Converting Layered Zinc Acetate Nanobelts to One-dimensional Structured ZnO Nanoparticle Aggregates and their Photocatalytic Activity

We were successful in synthesizing periodic layered zinc acetate nanobelts through a hydrothermal solution process. One-dimensional structured ZnO nanoparticle aggregate was obtained by simple thermal annealing of the above-mentioned layered ZnO acetate nanobelts at 300 °C. The morphology, microstructure, and composition of the synthesized ZnO and its precursors were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and infrared spectroscopy, respectively. Low angle X-ray diffraction spectra reveal that as-synthesized zinc acetate has a layered structure with two interlayer d-spacings (one is 1.32 nm and the other is 1.91 nm). SEM and TEM indicate that nanobelt precursors were 100–200 nm in width and possesses length up to 30 μm. Calcination of precursor in air results in the formation of one-dimensional structured ZnO nanoparticle aggregates. In addition, the as-prepared ZnO nanoparticle aggregates exhibit high photocatalytic activity for the photocatalytic degradation of methyl orange (MO)

Analysis of the Initiating Events in HIV-1 Particle Assembly and Genome Packaging

HIV-1 Gag drives a number of events during the genesis of virions and is the only viral protein required for the assembly of virus-like particles in vitro and in cells. Although a reasonable understanding of the processes that accompany the later stages of HIV-1 assembly has accrued, events that occur at the initiation of assembly are less well defined. In this regard, important uncertainties include where in the cell Gag first multimerizes and interacts with the viral RNA, and whether Gag-RNA interaction requires or induces Gag multimerization in a living cell. To address these questions, we developed assays in which protein crosslinking and RNA/protein co-immunoprecipitation were coupled with membrane flotation analyses in transfected or infected cells. We found that interaction between Gag and viral RNA occurred in the cytoplasm and was independent of the ability of Gag to localize to the plasma membrane. However, Gag:RNA binding was stabilized by the C-terminal domain (CTD) of capsid (CA), which participates in Gag-Gag interactions. We also found that Gag was present as monomers and low-order multimers (e.g. dimers) but did not form higher-order multimers in the cytoplasm. Rather, high-order multimers formed only at the plasma membrane and required the presence of a membrane-binding signal, but not a Gag domain (the CA-CTD) that is essential for complete particle assembly. Finally, sequential RNA-immunoprecipitation assays indicated that at least a fraction of Gag molecules can form multimers on viral genomes in the cytoplasm. Taken together, our results suggest that HIV-1 particle assembly is initiated by the interaction between Gag and viral RNA in the cytoplasm and that this initial Gag-RNA encounter involves Gag monomers or low order multimers. These interactions per se do not induce or require high-order Gag multimerization in the cytoplasm. Instead, membrane interactions are necessary for higher order Gag multimerization and subsequent particle assembly in cells

Temperature effects on a hydroxyapatite precursor solution

Multinuclear NMR spectroscopy has been used to monitor synthesis of hydroxyapatite (HAp) from diethyl hydrogen phosphonate and calcium diethoxide in solution at two different temperatures. Acetyl 2-hydroxyethyl phosphonate, bis(2-hydroxyethyl) phosphonate, and acetyl ethyl phosphonate have been identified for the first time in this reaction solution as intermediates. The formation of these compounds is shown to be crucial in controlling the phase purity of the final hydroxyapatite product. A possible mechanism for the formation of acetyl 2-hydroxyethyl phosphonate is discussed

Marine Structures as Templates for Biomaterials

During the last two decades, “learning from nature” has given us new directions for the use of natural organic and inorganic skeletons, drug delivery devices, new medical treatment methods initiating unique designs and devices ranging from nano- to macroscale. These materials and designs have been instrumental to introduce the simplest remedies to vital problems in regenerative medicine, providing frameworks and highly accessible sources of osteopromotive analogues, scaffolds and drug delivery device proteins. This is exemplified by the biological effectiveness of marine structures such as corals and shells and sponge skeletons, extracts of spongin and nacre, sea urchin, sea snails and Foraminifera. Organic matrix and inorganic marine skeletons possess a habitat suitable for proliferating added mesenchymal stem cell populations and promoting clinically acceptable bone formation. A wide range of applications of these marine structures and their conversion methods are covered by excellent review papers and chapters. In this chapter based on our research, published work and book chapters, we aim to cover the nature, morphology and the use of some of these structures for tissue engineering, bone grafts, drug delivery and specific extracts such as proteins for regenerative medicine