Antibodies against bisphenol-A (Ab proportional to BPA) and BPA-butyric-horseradish peroxidase (HRP) were generated and utilised to fabricate a gold-nanoparticles (AuNPs)-based electrochemical biosensor for the detection of BPA. The glassy carbon electrode surface was modified with AuNPs via chronoamperometry (CA) to increase the surface-to-volume ratio and provide a robust sensing surface. The Abs proportional to BPA were generated and immobilized on the AUNP-modified electrode using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N-hydroxysuccinimide (NHS) method with thioctic acid as linker. The assay was conducted using competition and displacement formats. Then, the working electrode, counter electrode and reference electrode were placed in a phosphate-buffered saline (PBS) containing ferrocenemethanol (FcOH) and H2O2. Sensitivity data were interpreted using the same sensor surface, enabling a direct comparison between the reduction currents of the oxidized form of ferrocenemethanol in the two assay formats which indicated the concentration of BPA bound to Ab proportional to BPA. Starting from a pre-blocked sensor surface, the competition assay was completed in 1 h and the displacement assay took 2 h. The limit of detection (LOD) in competition assay and displacement assay were 1235 mu g L-1 and 4.11 mu g L-1, respectively. (C) 2016 Elsevier B.V. All rights reserved.