A disposable immunosensor device for point-of-care test of tumor marker based on copper-mediated amplification

A paper-based immunodevice was fabricated for point-of-care test (POCT). The array device was simple and easily assembled. It comprised as many as 4×10 detection points on a single paper array. The immunosensor array was prepared by covalently immobilizing capture antibodies on corresponding working zone on a disposable paper array. With a sandwich-type immunoreaction, the CuO nanoparticles (CuO NPs)-labeled secondary antibody (Ab2) bioconjugates were captured in each working zone. The coordination of dithizone (DZ) at the surface of CdTe quantum dots (CdTe QDs) could strongly quench the green emission of CdTe QDs by a fluorescence resonance energy transfer (FRET) mechanism. After the Cu(2+) was released from CuO NPs-Ab2, the fluorescence of CdTe QDs-DZ was "turn-on". The fluorescence intensity would increase with the increasing of analytes. The calibration plot showed a good linear relationship between the fluorescence intensity and the logarithm value of the analytes concentration with the low detection limit. The immunosensor array was performed for cancer screening. The high throughput, low-cost, acceptable stability, reproducibility, sensitivity and accuracy showed good applicability of the proposed multiplex immunoassay in clinical diagnosis. The results indicated that the device could be applied to comprehensive sample and point-of-care detection.