Fluorescent peptidyl chemosensors for the measurement of divalent metal cation concentrations

Citation

Walkup, Grant Kingsley (1998) Fluorescent peptidyl chemosensors for the measurement of divalent metal cation concentrations. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/q7ve-nc61. https://resolver.caltech.edu/CaltechTHESIS:11212012-122025163

Abstract

Studies toward the production of fluorescent chemosensors for trace divalent metal ions have been conducted, with emphasis placed on the attainment of sufficient analyte selectivity and sensitivity for the measurement of environmental or biomedical samples. One technique that has historically been applied for the design of selective metal ion sensors is to prepare biosensors, devices that exploit proteins for their unmatched specificity in the recognition of small molecules. Alternately, the construction of abiotic chemosensors has been favored by other researchers, but the synthetic simplicity and enhanced durability exhibited by these agents comes at the expense of analyte-detection selectivity. By applying a strategy that is a hybrid of these approaches, selective and sensitive chemosensors for divalent zinc, copper, and nickel have been prepared. These devices combine the advantageous aspects of biosensors within a peptidyl architecture that by virtue of its synthetic origin contains an expanded repertoire of amino acids for metal ion binding and signaling.

Fluorescent chemosensors for Zn(II) have been prepared that are based upon the zinc finger domains and enable the quantitation of sub-micromolar concentrations of that ion in the presence of many other divalent ions. In addition, other fluorosensors have been prepared that employ nonnatural alpha-amino acid derivatives that contain the bidentate metal binding functionality of oxine (8-hydroxyquinoline). These also enable the selective detection of sub-micromolar concentrations of Zn(II), but require only seven amino acid residues as opposed to the 25 present in the zinc finger-based sensors.

By exploiting the metal binding properties of the amino terminal Cu(II)- and Ni(II)-binding (ATCUN) motif of the serum albumins, sensors have been prepared which enable the selective determination of sub-micromolar concentrations of the Cu(II) ion, even in the presence of elevated concentrations of Ni(II). Sensors for Ni(II) that employ a fluorescence resonance energy transer (FRET) mechanism for analyte detection have also been prepared. In addition, studies have been performed to convert these solution based chemosensing reagents into solid phase-attached devices, in order to perform realtime measurements with regenerable sensing materials.

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