Hydrogen peroxide detection under physiological conditions by Prussian blue stabilized using a polyelectrolyte–surfactant complex matrix

Poly(allylamine)–dodecylsulfate complex (PA–DS) is able to form a stable and layered structure onto graphite electrodes and can efficiently retain negatively charged ions like ferrocyanide. In this context, Prussian blue (PB) is electrochemically synthesized from a solution containing K3[Fe(CN)6] and FeCl3 at pH 1.7. The electrochemical behavior of the new system is investigated in different supporting electrolytes (K+ and Na+) and in acid and neutral media. Remarkable, well-defined and reversible voltammetric responses are obtained, especially under physiological conditions (neutral pH and 150 mM NaCl). In these conditions, the modified electrode is able to electrocatalyze the reduction of hydrogen peroxide (H2O2) at micromolar levels, with a low detection limit and good sensitivity. These results represent an important improvement regarding further uses of PB in bioanalytical applications.