Photoelectrochemical (PEC) analysis technique provides a unique route for sensitive biomolecular detection. In this paper, a novel visible-light-driven PEC sensor for detection of dopamine (DA) was fabricated based on ultrathin FeOOH cocatalyst modified nanoporous BiVO 4 photoanode. Scanning electrochemical microscopy (SECM) technique was employed to characterize the photocatalytic activities of the as-prepared photoanodes surfaces, and the first-order heterogenous electron transfer rate constants ( K eff ) were evaluated, which further revealed the photocatalytic performance of the modified photoanodes in water oxidation and the PEC sensing mechanism. A remarkable water oxidation photocurrent on the ITO/BiVO 4 /FeOOH photoanode could be achieved and served as anodic photocurrent of blank sample for PEC sensing dopamine (DA), which showed linearly range of 0.2–40 μM and 40–1400 μM with a detection limit of 0.09 μM. This method showed simplicity, high sensitivity and selectivity, high stability and wide linearity range, which provided a promising platform for the development of PEC sensor and offered an insight into the exploitation of BiVO 4 -based photolysis water materials for PEC bioanalytical purposes.
A dual-mode lab-on-paper device based on BiVO4/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 BiVO4/FeOOH nanocomposites were in situ synthesized onto the paper-working electrode (PWE) through hydrothermal synthesis of the BiVO4layer on cellulose fibers (paper-based BiVO4) 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 BiVO4to construct the paper-based BiVO4/FeOOH for the portable dual-mode lab-on-paper device. The obtained nanocomposites with an FeOOH needle-like structure deposited on the BiVO4layer 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 H2O2due 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−1and 0.5–100 ng·mL−1separately, with the limit of detection of 0.0008 and 0.013 ng·mL−1for 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.Keywords:PEC;colorimetric;lab-on-paper device;BiVO4/FeOOH;CEA
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