3D origami electrochemical immunodevice for sensitive point-of-care testing based on dual-signal amplification strategy

A dual signal amplification immunosensing strategy that offers high sensitivity and specificity for the detection of low-abundance biomarkers was designed on a 3D origami electrochemical device. High sensitivity was achieved by using novel Au nanorods modified paper working electrode (AuNRs-PWE) as sensor platform and metal ion-coated Au/bovine serum albumin (Au/BSA) nanospheres as tracing tags. High specificity was further obtained by the simultaneous measurement of two cancer markers on AuNRs-PWE surface using different metal ion-coated Au/BSA tracers. The metal ions could be detected directly through differential pulse voltammetry (DPV) without metal preconcentration, and the distinct voltammetric peaks had a close relationship with each sandwich-type immunoreaction. The position and size of the peaks reflected the identity and level of the corresponding antigen. Integrating the dual-signal amplification strategy, a novel 3D origami electrochemical immunodevice for simultaneous detecting carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125) with linear ranges of over 4 orders of magnitude with detection limits down to 0.08 pg mL−1 and 0.06 mU mL−1 was successfully developed. This strategy exhibits high sensitivity and specificity with excellent performance in real human serum assay. The AuNRs-PWE and the designed tracer on this immunodevice provided a new platform for low-cost, high-throughput and multiplex immunoassay and point-of-care testing in remote regions, developing or developed countries.