Cathode photoelectrochemical immunoassay usually shows better anti-interference capacity toward real samples than anode photoelectrochemical immunoassay. However, its poor photocurrent response has greatly restricted the detection sensitivity. Herein, a promising ultrasensitive cathode photoelectrochemical immunoassay was developed based on TiO2 photoanode-enhanced 3D Cu2O nanowire array (NWA) photocathode, and coupled with signal amplification by horseradish peroxidase (HRP)-induced biocatalytic precipitation (BCP). Carcinoembryonic antigen (CEA, Ag) was used as a detection model, TiO2 nanoparticle-modified indium tin oxide (ITO) electrode served as the photoanode, and Cu2O NWAs grown in situ on Cu mesh was both the photocathode and photoelectrochemical matrix to immobilize the capture CEA antibodies (Ab1). The signal CEA antibodies (Ab2) were labeled with HRP to form Ab2-HRP bioconjugates, and employed as signal amplifiers when the specific immunoreaction occurred. The developed photoanode-enhanced cathode photoelectrochemical immunoassay has good anti-interference capability, outstanding photocurrent response, and high sensitivity for target Ag detection, which was attributed to the synergistic effects of the 3D nanostructure of Cu2O NWA photocathode, the introduction of TiO2 photoanode as counter electrode, and the signal amplification of Ab2-HRP bioconjugate-induced BCP. The developed cathode photoelectrochemical immunoassay showed a low limit of detection (0.037 pg mL−1) with a wide linear range (from 0.1 pg mL−1 to 50 ng mL−1) for CEA detection. © 2018 Elsevier B.V.

Cathode photoelectrochemical immunoassay usually shows better anti-interference capacity toward real samples than anode photoelectrochemical immunoassay. However, its poor photocurrent response has greatly restricted the detection sensitivity. Herein, a promising ultrasensitive cathode photoelectrochemical immunoassay was developed based on TiO₂ photoanode-enhanced 3D Cu₂O nanowire array (NWA) photocathode, and coupled with signal amplification by horseradish peroxidase (HRP)-induced biocatalytic precipitation (BCP). Carcinoembryonic antigen (CEA, Ag) was used as a detection model, TiO₂ nanoparticle-modified indium tin oxide (ITO) electrode served as the photoanode, and Cu₂O NWAs grown in situ on Cu mesh was both the photocathode and photoelectrochemical matrix to immobilize the capture CEA antibodies (Ab₁). The signal CEA antibodies (Ab₂) were labeled with HRP to form Ab₂-HRP bioconjugates, and employed as signal amplifiers when the specific immunoreaction occurred. The developed photoanode-enhanced cathode photoelectrochemical immunoassay has good anti-interference capability, outstanding photocurrent response, and high sensitivity for target Ag detection, which was attributed to the synergistic effects of the 3D nanostructure of Cu₂O NWA photocathode, the introduction of TiO₂ photoanode as counter electrode, and the signal amplification of Ab₂-HRP bioconjugate-induced BCP. The developed cathode photoelectrochemical immunoassay showed a low limit of detection (0.037 pg mL⁻¹) with a wide linear range (from 0.1 pg mL⁻¹ to 50 ng mL⁻¹) for CEA detection.
© 2018 Elsevier B.V.

Cathode photoelectrochemical immunoassay usually shows better anti-interference capacity toward real samples than anode photoelectrochemical immunoassay. However, its poor photocurrent response has greatly restricted the detection sensitivity. Herein, a promising ultrasensitive cathode photoelectrochemical immunoassay was developed based on TiO2 photoanode-enhanced 3D Cu2O nanowire array (NWA) photocathode, and coupled with signal amplification by horseradish peroxidase (HRP)induced biocatalytic precipitation (BCP). Carcinoembryonic antigen (CEA, Ag) was used as a detection model, TiO2 nanoparticle-modified indium tin oxide (ITO) electrode served as the photoanode, and Cu2O NWAs grown in situ on Cu mesh was both the photocathode and photoelectrochemical matrix to immobilize the capture CEA antibodies (Ab(1)). The signal CEA antibodies (Ab(2)) were labeled with HRP to form Ab(2)-HRP bioconjugates, and employed as signal amplifiers when the specific immunoreaction occurred. The developed photoanode-enhanced cathode photoelectrochemical immunoassay has good anti-interference capability, outstanding photocurrent response, and high sensitivity for target Ag detection, which was attributed to the synergistic effects of the 3D nanostructure of Cu2O NWA photocathode, the introduction of TiO2 photoanode as counter electrode, and the signal amplification of Ab(2)-HRP bioconjugate-induced BCP. The developed cathode photoelectrochemical immunoassay showed a low limit of detection (0.037 pgmL(-1)) with a wide linear range ( from 0.1 pgmL(-1) to 50 ng mL(-1)) for CEA detection. (C) 2018 Elsevier B.V. All rights reserved.

During the past decade, biofuel cells (BFCs) have emerged as an emerging technology on account of their ability to directly generate electricity from biologically renewable catalysts and fuels. Due to the boost in nanotechnology, significant advances have been accomplished in BFCs. Although it is still challenging to promote the performance of BFCs, adopting nanostructured materials for BFC construction has been extensively proposed as an effective and promising strategy to achieve high energy production. In this review, we presented the major novel nanostructured materials applied for BFCs and highlighted the breakthroughs in this field. Based on different natures of the bio-catalysts and electron transfer process at the bio-electrode surfaces, the fundamentals of BFC systems, including enzymatic biofuel cells (EBFCs) and microbial fuel cells (MFCs), have been elucidated. In particular, the principle of electrode materials design has been detailed in terms of enhancing electrical communications between biological catalysts and electrodes. Furthermore, we have provided the applications of BFCs and potential challenges of this technology.

The enhancement of microbial activity and electrocatalysis through the design of new anode materials is essential to develop microbial fuel cells (MFCs) with longer lifetimes and higher output. In this research, a novel anode material, graphene/Fe3O4 (G/Fe3O4) composite, has been designed for Shewanella-inoculated MFCs. Because the Shewanella species could bind to Fe3O4 with high affinity and their growth could be supported by Fe3O4, the bacterial cells attached quickly onto the anode surface and their long-term activity improved. As a result, MFCs with reduced startup time and improved stability were obtained. Additionally, the introduction of graphene not only provided a large surface area for bacterial attachment, but also offered high electrical conductivity to facilitate extracellular electron transfer (EET). The results showed that the current and power densities of a G/Fe3O4 anode were much higher than those of each individual component as an anode.

Enzymatic biofuel cells (EBFCs) are considered as a promising approach to meet the requirements of power sources. Electrode materials, which are significant factors to affect the power output of EBFCs, have aroused great interest. Herein, we developed an EBFC using a Fe3O4-carbon nanofiber/gold nanoparticle hybrid as the substrate electrode for improving the performance of the power output. The open-circuit voltage (E-OCV) of the designed EBFC reached 0.68 +/- 0.03 V, and the maximum power density (P-max) reached 126 +/- 4.5 mu W cm(-2). The as-prepared EBFC showed 3 times higher P-max compared to the EBFC based on the carbon nanofiber/gold nanoparticle hybrid, which was ascribed to the good electrocatalytic activity of Fe3O4 NP loaded carbon nanofibers (CNFs), the 3D porous structure of CNFs as well as the uniform distribution of Au NPs. The Fe3O4-CNF/gold nanoparticle hybrid is considered as a promising candidate for constructing electrochemical biosensors and biofuel cells.