A novel electroactive polymer for pH-independent oxygen sensing

Methylene blue (MB+) and pyrrole were copolymerised to electrodeposit a novel electroactive polymer on a Au electrode which was assessed for O2 sensing. The electroactive polymer exhibits diffusion-limited behaviour and an electrochemical, followed by catalytic (EC′) mechanism in the presence of dissolved O2. Notably, it is pH-insensitive in both N2-purged and air-equilibrated phosphate buffered saline (PBS) from pH 4 to 8. It is stable over 18 days, possesses a good sensitivity of 256.335 µA mM−1 cm−2, wide linear range of 15 µM to 285 µM and detection limit of 1.47 µM (S/N=3) for dissolved O2. It is highly promising for use in biological investigations where pH fluctuations are expected.