Electrochemical immunosensor based on gold nanoparticles deposited on a conductive polymer to determine estrone in water samples

•An immunosensor was developed to detect estrone in water samples.•The immunosensor does not require labeling neither the antigen nor the antibody.•The platform is based on AuNPs electro-synthesized on 1-naphtylamine polymer film.•The modification time of the electrode surface with AuNPs is reduced considerably.•The immunosensor is selective, sensitive, and has good statistical parameters.

This paper describes the development of a simple and sensitive electrochemical immunosensor (EI) to quantify estrone (E) in water samples. This EI does not require the sample pre-treatment, to label neither the antigen nor the antibody, and its detection format is based on the fact that E is co-substrate of the horse radish peroxidase (HRP). Therefore, the EI was constructed by immobilization of the anti-E monoclonal antibody (mAbE) on a glassy carbon electrode (GCE) modified with gold nanoparticles (AuNPs) electro-synthesized on a 1-naphtylamine polymer (pNap) film. This format reduced significantly the time of EI preparation. Water samples were spiked with known E concentrations, and then incubated on mAbE-AuNPs-pNap-GCE disk electrode. The electrochemical response was proportional to the amount of pyrocatechol (H2Q), another enzyme co-substrate, and inversely proportional to the amount of E presents in water samples. The immunosensor showed a linear range from 8 × 10− 2 to 2 × 104 pg mL− 1. The limit of detection (LOD) was 0.061 pg mL− 1. Recovery percentages obtained were very good, with values of 98.20, 105.50, and 100.85% for 50, 100 and 200 pg mL− 1, respectively. Tests were also conducted to evaluate the cross-reactive of E with other hormones of similar structure such as 17β-estradiol, progesterone and estriol. The EI showed a high selectivity to determine E in the presence of these hormones. Thus, this EI is an attractive tool to determine E in water samples.