Figure 15.

a) Schematic illustration of the detection mechanism of the electrochemical-based multiplex 3DμPAD including a photoactive matrix. i) The working electrode was prepared by coating the paper with Au/Pd NPs. ii) ZNRs were grown on the modified electrode and coupled with CdS QDs. iii) Capture antibodies for CEA and AFP were immobilized on the ZNRs surface and the surface of the paper were blocked with BSA. iv) Nanoporous silver NPs-based labels including detection antibodies and GOx were introduced. v) Photocurrent activity under visible light (“on” or “off”) was recorded following the glucose addition to the electrode. Reproduced with permission.^[112] Copyright 2015, Royal Society of Chemistry. b) Layered paper configuration for multi-parameter aptamer-based electrochemical detection of protein biomarkers (CEA and NSE). (1) sample inlet, (2) filtration sit, (3) counter electrode, (4) reference electrode, (5) detection zone, (6) working electrode. Reproduced with permission.^[113] Copyright 2019, Elsevier.