A disposable paper-based electrochemiluminescence device for ultrasensitive monitoring of CEA based on Ru(bpy)32+@Au nanocages

In this work, an electrochemiluminescence (ECL) immunoassay integrated with the proposed 3D microfluidic origami device for the sensitive detection of carcinoembryonic antigen (CEA) was developed based on Ag nanospheres modified paper working electrode (Ag-PWE) as the sensor platform and Au nanocages functionalized tris-(bipyridine)-ruthenium(II) (Ru(bpy)(3)(2+)) as the ECL signal amplification label. The novel Ag-PWE with excellent conductivity was constructed through the growth of an Ag nanosphere layer on the surfaces of cellulose fibers and served to provide a good pathway for electron transfer and enhance the amount of captured antibody (Ab1). Au nanocages, which possessed a hollow structure, were first used to construct the ECL immunosensor as a signal amplification carrier. Both the inner and outer surfaces of the Au nanocages can adsorb Ru(bpy)(3)(2+), therefore the signal can be amplified as much as possible. In addition, this as-prepared 3D microfluidic origami ECL immunodevice had the advantages of high sensitivity, acceptable precision and reasonable accuracy. On the basis of the considerably amplified ECL signal and sandwich-type format, the as-proposed immunodevice successfully fulfilled the highly sensitive detection of CEA with a linear range of 0.001-50 ng mL(-1) and a detection limit of 0.0007 ng mL(-1). The resulting 3D microfluidic origami ECL immunodevice exhibited great promise in the point-of-care diagnostics application of clinical screening of tumor markers.