An ultrasensitive interleukin-6 immunosensor based on hollow NiCo@C nanocubes for ultrafast diagnosis of septic cardiomyopathy

Interleukin-6 (IL-6) is an essential serum biomarker in the diagnosis of the septic cardiomyopathy, which causes acute shock to increase the fatality rate of patients to about 80 %. However, due to the time-consuming nature of current clinical assay techniques, the on-site and rapid test of IL-6 during the surgery and emergencies remains a major challenge to save lives. In this work, we proposed an ultrasensitive electrochemical immunosensor to rapidly determine serum IL-6 within just 20 min, relying on the hollow carbon coated NiCo alloy nanocubes (NiCo@C). This NiCo@C architecture is derived from a Prussian blue analogue through a controlled pyrolysis process, which facilitates the in-situ reduction of the NiCo alloy inside the cavity while preserving the nanocubic carbon skeleton. This unique structure offers outstanding electrocatalysis and conductivity for the generation and amplification of the immune signal, as well as provides abundant binding domains for the immobilization of antibody. The resulting IL-6 immunosensor demonstrates a wide detection range from 0.1 pg/mL to 100 ng/mL and an ultralow detection limit of 0.03 pg/mL, as well as high reliability for assay and dynamic monitoring in human serum samples. This immunosensor will show tremendous potentials for the early-warning and monitoring of patients' vital signs in emergency settings.