Combined with the GOx-encapsulated zeolitic imidazolate framework-8 conjugated with antibody (GOx@ZIF-8-Ab2), the carcinoembryonic antigen (CEA), a cell surface glycoprotein related to lung, liver, pancreas, breast, cervix, and prostate cancer, was detected using colorimetric biosensing via catalytic cascade reactions (Fig. 7d), whose sensitivity was more than 6 times higher than that of HRP-based ELISA. Here, CEACAM5 is linked to prostate carcinoma.