A reliable and durable approach for real-time determination of cellular superoxide anion based on biomimetic superoxide dismutase stabilized by a zeolite

This paper demonstrates a reliable and durable method for in situ real-time determination of O(2)˙(-) based on direct electron transfer of Mn(3)(PO(4))(2), which acts as a superoxide dismutase (SOD). Mn(2+) is ion-exchanged into zeolite-ZSM-5 microstructures, and further coated with poly(diallyldimethylammonium chloride) (PDDA). Direct electron transfer of Mn(2+) is greatly facilitated by zeolite microstructures with the formal potential of 561 ± 6 mV vs. Ag|AgCl, which is just located between thermodynamic potentials of O(2)˙(-)/O(2) and O(2)˙(-)/H(2)O(2). The biomimetic catalytic activity of Mn(3)(PO(4))(2), together with the enhanced electron transfer of Mn(2+) obtained at the zeolite electrode has provided a platform for determination of O(2)˙(-) with high selectivity, wide linear range, low detection limit, and quick response. On the other hand, the present Mn(2+)-ZSM/PDDA electrode shows relatively long-term stability, good reproducibility, and biocompatibility, which opens up a way to adhering cells directly onto the film surface for in situ monitoring of cellular species. As a sequence, the remarkable analytical performance of the present O(2)˙(-) biosensor, combined with the characteristics of the Mn(2+)-ZSM/PDDA electrode surface has established a novel approach for real-time determination of O(2)˙(-) released from living cells.