Porous graphene based electrochemical immunosensor using Cu₃(BTC)₂ metal-organic framework as nonenzymatic label

An electrochemical immunosensor for highly sensitive detection of cancer biomarkers has been developed based on the combination of a sensing platform of polydopamine modified porous graphene and a nonenzymatic label of metal-organic framework (MOF) conjugated secondary antibody. This approach achieves a wide range of linear response from 0.1 to 10 ng/mL, low detection limit of 0.025 ng/mL (at a signal to noise ratio of 3), good reproducibility and selectivity for the detection of prostate specific antigen (PSA) as a model analyte. The high performance of the immunosensor is attributed to the high surface area from porous graphene and the strong adhesion of polydopamine, allowing a high load of the primary antibody of PSA, as well as the highly electrocatalytic activity of the Cu₃(BTC)₂ (BTC = benzene-1,3,5-tricarboxylic acid) MOF toward H₂O₂ to provide greatly amplified sensitivity. In this respect, the MOF-based nonenzymatic label shows promising application for the point-of-care detection of different cancer biomarkers in clinical diagnostics.