This sensor incorporates horseradish peroxidase-labeled SHBG antibody immobilized onto the CHIT/CuNPs/Fe3O4 NPs/GrONPs/Au surface, allowing for specific detection of SHBG antigen in PCOS patients with a lower limit of detection (LOD) at 0.01 nM (Figure 2A). Here, SHBG is linked to polycystic ovary syndrome.