Fig. 1

a Schematic illustration of an ELC immunoassay for CA 15−3 detection by using Ru(bpy)₆²⁺-functionalized amino-coated UiO-66 MOF NPs [150]. Reprinted with permission from Ref. [150], copyright 2019, Elsevier. b Schematic illustration of immune-based MOF EIS biosensors for cascade catalysis-initiated radical polymerization-stimulated signal intensification for CA15-3 detection [151]. Reprinted with permission from Ref. [151], copyright 2019, Elsevier.  GOx Glucose oxidase, ACAC acetylacetone, PNIPAM poly (N-isopropylacrylamide)