Switching, Gating and Signaling

By analogy to the aforementioned, porphyrin-doped mesoporous silica films have been used for the detection of TNT vapors by quenching of the porphyrin emission.The authors demonstrated that the use of mesoporous phases shows distinct advantages in terms of response when compared with functionalized amorphous silica. 

FIGURE 12. (a) Protamine detection with a gold electrode modified with a SAM of thioctic acid and [Ru(NH3)5] probe, (b) Heparin detection with the protamine-thioctic acid-gold electrode and [Fe(CN)6] probe. 

Selective electrochemical detection of over Na was achieved by using gold electrodes functionalized with bis-thioctic ester-terminated derivatives of oligoethylene glycol by cyclic voltammetry and impedance spectroscopy.  

ICSs have also been successfully employed for anion sensing. For instance, Umezawa et al. prepared an ion-channel sensor that is selective for phosphate ion in aqueous solution by surface functionalization of a gold electrode with a SAM of a bis-thiourea receptor. They studied the behavior of the material in the presence of several inorganic anions by cyclic voltammetry with [Fe(CN)g] as the redox marker. In the absence of anions, the surface 

Adenosine nucleotides were also electrochemically detected with ICSs. For these purposes, gold electrodes were functionalized by covalent anchoring of macrocyclic polyamines. [Ru(NFl3)6] was used as redox probe for the voltammetric detection of ATP, ADP, and AMP. The response mechanism originates from the inhibition of the redox reaction of the marker upon formation of supramolecular complexes between macrocyclic polyamine hosts and adenine nucleotide guests at the surface of the electrode. 

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Fig. 20.13 Example of effect of delay time on crosecond gate width and Q-switched Nd YAG signal-to-noise ratio for laser induced plasma laser with 75 mj laser pulse energy. Reprinted...

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