Nanostructured MXene-based biomimetic enzymes for amperometric detection of superoxide anions from HepG2 cells

A novel MXene-based biomimetic enzyme was synthesized using adenosine triphosphate (ATP) as a template to modify a Mn₃(PO₄)₂ nanostructure on Mxene-Ti₃C₂ nanosheets. The resulting composite was used as an electrode material in an electrochemical sensor for superoxide anion (O₂^•-). It displays excellent catalytic properties which is attributed to the synergistic effects of the two-dimensional conductive substrate and the Mn₃(PO₄)₂ nanoparticles. The addition of ATP results in the formation of a porous and ordered nanostructure of Mn₃(PO₄)₂. This facilitates the electron transfer between O₂^•- and electrode. The sensor, best operated at 0.75 V (vs. Ag/AgCl), displays a rapid amperometric response with a detection limit of 0.5 nM and an analytical range that extends from 2.5 nM to 14 μM. Conceivably, it has potential in the detection of O₂^•- released by living cells. Graphical abstract Nanostructured MXenes were synthesized by in-situ growth of Mn₃(PO₄)₂ on Ti₃C₂ nanosheets under the induction of adenosine triphosphate (ATP). They display enzyme mimickong properties. A sensor fabricated with the composites can be used for the detection of superoxide anions released by HepG2 cells.