Disulfide Hybrid Research Articles

Efficient interfacial charge separation in graphene quantum dots/tin disulfide hybrids for improved photoelectrochemical performance

Efficient interfacial charge separation in graphene quantum dots/tin disulfide hybrids for improved photoelectrochemical performance

Ruddlesden-Popper 2D Perovskite-MoS2 Hybrid Heterojunction Photocathodes for Efficient and Scalable Photo-Rechargeable Li-Ion Batteries.

Photo-rechargeable batteries (PRBs) can provide a compact solution to power autonomous smart devices located at remote sites that cannot be connected with the grid. The study reports the Ruddlesden-Popper (RP) metal halide perovskite (MHP) and molybdenum disulfide (MoS2) hybrid heterojunction-based photocathodes for Li-ion photo-rechargeable battery (Li-PRB) applications. Hybrid Lithium-ion batteries (LIBs) have demonstrated an average discharge specific capacity of 144.46 and 129.17 mAhg-1 for 50 cycles when operating at 176 and 294 mAg-1, respectively compared to the pristine LIBs which have shown specific capacity of 37.48 and 25.60 mAhg-1 under similar conditions. Hybrid Li-PRB has achieved an average dark discharge specific capacities of 128.66 mAhg-1 (capacity retention: 96.56%) which enhanced to 180.67 mAhg-1 under illumination (capacity retention: 97.39%; photo-enhancement: 40.42%) at 64 mAg-1. Excellent performance of hybrid Li-PRB is attributed to the formation of type-II heterojunction that leads to improved crystallinity and film morphology. The PRB has demonstrated a high photo conversion and storage efficiency (PC-SE) of 0.52% under standard 1 Sun illumination, which outperforms other previously reported MHP based LIBs and PRBs. This work provides a novel approach of harnessing the potential of MHPs for PRBs and offers new avenues for MHP photocathodes for various applications beyond PRBs.

Desirable Strong and Tough Adhesive Inspired by Dragonfly Wings and Plant Cell Walls.

The production of wood-based panels has a significant demand for mechanically strong and flexible biomass adhesives, serving as alternatives to nonrenewable and toxic formaldehyde-based adhesives. Nonetheless, plywood usually exhibits brittle fracture due to the inherent trade-off between rigidity and toughness, and it is susceptible to damage and deformation defects in production applications. Herein, inspired by the microstructure of dragonfly wings and the cross-linking structure of plant cell walls, a soybean meal (SM) adhesive with great strength and toughness was developed. The strategy was combined with a multiple assembly system based on the tannic acid (TA) stripping/modification of molybdenum disulfide (MoS2@TA) hybrids, phenylboronic acid/quaternary ammonium doubly functionalized chitosan (QCP), and SM. Motivated by the microstructure of dragonfly wings, MoS2@TA was tightly bonded with the SM framework through Schiff base and strong hydrogen bonding to dissipate stress energy through crack deflection, bridging, and immobilization. QCP imitated borate chemistry in plant cell walls to optimize interfacial interactions within the adhesive by borate ester bonds, boron-nitrogen coordination bonds, and electrostatic interactions and dissipate energy through sacrificial bonding. The shear strength and fracture toughness of the SM/QCP/MoS2@TA adhesive were 1.58 MPa and 0.87 J, respectively, which were 409.7% and 866.7% higher than those of the pure SM adhesive. In addition, MoS2@TA and QCP gave the adhesive good mildew resistance, durability, weatherability, and fire resistance. This bioinspired design strategy offers a viable and sustainable approach for creating multifunctional strong and tough biobased materials.

Unique synergistic effects of ternary multi-dimensional CNT/g-C3N4/MoS2 hybrid as a paraffin oil additive for improved tribological properties

Graphitic carbon nitride (g-C3N4) nanomaterials have drawn much interest in the lubrication and friction fields owing to their excellent self-lubrication and mechanical performances. However, the easy agglomeration and poor dispersion stability of single g-C3N4(CN) have always been a headache. In the work, multi-dimensional ternary carbon nanotube, graphite carbon nitride, and molybdenum disulfide (CNT, CN, and MoS2) hybrids were fabricated by hydrothermal method. The microstructure and its reinforcement impact on the tribological properties of the corresponding paraffin oil were systematically studied. The results showed that the zero-dimensional spherical MoS2, one-dimensional tubular CNT, and two-dimensional lamellar CN are uniformly compounded. The tribological test results display that average friction coefficient and wear rate of the 0.2 wt% CNT/CN/MoS2 are decreased by 39.23% and 91.97% lower than those of pure paraffin oil, CNT and CN/MoS2 with the same concentration, respectively. The significantly improved tribological properties of lubricating oil is ascribed to even dispersion of CNT, CN, MoS2 in CNT/CN/MoS2 hybrids, self-lubricating effect of MoS2 and CN, and load-bearing ability of CNT and CN nanosheets, and also the generation of lubricating film between friction pairs during the wear process.

Insights into nonlinear absorption transitions in a silver-incorporated reduced graphene oxide-molybdenum disulfide (Ag-rGO-MoS2) hybrid.

Optical nonlinearity in a silver-decorated reduced graphene oxide-molybdenum disulfide (Ag-rGO-MoS2) nanocomposite was experimentally investigated via the Z-scan technique using a Q-switched Nd:YAG nanopulsed green laser. An interesting switching behaviour from saturable to reverse saturable absorption with varying input on-axis intensity of the laser was demonstrated. Under low-intensity laser excitation, Ag-rGO-MoS2 displayed ground-state bleaching, which resulted in saturable absorption (SA) behaviour. Here, the prominent SPR phenomenon of Ag enforced plasmon absorption and is assigned to the SA process. Interestingly at higher intensity, the material switched its nonlinearity to reverse saturable absorption (RSA), attributed to two different mechanisms of two-photon absorption (2PA). At moderate laser pulse energies, the sample underwent sequential 2PA, which is underpinned by calculated varying nonlinear optical parameters and excited-state absorption cross-sections. However, at higher intensities, nonlinear absorption coefficients and excited-state absorption cross-sections remained constant, indicating the occurrence of genuine 2PA. In addition, theoretical estimation of the 2PA cross-section validates the observed transition. Thus, experimental evidence for the validity of nonlinear absorption theory (intensity-dependent transition from linear to nonlinear SA to nonlinear RSA to genuine 2PA via sequential 2PA) is provided for the first time in the literature.

Construction of a biomimetic wood structure with cellulose nanofiber/molybdenum disulfide hybrid aerogel for highly-efficient solar-driven interfacial evaporation

Solar-driven interfacial water evaporation is a promising solution to water scarcity and pollution problems because it can efficiently convert solar energy into thermal energy and produce sustainable clean water. In this work, inspired by the multi-channel structure in the xylem of plants, cellulose nanofibers (CNF) and molybdenum disulfide (MoS2) nanosheets were selected to construct CNF/MoS2 nanosheets aerogel (CMoA) with vertical pores by directional freeze-drying method. Then we utilized the aerogel as an interfacial solar evaporator. The super-hydrophilic and internal vertical pore structure of this evaporator gives CMoA a high capacity to store and transport water, with a water evaporation rate of 1.81 ± 0.06 kg·m−2·h−1 under 1 sun. The vertical pore structure and the strong ability to transport water of the evaporator also enable the salt on the evaporator surface to diffuse into the bulk water in time, without causing salt deposition. Therefore, CMoA has high salt resistance and stability and can achieve fast evaporation even in high-concentration salt water. In addition, CMoA can also produce water at a rate of up to 10.3 kg·m−2 per day in the outdoor environment. By combining the natural bio-based material CNF with the biomimetic wood structure of aerogel, CMoA has a facile water transport process similar to that of plants. Moreover, our CMoA is a monolayer structure, which makes the preparation process simple and less costly. These multiple advantages make CMoA a promising application for future practical desalination work.

Nanocarbon Black and Molybdenum Disulfide Hybrid Filler System for the Enhancement of Fracture Toughness and Electromechanical Sensing Properties in the Silicone Rubber-Based Energy Harvester.

Recently, hybrid fillers have been found to be more advantageous in energy-harvesting composites. This study investigated the mechanical and electromechanical performances of silicone rubber-based composites made from hybrid fillers containing conductive nanocarbon black (NCB) and molybdenum disulfide (MoS2). A hybrid filler system containing only 3 phr (per hundred grams of rubber) MoS2 and 17 phr NCB provided higher fracture strain, better tensile strength, and excellent toughness values compared to the 20 phr NCB-only-filled and 5 phr MoS2-only-filled rubber composites. The chemical cross-link densities suggest that NCB promoted the formation of cross-links, whereas MoS2 slightly reduced the cross-link density. The higher mechanical properties in the hybrid filler systems suggest that the filler particles were more uniformly distributed, which was confirmed by the scanning electron microscope study. Uniformly distributed filler particles with moderate cross-link density in hybrid filler systems greatly improved the fracture strain and fracture toughness. For example, the hybrid filler with a 17:3 ratio of NCB to MoS2 showed a 184% increment in fracture toughness, and a 93% increment in fracture strain, compared to the 20 phr NCB-only-filled composite. Regarding electromechanical sensing with 2 kPa of applied cyclic pressure, the hybrid filler (17:3 CB to MoS2) performed significantly better (~100%) than the 20 phr NCB-only compound. This may have been due to the excellent distribution of conducting NCB networks and piezoelectric MoS2 that caused symmetric charging-discharging in the toughened hybrid composite. Thus, hybrid composites with excellent fatigue resistance can find dynamic applications, such as in blood pressure measurement.

Mechanism on heterogeneous transfer film formed by diamond-like carbon film under molybdenum disulfide hybrid polyethylene glycol lubrication

Heterogeneous materials are an ideal platform for low friction, but most of the heterogeneous materials used in tribology field are artificially synthesized. Here, by matching the molybdenum disulfide (MoS2) hybrid polyethylene glycol (PEG 200) and diamond-like carbon (DLC) film, the spontaneous formation of heterogeneous transfer film was realized during sliding. Thus, the anti-friction/wear ability of the synergetic system is improved from the reduction of friction coefficient and wear rate by 33.3% and 32.1% contrast to DLC film, severally. The characterization results show that the heterogeneous transfer film is formed by the rehybridization and recrystallization of MoS2 and DLC combined with amorphous phase. The improvement on shearing capacity and bearing capacity of as-designed lubrication strategy better explicates the solid-liquid synergistic effect. The formation theory of heterojunction in solid-liquid composite lubrication is put forward, which has important reference value for the future solid-liquid composite lubrication technology.

Preparation of magnetic molybdenum disulfide for the extraction of neonicotinoid insecticides from environmental water samples

In this study, magnetic molybdenum disulfide hybrid composites (Fe3O4/MoS2) were successfully synthesized by in situ fabrication method and firstly applied as magnetic adsorbent for extracting neonicotinoid insecticides from environmental water samples. The Fe3O4/MoS2 composites were characterized in detail by scanning electron microscope, fourier transform infrared, X-ray diffraction and vibrating sample magnetometer, and possessed the faster adsorption capacity towards neonicotinoid insecticides (only 10 min). The parameters (solution pH, amounts of adsorbents, adsorption time, elution conditions and sample volume) effecting the performance of magnetic solid-phase extraction were carefully investigated. Under the optimal conditions, the magnetic solid-phase extraction-high performance liquid chromatography method based on Fe3O4/MoS2 composites for enriching and detecting neonicotinoid insecticides in environmental water samples was established. The good linearity (0.01–10 μg/mL) with correlation coefficients between 0.9949 and 0.9999 was obtained. The limits of detection and the limits of quantifications were 0.48–0.67 ng/mL and 1.44–2.02 ng/mL, respectively. With spiked at three different concentration levels (50, 100,500 ng/mL), the recovery was 66.0–91.3 % with relative standard deviations from 1.4 % to 8.3 %. These data demonstrated that the developed method was highly sensitive, repeatable and easily operated. Also, this study provided new adsorbents for other trace pollutants in the environment.

One-step synthesis of carbon sphere@ 1 T-MoS2 towards superior antiwear and lubricity

A novel carbon sphere (CS)@metallographic molybdenum disulfide (1 T-MoS2) hybrid was prepared by a straightforward one-step hydrothermal method and its synergistic effect on the tribology of polyethylene glycol 200 (PEG200) was reported. Systematical characterizations exhibited 1 T-MoS2 sheets were evenly anchored on the CS surface. Tribological results showed the friction coefficient of pure PEG200 oil decreased by 43% with adding 0.3125 wt% CS@ 1 T-MoS2. Optical images showed the diameters of wear marks were significantly reduced from 1860 µm for neat base oil to 880 µm for CS@ 1 T-MoS2. It was believed that the synergy between CS and 1 T-MoS2 played the crucial role in the friction reducing and anti-wear. Therefore, this work provides a facile approach to preparing lubricating additives by decorating 1 T-MoS2 on CS.

Soft computing and statistical approach for sensitivity analysis of heat transfer through the hybrid nanoliquid film in rotating heat pipe

In this paper, the numerical solution for heat transfer through a rotating heat pipe is studied and a sensitivity analysis is presented by using statistical experimental design technique. Graphene oxide-molybdenum disulfide (GO-MoS2) hybrid nanofluid is taken as working fluid inside the pipe. The impact of the heat pipe parameters (rotation speed, initial mass, temperature difference) on the heat transfer and liquid film thickness is investigated. The mathematical model coupling the fluid mass flow rate and liquid film evolution equations in evaporator, adiabatic, and condenser zones of the heat pipe is constructed. The mathematical model is solved by implementation of “Particle Swarm Optimization” along with the finite difference method. The outcomes demonstrate that hybrid nanoparticles help to improve the heat transfer through the heat pipe and reduce liquid film thickness. The heat transfer rises with increasing temperature difference and reducing inlet mass, and it reduces slightly with rising rotation speed. The difference in liquid film thickness between the evaporator and condenser zones increases with increasing temperature difference and decreasing rotation speed. The impact of increasing the volume fraction of GO on the liquid film thickness is higher than that in the case of the MoS2 nanoparticles. However, an increase of the heat transfer is noticed in case of increasing the volume fraction of GO relative to increasing MoS2 concentration. Statistical analysis of the computed numerical data and the identification of significant parameters for total heat transfer are found using the response surface method. At 95% level of significance, the GO concentration in the hybrid nanofluid, inlet mass of the hybrid nanofluid and the temperature difference inside the evaporator zone of the pipe are found to be significant linear parameters for increasing heat transfer.

Synthesis of 3D Hollow Layered Double Hydroxide-Molybdenum Disulfide Hybrid Materials and Their Application in Flame Retardant Thermoplastic Polyurethane.

The development of high-performance thermoplastic polyurethane (TPU) with high flame retardancy and low toxicity has always been the focus of its research. In this paper, the novel 3D hollow layered double hydroxide/molybdenum disulfide (LDH/MoS2) hybrid materials were synthesized by hydrothermal method using the MIL-88A as in situ sacrificial template and MoS2 as synergistic flame retardant. Among all TPU composites, the peak heat release rate, total heat release rate, and total smoke release rate of TPU/NiFeTb-LDH/MoS2 were reduced by 50.9%, 18.2%, and 35.8% compared with pure TPU, respectively. The results of the thermogravimetric infrared analysis demonstrated that the contents of combustible volatiles (hydrocarbons) and toxic volatiles (CO and HCN) emitted from TPU/LDH/MoS2 were significantly reduced, indicating that LDH/MoS2 hybrid materials can dramatically enhance the fire safety of TPU composites. Combined with the analysis of carbon residues and thermal stability of TPU composites, the enhanced flame retardancy and smoke suppression performances are primarily attributed to the catalytic carbonization of LDH and the physical barrier effect of MoS2.

Dynamics of ethylene glycol-based graphene and molybdenum disulfide hybrid nanofluid over a stretchable surface with slip conditions

In this research study, numerical and statistical explorations are accomplished to capture the flow features of the dynamics of ethylene glycol-based hybrid nanofluid flow over an exponentially stretchable sheet with velocity and thermal slip conditions. Physical insight of viscous dissipation, heat absorption and thermal radiation on the flow-field is scrutinized by dissolving the nanoparticles of molybdenum disulfide (MoS2) and graphene into ethylene glycol. The governing mathematical model is transformed into the system of similarity equations by utilizing the apt similarity variables. The numerical solution of resulting similarity equations with associated conditions are obtained employing three-stages Lobatto-IIIa-bvp4c-solver based on a finite difference scheme in MATLAB. The effects of emerging flow parameters on the flow-field are enumerated through various graphical and tabulated results. Additionally, to comprehend the connection between heat transport rate and emerging flow parameters, a quadratic regression approximation analysis on the numerical entities of local Nusselt numbers and skin friction coefficients is accomplished. The findings disclose that the suction and thermal radiation have an adverse influence on the skin friction coefficients and heat transport rate. Further, a slight augmentation in the thermal slip factor causes a considerable variation in the heat transport rate in comparison to the radiation effect.

Sensitivity Enhancement of Surface Plasmon Resonance (SPR) Sensor Assisted by BlueP/MoS2 Based Composite Heterostructure

This paper addresses a very high sensitivity of surface plasmon resonance (SPR) sensor assisted by novel BlueP/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> based composite heterostructure based on angular interrogation technique. Research on SPR techniques based on angular interrogation system is attracted a lot in recent years due to ease of implementation, robust, reliable and compatibility. These SPR sensors have wide applications in the field of biosensing, biochemical, gas detection, and biological science to mention a few. By these SPR techniques, performance parameters like figure of merit (F.O.M.), detection accuracy (D.A.), and most importantly sensitivity have been tremendously increased. In recent past 2D materials have attracted a massive response in SPR biosensors. Hence in this paper, 2D material like blue Phosphorene/molybdenum disulfide (i.e., BlueP/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) hybrid nanostructure as an integrating layer with the analyte is suggested to improve the sensitivity substantially of SPR sensor. In this connection performance of multilayer structure in conjunction with CaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> prism, Ag metal layer, Black Phosphorus, BlueP/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has been analyzed in this paper. The maximum sensitivity of the order of 458°/RIU has been obtained in this proposed scheme attributed to BlueP/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> based composite heterostructure at the visible wavelength of 662 nm. The proposed design analysis results in a significant improvement in sensitivity compared to traditional and graphene-based SPR sensors.

Fabrication of MERS-nanovesicle biosensor composed of multi-functional DNA aptamer/graphene-MoS2 nanocomposite based on electrochemical and surface-enhanced Raman spectroscopy

Middle East respiratory syndrome coronavirus (MERS-CoV) is one of the most harmful viruses for humans in nowadays. To prevent the spread of MERS-CoV, a valid detection method is highly needed. For the first time, a MERS-nanovesicle (NV) biosensor composed of multi-functional DNA aptamer and graphene oxide encapsulated molybdenum disulfide (GO-MoS2) hybrid nanocomposite was fabricated based on electrochemical (EC) and surface-enhanced Raman spectroscopy (SERS) techniques. The MERS-NV aptamer was designed for specifically binding to the spike protein on MERS-NVs and it is prepared using the systematic evolution of ligands by exponential enrichment (SELEX) technique. For constructing a multi-functional MERS aptamer (MF-aptamer), the prepared aptamer was connected to the DNA 3-way junction (3WJ) structure. DNA 3WJ has the three arms that can connect the three individual functional groups including MERS aptamer (bioprobe), methylene blue (signal reporter) and thiol group (linker) Then, GO-MoS2 hybrid nanocomposite was prepared for the substrate of EC/SERS-based MERS-NV biosensor construction. Then, the assembled multifunctional (MF) DNA aptamer was immobilized on GO-MoS2. The proposed biosensor can detect MERS-NVs not only in a phosphate-buffered saline (PBS) solution (SERS LOD: 0.176 pg/ml, EIS LOD: 0.405 pg/ml) but also in diluted 10% saliva (SERS LOD: 0.525 pg/ml, EIS LOD: 0.645 pg/ml).

Hematite/selenium disulfide hybrid catalyst for enhanced Fe(III)/Fe(II) redox cycling in advanced oxidation processes

Regeneration of Fe(II) is a key issue for heterogeneous advanced oxidation processes (AOPs) using iron-based catalysts. Herein, a hybrid catalyst was developed from α-Fe2O3 and SeS2 to enhance the Fe(III)/Fe(II) redox cycling in both hydrogen peroxide (H2O2) system and persulfate (PS) system. The regeneration of Fe(II) was evidenced by the increased Fe(II)/Fe(III) ratio in the used catalyst (205.8% in the H2O2 system or 125.4% in the PS system), compared to 68.4% in the fresh hybrid catalyst Fe/Se-3. Methyl orange was used as a model pollutant to evaluate the degradation performance of the hybrid catalyst. Owing to the promotion of Fe(II) regeneration, Fe/Se-3 achieved a pollutant removal efficiency of 100.0% in 12 min in both systems, significantly higher than that with pure α-Fe2O3 (33.9 ± 3.6% in the H2O2 system or 30.7 ± 2.8% in the PS system). The dominant active species were identified as hydroxyl radicals in the H2O2 system and sulfate radicals in the PS system. In the proposed mechanism, soluble and surface-bound Fe species are provided by α-Fe2O3 to activate H2O2 or PS to radicals, and SeS2 participates in the reactions via Se(IV) reducing Fe(III) to Fe(II) and S atoms being released through protonation to expose more active Se sites.

Hierarchical MoS2/polyaniline binary hybrids with high performance for improving fire safety of epoxy resin

AbstractHere we report a facile strategy to fabricate phosphoric acid doped polyaniline/molybdenum disulfide (PANI/MoS2) hybrids as high‐performance nanofillers in epoxy (EP) resin for the first time. In situ growth of PANI on the surface of two‐dimensional MoS2 template resulted in the uniform dispersion and strong interfacial adhesion of PANI/MoS2 hybrids within EP matrix, which can be confirmed by the obvious increase (13.5°C) in glass transition temperature (Tg) of EP composites. The MoS2 nanosheets also acted as a critical component to generate synergistic effect with PANI on reducing the fire hazards of EP resin. It resulted in a remarkable removal of flammable decomposed products and a considerable reduction of toxic CO yield. The dramatical decreases in real‐time smoke density and total smoke production, and high‐graphitized char layer in condensed phase were obtained for EP composite with 5 wt% PANI/MoS2 hybrids. The multiple synergistic effects (synergistic dispersion and synergistic char formation) are believed to be the primary source for these obvious enhancements of properties of EP composites. This facile strategy may achieve the potential application of functionalized MoS2 in polymeric nanocomposites.

Hierarchical porous carbon nanofibers with ultrasmall-sized cobalt disulfide/tungsten disulfide hybrid composites for high-rate lithium storage kinetics

Recently, transition metal dichalcogenides (TMDs) have attracted considerable attention as anode materials in ultrafast lithium ion batteries because of their high theoretical capacity and outstanding ion diffusion kinetics. Despite these remarkable properties, TMDs exhibit fast capacity fading and insufficient Li storage kinetics, owing to the excessive volume expansion and low electric/ionic transfer rate.The aim of this study is to reinforce the structural stability and Li storage kinetics of TMDs through the use of well-dispersed CoS2 and WS2 ultrasmall particles (USPs) embedded in hierarchical porous carbon nanofibers, including micro/mesoporous composite sturctures. As expected, this architecture offers a high specific capacity (718.0 mAh g−1) with the capacity retention of 93.4% after 100 cycles at 0.1 A g−1 owing to increased Li storage sites and prevention of volume expansion of CoS2 and WS2 USPs. In particular, a remarkable fast discharge capacity (444.5 mAh g−1) with the capacity retention of 90.2% after 1000 cycles are noted. These results are related to the high number of Li ion storage sites, effective prevention of volume expansion of well-dispersed CoS2 and WS2 USPs, short Li ion diffusion length, and favorable Li ion acceptability, which is caused by the hierarchical porous structure containing meso/micropores.

Fabrication of Electrochemical Influenza Virus (H1N1) Biosensor Composed of Multifunctional DNA Four-Way Junction and Molybdenum Disulfide Hybrid Material.

The outbreak of the influenza virus (H1N1) has symptoms such as coughing, fever, and a sore throat, and due to its high contagious power, it is fatal to humans. To detect H1N1 precisely, the present study proposed an electrochemical biosensor composed of a multifunctional DNA four-way junction (4WJ) and carboxyl molybdenum disulfide (carboxyl-MoS2) hybrid material. The DNA 4WJ was constructed to have the hemagglutinin aptamer on the head group (recognition part); each of the two arms has four silver ions (signal amplification part), and the tail group has an amine group (anchor). This fabricated multifunctional DNA 4WJ can specifically and selectively bind to hemagglutinin. Moreover, the carboxyl-MoS2 provides an increase in the sensitivity of this biosensor. Carboxyl-MoS2 was immobilized using a linker on the electrode, followed by the immobilization of the multifunctional 4WJ on the electrode. The synthesis of carboxyl-MoS2 was confirmed by field emission scanning electron microscopy (FE-SEM), and the surface of the electrode was confirmed by atomic force microscopy. When H1N1 was placed in the immobilized electrode, the presence of H1N1 was confirmed by electrochemical analysis (cyclic voltammetry, electrochemical impedance spectroscopy). Through selectivity tests, it was also possible to determine whether this sensor responds specifically and selectively to H1N1. We confirmed that the biosensor showed a linear response to H1N1, and that H1N1 could be detected from 100 nM to 10 pM. Finally, clinical tests, in which hemagglutinin was diluted with human serum, showed a similar tendency to those diluted with water. This study showed that the multi-functional DNA 4WJ and carboxyl-MoS2 hybrid material can be applied to a electrochemical H1N1 biosensor.

Preparation of magnetic flower-like molybdenum disulfide hybrid materials for the extraction of organophosphorus pesticides from environmental water samples

In this study, the magnetic flower-like molybdenum disulfide hybrid materials (Fe3O4/MoS2) were successfully synthesized by in-situ fabrication method and utilized in the magnetic solid-phase extraction of organophosphorus pesticides. Fe3O4 nanoparticles with different loading amounts of MoS2 were evaluated and detail characterized. The results showed that MoS2 played a key role with rapid and high adsorption capacity towards organophosphorus pesticides. The higher extraction efficiency and good magnetic performance were obtained with loading amount of 200 mg MoS2. Fe3O4 was attached on the surface of MoS2 with flower-like shape (500 nm in diameter). The parameters (amounts of adsorbents, adsorption time, solution pH, elution solvents and sample volumes) affecting magnetic solid-phase extraction efficiency were optimized. Under the optimum conditions, magnetic solid-phase extraction coupled with high liquid chromatography-tandem mass spectrometry for analyzing organophosphorus pesticides in environmental water samples was established. All the analytes exhibited good recoveries spiked at three different concentration levels (10, 20, 50 ng/mL) in water samples. The relative standard deviations were between 1.4% and 6.8%. The developed method showed high sensitivity and good potential use of this convenient and high efficient method for determining organophosphorus pesticides. More importantly, this study can provide a new magnetic adsorbent with extremely fast mass transfer rate for other potential trace contaminants.