Acidification of manganese dioxide for ultrasensitive electrochemical sensing of hydrogen peroxide in living cells

•MnO2 nanoflowers were synthesized by one-step method.•Acidification of MnO2 was performed to modify its catalytic reactive and active crystalline facets.•H2O2 electrochemical sensor was fabricated based on acidized MnO2 to detect H2O2 released from living cancer and normal cells.•The obtained sensor exhibited remarkable catalytic performance for H2O2 detection. Nanomaterials have been used widely for electrochemical analysis in biological system in recent years. In order to cover the shortage of singular materials, composite nanomaterials were provided, but in the meanwhile laborious synthetic procedures and complex analytic mechanism has to be faced. In this work, for the first time, one-step acidification of flower-like manganese dioxide (MnO2) was performed to modify its catalytic reactive and active crystalline facets, and nonenzymatic electrochemical sensor was fabricated based on the singular materials to detect hydrogen peroxide (H2O2) released from living cancer and normal cells. According to the SEM, XRD characterizations and electrochemical investigations, it was found that 001 and 002 facets probably be the reactive facets while 111 and 020 facets are active facets. Meanwhile, the obtained sensor exhibited a low detection limit of 0.02μM, a fast response and a wide linear range of 0.00008-12.78mM which can be applied successfully for quantitative detection of H2O2 released from living cells in stimulation of AA. The work provides a simple and efficient electrochemical biosensing platform based on modification of crystalline facets of metal oxide. Considering the good sensing property, simple catalyst synthesis and analytic mechanism, its potential uses can be exploited for analytic, catalytic, physiological and pathological studies.