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We report a highly sensitive electrochemical immunosensor based on a nanohybrid platform for the detection of the breast cancer biomarker human epidermal growth factor receptor 2 (HER 2). NanoDiamond (nanoD) and gold nanoparticles (AuNPs) immobilised by drop coating and electrodeposition methods, respectively, were employed to fabricate an immunosensor for HER 2 detections on a glassy carbon electrode (GCE). Voltammetry and electrochemical impedance spectroscopy (EIS) techniques were used to characterise each step of the modification process of the immunosensor. In addition, transmission electron microscopy (TEM), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques were used to characterise the materials used to fabricate the modified electrode. Under optimal conditions of temperature, time, and pH (35 °C, 50 min, and pH 7.2), different concentrations were investigated within a wide range of 1 pg mL−1 to 50 ng mL−1 using differential pulse voltammetry (DPV). With a low detection limit of 0.29 pg mL−1 from the DPV analysis, the immunosensor showed very good sensitivity and had a high specificity for HER 2. Additionally, the immunosensor demonstrated good applicability in the analysis of HER 2 in human serum samples, demonstrating a potential for use in the early identification of breast cancer.

We report an alpha – fetoprotein (AFP) cancer biomarker electrochemical immunosensor detected on a carbon nanofiber (CNF) and gold nanoparticles (AuNPs) platform. Functionalised carbon nanofiber and gold nanoparticles were immobilised through drop drying and electrodeposition techniques respectively on a glassy carbon electrode (GCE). AFP antibody was immobilised on the platform overnight followed by blocking of nonspecific binding sites with bovine serum albumin (BSA) for 4 h. The AFP antigen was incubated on the platform for 40 min at 35 °C for the antigen – antibody interaction. CNF and AuNPs were characterised by electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The modified electrodes and the immunosensor were characterised by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The electrochemical response of the GCE/CNF/AuNPs electrode and the resulting immunosensor was significantly enhanced by the nanocomposite of CNF and AuNPs. The electrochemical immunosensing measurement for AFP was carried out under optimal conditions at a concentration range from 0.005 to 500 ng mL−1 in 5 mM ferri/ferrocyanide solution. A low limit of detection of 0.50 pg mL−1 from square wave voltammetry (SWV) and 0.48 pg mL−1 from EIS measurements were obtained. The immunosensor exhibited good sensitivity, good selectivity, good repeatability, and was stable at 4 °C over a period of three weeks.