Potassium ion sensor

Kawabata Y., Tahara R., Imasaka T., Ishibashi N., Fiber-optic potassium ion sensor using alkyl-acridine orange in plasticized poly(vinyl chloride) membrane, Anal. Chem. 1990 62 1528. 

K. Suzuki, H. Ohzora, K. Tdida, K. Miyazaki, K. Watanabe, H. Inoue, and T. Shirai, Fibre-optic potassium ion sensors based on aneuttal ionophore and a novel lipophilic anionic dye, Anal Chim Acta 237, 155-164(1990). 

Materials with selective binding or transport properties will have a major impact on sensor design and fabrication. Selectivity in either binding or transport can be exploited for a variety of measurement needs. This selectivity can be either intrinsic, that is, built into the chemical properties of the material, or coupled with selective carriers that allow a non-selective material to be converted into a selective one (see the section on recognition chemistry). An example of the latter is the use of valinomycin as a selective carrier in a polyvinyl chloride membrane to form a potentiometric potassium ion sensor. Advances in the fields of gas separation materials for air purification and membrane development for desalinization are contemporary examples illustrating the importance of selective materials. As these materials are identified, they can be exploited for the design of selective measurement schemes. 

Pandey, P. C. Prakash, R. Polyindole modified potassium ion-sensor using dibenzo-18-crown-6 mediated PVC matrix membrane. Sens. Actuators. 1998, B46, 61-65... 

Pandey, P. C. Singh, G. Srivastava, P. K. Electrochemical synthesis of tetraphenylborate doped polypyrrole and its applications in designing a novel zinc and potassium ion sensor. Electroanalysis. 2002, 14, 427-432... 

Chart 13.4 Chemical structure of /V-(9-methyl-anthracene)-25,27-bis(l-propyloxy) calix[4]arene azacrown-5, used as a selective potassium ion sensor [39]. 

Ding et al. have reported [95] a novel potassium ion sensor based on valinomycin-incorporated bilayers supported on a gold electrode modified by a hexadecylmercaptan monolayer. The ion selectivity for K+ is 400 times greater than for Na. The system is stable for two months at -10 °C which is much more practical than the reported stability of many cationic bilayer membranes with longevities of less than 120 hrs [113]. The lipid membrane is prepared by the painted-frozen method [114] in which the SAM modified electrode is coated with the lipid solution and allowed to freeze (removing the solvent) the supported bilayers are then immersed into a solution of valinomycin to create the K+ sensor. 

Brown, J. Q. McShane, M. J. Core-referenced ratiometric fluorescent potassium ion sensors using self-assembled ultrathin films on europium nanoparticles. IEEE Sens. J. 2005, 5, 1197-1205. 

Although rum ammonia levels are not routinely measured, it is a useful indicator of Reye s syndrome and should be monitored in newborns at risk of developing hyperammonemia Ammonia is produced in many analytically useful enzyme reactions and the ammonium ISE has been used as the base sensor in several enzyme electrodes (see next section). In addition to valinomycin, other antibiotics such as the nonactin homalogs and gramicidins also behave as ionophores. The nonactin homolo were originally studied for their ability to selectively bind potassiiun ions It was then discovered that ammonium ions were preferred over potassium ions, and the selectivity coefficient Knh+ = 0.12 was reported. Since ammonia is present at fairly low levels in serum, this selectivity is not sufficient to to accurately measure NH4 in the presence of K. An extra measure of selectivity can be gained by using a gas permeable membrane to separate the ammonia gas from the sample matrix... 

Calcium sensors are merely representative of a much wider class of ion sensors, albeit probably the best understood. Fluorescent probes have now been developed for a wide range of metal ions of biological interest, particularly sodium, potassium, magnesium, and zinc. 

Murkovic I., Lobnik A., Mohr G.J., Wolfbeis O.S., Fluorescent potential-sensitive dyes for use in solid-state sensors for potassium ion, Anal. Chim. Acta, 1996 334 125. 

Brasuel M, Kopelman R, Miller TJ, Tjalkens R, Philbert MA (2001) Fluorescent nanosensors for intracellular chemical analysis decyl methacrylate liquid polymer matrix and ion-exchange-based potassium PEBBLE sensors with real-time application to viable rat C6 glioma cells. Anal Chem 73 2221-2228... 

Addition of potassium ions to the fibers leaves the fibrous structure intact but destroys the helicity [128]. Sandwich complexes between the cation and 114d are observed. With higher concentrations of potassium, the sandwich complexes break down and isolated 4K+114d are observed (Scheme 61). In both complexed forms the salt blocks the chirality transfer from the side chains to the supramolecular assemblies. Such fibers with controllable chirality can be interesting materials for molecular switches or in sensors devices. 

A potassium-ion-selective, dendritic, fluorescing chemosensor, bearing three crown ether moieties in the periphery, shows a linear increase in fluorescence intensity with increasing potassium concentration (in acetonitrile). An important criterion for potassium chemosensors is their mode of action (selectivity) in the presence of large amounts of sodium. The tris-crown ether sensor shown in Fig. 8.16 is able to detect very small traces of potassium ions, even if large quantities of sodium ions are present in the same solution - such as in body fluids [55]. 

The variations on the spacer module within 29 are available from Dabes-tani s laboratory [89]. The methylene spacer has been systematically extended to the tetramethylene case. As may be anticipated from previous studies on structurally similar aminoalkylaromatic PET systems [90-92], the fluorescence quantum yield (4>f) of the ion-free sensor rises gradually with increasing spacer length as the PET rate drops. Potassium ions cause moderate to small fluorescence enhancements, but the same trend can be discerned in the values, though muted. As usual, protons cause the largest enhancements of all and the ([>f values remain constant across the series since PET has been completely killed off. 

Figure 16.25 Semiconductor nanoparticle-based fluorescent sensors (a) Forster resonant energy transfer (FRET) between two nanoparticles induced by analyte, (b) crown ether receptor for potassium ions, and (c) operation principle of maltose fluorescent sensor. (Adapted from Chen et at. [144] and Medintz et at. [146])...

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