Detection of biomarkers for inflammatory diseases by an electrochemical immunoassay: The case of neopterin

In this study novel specific antibodies against neopterin were used and it was shown that, by replacing the traditional colorimetric detection with differential pulse voltammetry and the traditional plastic wells with screen-printed array of electrodes, multiplexed analysis of neopterin can be achieved. The electrochemical bioassay for neopterin was developed coupling magnetic beads with screen-printed array of electrodes. Protein A-coated magnetic beads were modified with the capture antibody. Neopterin- alkaline posphatase conjugate was used as label in a competitive assay scheme. The optimized electrochemical method, based on polyclonal antibodies, reached a limit of detection of 0.008 ?g/L with an average RSD % = 10. Serum samples collected from patients with sepsis, healthy volunteers and other patients without a confirmed clinical diagnosis were also analyzed. The obtained results, compared with those of a commercial ELISA kit, had a significant correlation, showing the possibility to distinguish among the serum samples from ill or healthy subjects. The electrochemical immunoassay resulted then a promising tool to predict the risk of a possible disease related with neopterin concentrations. This work was partially funded by the European Commission within the integrated project CARE-MAN (HealthCARE by Biosensor Measurements And Networking), NMP4-CT-2006- 01733