Biomimetic study of the Ca ²⁺-Mg ²⁺ and K ⁺-Li ⁺ antagonism

Illustrations

Figure 1 The changes of membrane PMPy-ATP-K (A) and PMPy-ATP-Mg (B) potential with time recorded during calibration processes and calibration curves: (open squares) - without conditioning, (open triangles) - after 1 day and (open circles) - after 1 week conditioning in alkaline solution of main ion (where: pMe = -log a_(Me) for Me = K, Mg).

Figure 2 The relation between the stability constants of complexes ATP ions with Mg²⁺, Ca²⁺, Li⁺ Na⁺ and K⁺ cations (black plot) and the potentiometric selectivity coefficients of CP-ATP-Na (grey plot with circles) and CP-ATP-Mg (grey plot with triangles) membranes.

Figure 3 The exemplary (A) LA-ICP-MS spectra recorded for PMPy-ATP films before and after conditioning process in lithium alkaline solution and (B) XPS spectra for PPy-Asn films: i) freshly deposited and unsoaked, ii) after conditioning in alkaline magnesium solution, iii) after conditioning in alkaline calcium solution.

Figure 4 The exemplary EDAX spectra for PMPy-ATP films: A) without soaking, B) after 2 weeks’ soaking in the alkaline solution of 0.1M NaCl.

Figure 5 Potential-time behaviour of sodium (A, B), potassium (C) sensitive PMPy-ATP and calcium and magnesium (D) PPy-Asn films observed after increase of a bulk concentration of: (A) Li⁺, (B) K⁺, (C) Li⁺ (triangles), Na⁺ (circles), (D) Ca²⁺ (triangles), Mg²⁺ (circles) ions.

Figure 6 The simplified view of ion-exchange processes on (A) CP-ATP-Ca and (B) CP-ATP-Mg electrode in the mixed solution of Mg²⁺ and Ca²⁺ ions: just after (A) magnesium and (B) calcium concentration change.

Figure 7 The current (I) - time (t) response of PMPy-ATP-Na electrode recorded in chloride salt of the main and interfering ions under different value of potential (A) first - 5 mV then + 5 mV (B) + first + 10 mV then - 10 mV.