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As a carbon-free reaction process, the electrocatalytic nitrogen reduction reaction (eNRR) under mild conditions has broad prospects for green and sustainable NH3 production. In this work, bimetallic RhRu nanoalloys (NAs) with cross-linked curly nanosheets were successfully prepared and exhibited exciting results in the eNRR process. Furthermore, the composition effect of RhRu NAs on eNRR activity was studied systematically, and the results showed that Rh0.6Ru0.4 NAs/CP exhibited the highest NH3 yield rate of 57.75 μg h−1 mgcat.−1 and faradaic efficiency of 3.39%. As an eNRR catalyst with great potential, Rh0.6Ru0.4 NAs extend the possibility of alloy-nanomaterials in the eNRR field and further provide an idea for the precise structure of more effective and stable electrocatalysts. [ABSTRACT FROM AUTHOR]

In this study, a sensitive label-free electrochemical immunosensor was designed based on nanoporous Fe3O4 and a biotin–streptavidin system to specifically detect zearalenone (ZEN). Herein, nanoporous Fe3O4 was employed to carry streptavidin to prepare the highly sensitive immunosensor. The application of nanoporous Fe3O4 and the biotin–streptavidin reaction provided large amounts of antibodies on each conjugate, thus amplifying the detected signal. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted to characterize the modification with ZEN. Factors which might influence the properties of the immunosensor, including concentration of nanoporous Fe3O4, pH of the buffer, incubation time and temperature were studied. Under the best conditions, the immunosensor displayed a highly sensitive response toward ZEN, ranging in concentration from 10.0 pg mL−1 to 3.00 ng mL−1 and 3.00 ng mL−1 to 12.0 ng mL−1, with a low detection limit of 3.7 pg mL−1. The results for analysis of human urine samples were satisfactory. Furthermore, this proposed method may find promising applications in the detection of other mycotoxins. [ABSTRACT FROM AUTHOR]

Using nitrogen-doped carbon quantum dots (NCQDs) and antimony trisulfide (Sb2S3) to co-sensitize hydrangea-shaped tungsten trioxide (WO3), a novel photoelectrochemical (PEC) immunosensor was constructed to sensitively detect procalcitonin (PCT). WO3 possessed a three-dimensional structure with uniform size and large surface area on the indium tin oxide (ITO) electrode. NCQDs with abundant carboxy groups and excitation-independent PEC behavior were modified on the surface of the WO3 coating to enhance photochemical activity. Hence, the hydrangea-shaped WO3/NCQDs/Sb2S3 composite was obtained by modifying NCQDs and well-crystallized Sb2S3 nanoparticles on WO3 through a layer-by-layer assembly. It is worth noting that the photoelectric signal of WO3/NCQDs/Sb2S3 was about 8 times that of pure WO3 under visible light excitation. Moreover, the PEC immunosensor showed a large-scale response (0.001–100 ng mL−1) and a low detection limit (0.42 pg mL−1) under the best experimental conditions. This PEC immunosensor has advantages such as simplicity, facile fabrication, high sensitivity and strong stability, which have good research value in the analysis and detection of disease biomarkers. [ABSTRACT FROM AUTHOR]

An ultrasensitive label-free photoelectrochemical (PEC) immunosensor was developed to detect amyloid β-protein (Aβ) based on CdS/CdTe-cosensitized SnO2 nanoflowers. Specifically, SnO2 with a flower-like porous nanostructure was utilized as a perfect substrate for the construction of PEC immunosensors, and the SnO2-modified electrode was first coated with CdTe quantum dots (QDs) and then further deposited with CdS by successive ionic layer adsorption and reaction techniques. The formed SnO2/CdS/CdTe-cosensitized structure exhibited excellent photocurrent intensity and was employed as an excellent photoactive matrix to immobilize Aβ antibody to further construct the immunosensor. Under optimal conditions, the as-constructed PEC immunosensor was used to detect Aβ and exhibited a wide linear concentration range from 0.5 pg mL−1 to 10 ng mL−1, with a low limit of detection (LOD, 0.18 pg mL−1, S/N = 3). Meanwhile, it also presented good reproducibility, specificity, and stability and may open a new promising platform for the clinical detection of Aβ or other biomarkers. [ABSTRACT FROM AUTHOR]

In this work, a photoelectrochemical (PEC) aptasensor for the detection of 17β-estradiol (E2) based on an In2S3 and CdS co-sensitized cerium (Ce) doped TiO2 (Ce:TiO2) electrode was constructed successfully. In2S3 with superior properties, such as narrow band gap, attractive photoelectric conversion efficiency, hypotoxicity and low pollution, could act as a promising material in the PEC sensing detection field. Here, a PEC aptasensor based on In2S3 was fabricated for the detection of E2. Besides, Ce doped into TiO2 introduced a new intrinsic energy band into TiO2, which created an easier electron transfer path. In2S3 and CdS co-loaded on Ce:TiO2 not only improved the photocurrent response but also expanded the light absorption range. Meanwhile, an aptamer with a specific sequence, serving as a recognition unit, was used to specifically bind with E2 to enable detection. Under optimal conditions, the as-prepared aptasensor exhibited a linearity range of 10−5–100 ng mL−1 with a detection limit of 4.0 fg mL−1. The aptasensor also showed satisfactory selectivity, stability and acceptable reproducibility. [ABSTRACT FROM AUTHOR]

In this work, the heterostructures of Au nanoparticles loaded on 3D flower-like α-Fe2O3 (Au NPs/α-Fe2O3) as a platform and core–shell CdSe@CdS quantum dots sensitized graphene oxide (GO/CdSe@CdS QDs) as a signal amplification label were established in an ultrasensitive sandwich-type photoelectrochemical (PEC) immunosensor based on the “signal-on” type amplification method for detection of amyloid β-protein (Aβ). Specifically, the ultrahigh sensitivity of the proposed immunosensor came from two main properties. First, Au NPs/α-Fe2O3 could partially absorb visible-light, which dramatically promotes electron transfer because of the excellent conductivity of Au NPs, and effectively inhibits the electron–hole recombination, thanks to the effect of heterostructures. Second, the signal-on type is based on the signal amplification label of GO/CdSe@CdS QDs which on adequate absorption of visible-light can improve generation of photogenerated electron–hole pairs effectively. Under optimal conditions, the well-prepared PEC immunosensor exhibited a low detection limit of 0.02 pg mL−1 and a wide linear range from 0.06 pg mL−1 to 350 ng mL−1 for Aβ detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising pathway for detection of other important biomarkers. [ABSTRACT FROM AUTHOR]

Four simple trans-AB-porphyrins 3a–3d either without any alkoxyl substituent, or with a mono-alkoxyl chain at different (ortho and para) positions of the meso-phenyl ring, or with two alkoxyl chains at two ortho positions of the meso-phenyl ring were designed and synthesized via three steps. The synthesis is simple and no expensive metal catalyst is involved. All compounds were characterized by 1H-NMR and mass spectraometry. UV-Vis absorption spectra and B band-excited fluorescence emission spectra were also obtained. The synthesized porphyrins were applied in dye-sensitized solar cells (DSSCs). Up to 3.05% conversion efficiency was realized for 3d under our experimental conditions, attributed to the two long alkoxyl chains present at the ortho positions of the meso-phenyl group. The influences of the position and the number of the alkoxyl chains at the macrocyclic meso-phenyl group on the photovoltaic performance of DSSCs are well explained via DFT calculations. It was shown that the VOC and JSC of the sensitizers are determined by μnormal, ΔGinject and LHE. [ABSTRACT FROM AUTHOR]

In this work, a photoelectrochemical (PEC) aptasensor for the detection of 17β-estradiol (E2) based on an In2S3 and CdS co-sensitized cerium (Ce) doped TiO2 (Ce:TiO2) electrode was constructed successfully. In2S3 with superior properties, such as narrow band gap, attractive photoelectric conversion efficiency, hypotoxicity and low pollution, could act as a promising material in the PEC sensing detection field. Here, a PEC aptasensor based on In2S3 was fabricated for the detection of E2. Besides, Ce doped into TiO2 introduced a new intrinsic energy band into TiO2, which created an easier electron transfer path. In2S3 and CdS co-loaded on Ce:TiO2 not only improved the photocurrent response but also expanded the light absorption range. Meanwhile, an aptamer with a specific sequence, serving as a recognition unit, was used to specifically bind with E2 to enable detection. Under optimal conditions, the as-prepared aptasensor exhibited a linearity range of 10−5–100 ng mL−1 with a detection limit of 4.0 fg mL−1. The aptasensor also showed satisfactory selectivity, stability and acceptable reproducibility. [ABSTRACT FROM AUTHOR]

In this study, a sensitive label-free electrochemical immunosensor was designed based on nanoporous Fe3O4 and a biotin-streptavidin system to specifically detect zearalenone (ZEN). Herein, nanoporous Fe3O4 was employed to carry streptavidin to prepare the highly sensitive immunosensor. The application of nanoporous Fe3O4 and the biotin-streptavidin reaction provided large amounts of antibodies on each conjugate, thus amplifying the detected signal. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted to characterize the modification with ZEN. Factors which might influence the properties of the immunosensor, including concentration of nanoporous Fe3O4, pH of the buffer, incubation time and temperature were studied. Under the best conditions, the immunosensor displayed a highly sensitive response toward ZEN, ranging in concentration from 10.0 pg mL-1 to 3.00 ng mL-1 and 3.00 ng mL-1 to 12.0 ng mL-1, with a low detection limit of 3.7 pg mL-1. The results for analysis of human urine samples were satisfactory. Furthermore, this proposed method may find promising applications in the detection of other mycotoxins.