EN2 and cancer: Although EN2 is detected as a cancer marker for proof‐of‐concept in this study, the 3p3 immunoassay can be applied to the detection of a variety of other urinary cancer markers, because any antibodies (IgG) can be readily attached to the surface of SPAB‐presenting HBVC via specific interaction between SPAB and Fc region of anti‐marker IgG, leading to the construction of 3D‐IgG probes for detecting any cancer markers.