Development of a reusable and disposable sensor for the rapid determination of the human chorionic gonadotropin (hCG) biomarker

Herein, we developed a previously undescribed electrochemical nanoMIP-based sensor for the sensitive, reusable and accurate determination of human chorionic gonadotropin (hCG). Using a proprietary rapid and scalable method, hCG-selective polyacrylamide nanoMIP particles were produced within 2 h in high yields of 11 mg per 1 mL reaction batch with hCG-modified magnetic nanoparticles (MNPs@CHO@hCG). The MNPs were reusable for 5 sequential cycles of nanoMIP production. The nanoMIPs were integrated with gold screen printed electrodes by electropolymerisation within an electrochemically grown polyacrylamide layer. The ensuing hCG sensor was characterised using cyclic voltammetry and electrochemical impedance spectroscopy. Both electrochemical modes were shown to be suitable for determining the selective binding of the biomarker. The sensor was also tested using a non-target protein (SARS-CoV-2 nucleocapsid protein) and was shown to be 20× more selective for target hCG compared with the non-target. The linear range was shown to be 1.5–384 mIU with a LOD of 3 mIU and saturation occurring beyond 1000 mIU. We also electrochemically determined the equilibrium dissociation constant (K_D) to be 1.4 × 10⁻¹⁰ M using EIS, which is on par with monoclonal antibodies produced for hCG. Sensor reusability studies demonstrated that the same sensor, once regenerated after sodium dodecyl sulphate/acetic acid treatment, could be used for 3 subsequent measurements. We present an effective method that can be used for both pregnancy testing and testicular cancer monitoring.