Paper-based three-dimensional electrochemical immunodevice based on multi-walled carbon nanotubes functionalized paper for sensitive point-of-care testing

In this study, electrochemical immunoassay was introduced into the recently proposed microfluidic paper-based analytical device (μPADs). To improve the performance of electrochemical immunoassay on μPAD for point-of-care testing (POCT), a novel wax-patterned microfluidic paper-based three-dimensional electrochemical device (3D-μPED) was demonstrated based on the multi-walled carbon nanotubes (MWCNTs) modified μPAD. Using typical HRP-O-Phenylenediamine-H2O2 electrochemical system, a sandwich immunoassay on this 3D-μPED for sensitive diagnosis of two tumor markers simultaneously in real clinical serum samples was developed with a linear range of 0.001–75.0 U mL−1 for cancer antigen 125 and 0.05–50.0 ng mL−1 for carcinoembryonic antigen. In addition, this 3D-μPED can be easily integrated and combined with the recently emerging paper electronics to further develop simple, sensitive, low-cost, disposable and portable μPAD for POCT, public health and environmental monitoring in remote regions, developing or developed countries.

► Sandwich electro-immunoassay was introduced onto μPAD for sensitive POCT for the first time.
► A novel 3D μPEID was demonstrated to perform high-performance electro-immunoassay for POCT.
► MWCNTs and CS were used to modified μPAD for high-performance electrochemical POCT.