Amperometric immunosensor for granulocyte-macrophage colony-stimulating factor using screen-printed electrodes Original Research Article

An amperometric immunosensor for the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) has been developed. Carbon-based screen-printed electrodes were mass-produced and characterised prior to use. Blocking studies were carried out to assess and minimise non-specific binding. A competitive assay was employed, using free and alkaline phosphatase labelled GM-CSF. p-Aminophenyl phosphate was converted to p-aminophenol in the presence of alkaline phosphatase (EC 3.1.3.1), and current was generated by its subsequent oxidation at +300 mV vs. Ag/AgCl. Parameters such as linear range, incubation time, reproducibility, re-use and stability were tested. The final sensor required 35 min for analyte incubation and signal detection. The linear range was 1.1–30 μg ml−1 with a detection limit of 0.10 μg ml−1.