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

• An electrochemical immunosensor for neopterin detection is reported.
• Recently produced specific antibodies against neopterin were used.
• Disposable array of electrodes were used to develop the assay.
• Serum samples collected from patients with sepsis, healthy volunteers and other patients without a confirmed clinical diagnosis were analyzed.

An electrochemical immunoassay for neopterin was developed using recently produced specific antibodies immobilized to protein A-coated magnetic beads in combination with differential pulse voltammetry and screen-printed array of electrodes. Neopterin–alkaline phosphatase conjugate was used as label in a competitive assay format. Multiplexed analysis of neopterin was demonstrated by replacing the traditional ELISA with electrochemical detection and the traditional plastic wells with screen-printed array of electrodes. The optimized electrochemical method, based on polyclonal antibodies, reached a limit of detection of 0.008 ng/mL 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.

Magnetic beads coated with protein A were modified by immobilization of specific antibodies against neopterin and then the competition between neopterin and neopterin labeled with alkaline phosphatase was performed. After the immunosensing step, beads were captured by a magnet onto the working surfaces of screen-printed arrays for the electrochemical detection. Figure optionsDownload as PowerPoint slide