Beryllium is the second lightest metal, has a high melting point and high strength-to-weight ratio, and is chemically stable. These unique chemical characteristics make beryllium metal an ideal choice as a component material for a wide variety of applications in aerospace, defense, nuclear weapons, and industry. However, inhalation of beryllium dust or fumes induces significant health effects, including chronic beryllium disease and lung cancer. In this study, the mutagenicity of beryllium sulfate (BeSO(4)) and the comutagenicity of beryllium with a known mutagen 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) were evaluated using a forward mutant detection system developed in Escherichia coli. In this system, BeSO(4) was shown to be weakly mutagenic alone and significantly enhanced the mutagenicity of MNNG up to 3.5-fold over MNNG alone. Based on these results a proteomic study was conducted to identify the proteins regulated by BeSO(4). Using the techniques of 2-DE and oMALDI-TOF MS, we successfully identified 32 proteins being differentially regulated by beryllium and/or MNNG in the E. coli test system. This is the first study to describe the proteins regulated by beryllium in vitro, and the results suggest several potential pathways for the focus of further research into the mechanisms underlying beryllium-induced genotoxicity.

Eine edle Struktur: Eine Heterometallspezies mit einer Struktur, die der natürlichen Beryllstruktur ähnelt, ist der 1:1:2-Titelkomplex (siehe Struktur). Sein Kern besteht aus sich abwechselnden Al- und Be-Atomen, die durch die aliphatischen Zitronensäure-Hydroxygruppen verbrückt sind. Ein 1:1:1-Komplex, der aus einem Phosphatpuffer erhalten wurde, besteht aus Clustern aus sechs Al-Be-Citrat-Spezies, die durch Phosphatgruppen verbrückt sind.

Beryllium speciation at physiological conditions is critical to understanding chronic beryllium disease (CBD). The MHC-class II receptor alleles that have been linked to CBD have more than six carboxylates in a short 20 amino acid segment of the binding pocket and it has been suggested that beryllium may bind within the MHC-class II receptor via the carboxylates. Previous reports also show that citric acid binds beryllium significantly stronger than similar carboxylate ligands such as tartaric acid and is one of the few ligands that can compete with hydrolysis to solubilize beryllium across the entire pH range at molar concentrations. We have characterized the binding of Be to citric acid and shown using a combination of NMR, mass spectrometry and ligand competition studies that Be2L and Be4L2 species dominate. A Be-O-Be linkage with the bridging oxygen coming from the aliphatic alcohol is critical to the stability of the complex. We show through competition experiments that the most stable Be-O-Be arrangement has one Be in a five-member ring and the other Be in a six-member ring. The unusual deprotonation of an aliphatic alcohol (pK(a) = 18) at neutral pH has significant ramifications on the potential interactions of Be with biological ligands such as carbohydrates and Ser and Thr residues.

We report on a fluorescent test for beryllium designed for analyzing swipes. The detection is rapid, quantitative and deployable in the field with $5,000 portable fluorimeter. Swipes are placed in a vial and a dilution solution is added. The vials are then rotated for 30 minutes and then syringe filtered. An aliquot of 100 pL is added to a detector solution and fluorescence measured with a portable ocean optics unit. We can readily detect down to 0.02 {micro}g on a filter paper. Interference studies have been carried out with various metals including Al, Fe, Pb, U, Ca, W, Ni, Co and Cu. The technique has proven to be successful under various conditions including a variety of surfaces both in the lab and in field. It is a user-friendly, cost effective method.

The applicability of water-soluble polymers as extractants for the remediation of heavy metal-contaminated soils has been explored using a lead-contaminated Superfund soil as a sample system. Polyethylenimine (PEI) was functionalized with bromo- or chloroacetic acid to give an aminocarboxylate chelating group, which effectively binds lead. The resulting polymer, PEIC, has extraction properties similar to the molecular chelator ethylenediaminetetraacetic acid. A series of studies was done to probe optimum conditions for lead extraction from soils obtained from the Cal-West Superfund site in New Mexico that contained approximately 10,000 ppm of Pb. In batch extraction experiments using polymer functionalized at two different levels, the polymers removed greater than 97% of the lead from the soils. Subsequent experiments demonstrated that the selective extraction of lead could be controlled by varying polymer functionalization levels. Concentration and regeneration of the polymers using ultrafiltration was also demonstrated. Release of lead from the polymer was accomplished by acidification to pH 1 with HCl. Subsequent ultrafiltration allowed recovery of the extractant polymer for reuse.

We investigated water-soluble dendrimers and polymers as ligands for selective anion binding. PAMAM Starburst dendrimers and polyethylenimine have been chemically modified to incorporate new ligands or hydrogen bonding groups at the primary amines. These molecules, along with the unmodified parent compounds, bind arsenate, chromate, and phosphate, even in the presence of competing anions such as chloride. Such systems could potentially be employed for remediation of contaminated water and soils using well-established ultrafiltration technology. Selectivity is achieved through bringing together moieties with a combination of electrostatic and hydrogen bonding capabilities. Total binding capacity for several metallooxyanions has been determined, as well as relative ion selectivity.

In an effort to understand the molecular basis of chronic beryllium disease (CBD), a study of the chemical relationship between beryllium, antigen, and the major histocompatibility complex II, HLA-DP, was undertaken. A homology model of the HLA-DP protein was developed. An analysis of the sequences of HLA-DPB1 and HLA-DPA1 alleles most common among CBD patients revealed several carboxylate rich regions in the peptide-binding cleft. These regions contain many hard Lewis base sites that may provide bonding opportunities for beryllium, a hard Lewis acid. Quantum chemistry calculations and structural database results support the presence of beryllium clusters, bridged by carboxylate, hydroxo, and/or oxo ligands, in the HLA-DP binding cleft. These results strongly suggest that beryllium clusters are an integral part of the antigen, and may even act solely as antigen. This work provides an initial model for thinking about beryllium interactions with proteins relevant to CBD and other metal-induced diseases.

A series of polyethylenimine (PEI)-based water-soluble polymers (WSPs) were prepared by attaching functional groups (beta-diketones, carboxylic acid, salicylic acids) to the polymer backbone, with the goal of characterizing the interaction between beryllium and the various polymers. The extraction of beryllium from aqueous solutions by the WSPs was examined as a function of pH and ionic strength to evaluate the potential for the WSPs to isolate beryllium from contaminated aqueous waste streams. The loading capacities of these polymers for beryllium at near-neutral pH were unusually high in the absence of ionic strength adjustment compared to that for other +2 cations, suggesting that polynuclear beryllium species were interacting with the polymers. Beryllium loading capacity values were similar for all polymers evaluated in the absence of ionic strength adjustment. However, when the ionic strength of the solutions was adjusted to 0.1 N (NaNO3) the loading capacities were significantly reduced, indicating that electrostatic attraction played a dominant role in the interaction between beryllium and the polymers. The extraction curves of beryllium for all polymers evaluated, even those not designed to be selective for beryllium extraction, were nearly identical irrespective of the nature of the functional groups. Collectively, these results suggest that oligomeric beryllium species were formed, which can bind to the polymers through a combination of electrostatic forces and, potentially, hydrogen bonding.

We report on the development of membranes with an ultra-thin hydrophobic layer that can be used to support a liquid membrane or serve as a selective gate without further modification when the pore size is small enough. We use a thin layer of gold deposited on commercially available alumina supports to generate a layer on the surface that can be readily modified with thiols to control the hydrophobicity. Transport of 2,4,6-trichlorophenol (TCP) was attained with thiol-modified gold-coated alumina membranes sealed with dodecane. The flux rates through these membranes are five times faster than control experiments through unmodified membranes and show complete selectivity. This provides strong evidence that the flux rates are high enough to be limited by simple diffusion through the alumina support. We have also demonstrated that it is possible to make ultra-thin gates with the alkyl chain itself serving as the hydrophobic barrier. With a 17 carbon chain thiol attached to the membrane in the absence of dodecane, quantitative transport is observed with the same high flux rates observed for the dodecane-treated membranes. Fixing the hydrophobic barrier to the surface should allow for more stable membranes.

Thin layers of gold (700Å) were deposited on manufactured alumina pourous supports to yield nanopores with openings of <7nm. A self-assembled monolayer (SAM) of alkyl thiols was then attached to provide a hydrophobic support for trialkyl phosphine oxide-based metal ion carriers. The resulting gated membranes provided a barrier to ions including H+, and Ca2+, NO3−, and CH3COO−. When an aqueous feed solution of 4.2mM uranyl nitrate and 1M lithium nitrate pH 4, and a receiving solution of 1M sodium acetate pH 5.5 were used 100% of the metal was transported across the membrane by facilitated transport via the phosphate or phosphine oxide carrier. The thin gates transported metal ions as neutral nitrate complexes with fluxes high enough to be limited by the alumina support. The flux rates of 200,000 metal ions per pore per second are only a factor of 5 below that observed for the potassium channel. High selectivity of U over Eu is observed until the [U] is <0.84mM in the feed solution, despite the fact the Eu actually transports faster when U is not present. This work demonstrates that selectivity can be added without impeding transport by using thin selective layers.