A label-free electrochemical immunosensor based on PtCoCu PNPs/NB-rGO as a dual signal amplification platform for sensitive detection of β-Amyloid1-42

•PtCoCu PNPs had high catalytic ability and biocompatibility.•The NB-rGO demonstrated good catalytic performance and offered high surface area to disperse PtCoCu PNPs through electrostatic adsorption and dative bonds.•Compared the effective electroactive area of PtCoCu PNPs/NB-rGO with PtCoCu PNPs by Randles-Sevcik equation.•The designed platform achieved dual signal amplification based on the synergy catalytic effect of PtCoCu PNPs/NB-rGO.•The immunosensor exhibited a broad linear range with extremely low detection limit for Aβ. In this work, a label-free electrochemical immunosensor based on popcorn-shaped PtCoCu nanoparticles supported on N- and B-codoped reduced graphene oxide (PtCoCu PNPs/NB-rGO) was constructed to sensitively detect concentration level of β-Amyloid1-42 oligomers (Aβ). The PtCoCu PNPs exhibits excellent catalytic ability due to its popcorn structure which improves the specific surface area and porosity, resulting in more active sites being exposed and fast transport paths for ion/electron. NB-rGO with large surface area and unique pleated structure could disperse PtCoCu PNPs through electrostatic adsorption and formation of d-p dative bonds between the metal ion and pyridinic N of NB-rGO. In addition, the doping of B atoms enhances the catalytic ability of GO enormously and achieves further signal amplification. Besides, both PtCoCu PNPs and NB-rGO are able to fix abundant antibodies through M(Pt, Co, Cu)-N bonds and amide bonds respectively without any other complex processing procedures such as carboxylation, ect. The designed platform achieved the dual amplification of electrocatalytic signal and effectively immobilization of antibodies. Under the optimum conditions, the designed electrochemical immunosensor presented wide linear rang (50.0 fg/mL ∼ 100 ng/mL) and low detection limits (3.5 fg/mL). The results demonstrated that the prepared immunosensor will be promising in sensitive detection of AD biomarkers.