A disposable paper-based microfluidic immunosensor based on reduced graphene oxide-tetraethylene pentamine/Au nanocomposite decorated carbon screen-printed electrodes

A novel, disposable and sensitive microfluidic paper-based electrochemical immunosensor (μ-PEI) was developed by using gold nanoparticles (Au NPs) decorated reduced graphene oxide-tetraethylene pentamine (rGO-TEPA/Au nanocomposite) as electrode materials. The rGO-TEPA greatly amplified the current response due to its excellent conductivity and large surface area. Au NPs was decorated on the surface of rGO-TEPA to increase the biocompatibility and retained good stability for rGO-TEPA/Au nanocomposite, which was used as an effective sensor platform for anchoring the capturing antibodies (Ab1) and accelerating the electron transfer to the screen-printed electrodes (SPEs). The simple and disposable paper-based microfluidic channel patterned on the rGO-TEPA/Au nanocomposite modified SPEs (SPEs/rGO-TEPA/Au) was designed for combination of immunochromatography and immunofiltration simultaneously. With the combination of portable SPEs/rGO-TEPA/Au and simple paper-based microfluidic devices, horseradish peroxidase (HRP) and labeled signal antibodies (Ab2) co-immobilized gold nanorods (HRP-GNRs-Ab2) was explored as the tracers for square wave voltammetry (SWV) detection. Using Alpha-Fetoprotein (AFP) as a model analyte, the proposed μ-PEI exhibited a satisfactory performance like simple fabrication, high stability, selectivity, wide linear range (0.01 ng mL−1-100.0 ng mL−1) with a low detection limit (0.005 ng mL−1). Furthermore, human serum were applied to the obtained μ-PEI and determined with satisfactory results.