Inorganic nanomaterials hybridized with other functional inorganic, organic, and/or bio molecules are attracting great interest in science and technology. This review demonstrates the bio-inorganic nanohybrids with drug delivery function, where drug or gene molecules are intercalted into the layered double hydroxide (LDH), anionic clay. The enhanced drug efficacy of drug-LDH nanohybrids are described in detail with the biocompatibility of LDH, delivery vehicle. According to the cellular uptake experiments on various cell culture lines, we could conclude that the LDH nanoparticles are internalized into cells via clathrin-mediated endocytosis, delivering encapsulated drugs efficiently.

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Smart nanocomposites of the conducting polymers such as polyaniline and polypyrrole with clay were investigated especially for electro-responsive electrorheological (ER) materials. These conducting polymer/clay nanocomposites were prepared via either in-situ polymerization, emulsion polymerization or solvent intercalation as well as pickering emulsion. Internal structure and thermal properties of these nanocomposites were examined via XRD, TEM, and thermogravimetric analyzer. Moreover, their ER behaviors were measured via a rotational rheometer with an external electric field controller. ER fluids based on different conducting polymer/clay nanocomposites demonstrated diverse ER characteristics such as yield stress and flow curve. Typical models were also used to investigate the rheological behaviors of the polymer/clay based ER fluid.

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Environmental nanoparticles exist in the hydrosphere, pedosphere, biosphere and atmosphere. However, efficiently collecting nanoparticles in large quantities of time consuming from both pure and natural systems is a major challenge in nanoscience. This review paper aimed to use zeolite A and highly weathered red soils as examples, employed an automated ultrafiltration device (AUD) to fractionate nanoparticles (i.e., 1-100nm) from aqueous suspensions, and characterized the properties of nanoparticles. We have successfully overcome the problems and collected large quantities of nanoparticles with AUD system. Freeze-dried zeolite A and soil nanoparticles were characterized by conventional and synchrotron X-ray diffraction (XRD) with petrographic glass slides of oriented samples and random powder samples, as well as by synchrotron powder XRD analysis. The chemical properties of a zeolite are dependent on its framework structure, which is formed by connecting truncated octahedra (sodalite) through the simple double four rings (D4-R) with external linkage in each sodalite. With decreasing particle size, the T(Si, Al)-O asymmetric and symmetric stretching vibrations shifted toward higher frequencies and the Si to Al molar ratio increased consistently from 1.8 to 5.2. Comparing the various particle-size fractions (PSFs) showed significant differences in surface area, Si to Al molar ratio, morphology, crystallinity, framework structure, and surface atomic structure of nanoparticles from those of the bulk sample (i.e., <2000nm) prior to particle-size fractionations. Our results reveal the degree of crystallinity of the soil particles, and they can be used to identify the presence or absence of minerals at various PSFs (450-2000, 100-450, and 1-100nm). Kaolinite, illite, goethite and hematite were identified in the 1-100nm size fraction by synchrotron high-resolution XRD and by transmission electron microscopy (TEM). The XRD patterns of the various PSFs, shows that synchrotron XRD is better at identifying soil nanoparticles (1-100nm) than conventional XRD using powder samples due to its use of higher photon energies. Synchrotron XRD analysis is also a more straightforward and powerful technique for identifying mineral nanoparticles, particularly those of phyllosilicate minerals.

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Layered double hydroxides (LDHs) are class of materials with useful properties associated with their anion exchange abilities for a wide range of applications including bio and environmental problems. Synthetic methods have been examined to prepare LDHs with controlled structure, composition and particle morphology. Co-precipitation is a method used most widely while efforts have been made to conduct under controlled reactions conditions. In the present review article, synthetic methods for LDHs are overviewed with the emphasis on the authors' contribution.

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Extracellular proteins are important biological molecules present in the various earth surface environments. These proteins have a strong adsorption affinity for the mineral surfaces, however there is little information about the effects on the rate and extent of mineral dissolution. Recent experimental studies of amorphous silica dissolution by interaction with bovine serum albumin (BSA) and related organic molecules such as amino acids and some heterocyclic compounds indicate that these molecules exhibit significant rate-enhancement effects on the dissolution of amorphous silica depending mainly on their functional properties. This paper summarizes the rate-enhancement effects of these organic molecules on amorphous silica dissolution, and discusses the interaction mechanism enhancing the dissolution.

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