Submicron hard X-ray fluorescence imaging of synthetic elements.

Synchrotron-based X-ray fluorescence microscopy (XFM) using hard X-rays focused into sub-micron spots is a powerful technique for elemental quantification and mapping, as well as microspectroscopic measurements such as μ-XANES (X-ray absorption near edge structure). We have used XFM to image and simultaneously quantify the transuranic element plutonium at the L(3) or L(2)-edge as well as Th and lighter biologically essential elements in individual rat pheochromocytoma (PC12) cells after exposure to the long-lived plutonium isotope (242)Pu. Elemental maps demonstrate that plutonium localizes principally in the cytoplasm of the cells and avoids the cell nucleus, which is marked by the highest concentrations of phosphorus and zinc, under the conditions of our experiments.

A proteomic approach to identification of plutonium-binding proteins in mammalian cells.

Plutonium can enter the body through different routes and remains there for decades; however its specific biochemical interactions are poorly defined. We, for the first time, have studied plutonium-binding proteins using a metalloproteomic approach with rat PC12 cells. A combination of immobilized metal ion chromatography, 2D gel electrophoresis, and mass spectrometry was employed to analyze potential plutonium-binding proteins.

Binding of ReO4(-) with an engineered MoO4(2-)-binding protein: towards a new approach in radiopharmaceutical applications.

Radiolabeled biomolecules are routinely used for clinical diagnostics. (99m)Tc is the most commonly used radioactive tracer in radiopharmaceuticals. (188)Re and (186)Re are also commonly used as radioactive tracers in medicine.

Plutonium uptake and distribution in mammalian cells: molecular vs. polymeric plutonium.

Purpose: To study the cellular responses to molecular and polymeric forms of plutonium using PC12 cells derived from a rat pheochromocytoma.

Materials And Methods: Serum starved PC12 cells were exposed to polymeric and molecular forms of plutonium for 3 h. Cells were washed with 10 mM ethylene glycol tetraacetic acid (EGTA), 100 mM NaCl at pH 7.

Direct determination of the intracellular oxidation state of plutonium.

Microprobe X-ray absorption near edge structure (μ-XANES) measurements were used to determine directly, for the first time, the oxidation state of intracellular plutonium in individual 0.1-μm(2) areas within single rat pheochromocytoma cells (PC12). The living cells were incubated in vitro for 3 h in the presence of Pu added to the media in different oxidation states (Pu(III), Pu(IV), and Pu(VI)) and in different chemical forms.

Polyhistidine fusion proteins can nucleate the growth of CdSe nanoparticles.

A (His-Asn)6 domain fused to fatty acid binding protein provides the low-temperature assembly of CdSe nanoparticles starting with common inorganic salt precursors. This observation is significant, since fusion proteins with this protein domain are common for affinity purification. While not optimized, this domain readily provides CdSe nanoparticles from room-temperature solutions.

Electron donor solvent effects provide biosensing with quantum dots.

A palmitate biosensor that uses the emission intensity of a semiconducting nanoparticle to report palmitate concentration is presented. This method uses electron transfer to quench the emission from a ZnS-coated CdSe nanoparticle. The fatty acid binding pocket of intestinal fatty acid binding protein is used to modulate the electron transfer properties of [Ru(L)(NH3)4](PF6)2 (L = 5-maleimido-1,10-phenanthroline) that is covalently attached within this pocket.