Dual-function core-shell nanocube probes enabling continuous production of cortisol-sensing yarns via conjugate electrospinning

With the growing global burden of chronic stress, there is an increasing need for real-time, non-invasive monitoring of cortisol dynamics. Molecularly imprinted polymer (MIP)-based sensing technology is known for its cost-effectiveness and low susceptibility to deactivation. Current invasive MIP-based cortisol sensors face fundamental requirements for improving sensitivity and widening the detection range. In addition, they encounter challenges in improving wearability and portability, as well as in developing commercially viable techniques. This work designs dual-function core-shell nickel hexacyanoferrate-MIP nanocubes (NiHCF-MIP NCs) and accordingly proposes a one-step conjugate electrospinning technique to yield coaxial cortisol-sensing yarns. The core-shell architecture effectively integrates the redox signal transduction capability of NiHCF with the cortisol-specific recognition function of MIP, enabling a continuous one-step fabrication process. The utilization of conjugate electrospinning technology not only supports scalable manufacturing but also creates a coaxial yarn structure that combines the advantages of the spun nanofiber network cortex and core threads. The as-produced yarns simultaneously possess high conductivity, flexibility, wearability, and rapid body fluid absorption, collectively enhancing the sensing performance. Consequently, the electrospun yarns exhibit a high sensitivity of 2.08 μA·dec^-1, and the limit of detection (LOD) is theoretically calculated to be 0.4 nmol/L. This synergistic strategy combines core-shell dual-function nanomaterials with a one-step continuous conjugate electrospinning technique. It provides an innovative pathway for developing integrated wearable biosensing textiles for personal real-time stress monitoring and telehealth applications.