Phosphate Polyions

The counterion-binding properties of polyions with phosphate groups are of special interest because of the biological importance of the role that 

The log (Kp app value calculated in this way are plotted against 6 in Fig. 59. It can be seen that the plots are composed of at least two lines that intersect at about 6h = 0.5. In the high-G j regions, i.e., 0.5, the log 

H ion binding to the linear polyion. A similar pattern of protonation has recently been reported for spedlied polyions with carboxylate groups, i.e., polymers of maleic acid and fomaric acid, whose distance between the adjacent carboxylate groups is as short as ca. 2 A [76]. 

Also the contribution to 0 by site-bound Ag ions, (0Ag)site Ag expressed by use of an intrinsic stability constant, (Pi)d, of the monodentate complex, [Ag(P03)]°, and the free phosphate unit concentration in the Donnan phase, [Pj.  

Since (0Ag)si,e is defined as the difference between the amounts of the total and the free silver ions in the Donnan phase, (0Ag)si,e can be expressed with the following equation as 

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Clinical chemistry, particularly the determination of the biologically relevant electrolytes in physiological fluids, remains the key area of ISEs application [15], as billions of routine measurements with ISEs are performed each year all over the world [16], The concentration ranges for the most important physiological ions detectable in blood fluids with polymeric ISEs are shown in Table 4.1. Sensors for pH and for ionized calcium, potassium and sodium are approved by the International Federation of Clinical Chemistry (IFCC) and implemented into commercially available clinical analyzers [17], Moreover, magnesium, lithium, and chloride ions are also widely detected by corresponding ISEs in blood liquids, urine, hemodialysis solutions, and elsewhere. Sensors for the determination of physiologically relevant polyions (heparin and protamine), dissolved carbon dioxide, phosphates, and other blood analytes, intensively studied over the years, are on their way to replace less reliable and/or awkward analytical procedures for blood analysis (see below). 

Among other polyions Meyerhoff s group demonstrated successful detection of pentosan polysulfate (PPS) [45], an anti-osteoarthritis drug, in plasma and polyanions with high phosphate content, including polyphosphates and nucleic acids in saline solutions [46],... 

J.M. Esson and M.E. Meyerhoff, Polyion-sensitive membrane electrodes for detecting phosphate-rich biological polyanions. Electroanalysis 9, 1325-1330 (1997). 

The phosphate groups in DNA are ionized at physiological pH [31]. Consequently, the macromolecule is a polyanion [31]. In solution the polyion is endowed with an equal number of counterions due to electroneutrality. However, if the solution contains excess salt, then these ions together with the mobile counterions form the ion atmosphere [31]. 

The concentration of the phosphate charges in molarity is cd = d/V7Va-where V is the volume of the unit cell in the simulation. At the end of the simulation, the number of ion pairs IV3 will be determined. The salt concentration follows from the relation C3 = N /VNa- Consequently, T was calculated from the slope of C3 versus the polyion concentration cD, the later was be varied in the range around 1 mM [74],... 

Polarizabilities are simulated also in salt solutions [48], This time the contribution of coions to the electroneutrality condition must be taken into account. We consider that polyion phosphate charge is compensated by the same amount of net charge. At every simulation step we numerically sort all the small ions in increasing order of the sum of their distances from both ends of the polyion. Then if we find a coion in the sorting list, we search a... 

In order to simplify the model we present in Figure 8 the DNA in the double helical B form as a rodlike polyion. If the solvent is NaQ, the compensating counterions of negative phosphate sites are Na" and the coions of the electrolyte are Cl . It is possible to show that a correlation exists between the conformation of the macroion and some characteristic parameters of the electrolyte. ... 

Scaffolds can also be used for the delivery of genes. Kido et al. prepared scaffolds of gelatin and (3-tricalcium phosphate ((3-TCP) to search their gene transfection capabilities. The scaffolds were loaded with a spermine-pullulan luciferase plasmid DNA polyion complex and then stem cells were seeded into the scaffolds. It was shown that the level of plasmid DNA transfection was dependent on the method of the scaffold preparation. ... 

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