Electrochemical bioassay for the detection of TNF-α using magnetic beads and disposable screen-printed array of electrodes.

Background: In this study we have developed an electrochemical bioassay for the analysis of TNF-alpha, coupling magnetic beads with disposable electrochemical platforms. TNF-alpha is a pro inflammatory cytokine that participates in the regulation of immune defense against various pathogens and the recovery from injury. It plays a central role in the development of many inflammatory diseases. The bioassay was based on a sandwich format using alkaline phosphatase as an enzymatic label and an eight-sensor screen-printed array as an electrochemical transducer. Results: The modified magnetic beads were captured by a magnet on the surface of each graphite working electrode of the array and the electrochemical detection was thus achieved through the addition of the alkaline phosphatase substrate (1-naphthylphosphate); 1-naphthol produced during the enzymatic reaction was detected using differential pulse voltammetry. The parameters influencing the different steps of the assay were optimized in order to reach the best sensitivity and specificity. Conclusion: The proposed strategy offers great promise for analysis of clinical diagnostics, considering also that arrays allow the simultaneous analysis of different samples.