Loading thionine onto MXene enhances electron transfer and ultrasensitive electrochemical detection of H2O2

Abstract

As an important reactive oxygen species (ROS) signal molecule in plant physiological regulation, H₂O₂ maintains cellular homeostasis through concentration regulation. It is worth paying attention to the concentration imbalance of H₂O₂ caused by various stresses, resulting in programed cell death or even developmental arrest in plants. To accurately quantify alterations in H₂O₂ concentration induced by these stress factors, and deeply understand the H₂O₂-related physiological processes, a highly efficient hybrid electrode material of thionine@Ti₃C₂T_x (Th@MXene) composite was developed. MXene nanosheets not only performed as carriers with high specific surface area for loading Th but also contributed to the enhancement of electrical conductivity. Meanwhile, Th was uniformly loaded on the MXene surface, facilitating electron transport from the analyte to the modified electrode. Under the optimal detection conditions, the sensing electrode (Th@MXene/GCE) was employed to quantify H₂O₂ through Square-wave Voltammetry signals with a good linear relationship (correlation coefficient is 0.9997), and a wide calibration range of the sensor was 0.1 to 10,000 nM. Above all, the detection limit can be as low as 34 pM, demonstrating excellent sensitivity. Additionally, the sensor exhibited repeatability in real samples, demonstrating exceptional practicality.