Shang et al. created a dual-potential ratiometric ECL sensorderived from single luminophore and coreactant, using palladium nanoclusters(Pd-NCs) prepared with a DNA duplex as a template, thereby achievingsensitive detection of CEA, with a detection limit of 87.1 ag/mL (S/N= 3) and a linear range from 100 ag/mL to 10 ng/mL, providing newtechnical support for early cancer diagnosis. CA-242 is a common diagnostic biomarker for detecting pancreaticcancer and colorectal cancer. Here, CEACAM5 is linked to cancer.