Simple one-pot aqueous synthesis of 3D superstructured PtCoCuPd alloyed tripods with hierarchical branches for ultrasensitive immunoassay of cardiac troponin I.

By integrating the amplified electrochemical signals and effective capture of antibodies together, advanced multimetallic superstructured nanocrystals endow label-free immunosensors promising applications in early diagnosis and monitoring of diseases. Herein, four-metallic PtCoCuPd hierarchical branch-like tripods (HBTPs) were directly synthesized by a green one-pot aqueous method without any seed or organic solvent involved, which were applied to construct a novel label-free immunosensor for detecting cardiac troponin I (cTnI). The specific hierarchical micro/nanostructures greatly improved the immobilization of antibodies and enhanced the catalytic activity for KFe(CN), which would effectively amplify the electrochemical signals, thereby improving the detection sensitivity. Under the optimal conditions, the as-developed immunosensor exhibited a wide linear range (0.001-100.0 ng mL) and a low detection limit (0.2 pg mL, S/N = 3) for the assay of cTnI. The immunosensor provides a powerful platform for quantitative detection of cTnI, which can be explored to detect other tumor markers in actual sample analysis.