A dual-mode of homogeneous electrochemical-colorimetric biosensing sensor for carcinoembryonic antigen detection based on microfluidic paper-based analysis device

Dual-mode based sensors have drawn a lot of interest due to their high accuracy and sensitivity compared to single-response systems. A simple electrochemical and colorimetric dual-mode sensor based on enzyme-linked immunosorbent assay (ELISA), without complex electrode surface modification, was developed for accurate and sensitive detection of carcinoembryonic antigen (CEA). A target CEA is recognized by an antibody coupled to horseradish peroxidase (HRP), which then oxidizes the substrate 3,3',5,5'-tetramethylbenzidine (TMB) to generate both a colorimetric and an electrochemical signal. A paper-based analysis device (μPAD) with dual-mode homogeneous sensing microfluidic was created, three paper-based detection areas for colorimetric testing, and a two-electrode embedded detection area for electrochemical testing. When applying colorimetric analysis technology, the linear range of CEA detection is 0.6–40 ng/mL, and the limit of detection (LOD) is 0.2 ng/mL. The linear range is 0.1-40 ng/mL and the LOD is 0.03 ng/mL by applying electrochemical analysis. The visibility and intuitiveness of colorimetry provide a reference for higher sensitivity and quick response of the electrochemical method. a smartphone application（APP） was also developed to realize the dual extraction of colorimetric signals. The colorimetric detection system based on ELISA can provide a new path for the development of electrochemical sensing and makes it have inherent self-verification and self-correction functions and is expected to provide more reliable and accurate detection results.