Copper-responsive magnetic resonance imaging contrast agents.

The design, synthesis, and evaluation of the Copper-Gad (CG) family, a new class of copper-activated magnetic resonance imaging (MRI) contrast agents, are presented. These indicators comprise a Gd(3+)-DO3A core coupled to various thioether-rich receptors for copper-induced relaxivity switching. In the absence of copper ions, inner-sphere water binding to the Gd(3+) chelate is restricted, resulting in low longitudinal relaxivity values (r(1) = 1.

A selective fluorescent sensor for detecting lead in living cells.

We present the synthesis, properties, and biological applications of Leadfluor-1 (LF1), a new water-soluble, turn-on fluorescent sensor that is capable of selectively imaging Pb2+ in aqueous solution and in living cells. LF1 combines a fluorescein chromophore and a pseudocrown receptor to provide good selectivity for Pb2+ over a range of biologically and environmentally relevant metal ions in aqueous solution, with sensitivity to parts per billion EPA limits for allowable lead in drinking water. In addition to these attributes, imaging experiments further show that LF1 is the first small-molecule reagent that can be delivered into living cells and report changes in intracellular Pb2+ levels.

Screening mercury levels in fish with a selective fluorescent chemosensor.

Societal concerns over toxic mercury accumulation in humans from fish and other dietary and environmental sources provide motivation to develop new tools and tactics for mercury detection in a wide range of laboratory and field settings. Here we report the synthesis, properties, and application of a selective and sensitive small-molecule chemosensor for fluorescence screening of mercury levels in fish. Mercuryfluor-1 (MF1) is a water-soluble, fluorescein-based reagent that features excellent selectivity for Hg2+ over competing analytes and the largest turn-on fluorescence response to date (>170-fold increase) for reporting this heavy metal ion in aqueous solution.