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

An amperometric immunosensor for the cytokine granulocyte-macrophage colony -stimulating factor (GM-CSF) has been developed. Carbon-based screen-printe d electrodes were mass-produced and characterised prior to use. Blocking st udies were carried out to assess and minimise non-specific binding. A compe titive 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 subs equent oxidation at +300 mV vs. Ag/AgCl. Parameters such as linear range, i ncubation time, reproducibility, re-use and stability were tested. The fina l sensor required 35 min for analyte incubation and signal detection. The L inear range was 1.1-30 mu g ml(-1) with a detection limit of 0.10 mu g ml(- 1). (C) 1999 Elsevier Science B.V. All rights reserved.