An ultrasensitive electrochemical cytosensor based on the magnetic field assisted binanozymes synergistic catalysis of Fe_3O_4 nanozyme and reduced graphene oxide/molybdenum disulfide nanozyme

摘要

An ultrasensitive electrochemical circulating tumor cells (CTCs) detection strategy was developed based on magnetic field-induced, targeted separation and enrichment, and reduced graphene oxide/molybdenum disulfide (rGO/MoS2) composites and Fe3O4NPs binanozyme synergistic catalysis for signal amplification. Immunomagnetic beads (Fe3O4NPs) act as both separation and enrichment CTCs and as enzyme mimics with rGO/MoS2synergistic catalysis for signal amplification in cytosensors for the first time. Notably, rGO/MoS2composite showed a good electrocatalytic activity towards H2O2synergistic catalysis with Fe3O4NPs. The utilization of rGO/MoS2and Fe3O4NPs as electrochemical signal indicator and enhancer to fabricate biosensor could avoid the need for additional redox mediator for detection sensitivity amplification. The immunomagnetic beads were coated on the magnetic glassy carbon electrode (MGCE) surface by inserting a magnet for electrochemical cytosensing fabrication. Furthermore, this cytosensor could be regenerated by simply pulling out the magnet. Under the optimized experimental conditions, the proposed cytosensor exhibited significant analytical performance for MCF-7 circulating tumor cells detection. The proposed electrochemical biosensor detected MCF-7 down to 6 cells mL−1with a linear range from 15 to 45 cells mL−1at the acceptable stability condition and reproducibility. With rGO/MoS2composites, Fe3O4NPs bienzyme mimics and electrochemical immunomagnetic cytosensor fabrication, this strategy possesses the advantages of high efficiency, high sensitivity, low cost and versatility, thus holds great promise for other low-abundance circulating tumor cells detection.