Determination of Trace Gibberellin A3 by Magnetic Self-assembly Molecularly Imprinted Electrochemical Sensor

Magnetic Fe3O4 nanoparticles were synthesized by co-precipitation method, and then magnetic Fe3O4@Au nanoparticle were synthesized to improve the affinity of particle surface. L-Cys-GA3 was grafted on the particle surface by self-assembly method, and then dropped it on glass carbon electrode. The MIP/Fe3O4@Au was further fabricated by electropolymerization of L-Cys. The surface morphology and particle size distribution of the Fe3O4@Au particle were studied by TEM. The structure and composition of GA3, MIP and nMIP were studied by IR. Under the optimum conditions including 30 cycles of electropolymerization period, 5 min of elution time, 7 min of rebinding time and with acetic acid-methanol (1:8, V/V) mixed solution as eluent, high stability and good recognition ability for GA3 were obtained through the sensor. The results showed that the concentration of GA3 in the range of 1.0 x 10(-11)-1.0 x 10(-8) M had a linear relationship with the intensity of the oxidation peak current, with the detection limit of 2.6 x 10(-12) M. The sensor was successfully used for the determination of GA3 in beer sample.