Paper-based electrochemical immunosensor device via Ni-Co MOF nanosheet as a peroxidase mimic for the label-free detection of alpha-fetoprotein

Abstract

The quantitative detection of tumor biomarkers (TMs) is of great importance in clinical cancer diagnosis and curative effect evaluation. Conventional TM detection methods require bulky equipment and well-trained personnel, resulting in high complexity and cost for diagnostics. To resolve these issues, a paper-based electrochemical immunosensor device coupled with a Ni-Co metal-organic framework (Ni-Co MOF) as a peroxidase mimic was constructed for the label-free detection of alpha-fetoprotein (AFP). First, aminated Ni-Co MOF nanosheets were synthesized by a facile solvothermal method, and then carbon nanotubes and streptavidin-functionalized Ni-Co MOF were successively modified onto a graphene nanosheet-printed polyethylene terephthalate (GNP) electrode. The Ni-Co MOF provided a large specific surface area for capturing the biotin-antibody of AFP efficiently. Afterward, a prepared three-electrode system was assembled with patterned paper to fabricate a highly integrated paper-based electrochemical immunosensor for AFP. Due to the remarkable peroxidase-like activity of the Ni-Co MOF, it was found to amplify the electrode signal obviously. After the formation of the immune complex, the catalytic activity of the MOF was greatly inhibited and led to a reduced current signal, and the highly sensitive and selective detection of AFP with a linear range of 1–200 ng/mL and a detection limit of 0.3 ng/mL was realized. The integrated paper-based immunosensor based on a Ni-Co MOF peroxidase mimic shows great application potential in the personalized point-of-care diagnosis of disease.