonstrated. The ability to make 3D structures over a large area, with low defect densities and periodicities on the sub/i scale opens a whole range of opportunities including such diverse areas as photonic crystals, phononic crystals, drug delivery, microtrusses, tissue scaffolds, microfluidics and colloidal crystallization. A correlation between structure and photonic band gap properties was established by systematically exploring the 11 FCC space groups. This resulted in a technique to search for photonic band gap structures. It was found that a fundamental connectivity caused by simple Fourier elements tended to support gaps. 2-3, 5-6 and 8-9 gaps were opened in the f.c.c lattices. The F-RD and 216 structures were newly shown to have complete band gaps. Two of the three previously established champion photonic crystal structures, viz. the Diamond and the Gyroid presented practical fabrication challenges...

SWNT and Graphene Colloidal Dispersions: Phase behavior, Material Fabrication and Characterization

Dan, Budhadipta
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
27.85434%
This dissertation explores the microstructural properties, flow, and phase behavior of aqueous suspensions of single-walled carbon nanotube (SWNT) and graphene. Liquid phase processing with scalable and industrially viable methods is used for fabrication of basic engineering materials like thin films, coatings and 1-D fibrillar structures. The electro-optical transport properties of these novel materials are characterized. A recipe for formulation of an aqueous colloidal suspension with high SWNT concentration is presented. A combination of two surfactants provides optimal rheological behavior for "rod coating" uniform transparent conductive SWNT thin films, with minimal dewetting, rupture and defects. "Doping" with acids and metallic nanoparticles yield SWNT films with electrical sheet resistance of 100 and 300 OJ sq for respective optical transparency of 70% and 90%. SWNT thin films with local nematic ordering and alignment are fabricated using a "slow vacuum filtration" process. The technique is successfully demonstrated on several aqueous SWNT suspensions, employing different ionic and non-ionic surfactants, as well as on dispersions enriched in metallic SWNTs, produced by density gradient ultracentrifugation. Scanning electron microscopy and image analysis revealed a local nematic order parameter of 8 "" 0.7-0.8 for the SWNT films. Aligned SWNT films and fibers are employed as templates...

Colloidal crystal approach to the fabrication of photonic band gap materials

Jiang, Peng
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text Formato: 208 p.; application/pdf
ENG
Relevância na Pesquisa
28.051003%
Planar single-crystalline colloidal crystals are fabricated by exploiting the spontaneous crystallization of monodisperse silica spheres into close-packed arrays using a convective self-assembly method. Film thicknesses ranging from single monolayers to over 200 layers can be precisely controlled through varying solution concentration and colloid diameter. These high quality periodic arrays exhibit partial photonic band gaps, whose positions and band width depends on the sphere diameters and the number of layers. Their optical transmission is well described by the scalar wave approximation to Maxwell's equations. The thickness dependence of the photonic band gap has also been studied for the first time. Superlattice colloidal crystals comprised of alternating layers of different sphere sizes can also be formed by the convective self-assembly method. The resulting photonic crystal structures exhibit optical properties which resemble the superposition of the properties of each individual component, with additional structure that suggests the onset of superlattice-type miniband formation. These superlattice structures thus provide a new way to couple light into and out of photonic crystals. These planar colloidal films are then used as scaffolds to make macroporous materials with crystalline arrays of voids. Macroporous polymers are formed by filling the interstitial area with monomer which is subsequently polymerized. The silica templates can be removed by etching with hydrofluoric acid. The large voids defined by the silica colloids are not isolated...

Monte Carlo computer simulations and electron microscopy of colloidal cluster formation via emulsion droplet evaporation

Schwarz, Ingmar; Fortini, Andrea; Wagner, Claudia Simone; Wittemann, Alexander; Schmidt, Matthias
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.644565%
We consider a theoretical model for a binary mixture of colloidal particles and spherical emulsion droplets. The hard sphere colloids interact via additional short-ranged attraction and long-ranged repulsion. The droplet-colloid interaction is an attractive well at the droplet surface, which induces the Pickering effect. The droplet-droplet interaction is a hard-core interaction. The droplets shrink in time, which models the evaporation of the dispersed (oil) phase, and we use Monte Carlo simulations for the dynamics. In the experiments, polystyrene particles were assembled using toluene droplets as templates. The arrangement of the particles on the surface of the droplets was analyzed with cryogenic field emission scanning electron microscopy. Before evaporation of the oil, the particle distribution on the droplet surface was found to be disordered in experiments, and the simulations reproduce this effect. After complete evaporation, ordered colloidal clusters are formed that are stable against thermal fluctuations. Both in the simulations and with field emission scanning electron microscopy, we find stable packings that range from doublets, triplets, and tetrahedra to complex polyhedra of colloids. The simulated cluster structures and size distribution agree well with the experimental results. We also simulate hierarchical assembly in a mixture of tetrahedral clusters and droplets...

Layer-by-layer assembly of colloidal particles deposited onto the polymer-grafted elastic substrate

Chen, Kang; Ma, Yu-qiang
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/11/2006
Relevância na Pesquisa
27.85434%
We demonstrate a novel route of spatially organizing the colloid arrangements on the polymer-grafted substrate by use of self-consistent field and density functional theories. We find that grafting of polymers onto a substrate can effectively control spatial dispersions of deposited colloids as a result of the balance between colloidal settling force and entropically elastic force of brushes, and colloids can form unexpected ordered structures on a grafting substrate. The depositing process of colloidal particles onto the elastic "soft" substrate includes two steps: brush-mediated one-dimensional arrangement of colloidal crystals and controlled layer-by-layer growth driven entropically by non-adsorbing polymer solvent with increasing the particles. The result indicates a possibility for the production of highly ordered and defect-free structures by simply using the grafted substrate instead of periodically patterned templates, under appropriate selection of colloidal size, effective depositing potential, and brush coverage density.

Clays: Colloidal Properties in Nanodomain

Siddhartha S. Mukhopadhyay
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Conferência ou Objeto de Conferência
Relevância na Pesquisa
27.441345%
The ever-growing application of clays in nanotechnology rests on fundamental principles of colloid chemistry. They make soils as nature’s great electrostatic chemical reactor. Highly anisotropic and often irregular particle shape, broad particle size distribution, different types of charges within the unit cells, heterogeneity of layer charges, pronounced CEC, dis-articulation and flexibility of layers, and different modes of aggregation make clays different from other colloidal materials. Their inseparable association with the genesis of life on Earth and evolutionary diversification of Neoproterozoic life is a safety-belt of nanotechnology. Nanotechnology promises to be the greatest technological breakthrough in history, doing for our control of matter what computers did for our control of information. The origins of nanoscience can be traced to clay mineralogy and crystallography when it was discovered that clay minerals were crystalline and of micrometer size. The unit cell dimensions of clay minerals are in nanometer scale in all three axes (x, y, and z). The advantages of clays are: (i) their ordered arrangements, (ii) their large adsorption capacity, (iii) their shielding against sunlight (ultraviolet radiation)...