LAUSR

Abstract A porous thiolated polymer nanocomposite for sensitive and selective amperometric immunoassay of phytohormone (with indole-3-acetic acid (IAA) as the model) was reported, with a detection limit down to 0.13 pg/mL for IAA. Briefly, porous thiolated polymer nanocomposite was prepared via electro-assisted thiol-ene reaction of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) with oxidized polypyrrole (PPy) which was electrosynthesized on a porous graphene (PG) modified glassy carbon electrode, yielding thiolated PPy (TPPy)-PG, then gold nanoparticles (AuNPs) was deposited on the TPPy-PG by electrochemical method to obtain AuNPs/TPPy-PG nanocomposite. Finally, the AuNPs-antibody (Ab)/AuNPs/TPPy-PG nanocomposite film was constructed via the specific chemical reaction between boronic acid functionalized AuNPs/TPPy-PG and the vicinal diol functionalized AuNPs labeled immunoglobulins G (AuNPs-IgG). Scanning electron microscopy (SEM), cyclic voltammetry (CV), ultraviolet visible spectroscopy (UV–vis) and differential pulse voltammetry (DPV) were used to characterize the nanocomposite film and the stepwise modification of the immunosensor. The prepared AuNPs-Ab/AuNPs/TPPy-PG nanocomposite material has uniform dispersion of the AuNPs on porous thiolated polymer nanocomposite as verified by SEM, and high activity of the immobilized Ab proved via DPV. The electrochemical immunosensor show good sensitivity, acceptable selectivity, reproducibility and stability.