A sustainable electrochemical analytical platform for rapid detection of indole-3-acetic acid in Marchantia polymorpha

Auxin (mainly indole-3-acetic acid, IAA) is one of the most essential phytohormones with various roles for land plants at different evolution stages and its polar transportation in plants suggested the importance of obtaining its amounts in different plant tissues. Because Marchantia polymorpha is at the entry evolution level, the IAA contents in its tissues would be useful for the study of IAA evolution. Although electrochemical detection offers a possible method for the measurement of IAA amounts, the cost for fabrication of electrochemical sensors is still high given the amounts of IAA tests in the future. Herein a low-cost disposable electrochemical analytical platform was constructed for analysis of IAA in tiny plant samples. Specifically, disposable carbon electrodes were prepared by modifying stainless steel wire mesh with inexpensive carbon ink because of less amounts of materials. The electrode was then integrated with a paper-based analytical device to form a disposable and low-cost platform for rapid electrochemical detection of IAA. For the modified electrode, the highest electrochemical responses for IAA could be obtained when the carbon ink was diluted for 3.5 times. The optimized pH value of the buffer solution for testing was 7.0, which is close to the physiological condition. Coupled with sample treatment using zirconium beads, this approach could successfully differentiate IAA in different tissues of Marchantia polymorpha. The obtained results agreed well with previous reports. This study suggested a sustainable electrochemical analytical detection platform for the study of IAA in practical applications.