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An electrochemical immunosensor based on carbon nanofibers (CNFs) and gold nanoparticles (AuNPs) was developed for detecting anti-Toxoplasma gondii antibodies (anti-T. gondii) IgG in human serum. CNFs were produced using electrospinning and carbonization processes. Screen-printed carbon electrode (SPCE) surface was modified with CNFs and AuNPs which were electrodeposited onto the CNFs. Then, T. gondii antigen was immobilized onto the AuNPs/CNFs/SPCE. Afterward, anti-T. gondii IgG positive serum samples were coated on the modified electrode and assessed via adding anti-human IgG labeled with horseradish peroxidase (HRP) enzyme. The morphology of SPCE, CNFs, and AuNPs/CNFs/SPCE surface was characterized using field emission scanning electron microscopy (FESEM) equipped with energy dispersive spectroscopy (EDS). Characterization of CNFs was evaluated by Raman spectroscopy and X-ray diffraction (XRD). Electrochemical characterization of the immunosensor was verified using cyclic voltammetry (CV), and electrochemical response of modified electrode for anti-T. gondii IgG was detected via differential pulse voltammetry (DPV). This immunosensor was detected in the range 0–200 U mL−1 with a low detection limit (9 × 10−3 U mL−1). In addition, the proposed immunosensor was exhibited with high selectivity, strong stability, and acceptable reproducibility and repeatability. Furthermore, there was a strong correlation between results obtained via the designed immunosensor and enzyme-linked immunosorbent assay (ELISA) as gold standard. In conclusion, the developed immunosensor is a promising route for rapid and accurate clinical diagnosis of toxoplasmosis. [ABSTRACT FROM AUTHOR]

An electrochemical aptamer-based sensor was designed to detect tetracycline (Tet) in chicken ham. First, polyacrylonitrile (PAN) polymer was used to prepare electrospun PAN nanofibers. PAN nanofibers were heat treated to form electrospun carbon nanofiber (CNF) mat. The electrospun CNF mat electrode was modified with Au and the aptamer of Tet was placed on the mat electrode. Raman spectroscopy and scanning electron microscopy equipped with energy-dispersive spectroscopy were used to identify the structure and morphology of electrospun CNFs, respectively. The behavior of CNF mat electrode was evaluated via cyclic voltammetry. The designed aptamer biosensor had a good repeatability, reproducibility, stability, and specific function for the detection of Tet in chicken ham. This biosensor was able to detect the Tet in the linear range of 1 × 10–9 M to 1 × 10–4 M with the detection limit of 1.2 × 10–10 M and preserve about 95% of its primary response after 20 days. In addition, the recoveries of Tet were achieved ranging from 96.92 to 104.31%. [ABSTRACT FROM AUTHOR]