PEC/Colorimetric Dual-Mode Lab-on-Paper Device via BiVO(4)/FeOOH Nanocomposite In Situ Modification on Paper Fibers for Sensitive CEA Detection

A dual-mode lab-on-paper device based on BiVO(4)/FeOOH nanocomposites as an efficient generating photoelectrochemical (PEC)/colorimetric signal reporter has been successfully constructed by integration of the lab-on-paper sensing platform and PEC/colorimetric detection technologies for sensitive detection of carcinoembryonic antigen (CEA). Concretely, the BiVO(4)/FeOOH nanocomposites were in situ synthesized onto the paper-working electrode (PWE) through hydrothermal synthesis of the BiVO(4) layer on cellulose fibers (paper-based BiVO(4)) which were initially modified by Au nanoparticles for improving the conductivity of three dimensional PWE, and then the photo-electrodeposition of FeOOH onto the paper-based BiVO(4) to construct the paper-based BiVO(4)/FeOOH for the portable dual-mode lab-on-paper device. The obtained nanocomposites with an FeOOH needle-like structure deposited on the BiVO(4) layer exhibits enhanced PEC response activity due to its effective separation of the electron–hole pair which could further accelerate the PEC conversion efficiency during the sensing process. With the introduction of CEA targets onto the surface of nanocomposite-modified PWE assisted by the interaction with the CEA antibody from a specific recognition property, a signal-off PEC signal state with a remarkable photocurrent response decreasing trend can be achieved, realizing the quantitative detection of CEA with the PEC signal readout mode. By means of a smart origami paper folding, the colorimetric signal readout is achieved by catalyzing 3,3′,5,5′-tetramethylbenzidine (TMB) to generate blue oxidized TMB in the presence of H(2)O(2) due to the satisfied enzyme-like catalytic activity of the needle-like structure, FeOOH, thereby achieving the dual-mode signal readout system for the proposed lab-on-paper device. Under the optimal conditions, the PEC and colorimetric signals measurement were effectively carried out, and the corresponding linear ranges were 0.001–200 ng·mL(−1) and 0.5–100 ng·mL(−1) separately, with the limit of detection of 0.0008 and 0.013 ng·mL(−1) for each dual-mode. The prepared lab-on-paper device also presented a successful application in serum samples for the detection of CEA, providing a potential pathway for the sensitive detection of target biomarkers in clinical application.