The Ca
2+ -release device was a carbon paste electrode including a ternary complex consisting of poly(vinyl sulfate) ion (PVS
−), 11-ferrocenylammonium ion trimethylundecyl (FeTMUA
+), and Ca
2+. The ternary complex was characterized by potentiometric titrations. The potentiometric colloidal titration of PVS
− with FeTMUA
+ using a surfactant electrode indicated that the potentials in the titration curve sharply increased at the equivalent point, and then the complexation was strong. The potentiometric titration of PVS
− with Ca
2+ using a Ca
2+-selective electrode had no significant endpoint because of weak complexation. The binding behavior of Ca
2+ with PVS
− was independent of the co-existence of FeTMUA
+. The carbon paste electrode (CPE) including the ternary complex was characterized by cyclic voltammetry. The peak of the oxidation wave of FeTMUA
+ was observed at 800 mV (
vs. saturated Ag/AgCl), which was larger than the oxidation potential of FeTMUA
+ adsorbed on CPE from an aqueous solution. The release amount of Ca
2+ was evaluated by atomic adsorption spectroscopy. After electrolysis, the release amount of Ca
2+ increased with the content amount; the high content CPE released Ca
2+ even without electrolysis, but the low content CPE did not release a significant amount without electrolysis. At last, a Ca
2+ release electrochemical device was fabricated; a thin end (φ 0.5 mm) of a polypropylene tip was stopped with the CPE and a Pt wire inserted into the CPE. The slight amount of Ca
2+ released from the limited area of the tip was monitored by a CCD Ca
2+ image sensor. The released amount of Ca
2+ increased with the electrolysis time only just under the tip, while the other area had no significate change of Ca
2+. The small device can locally release Ca
2+ to only a limited area. In addition, the analysis of the image sensor displayed that the Ca
2+ release of the device was a two-stage discharge: in first stage Ca
2+ released from the surface, and in second stage a large amount of Ca
2+ was released independent of electrolysis. The CCD Ca
2+ image sensor was very useful to characterize the Ca
2+ release device.
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