Atomic-Thick PtNi Nanowires Assembled on Graphene for High-Sensitivity Extracellular Hydrogen Peroxide Sensors

H₂O₂ sensors with high sensitivity and selectivity are essential for monitoring the normal activities of cells. Inorganic catalytic nanomaterials show the obvious advantage in boosting the sensitivity of H₂O₂ sensors; however, the H₂O₂ detection limit of reported inorganic catalysts is still limited, which is not suitable for high-sensitivity detection of H₂O₂ in real cells. Herein, novel atomic-thick PtNi nanowires (NWs) were synthesized and assembled on reduced graphene oxide (rGO) via an ultrasonic self-assembly method to attain PtNi NWs/rGO composite for boosting the electroanalysis of H₂O₂. In 0.05 M phosphate-buffered saline (pH 7.4) solution, the as-prepared PtNi NWs/rGO shows an extraordinary performance in quantifying H₂O₂ in a wide range of concentrations from 1 nM to 5.3 mM. Significantly, the detection limit of PtNi NWs/rGO reaches unprecedented 0.3 nM at an applied potential of -0.6 V (vs Ag/AgCl), which enables the detection of traced amounts of H₂O₂ released from Raw 264.7 cells. The excellent performance of H₂O₂ detection on PtNi NWs/rGO is ascribed to the high-density active sites of atomic-thick PtNi NWs.