PANI-encapsulated NiCo alloy nanoflowers for ultrasensitive immunosensing of procalcitonin

Sepsis, a life-threatening condition, remains a leading cause of global mortality. It is frequently accompanied by systemic inflammatory response syndrome (SIRS), which triggers excessive release of inflammatory factors and may lead to a cytokine storm. The sensitive detection of procalcitonin (PCT) is therefore critical for early prediction and clinical management of sepsis. In this work, an electrochemical immunosensor was developed based on polyaniline-encapsulated NiCo alloy (NiCo@PANI) nanoflowers for the ultrasensitive detection of PCT. The NiCo alloy ensures rapid electron transfer, and the in-situ polymerization of PANI on the surface of NiCo nanoflowers not only enhances their antioxidant stability but also offers an efficient matrix for antibody immobilization. During the detection process, the specific binding of PCT to the antibody on the electrode surface increases the electron transfer resistance and the steric resistance, resulting in a decrease in current value. By fitting the linear relationship between the attenuated signal and the PCT concentration, the quantitative identification of PCT can be achieved. The fabricated immunosensor achieves ultrasensitive detection of PCT within 20 min, exhibiting a broad linear range from 0.1 pg/mL to 100 ng/mL and a detection limit as low as 0.015 pg/mL. Moreover, it exhibited high selectivity, excellent stability, and satisfactory reproducibility, along with accurate PCT detection in real human serum samples. This work provides a promising platform for ultrasensitive PCT monitoring, with potential applications in early disease diagnosis and point-of-care health assessment.