Dual-signal sandwich electrochemical immunosensor for amyloid β-protein detection based on Cu-Al2O3-g-C3N4-Pd and UiO-66@PANI-MB.

Combining of amperometric and square wave voltammetric methods (SWV), the dual-signal sandwich electrochemical immunosensor was developed for quantitative determination of amyloid β-protein (Aβ). Cu was doped into Al2O3 lattice (Cu-Al2O3) and reacts with graphite carbon nitride (g-C3N4) to generate Cu-Al2O3-g-C3N4 with internal dual-reaction center structure, which has good catalytic properties of hydrogen peroxide (H2O2). Subsequently, palladium nanoparticles (Pd NPs) was introduced into Cu-Al2O3-g-C3N4 (Cu-Al2O3-g-C3N4-Pd) that not only synergistically catalyzed H2O2 but also immobilized anti-Aβ (Ab1) via Pd-NH2. The Cu-Al2O3-g-C3N4-Pd was used as matrix material to modify the electrode, which can produce obviously electrochemical signals through Amperometry i-t curve. Meanwhile, the Zr6O4(OH)4(CO2)12 (UiO-66) modified with polyaniline (PANI) has the large specific surface, good conductivity and adsorption capacity, which can support methylene blue (MB) as signal label of anti-Aβ (Ab2). Therefore, the UiO-66@PANI-MB can provide an obviously electrochemical signal about MB through SWV. Under optimal conditions, the dual-signal sandwich electrochemical immunosensor has salient analytical performance and both signal platforms provide more accurate results. The linear range of detection obtained by the immunosensor was 10 fg/mL-100 ng/mL, and the detection limit was 3.3 fg/mL. This method not only provided a reliable guarantee for the experimental detection but also provided an effective strategy for the detection of other biological.