Fabrication of dendrite PtPd bimetallic nanocomposites modified carbon fiber microelectrodes for detecting superoxide anion released from living cells

[Display omitted] •PtPd@ERGO-CNT-CFME was prepared by adsorption and stepwise electro-deposition.•The unique morphology of dendrite PtPd alloy exposed abundant catalytic sites.•The microsensor achieved the detection of O2− with high sensitivity.•The microsensor realized the monitoring of O2− released from living cells. In this work, the carbon fiber microelectrode (CFME) coated by ERGO-CNT network was used as a substrate to support dendrite PtPd nanoclusters. An enzyme-free O2− electrochemical sensor (PtPd@ERGO-CNT-CFME) was prepared based on this strategy. Due to the brilliant loading and dispersing abilities of the substrate and the excellent electrochemical activity of the dendrite PtPd alloy, PtPd@ERGO-CNT-CFME demonstrated outstanding detection ability towards O2−. The as-constructed sensor showed a wide-linear range of 16–744 μM and 744–3064 μM with high sensitivity of 6967.3 μA mM−1 cm−2 and 4124.3 μA mM−1 cm−2, and the detection limit was 5.07 μM. Furthermore, PtPd@ERGO-CNT-CFME was successfully applied to monitor O2− released from living cells. This phenomenon indicated the application potential for O2− detection in biological samples.