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 Al 2 O 3 lattice (Cu–Al 2 O 3) and reacts with graphite carbon nitride (g-C 3 N 4) to generate Cu–Al 2 O 3 -g-C 3 N 4 with internal dual-reaction center structure, which has good catalytic properties of hydrogen peroxide (H 2 O 2). Subsequently, palladium nanoparticles (Pd NPs) was introduced into Cu–Al 2 O 3 -g-C 3 N 4 (Cu–Al 2 O 3 -g–C 3 N 4 –Pd) that not only synergistically catalyzed H 2 O 2 but also immobilized anti-Aβ (Ab 1) via Pd–NH 2. The Cu–Al 2 O 3 -g–C 3 N 4 –Pd was used as matrix material to modify the electrode, which can produce obviously electrochemical signals through Amperometry i-t curve. Meanwhile, the Zr 6 O 4 (OH) 4 (CO 2) 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 (Ab 2). 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. Cu–Al 2 O 3 -g–C 3 N 4 –Pd catalyze H 2 O 2 to generate electrochemical signal and UiO-66@PANI-MB can produce the peak current through Amperometry i-t curve, which together constructed the dual-signal sandwich electrochemical immunosensor. Image 1 • A dual-signal sandwich electrochemical immunosensor was fabricated. • Cu–Al 2 O 3 -g–C 3 N 4 –Pd owned excellent properties for catalyzing hydrogen peroxide. • UiO-66@PANI-MB was used as a novel signal label. • The electrochemical immunosensor utilized SWV and Amperometry i-t curve. • The designed immunosensor exhibited low detection limit of 3.3 fg/mL for Aβ. [ABSTRACT FROM AUTHOR]