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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]

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]

Food adhesion on containers could increase food waste and pollution; this problem can be effectively alleviated by introducing a superhydrophobic surface. In this research, edible superhydrophobic Fe foils (ESFFs) were prepared by fumigating edible low surface free energy substances including lard, beeswax, and food grade paraffin on calcined Fe foil. All of the three obtained ESFF samples exhibited excellent superhydrophobicity and attractive stability under different working conditions, and the used sample can be easily recovered by re-fumigation. Most tested liquid foods and starch slurries can be effectively repelled by ESFF without observable residues. The ESFF shows promising prospects as a green and useful superhydrophobic material. [ABSTRACT FROM AUTHOR]

A novel fluorescent turn-on aptasensor has been developed for the detection of mercuric ions (Hg2+) based on carbon dots (CDs) as donor molecules and MnO2 nanosheets as acceptor molecules. In this work, an effective fluorescent probe was fabricated through the conjugation of a single-stranded oligodeoxyribonucleotide (ssDNA) on the surface of CDs. In the absence of the target Hg2+, the CDs labeled with ssDNA were adsorbed on the MnO2 surface via van der Waals forces. The fluorescence signal of CDs was then quenched by MnO2 nanosheets via the fluorescence resonance energy transfer (FRET) mechanism. While Hg2+ was introduced, the specific affinity interactions between ssDNA and Hg2+ could detach CDs-labeled ssDNA (ssDNA-CDs) from the MnO2 surface because of the production of the thymine–Hg2+–thymine (T–Hg2+–T) complex, leading to the recovery of the fluorescence intensity. Under the optimal reaction conditions, the fluorescence intensity of CDs enhanced gradually with the increasing concentration of Hg2+ ions in the range from 2 to 200 nmol L−1 and the limit of detection was found to be 0.67 nmol L−1. In addition, the proposed strategy developed its application in the determination of Hg2+ in real samples with excellent performance. These features illustrated that the designed fluorescent sensing platform is a reliable quantitative candidate for potential applications in biological and analytical fields. [ABSTRACT FROM AUTHOR]

Herein, we demonstrated the protocol of a visible light induced photoelectrochemical cytoassay on the basis of TiO2 nanorods/carboxylated g-C3N4/ox-graphene quantum dots coupling with a biospecific interaction for the ultrasensitive detection of fibroblast-like synoviocyte cells. The nanohybridization assembly of TiO2 NRs, carboxylated g-C3N4 and ox-GQDs showed good PEC performance through the excellent electrical conductivity as well as the high photon-to-electron conversion efficiency and improved the sensitivity of the cytosensor. To perform the cytoassay, CD95 antibody, a marker of FLS cells, was conjugated onto the TiO2 NR/carboxylated g-C3N4/ox-GQD modified electrode to trap the cell target by using EDC/NHS coupling reactions. The concentrations of FLS cells were determined by the decrease in photocurrent intensity resulting from the increase in steric hindrance from FLS cells. This strategy opens a simple perspective for the application of carboxylated g-C3N4 and ox-GQDs as light-harvesting architectures. [ABSTRACT FROM AUTHOR]

An ultrasensitive electrochemical immunosensor for the detection of cluster of differentiation 146 antigen (CD146) based on TiO2 colloidal sphere laden Au/Pd nanoparticles (Au/Pd@TiO2) was developed. In this work, reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) was applied as an electrode modifying material to modify the surface of a glassy carbon electrode (GCE). Au/Pd@TiO2 was used as the secondary-antibody (Ab2) label for the fabrication of the immunosensor. Amperometric response of the immunosensor for electrocatalytic reduction of hydrogen peroxide (H2O2) was recorded. Electrochemical impedance spectroscopy (EIS) proved that fabrication of the immunosensor was successful. The anti-CD146 primary antibody (Ab1) was immobilized on the rGO-TEPA modified GCE by a cross-linking reagent of glutaraldehyde (GA). With Ab1 immobilized onto the rGO-TEPA modified GCE and Ab2 linked with Au/Pd@TiO2, the immunosensor displayed a wide linear range (0.0050–20 ng mL−1), a low detection limit (1.6 pg mL−1), good reproducibility, good selectivity and acceptable stability. The designed sensing strategy may provide a potential application in the detection of other tumor markers. [ABSTRACT FROM AUTHOR]

In this paper, carboxymethyl functionalized chitosan was used for the synthesis of a magnetic polysaccharide–graphene oxide composite (SCGO). Compared with the magnetic chitosan–graphene oxide composite reported before, adsorption capacity in this research had improved significantly. The calculated maximum adsorption capacity values for methylene blue (MB) and malachite green (MG) were 358.4 mg g−1 and 289.1 mg g−1, respectively. The morphology, chemical properties and physical structure of SCGO were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The influence factors which included pH, adsorbent dose, ionic strength and contact time on the adsorption properties of MB and MG onto SCGO were investigated. The adsorption kinetics of MB and MG on SCGO were well-described by pseudo-second order kinetic models. The experimental data of the isotherm followed the Temkin isotherm model and the Langmuir model, respectively. Thermodynamic analysis was also performed to calculate the changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS). The results obtained from this research suggested that SCGO was a potential adsorbent for effective removal of methylene blue and malachite green. [ABSTRACT FROM AUTHOR]

The excellent catalytic activity of a novel nanomaterial was introduced to ultrasensitive sandwich-type electrochemical immunosensor applications for detection of carcinoembryonic antigen (CEA). Amino-functionalized multi-walled carbon nanotube (MWCNT-NH2) supported PdPt nanocages were used as catalytic labels of secondary anti-CEA. PdPt nanocages with hollow interiors and porous walls could efficiently enhance electrocatalysis for reduction of H2O2. Meanwhile, with good dispersion, large specific surface area and amino groups, MWCNT-NH2 can immobilize a large amount of PdPt nanocages to improve the sensitivity and amplify the signal of the immunosensor. For the immobilization of primary antibodies, 3-aminopropyltriethoxysilane functionalized graphene sheets were used as transducing materials to modify glassy carbon electrodes and to enhance the electron transfer efficiently. Under the optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.001–20 ng mL−1 with a low detection limit of 0.2 pg mL−1 for CEA. The proposed sensing strategy enriches electrochemical immunoassays and may have a promising application in bioassay analysis. [ABSTRACT FROM AUTHOR]

Glass transition temperature ( T g ) always deteriorates while improving the strength of epoxy resins which inherently suffer from brittleness. Herein, novel linear polyhedral oligomeric silsesquioxane (POSS)-epoxy nano-modifiers are synthesized with variable contents of POSS. The thermomechanical properties and chemical structure study of the POSS-epoxy indicates significant differences of the rigid POSS content in the linear nano-modifiers. By taking advantage of the synergistic effect of nanofillers and linear polymers, the modifiers disperse at the molecular level when POSS-epoxy is utilized as a co-curing agent for epoxy resins, allowing the applied force to be transferred into the polymer matrix. A good balance of T g , stiffness, and fracture toughness can be obtained. At 5 wt% of the nano-modifier, the resultant epoxy resins showed 27% enhancement in the Young's modulus relative to the neat epoxy. In addition, the T g and strength of epoxy thermosets are improved due to the increased cross-linking density, rough surface and tortuous path that resulted in good dispersion of energy during crack propagation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

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.

Herein, we demonstrated the protocol of a visible light induced photoelectrochemical cytoassay on the basis of TiO 2 nanorods/carboxylated g-C 3 N 4 /ox-graphene quantum dots coupling with a biospecific interaction for the ultrasensitive detection of fibroblast-like synoviocyte cells. The nanohybridization assembly of TiO 2 NRs, carboxylated g-C 3 N 4 and ox-GQDs showed good PEC performance through the excellent electrical conductivity as well as the high photon-to-electron conversion efficiency and improved the sensitivity of the cytosensor. To perform the cytoassay, CD95 antibody, a marker of FLS cells, was conjugated onto the TiO 2 NR/carboxylated g-C 3 N 4 /ox-GQD modified electrode to trap the cell target by using EDC/NHS coupling reactions. The concentrations of FLS cells were determined by the decrease in photocurrent intensity resulting from the increase in steric hindrance from FLS cells. This strategy opens a simple perspective for the application of carboxylated g-C 3 N 4 and ox-GQDs as light-harvesting architectures.

An ultrasensitive electrochemical immunosensor for the detection of cluster of differentiation 146 antigen (CD146) based on TiO2 colloidal sphere laden Au/Pd nanoparticles (Au/Pd@TiO2) was developed. In this work, reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) was applied as an electrode modifying material to modify the surface of a glassy carbon electrode (GCE). Au/Pd@TiO2 was used as the secondary-antibody (Ab2) label for the fabrication of the immunosensor. Amperometric response of the immunosensor for electrocatalytic reduction of hydrogen peroxide (H2O2) was recorded. Electrochemical impedance spectroscopy (EIS) proved that fabrication of the immunosensor was successful. The anti-CD146 primary antibody (Ab1) was immobilized on the rGO-TEPA modified GCE by a cross-linking reagent of glutaraldehyde (GA). With Ab1 immobilized onto the rGO-TEPA modified GCE and Ab2 linked with Au/Pd@TiO2, the immunosensor displayed a wide linear range (0.0050-20 ng mL(-1)), a low detection limit (1.6 pg mL(-1)), good reproducibility, good selectivity and acceptable stability. The designed sensing strategy may provide a potential application in the detection of other tumor markers.

The excellent catalytic activity of a novel nanomaterial was introduced to ultrasensitive sandwich-type electrochemical immunosensor applications for detection of carcinoembryonic antigen (CEA). Amino-functionalized multi-walled carbon nanotube (MWCNT-NH 2 ) supported PdPt nanocages were used as catalytic labels of secondary anti-CEA. PdPt nanocages with hollow interiors and porous walls could efficiently enhance electrocatalysis for reduction of H 2 O 2 . Meanwhile, with good dispersion, large specific surface area and amino groups, MWCNT-NH 2 can immobilize a large amount of PdPt nanocages to improve the sensitivity and amplify the signal of the immunosensor. For the immobilization of primary antibodies, 3-aminopropyltriethoxysilane functionalized graphene sheets were used as transducing materials to modify glassy carbon electrodes and to enhance the electron transfer efficiently. Under the optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.001-20 ng mL -1 with a low detection limit of 0.2 pg mL -1 for CEA. The proposed sensing strategy enriches electrochemical immunoassays and may have a promising application in bioassay analysis.