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 (mu PADs). To improve the performance of electrochemical immunoassay on mu PAD for point-of-care testing (POCT), a novel wax-patterned microfluidic paper-based three-dimensional electrochemical device (3D-mu PED) was demonstrated based on the multi-walled carbon nanotubes (MWCNTs) modified mu PAD. Using typical HRP-O-Phenylenediamine-H2O2 electrochemical system, a sandwich immunoassay on this 3D-mu PED 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-mu PED can be easily integrated and combined with the recently emerging paper electronics to further develop simple, sensitive, low-cost, disposable and portable mu PAD for POCT, public health and environmental monitoring in remote regions, developing or developed countries. (C) 2011 Elsevier B.V. All rights reserved.