New amperometric immunosensor with response enhanced by PAMAM-dendrimers linked via self assembled monolayers for determination of alpha-fetoprotein in human serum

A new amperometric immunosensor for alpha-fetoprotein (AFP), based on nanobiocomposite substrate and with response enhanced by polyamidoaminic (PAMAM) dendrimers was developed and characterized. The nanostructurated substrate obtained by electrochemical deposition of 100 nm-sized gold nanoparticles on glassy carbon electrodes (GCE) was functionalized by deposition of a SAM of 2-aminoethanethiol (AET), used as linker for the subsequent immobilization of polyamidoaminic dendrimers (PAMAM G.1.5). Two different modes were investigated for the reading of the assay: cyclic voltammetry (CV) or Double Step ChronoAmperometry (DSCA). Satisfying results in terms of response range and precision were reached with both methods. Immunosensors were tested and validated for AFP determination in human serum, showing a limit of detection of 3 ng/mL and a limit of quantitation of 15 ng/mL. The enhanced immunosensor has proved an attractive diagnostic tool able to match the needs of clinical monitoring purposes for AFP quantification in human serum at levels useful both for prognosis of pregnancy progression, and for the identification of the occurrence of neoplastic diseases.