Aldo Ponce

Nanocrystalline Metal Oxides as Unique Chemical Reagents/Sorbents

A new family of porous inorganic solids based on nanocrystalline metal oxides is discussed. These materials, made up of 4-7 nm MgO, CaO, Al2O3, ZnO, and others, exhibit unparalleled destructive adsorption properties for acid gases, polar organics, and even chemical/biological warfare agents. These unique sorption properties are due to nanocrystal shape, polar surfaces, and high surface areas. Free-flowing powders or consolidated pellets are effective, and pore structure can be controlled by consolidation pressures. Chemical properties can be adjusted by choice of metal oxide as well as by incorporating other oxides as monolayer films.

Differential Binding of Mutant (R116C) and Wildtype AlphaA Crystallin to Actin

Purpose: Quantitate the interaction of mutant (R116C) and wildtype human alphaA crystallins with actin. Methods: AlphaA crystallins, expressed in a recombinant system, were purified, followed by passage through an actin affinity column. Results: Binding of mutant alphaA crystallin was significantly less than binding of wildtype alphaA crystallin. Conclusions: The R116C mutation of alphaA crystallin found in human cataracts binds less to the cytoskeletal component actin. Since both alphaA crystallin and actin are necessary for proper development of the lens, decreased binding of the mutant protein to actin may perturb normal differentiation processes of lens cells which are necessary for transparency.

Nanocrystal Superlattices of Copper, Silver and Gold, by Nanomachining

Synthesis of metallic nanoparticles has captured the attention of scientists for decades, especially for their application in the area of catalysis, but more recently due to their unusual properties, different from those of the atomic or bulk metal. In addition, ordered structures of metallic nanoparticles display properties that lie between those of the isolated particles and the bulk material. Nanoparticles can act as building blocks to form well-organized structures, known as nanocrystal superlattices (NCSL). A narrow particle size distribution is required to obtain long-range superlattice ordering. The collective properties of metallic NCSL can be engineered by controlling the particle size and the type of ligand used to stabilize the colloidal system. The most widely studied metallic systems have been the ones prepared using gold nanoparticles [1,2,3], but there are other studies where silver [4,5,6,7], and cobalt [8] have been used to prepare NCSL. In this paper, we present for the first time the synthesis of NCSL by selfassembly of thiol stabilized copper nanoparticles, which have been prepared using the solvated metal atom dispersion (SMAD) method. The main advantage of the SMAD technique is that it allows us to prepare large quantities of the metal colloid, free of impurities. This is in great contrast to other techniques such as chemical reduction. A novel method discovered in our laboratories [9,10,11], called “digestive ripening” (i.e. allowing sufficient time and temperature (usually at the solvent’s boiling point) to attain a structural equilibrium.), has been used to attain a narrow particle size distribution. The same procedure as described here has previously been used to prepare NCSL from gold and silver colloids. Herein, it is shown to be applicable for copper as well.