A disposable label-free electrochemiluminescent immunosensor for transferrin detection based on a luminol-reduced gold nanoparticle-modified screen-printed carbon electrode

A label-free electrochemiluminescence (ECL) immunosensor using a luminol-reduced gold nanoparticle (Lu-Re-GNP)-modified screen-printed carbon electrode (SPCE) as the sensing platform was proposed for the sensitive detection of transferrin (TRF), an anemia biomarker in human serum. To achieve the purpose of low cost and disposable use, a SPCE was used as the substrate of the immunosensor. The Lu-Re-GNP-modified sensing platform exhibited a stable and strong ECL emission, which could be employed for the recognition of the target antigen with the aid of the unconjugated antibody immobilized on the electrode. With a simple label-free mode, the SPCE-based ECL assay with the advantages of low cost and facile manipulation was established successfully. In the presence of TRF, a decrease in the ECL intensity could be observed because of the immuno-binding event. This decrease in ECL intensity permitted sensitive detection of TRF in a linear range of 0.10–18 ng mL−1, with a detection limit of 0.033 ng mL−1. The assay results of TRF in serum samples were in good agreement with those of ELISA. The reproducibility, the stability and the specificity of the proposed strategy were acceptable. The approach could also be further extended to facile immunoassay of other biomarker proteins.