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.