Schematic representation of the amperometric sensor for FGFR4 determination using magnetic immunocarriers and a sandwich format.

<p>Schematic representation of the amperometric sensor for FGFR4 determination using magnetic immunocarriers and a sandwich format.</p

Dependence of the amperometric responses obtained with the developed immunosensor with the BDAb concentration (a), and the number of steps carried out to perform the immunoassay (b).

<p>Results are shown in the absence (white bars) or in the presence of 5,000 pg mL^-1 FGFR4 (grey bars) together with the corresponding S/B ratio (). 2(A), two sequential steps involving 30 min incubation of the CAb-MBs in a mixture solution containing FGFR4 and BDAb, and 30 min incubation in the Strep-HRP solution; 2(B) two steps involving 30 min incubation of the Cab-MBs with FGFR4 solution, followed by a 30 min incubation step in a mixture solution containing BDAb and Strep-HRP. Error bars estimated as triple of the standard deviation (n = 3).</p

Evaluation of the selectivity of the developed immunosensor for FGFR4.

<p>Amperometric signals measured in the absence (white bars) and in the presence of 2,500 pg mL^-1 FGFR4 (grey bars) and the corresponding S/B ratio () in the absence (1) and in the presence of 10 ng mL^-1 TNFα (2), 200 ng mL^-1 human p53 (3), 5 mg mL^-1 BSA (4), 5 mg mL^-1 hemoglobin (5) and 1 mg mL^-1 human IgG (6). Error bars estimated as triple of the standard deviation (n = 3).</p

Optimization of the experimental variables tested, according to the measured S/B ratio in the absence and in the presence of 5,000 pg mL^-1 FGFR4 standard solutions, for the preparation of the amperometric immunosensor for FGFR4.

<p>Optimization of the experimental variables tested, according to the measured S/B ratio in the absence and in the presence of 5,000 pg mL^-1 FGFR4 standard solutions, for the preparation of the amperometric immunosensor for FGFR4.</p

Dependence of the amperometric response measured with the developed magnetic immunocarriers-based sensor with the concentration of FGFR4 standards.

<p>Error bars estimated as triple of the standard deviation (n = 3).</p

Determination of endogenous FGFR4 concentration (in pg μg^-1) in different cancer cell lysates (2.5 μg).

<p>Comparison of the results provided by the developed amperometric immunosensor with those obtained using a commercial ELISA spectrophotometric kit by performing three different determinations over the same cell lysate.</p