Signal transduction metal signals

Metal NPs have received tremendous attention in the field of bio-analytical science, in particular the sequence-specific DNA detection [23,24]. This is attributed to their unique properties in the conjugation with biological recognition elements (e.g., DNA oligonucleotide probe) as well as in the signal transduction with optical [22,25], electrical [26], microgravimetric [27] and electrochemical [23,28-30] methods. 

Alkali metal transport in biochemistry is a vital process in maintenance of cell membrane potentials of use, for example, in nerve signal transduction and is at the core of some of the early work on artificial ionophores that mimic natural ion carriers such as valinomycin. Ionophore mediated ion transport is much slower than transport through cation and anion ion channel proteins, however. 

Figure 27.14. Activation of intracellular signaling pathways and cytokine gene expression by air pollution particles containing transition metals and endotoxin. (From Walters, D. M., and Bonner, J. C. Signal transduction and cytokine expression in particulate matter (PM)-induced airway remodeling. In Foster, W. M., and Costa, D. L. (Eds.). Air Pollutants and the Respiratory Tract, 2nd edition, Taylor Francis, New York, 2005, pp. 233-258.)...

Although not an ion, glucose can be detected by virtue of an MIP-derived ion. The pH electrode is simply an ISE for H". Glass and ion-selective field effect transistors pH electrodes are the best characterised and the most successful ISEs. Many sensors employ chemical reactions to produce H" or OH ions and employ pH electrodes for signal transduction. An imprinted sensor based on this approach is the glucose sensor produced by Arnold s group [10]. This polymer employs a metal ion (Cu " ) in the imprinted site and makes use of the metal s... 

Interestingly, if the same titration experiment is performed in presence of any other 3d divalent cation (Mn Fe, Co, Zn ), no fluorescence quenching is observed over the entire 2-12 pH interval. In this connection, it must be noted that deprotonation of the amide groups of the dioxocyclam subunit is an especially endothermic process, which can take place only if the unfavorable heat effect is compensated by the exothermic formation of strong metal-ligand bonds. This situation occurs only with metal ions late in the 3d series, e.g., Ni and Cu , but not with cations earlier in the same series. Thus, the anthracene functionalized dioxocyclam system represents a selective fluorescent sensor for Cu" and Ni , whose signal transduction mechanism is an electron transfer process [13]. 

A second model compound is provided by a stable Fe -porphyrin alkanethio-late complex in which the sulfur atom is protected from reactive molecules such as O2 or NO by a sterically crowded group. In this way NO can bind directly to the metal center simulating the role played by heme proteins in the biosynthesis of NO and in signal transduction mediated by NO [4]. 

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