A renewable amperometric immunosensor for phytohormone β-indole acetic acid assay

A rapid, convenient and accurate method using a sol–gel–alginate–carbon composite electrode (SACE) is described for the determination of β-indole acetic acid (IAA) in plant samples. The determination is based on an enzyme-linked competitive immunoreaction between free IAA and IAA labeled with HRP to bind on the anti-IAA IgG immobilized on the SACE surface. The response signal expressed as percentage current reduction (CR%, y) is linearly related to the logarithm of the concentration of IAA (x) in range of 5–500μgml−1 with a regression equation of the form y=37.80x−22.47 and correlation coefficient of 0.9922. The immunosensor was used to determine the IAA content in the hybrid rice grain samples taken in the growing period.