An ultrasensitive probe-free electrochemical immunosensor for gibberellins employing polydopamine-antibody nanoparticles modified electrode.

Gibberellins (GA) is an ubiquitous plant hormone, which plays a regulatory role in different growth stages of plants, so it is of great significance to develop a sensitive quantitative analysis method for GA. In this study, carboxylated graphene oxide- carboxylated multi-walled carbon nanotubes-Fc (GO-MWNT-Fc) composite material and PDANPs-antibody (PDANPs-Ab) were sequentially modified to screen-printed electrodes (SPEs), and an ultrasensitive probe-free immunosensor for GA was developed. Fc was applied to generate electrochemical signals. GO-COOH and MWNT-COOH can increase the catalytic ability of the sensor and bind the PDANPs-Ab nanoparticles. PDANPs nanomaterial were synthetized by a facile self-polymerization and used to bind with antibody, so as to increase the antibody loading of the sensor. The as-prepared immunosensor has the widest detection range (100 aM-1 mM) and lowest detection limit (17.4 aM) for GA up to date. To our knowledge, it is the first electrochemical immunosensor for GA. By changing the GA antibody to ABA antibody, a sensitive and selective immunosensor for ABA was also fabricated. This immunosensor platform is simple, sensitive, and low cost. It opens broad prospect in on-site applications for biosensors in detecting of various biomolecules in precision agriculture.