In this review, we describe four approaches to the materials synthesis of organized inorganic matter. These include the use of self-assembled organic templates (transcriptive synthesis), cooperative assemblies of templates and building blocks (synergistic synthesis), spatially restricted reaction fields (morphosynthesis), and combinations of these approaches (integrative synthesis) in the area of sol-gel chemistry. We illustrate these strategies, respectively, by describing recent work on the formation of silica-based organized materials, viz. the preparation of ordered silica macrostructures using bacterial templates, templatedirected synthesis of ordered hybrid mesophases and organoclays, synthesis of microskeletal frameworks of silica and other metal oxides in compartmentalized liquids, and use of bacterial superstructures in the fabrication of hierarchical macrostructures of mesoscopically ordered silica.

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Silver or gold-containing porous frameworks have been used extensively in catalysis, electrochemistry, heat dissipation and biofiltration. These materials are often prepared by thermal reduction of metal-ion-impregnated porous insoluble supports (such as alumina and pumice), and have surface areas of about 1 m(2) g(-1), which is typically higher than that obtained for pure metal powders or foils prepared electrolytically or by infiltration and thermal decomposition of insoluble cellulose supports. Starch gels have been used in association with zeolite nanoparticles to produce porous inorganic materials with structural hierarchy, but the use of soft sacrificial templates in the synthesis of metallic sponges has not been investigated. Here we demonstrate that self-supporting macroporous frameworks of silver, gold and copper oxide, as well as composites of silver/copper oxide or silver/titania can be routinely prepared by heating metal-salt-containing pastes of the polysaccharide, dextran, to temperatures between 500 and 900 degrees C. Magnetic sponges were similarly prepared by replacing the metal salt precursor with preformed iron oxide (magnetite) nanoparticles. The use of dextran as a sacrificial template for the fabrication of metallic and metal oxide sponges should have significant benefits over existing technologies because the method is facile, inexpensive, environmentally benign, and amenable to scale-up and processing.

This Full Paper investigates the adsorption and desorption of the anticancer drugs cis‐diamminedichloroplatinum(II) (CDDP, cisplatin) and the new platinum(II) complex di(ethylenediamineplatinum)medronate (DPM), as well as the clinically relevant bisphosphonate alendronate, towards two biomimetic synthetic HA nanocrystalline materials with either plate‐shaped (HAps) or needle‐shaped (HAns) morphologies and different chemico‐physical properties. The adsorption and desorption kinetics are dependent on the specific properties of the drugs and the morphology of the HA nanoparticles. Adsorption of the platinum complexes occurs with retention of the nitrogen ligands but the chloride ligands of cisplatin are displaced. Despite their opposite charges, the negatively charged alendronate bisphosphonate and the positively charged aquated cisplatin are strongly adsorbed, while the neutral DPM complex shows lower affinity towards the negatively charged apatitic surface. The data suggest that adsorption of the two platinum complexes is driven by electrostatic attractions, while interaction between the alendronate and the HA surface takes place by ligand exchange in which the two phosphonate groups of the drug molecule replace two surface phosphate groups. Significantly, adsorption of positively charged hydrolysis species of cisplatin is more favored on the phosphate‐rich HAns surface while adsorption of negatively charged alendronate is more favored on the calcium‐rich HAps surface. The latter type of short‐range electrostatic interactions also appear to dominate the desorption kinetics; consequently, drug release is greater for neutral DPM than for charged alendronate and aquated cisplatin. Moreover, while the release per unit area of charged species is the same for the two types of HAs, the release of DPM is faster from HAns, which is lower in surface calcium, than for HAps. Overall, this work demonstrates that the properties of HA nanocrystals can be modulated in such a way to produce HA/biomolecule conjugates tailored for specific therapeutic applications.

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distribution of 2.0 ml of a 0.32 % (w/w) complex-dispersion uniformly on a 100´100 mm large sheet at 50 C. For this an air-brush was employed. The complex was dried for 30 min at 70 C in an air stream, followed by washing with water for 5 min and subsequent drying for 30 min at 70 C. Washing with water was performed to remove excess surfactant and lithium ions. In the final step the complex surface was polished with a soft cotton tissue. This procedure results in coatings with a thickness of about 400 nm as determined using a Surface profiler Dektak 3 ST from Veeco Instruments. Contact angle measurements were performed on a Krüss G10 contact angle goniometer. The contact angles reported are the average from five measurements. The advancing contact angle was read by injecting a 5 mL liquid drop. The receding contact angle was measured by removing about 3 mL of liquid from the drop, and the static contact angle was obtained from a drop (ca. 5 mL) on the surface. Linear alkanes, methyl-terminated poly-(dimethylsiloxane) oligomer (Geltest Inc.), a-bromonaphthalene, diiodomethane and water (millipore) were used as standards to measure the critical surface tension. Wide angle X-ray scattering (WAXS) measurements were carried out with a Nonius PDS120 powder diffractometer in transmission geometry. A FR590 generator was used as the source for Cu Ka radiation, monochromatization of the primary beam was achieved by means of a curved Ge crystal, and the scattered radiation was measured with a Nonius CPS120 positionsensitive detector. The resolution of this detector is better than 0.018.Small-angle scattering measurements were recorded with an X-ray vacuum camera with a pinhole collimator (Anton Paar, Austria; model A-8054) equipped with image plates (type BAS III, Fuji, Japan). The image plates were read with a MACScience Dip-Scanner IPR-420 and IP reader DIPR-420 (Japan).

Double-hydrophilic block copolymers consisting of a long poly(ethylene oxide) block and a short poly(methacrylic acid) block, modified by partial alkylation with dodecylamine (PEO-b-PMAA-C 12 ) were employed as dispersed templates for the controlled precipitation of calcium phosphate from aqueous solution at different pH values. Two new and nontrivial superstructures of an organized inorganic/organic hybrid material were characterized by ultracentrifugation, small-and wide-angle X-ray analysis, and electron microscopy. At pH 3.5 and 4.0, and pH 4.5, 5.0, and 6.3, two different types of discrete nested structures are obtained which consist of hybrid nanofilaments arranged to give an unusual neuronlike morphology. The fibers originate from a core of similar size to the primary polymer aggregates, suggesting that cooperative interactions at a local level between dissolving calcium phosphate clusters and disassembling polymer units could be responsible for the highly anisotropic nature of the secondary growth process.Aging of the nanofilaments grown in acidic solution results in a second hybrid morphology, consisting of compact aggregates with a diameter of about 130 nm, which show the interlocked layer structure of an ordered inorganic/ organic mesophase with a repeat period of about 3 nm. Such calcium phosphate/ polymer nanohybrids with complex morphologies are interesting from the viewpoint of prebiotic structure formation, and might also be useful as novel ceramics precursors, reinforcing fillers, or biomedical implants.