Cyclic voltammetric measurements were performed in a 5mM
[Fe(CN)6]3−/4− probe solution containing 0.1M KCl. In Fig. 3,
compared with the CPE, the peak current declined slightly was
obtained on the HAP-CPE. It may be ascribed to the non-conductive
hydroxyapatite. However, a pair of well-defined redox peaks of
[Fe(CN)6]3−/4− was observed on the CILE (Fig. 3c), because of
good electrocatalytic activity and conductibility of the ionic liquid
(OPPF6). Additionally, the peak potential separation (Ep) value at
HAP-CILE (128mV) is larger than that obtained at CILE (90 mV), but
a remarkable increase of peak current was obtained at HAP-CILE
compare with CILE.