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Photosystem I (PSI), a robust and abundant biomolecule capable of delivering high‐energy photoelectrons, has a great potential for the fabrication of light‐driven semi‐artificial bioelectrodes. Although possibilities have been explored in this regard, the true capabilities of this technology have not been achieved yet, particularly for their use as bioanodes. Here, the use of PSI Langmuir monolayers and their electrical wiring with specifically designed redox polymers is shown, ensuring an efficient mediated electron transfer as the basis for the fabrication of an advanced biophotoanode. The bioelectrode is rationally implemented and optimized for enabling the generation of substantial photocurrents of up to 17.6 µA cm−2 and is even capable of delivering photocurrents at potentials as low as −300 mV vs standard hydrogen electrode, surpassing the performance of comparable devices. To highlight the applicability of the developed light‐driven bioanode, a biophotovoltaic cell is assembled in combination with a gas‐breathing biocathode. The assembly operates in a single compartment cell and delivers considerable power outputs at large cell voltages. The implemented biophotoanode constitutes an important step toward the development of advanced biophotovoltaic devices. [ABSTRACT FROM AUTHOR]

Well‐defined assemblies of photosynthetic protein complexes are required for an optimal performance of semi‐artificial energy conversion devices, capable of providing unidirectional electron flow when light‐harvesting proteins are interfaced with electrode surfaces. We present mixed photosystem I (PSI) monolayers constituted of native cyanobacterial PSI trimers in combination with isolated PSI monomers from the same organism. The resulting compact arrangement ensures a high density of photoactive protein complexes per unit area, providing the basis to effectively minimize short‐circuiting processes that typically limit the performance of PSI‐based bioelectrodes. The PSI film is further interfaced with redox polymers for optimal electron transfer, enabling highly efficient light‐induced photocurrent generation. Coupling of the photocathode with a [NiFeSe]‐hydrogenase confirms the possibility to realize light‐induced H2 evolution. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (GNPs) were deposited directly onto the surface of indium tin oxide (ITO) thin film-coated glass by electrochemical method. It was used as a photoanode in a photoelectrochemical (PEC) cell for sensitive detection of hydroquinone (HQ) at an applied bias potential of 0.15 V vs. saturated calomel electrode. This heterostructure showed dramatically enhanced PEC properties due to the introduction of the Au/ITO interface. Under the irradiation, the marked photocurrent response was observed at the GNPs/ITO photoelectrode compared with bare ITO electrode. The anodic photocurrent could be further largely enhanced by HQ. A new PEC strategy for sensitive detection of HQ at a relative low potential was developed. The linear range for HQ determination was 0.25 to 150 μM, with a detection limit of 0.1 μM. The sensitivity on the GNPs/ITO electrode at the irradiation was ~ 3.3 times higher than that in dark. These results demonstrate that the simple GNPs/ITO electrodes have great potential for PEC analysis application. [ABSTRACT FROM AUTHOR]

A cathodic “signal-on” method was developed for the photoelectrochemical detection of Hg 2+ ions. Here, ZnS quantum dots (QDs) capped with mercaptoacetic acid was assembled on the surface of an indium tin oxide (ITO) electrode through electrostatic interaction between poly dimethyl diallyl ammonium chloride (PDDA) and the ZnS QDs. HgS was formed on the ZnS surface by ion-exchange in the presence of Hg 2+ ions in solution. The cathodic photocurrent increased under visible light irradiation with a light-emitting diode lamp. This novel strategy exhibits high sensitivity and good selectivity owing to the low background signal and the benefits of ion-exchange technology. The cathodic photocurrent increases linearly with Hg 2+ concentration in the range 1 × 10 −11 –1 × 10 −6 M, providing a detection limit of 2 pM (S/N = 3). This sensor provides a promising new strategy for the detection of trace heavy metal ions. [ABSTRACT FROM AUTHOR]

A novel self-assemble approach was developed for constructing a linear bicontinuous donor–acceptor, (H 2 BCPP) n –C 60 , arrays on indium-tin oxide electrode. Electronic absorption spectra, fluorescence spectra and atomic force microscopy were used as powerful tools to characterize H 2 BCPP, (H 2 BCPP) n arrays and (H 2 BCPP) n –C 60 arrays. The (H 2 BCPP) n –C 60 arrays enhanced the photocurrent generation capability, and presented an efficient photoelectrochemical immunosensing platform for the ultrasensitive detection of carcinoembryonic antigen (CEA). The quantitative measurement of CEA was based on the decrease in the photocurrent intensity of the (H 2 BCPP) n –C 60 arrays, which was resulted from the competition between CEA and CEA-CdTe. A linear relationship between the photocurrent decrease and the CEA concentration was obtained in the wide range from 0.01 to 60 ng mL −1 with a detection limit of 3.4 pg mL −1 . The proposed sensor showed high sensitivity, stability and reproducibility, and provided a promising platform for other biomolecular detection. [ABSTRACT FROM AUTHOR]

Abstract: Combining microfluidic paper-based analytical device (μ-PAD) and the molecular imprinting technique, a visible light photoelectrochemical (PEC) sensing platform for the detection of pentachlorophenol (PCP) was established on gold nanoparticles (AuNPs) decorated paper working electrode using polypyrrole-functionalized ZnO nanoparticles. Ascorbic acid (AA) was exploited as an efficient and nontoxic electron donor for scavenging photogenerated holes under mild solution medium and facilitating the generation of stable photocurrent. The microfluidic molecular imprinted polymer-based PEC analytical origami device is developed for the detection of PCP in the linear range from 0.01ngmL−1 to 100ngmL−1 with a low detection limit of 4pgmL−1. This disposable microfluidic PEC origami device would provide a new platform for sensitive, specific, and multiplex assay in public health, environmental monitoring, and the developing world. [Copyright &y& Elsevier]

A molecular imprinted polymer thin film for photoelectrochemical (PEC) sensing of chlorpyrifos molecules was first constructed by electropolymerizing the o-phenylenediamine (o-PD) monomer and chlorpyrifos template molecule on gold nanoparticles-modified titanium dioxide nanotubes. The resulting PEC sensors were characterized by scanning electron microscopy, ultraviolet (UV)-vis spectra and electrochemical impedance spectra. Clearly, the imprinted film showed high selectivity to chlorpyrifos in our case. Under visible light irradiation, poly(o-phenylenediamine) (PoPD) can generate the photoelectric transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), delivering the excited electrons to the AuNPs, and then to the conduction band (CB) of the titanium dioxide nanotubes (TiO2 NTs). Simultaneously, it is believed that a positively charged hole (h+) of PoPD that took part in the oxidation process was consumed to promote the amplification of photocurrent response. Under the optimal experimental conditions, the photocurrents were proportional to the concentrations of chlorpyrifos ranging from 0.05 to 10 μmol L−1 with the detection limit of 0.96 nmol L−1. The PEC sensor had an excellent specificity and could be successfully applied to the detection of reduced chlorpyrifos in green vegetables, indicating a promising application in PEC sensing. [ABSTRACT FROM AUTHOR]

An ultrasensitive photoelectrochemical (PEC) immunoassay was introduced into microfluidic paper-based analytical devices (μ-PADs) based on a multiple electron transfer system for the first time, which was constructed using narrow-band-gap semiconductor nanoparticles (NPs), wide-band-gap semiconductor NPs, and an electron-accepting medium. [ABSTRACT FROM AUTHOR]

A chemiluminescent (CL) excited photoelectrochemical (PEC) immunosensor for detection of carcinoembryonic antigen (CEA) was introduced into microfluidic paper-based analytical devices (μ-PADs) integrated with a paper supercapacitor (PS) amplifier, and a terminal digital multi-meter (DMM) detector, based on CdS/TiO 2 hybrid modified porous Au-paper electrode. The effective matching of energy levels between the conduction bands of CdS and TiO 2 allowed for fast electron injection from excited CdS to TiO 2 upon irradiation, which inhibited the recombination process of electron–hole pairs and prompted PEC performance. Using CEA/ABEI-AuNPs-GOx bioconjugates as signal labels which featured CEA, N-(aminobutyl)-N-(ethylisoluminol) (ABEI) and glucose oxidase (GOx) linked to Au nanoparticles for signal amplification could greatly enhance the sensitivity. GOx could catalyze glucose to produce H 2 O 2 , which acted as a co-reactant in the ABEI-AuNPs-H 2 O 2 - p -iodophenol (PIP) CL system as well as sacrificial electron donor to scavenge the photogenerated holes in the valence band of CdS QDs, further causing an enhanced photocurrent. The quantification mechanism of this strategy is based on the charging of this PS by the photocurrent. The generated photocurrent could be stored by the PS and released instantaneously through a low cost, portable, and simple DMM to obtain an amplified current for the quantification of CEA. Under the optimal conditions, this analytical platform could detect CEA at concentrations at picomole level. This work offers a new route to highly selective and sensitive detection of biologically important small molecules. [ABSTRACT FROM AUTHOR]