Hierarchically porous hybrid microparticles, strikingly reminiscent in their structure of the silica skeletons of single-cell algae, diatoms, but composed of titanium dioxide, and the chemically bound amphiphilic amino acids or small proteins can be prepared by a simple one-step biomimetic procedure, using hydrolysis of titanium alkoxides modified by these ligands. The growth of the hierarchical structure results from the conditions mimicking the growth of skeletons in real diatoms--the self-assembly of hydrolysis-generated titanium dioxide nanoparticles, templated by the microemulsion, originating from mixing the hydrocarbon solvent and water on action of amino acids as surfactants. The obtained microsize nanoparticle aggregates possess remarkable chemical and thermal stability and are promising substrates for applications in drug delivery and catalysis. They can be provided with pronounced surface chirality through application of chiral modifying ligands. They display also high selectivity in sorption of phosphorylated biomolecules or medicines as demonstrated by (1)H and (31)P NMR studies and by in vitro modeling using (32)P-marked ATP as a substrate. The release of the adsorbed model compounds in an inert medium is a very slow process directed by desorption kinetics. It is enhanced, however, noticeably in contact with biological fluids modeling those of the tissues suffering inflammation, which makes the produced material highly attractive for application in medical implants. The developed synthetic approach has been applied successfully also for the preparation of analogous hybrid microparticles based on zirconium dioxide or aluminum sesquioxide.

A combination of original, powerful characterization techniques was used to make a thorough description of solid geopolymers and of the associated effect of varying the alkali cation sourceNaOH, KOH, or CsOHand aging for up to several years. More specifically, the local and pore structures were progressively determined from atomic local scale up to several nanometers by pair distribution function analysis (PDF), small-angle X-ray scattering (SAXS), and longer correlation concerning the pore network, and possible diffusion and accumulation phenomena were unraveled by thermoporosimetry and electrochemical impedance spectroscopy (EIS), respectively. These complementary observations resulted in a picture of an interface between the mineral and the porous network that was correlated to the solvated alkali cation present in the porous solution. After a short time of a few months, the Na-based geopolymer was found to exhibit a smooth interface built up from small "elementary" particles. This contrasted with the K-and Cs-based geopolymers, which presented developed interfaces arising from hierarchically organized smooth particles forming aggregates of fractal outer surface. This striking difference unraveled by SAXS and EIS is ascribed for the Na geopolymer to the contact of the solvated Na(H 2 O) x + cations with the amorphous mineral surface. The K(H 2 O) x + and Cs(H 2 O) x + solvated cations were an integral part of the porous solution, without direct contact with the mineral surface, thus leading to apparently rough interfaces. Dewatering occurred with time, mostly impacting the Na series. Overall, we obtained a detailed picture of the geopolymer series and their changes in time. The environment generated around the kosmotropic (ordermaking) Na + alkali cation was more prone to change upon aging toward a non-Debye type relaxation than the initially developed interface supplied by the chaotropic Cs + alkali cation, which was found to be relatively stable after 5 years. INTRODUCTIONGeopolymers are a class of largely X-ray amorphous threedimensional aluminosilicate binder materials, synthesized by the reaction of an aluminosilicate powder with a concentrated alkali metal silicate or hydroxide solution. 1 The geopolymerization mechanism is well described 2 and agreed upon, 3,4 proceeding with a dissolution−polycondensation that yields a gel of a three-dimensional network subsequently turning into a solid-state material through a structural reorganization of the binder. 5 The synthesis conditions, particularly the temperature, 5,6 and the reactants (aluminosilicate source and the nature and concentration of the alkali ions added to the activation solution) 6−9 are of prime importance for the