Phosphate electrochemical techniques

Recently, Brzozowska et al. used NR and ex situ electrochemical techniques to characterize an innovative type of monolayer system intended to serve as a support for a bUayer lipid membrane on a gold electrode surface [51]. Zr ions were used to noncovalendy couple a phosphate-terminated self-assembled monolayer (SAM) formed on a gold surface to the carboxylate groups of negatively charged phos-phatidylserrne (PS). This tethered surface was then used for the formation of a PS hpid bilayer structure formed by vesicle fusion and spreading. NR studies revealed the presence of an aqueous environment associated with the tether layer which arises from nonstoichiometric water associated with the zirconium phosphate moieties [52]. 

The quartz crystal microbalance has been applied to phosphating of zinc [17, 54]. This technique complements other electrochemical techniques as ideally, it gives the mass as a function of time. A typical example is shown in Fig. 9 in which the variations of the open-circuit... 

In another study also, electrochemical impedance technique has been shown to be a useful method for a DNA biosensor using a multinuclear nickel(II) salicylaldimine metallodendrimer platform [164], Both the preparation of the dendrimer-modified GCE surface and the immobilization of DNA have been effectively done by simple drop-coating procedures. The metallodendrimer is electroactive exhibiting two redox couples in phosphate buffer solution. The impedance study demonstrated that the DNA biosensor responded well to 5 nM of target DNA by displaying a decrease in charge transfer resistance in phosphate buffer solution and increase in charge transfer resistance in the presence of the [Fe(CN)6]3/4" redox probe. 

We recently incorporated the ruthenium(II) bipyridyl moiety into acyclic, macrocyclic, and lower rim caUx[4Jarene structural frameworks to produce a new class of anion receptor capable of optical and electrochemical sensing (226, 253. 254). Stability constant determinations in DMSO using H NMR titration techniques demonstrated that these acyclic receptors (131 and 132) form strong complexes with chloride and dihydrogen phosphate anions (stronger than with analogous monopositive cobaltocenium based receptors). The ruthenium ion is dipositive and hence the electrostatic interactions are particularly favorable. The 4,4 -substituted ruthenium bipyridyls were observed to bind anions more... 

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