Distance-based carcinoembryonic antigen assay on microfluidic paper immunodevice

Recently, distance readout paper-based devices have been paid more attention for the advantages of straightforward, simple and equipment-free. In this work, a distance-based immunoassay on paper-based device for semi-quantitative detection of carcinoembryonic antigen (CEA) was developed. After the capture antibody, antigen and horseradish peroxidase (HRP)-labeled signal antibody were sequently added on the sample area, the washing buffer would carry the nonspecific signal antibody into the straight channel. A visible bar was produced with the precipitated 3,3',5,5'-tetramethyl benzidine (TMB) and hydrogen peroxide whose length was negatively correlated to the concentration of the targets. The distance-based visual semi-quantitative platform for CEA detection was achieved in the human serum. CEA levels as low as 5 ng/mL can be successfully detected with the distance readout in human serum and the detection limit of 2 ng/mL can be achieved in this work. With the advantages of low cost, ease of operation, general applicability and disposability, the method with distance readout on the paper-based devices would provide broad application as a class of inexpensive sensor technology in point-of-care (POC) field. (c) 2017 Elsevier B.V. All rights reserved.