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The aim of this work was to design and develop an electrochemical immunosensor based on electrospun carbon nanofiber (ECNF) mat for the detection of human epidermal growth factor receptor 2 (Her-2). First, ECNF mat was fabricated by electrospinning method and heat-treatment and used directly as a novel electrode. To determine Her-2, this ECNF mat electrode was modified by Au nanparticles (NPs), cysteamine (Cys) molecules, carbon nanotubes (CNTs), and antibody (Ab) molecules, respectively. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) analysis were used to characterize Au NPs modified ECNF mat electrode. In addition, analysis of Her-2 in spiked human blood serum samples were investigated by cyclic voltammetry (CV) using [Fe(CN)6]−3/−4 as a redox probe and the experiments were compared using commercial kit. The linear response range of the developed immunosensor was from 5 to 80 ng ml−1 with a limit of detection (LOD) of 0.45 ng ml−1. The results indicated that the designed immunosensor has high potential for the determination of Her-2 due to non-invasive, precise and rapid analysis. [ABSTRACT FROM AUTHOR]

The purpose of this work was to fabricate an electrochemical DNA biosensor for detecting hepatitis B virus. Gold nanorods (GNRs), which are known for their conductivity, were used to increase surface area and consequently increase the immobilization of single-stranded DNA (ss-DNA) on the modified gold electrode. The GNRs were characterized via transmission electron microscopy. The morphology of the gold electrode before and after modification with GNRs was characterized by scanning electron microscopy. Atomic-force microscopy was used to evaluate the morphology of the GNR electrode surface before and after interaction with ss-DNA. Cyclic voltammetry was used to monitor DNA immobilization and hybridization, using [Co(phen)] as an electrochemical indicator. The target DNA sequences were quantified at a linear range from 1.0 × 10 to 10.0 × 10 mol L, with a detection limit of 2.0 × 10 mol L by 3 σ. The biosensor had good specificity for distinguishing complementary DNA in the presence of non-complementary and mismatched DNA sequences. [ABSTRACT FROM AUTHOR]