Wearable electrochemical immunosensor based on ultra-thin flexible stainless steel sheets for detection of methyl jasmonate in tomato leaves

Methyl jasmonate (MeJA), a key plant hormone, plays essential roles in plant growth, development, biotic stress responses, and wound-induced defense. Monitoring dynamic changes in MeJA in situ is vital for botanical research. Herein, coupling with paper-based analytical devices, the ultra-thin flexible stainless steel sheets with the excellent flexibility and conductivity were used to develop wearable electrochemical immunosensor for in situ and continuous detection of MeJA in plants. The ultra-thin flexible stainless steel sheets were modified with conducting carbon cement, ferrocene - graphene oxide - multi-walled carbon nanotubes composites, and MeJA antibodies to construct the wearable electrochemical immunosensor, which can detect the MeJA in the range of 10 pM-100 μM, and with a limit of detection of 5.4 pM. Using this wearable electrochemical immunosensor, the MeJA content in tomato leaves under wound stimulation was detected in situ and continuously. The results showed that MeJA levels in tomato leaves increased significantly with mechanical damage. A significant difference was observed between the untreated control group (0 cm) and the mechanically damaged group (2.0 cm), confirming the sensor's capability to monitor dynamic changes in MeJA in response to stress in real-time. In all, this study not only suggested that the ultra-thin flexible stainless steel sheets with the excellent flexibility and conductivity can be used to fabricated the wearable electrochemical sensors, but also provided a novel method for continuous in situ MeJA detection, which contributed to the understanding of MeJA regulatory mechanisms in plants and advancing precision agriculture technologies.