Template packing structure

Three-dimensionally ordered macroporous ceramic with high LR ion conductivity was prepared by colloidal crystal templating method using monodispersed polystyrene beads [12]. Monodispersed polystyrene beads with 3 pm diameter were dispersed in water and then filtrated by using a membrane filter under a small pressure difference. After this treatment, polystyrene beads were accumulated on the membrane filter with closed pack structure, as shown in Fig. 4.2. Then, the membrane consisting of accumulated polystyrene beads was removed from the membrane filter and put on a glass substrate. After drying at room temperature, the... 

In the present section, we cover the two steps for creating stationary phases from colloidal assembly. In the first step, the colloids are assembled into a regular, close-packed structure through the evaporation of the solvent or a flow-through system. As we will see later, the colloidal crystal, when filled with electrophoresis buffer, can be used directly as a solid support for capillary electrophoresis [20,21]. Alternatively, a polymeric structure can be formed around the bead template. After dissolving the beads, one is left with a regular structure of cavities and pores that can also serve as an electrophoresis support [22]. 

Monodisperse latex spheres of a controlled size can be arranged into three-dimensional arrays and are used as templates to prepare well-defined cavities and structures once the latex sphere template has been removed. These latex spheres are identical to one another in size and shape and are often prepared from colloidal clusters resulting from the aggregation of sol-gel colloids (Section 5.6). The spherical polymer clusters can be fabricated by the slow addition of an aqueous solution into a reservoir of hydrophobic silicone liquid, forming emulsion droplets. This produces a highly structured porous matrix with a well-defined structure upon polymerisation. The size of the droplets is controlled by the concentration of the aqueous latex, the speed at which the suspension is stirred and the ratio between the silicone liquid and latex. As the concentration of the latex spheres increases to its critical concentration, i.e. the concentration at which the colloidal spheres start to order themselves into a close-packed structure, the balls are filtered off and are dried, ready to be used as templates. 

Pander J W and F M Richards 1987. Tertiary Templates for Proteins. Use of Packing Criteria in Enumeration of Allowed Sequences for Different Structural Classes. Journal of Molecular Bio 193 775-791. 

JW Ponder, FM Richards. Tertiary templates for proteins Use of packing criteria m the enumeration of allowed sequences for different structural classes. J Mol Biol 193 775-792, 1987. 

The use of DNA as a template to fabricate mesoscale structures was also demonstrated in a recent work of Torimoto and coworkers. They used preformed, positively charged 3-nm CdS nanoparticles with a thiocholine-modified surface to be assembled into chains by using the electrostatic interaction between positively charged nanoparticle snr-faces and the phosphate groups of DNA. As determined by TEM analysis, the CdS nanoparticles were arranged in a qnasi-one-dimensional dense packing. This revealed interparticle distances of about 3.5 nm, which is almost equal to the height of one helical tnm of the DNA double strand [98]. 

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