To understand the mechanism of quail eggshell biomineralization, we have performed two CaCO(3) precipitation experiments. In the reprecipitation experiments, supersaturated Ca(HCO(3))(2) was prepared by bubbling CO(2) through a slurry of biogenic CaCO(3) obtained from bleach-treated eggshell followed by filtration to obtain a clear solution for crystallization experiments. The nucleated crystals were collected at various time intervals and analyzed. In the second experiment, the extracted SOM from the bleach-treated eggshell was added to the supersaturated clear solution of Ca(HCO(3))(2) solution obtained by bubbling CO(2) gas through a slurry of synthetic CaCO(3) followed by filtration. The crystals/precipitates collected at various time intervals were analyzed. Both experiments showed that amorphous CaCO(3) (ACC) was precipitated in the early stages, which then transformed to the most stable crystalline calcite phase. Amino acid analysis of the soluble organic matrixes (SOM) indicated the presence of high amounts of Glx and Asx amino acids. Ovomucoid--an acidic glycoprotein, and lysozyme--a basic protein, are the two major components along with a few low molecular weight peptides present in the SOM of quail eggshell matrix. Both ovomucoid and lysozyme did not induce precipitation of the ACC phase in in vitro conditions, while the fraction containing low molecular weight peptides induced the precipitation of ACC, suggesting that the latter play an important role in the eggshell biomineralization. Thus, organisms can produce inorganic minerals which assume nonequilibrium morphologies and intricate architecture by precipitating transient ACC, which then transformed into the crystalline phase. Altogether, these observations further demonstrate that this strategy may be common in both vertebrate and invertebrate mineralized structures.

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We report a simple and effective approach to organize micron- and submicron-sized particles in a size selective manner. This approach utilizes the template assisted directed self-assembly technique. A topographically patterned photoresist surface is fabricated and used to create an ordered array of colloidal particles from their aqueous suspensions. Assembly of particles on this template is then achieved by using a conventional spin coating technique. Feasibility of this technique to form a large area of patterned particle assemblies has been investigated. To arrange the particles on the template, the physical confinement offered by the surface topography must overcome a joint effect of centrifugal force and the hydrophobic nature of the photoresist surface. This concept has been extended to the size selective sorting of colloidal particles. The capability of this technique for sorting and organizing colloidal particles of a particular diameter from a mixture of microspheres is demonstrated.

The direct nanopatterning of polycarbazole on ultrathin films of a "precursor polymer" and monomer under ambient conditions is reported. In contrast to previous reports on electrochemical dip-pen nanolithography using monomer ink or electrolyte-saturated films in electrostatic nanolithography, these features were directly patterned on spin-cast films of carbazole monomer and poly(vinylcarbazole) (PVK) under room temperature and humidity conditions. Using a voltage-biased atomic force microscope (AFM) tip, electric-field-induced polymerization and cross-linking occurred with nanopatterning in these films. Different parameters, including writing speed and bias voltages, were studied to demonstrate line width and patterning geometry control. The conducting property (current-voltage (I-V) curves) of these nanopatterns was also investigated using a conducting-AFM (C-AFM) setup, and the thermal stability of the patterns was evaluated by annealing the polymer/monomer film above the glass transition (T(g)) temperature of the precursor polymer. To the best of our knowledge, this is the first report in which thermally stable conducting nanopatterns were drawn directly on monomer or polymer film substrates using an electrochemical nanolithography technique under ambient conditions.