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To support the development and implementation of biological monitoring programs, we need quantitative technologies for measuring xenobiotic exposure. Microanalytical based sensors that work with complex biomatrices such as blood, urine, or saliva are being developed and validated and will improve our ability to make definitive associations between chemical exposures and disease. Among toxic metals, lead continues to be one of the most problematic. Despite considerable efforts to identify and eliminate Pb exposure sources, this metal remains a significant health concern, particularly for young children. Ongoing research focuses on the development of portable metal analyzers that have many advantages over current available technologies, thus potentially representing the next generation of toxic metal analyzers. In this article, we highlight the development and validation of two classes of metal analyzers for the voltammetric detection of Pb, including: a) an analyzer based on flow injection analysis and anodic stripping voltammetry at a mercury-film electrode, and b) Hg-free metal analyzers employing adsorptive stripping voltammetry and novel nanostructure materials that include the self-assembled monolayers on mesoporous supports and carbon nanotubes. These sensors have been optimized to detect Pb in urine, blood, and saliva as accurately as the state-of-the-art inductively coupled plasma-mass spectrometry with high reproducibility, and sensitivity allows. These improved and portable analytical sensor platforms will facilitate our ability to conduct biological monitoring programs to understand the relationship between chemical exposure assessment and disease outcomes. Key words: biomonitoring, dosimetry technology, electrochemical sensors, exposure assessment, lead (Pb). Environ Health Perspect 115:1683-1690 (2007). doi:10.1289/ehp.10190 available via http://dx.doi.org/ [Online 21 September 2007], Biological monitoring (biomonitoring) can integrate total exposure to a chemical from all potential sources (i.e., air, soil, water, and food residues) and exposure routes (i.e., inhalation, oral, and dermal), thereby [...]

Rhodium(II) acetate catalyzes the formation of cyclic carbonyl ylides from acyclic 5-alkenyl-1-diazo-2,5-pentadiones, with the alkenyl group serving as a tether. When the tether has three to four methylenes and is attached to the positive end of the zwitterion, it readily undergoes intramolecular cycloaddition to form a tricyclic compound. Shorter or longer tethers impose too much steric strain on the transition state to allow cyclization. Upon intervention of an ester function, the dipole fails to undergo internal cyclization even though bimolecular trapping studies show that the ylide indeedis formed.

Nanoporous tin(II/IV) phosphate materials, with spherical morphology, are synthesized using cetyltrimethylammonium chloride [CH3(CH2)15N(CH3)3Cl] as the surfactant. Results reveal that tin(II) phosphate removes >95% of all contaminants investigated from solution.

A facile and effective method for the modification of multiwall carbon nanotubes with molecular anchor molecules is described using supercritical fluids (SCFs). It represents a potential advantage of SCFs over liquid solvents for anchor deposition.

A novel, inexpensive bifunctional trifluoroethylester (TFEE) poly(ethylene glycol)(PEG) silane that has low molecular weight and can be easily self-assemble on metal oxide based nanoparticles. The functional PEG silane allows covalent immobilization of PEG to the nanoparticle surface to increase particle circulation time in blood and particulate dispersion.

An attempt was made to prepare thermal-sensitive surfaces by grafting poly(N-isopropylacrylamide) PNIPAAm on the surface of silicone wafers without a cross-linking agent. Dramatic changes of the hydrophilic/hydrophobic surface were observed by investigating the variation of the advancing contact angles.

Molecular conformations and assembly mechanisms are discussed and the principles involved in fabricating sophisticated molecular structures in the pore channels are illustrated. In conclusion, the assembly of multifunctional groups and structures would allow the development of sophisticated nanoscale materials with 'enzyme mimic' and 'biomimic' properties.

After nuclear disasters, there is a need to monitor released radionuclides in aquatic systems. A novel in situ gamma spectrometer deployable on mobile and stationary platforms can detect individual radionuclides, provided concentrations are high enough. Owing to rapid dilution effects, efficient sorbents are needed for preconcentration of radionuclides. Here, we report results of particle-water distribution coefficients, KD, on three novel MnO2 sorbents mounted in high-capacity cartridges using a set of artificial (57Co, 106Ru, 125Sb, 133Ba, 137Cs) and natural (7Be, 210Pb, 233Pa, 234Th) radionuclides in small batch experiments. Compared with conventionally impregnated MnO2 sorbents, novel nanostructured MnO2 sorbents displayed superior sorption for some artificial radionuclides, displaying up to one order of magnitude greater KD values than traditionally impregnated MnO2. In particular, the log KD value of 210Pb was highest (4.48 ± 0.23) compared with all values using the other MnO2 sorbents, whereas that of 233Pa was among the lowest (3.24 ± 0.16). These results promise some improvements for capturing not only artificially produced radionuclides, but also naturally produced 7Be from seawater using nanostructured MnO2. We also show that colloidal forms of selected radionuclides are not captured by MnO2 phases. If they could be sorbed by another sorbent, KD values could be considerably higher for Th, Po and other radionuclides. Finally, our results might add further complexities to the discussion of the potential of Th/Pa fractionation by MnO2 phases in seawater. [ABSTRACT FROM AUTHOR]