Disulfide Nanosheets Research Articles

A new plant-esterase inhibition based electrochemical sensor with signal amplification by MoS2@N-CDs for chlorpyrifos detection.

Chlorpyrifos (CPF) is the most common pesticide entering the food chain and posing a threat to human health. This study presents a new electrochemical biosensor based on molybdenum disulfide nanosheets and nitrogen-doped carbon dot nanocomposite (MoS2@N-CDs) and kidney bean esterase (KdBE), and it is shown to achieve accurate detection of CPF. MoS2@N-CDs were prepared by a facile solvothermal method and characterized by electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Electrochemical characterization confirmed that MoS2@N-CDs facilitated electron transfer and increased the electroactive surface area of the electrode, thereby improved the sensing performance of the electrode. The oxidation peak current of 1-naphthol, which was produced by the hydrolysis of 1-naphthyl acetate catalyzed by KdBE, was adopted as the signal of the sensor. CPF can suppress KdBE activity and consequently cause a decrease in the sensing signal. The experimental results show that the variation of sensing signal is a reliable index to evaluate the CPF level. Under the optimized conditions, the developed enzyme sensor showed superior CPF assay performance with a linear detection range as wide as 0.01-500 μg L-1 and LOD as low as 3.5 × 10-3 μg L-1 (S/N = 3). The inter- and intra-batch RSDs for electrode testing were 4.02% and 2.69%, respectively. Moreover, the developed biosensor also showed good stability and anti-interference. The spiked recoveries of CPF in oilseed rape and cabbage ranged from 98.09% to 106.01% with low relative standard deviation (RSD) (<5.23%), suggesting that the sensor is a promising tool to enable simple, low-cost but highly sensitive large-scale screening of CPF residues in food.

A point-of-care aptasensor based on the upconversion nanoparticles/MoS2 FRET system for the detection of Pseudomonas aeruginosa infection.

The rapid detection of Pseudomonas aeruginosa (P. aeruginosa) is of great significance for the diagnosis of medical infection. In view of the above, a novel aptasensor based on fluorescence resonance energy transfer (FRET) was developed. It contained aptamer-coupled upconversion nanoparticles (UCNPs-apt) as a donor (excitation 980nm) and molybdenum disulfide (MoS2) nanosheets as an acceptor. The upconversion fluorescence aptamer system was investigated to obtain the optimal parameters of MoS2 concentration, the incubation time of UCNPs-apt/MoS2 and P. aeruginosa, and pH. Based on the optimal parameters, a linear calibrationequation (emission 654nm) with a wide detection range 8.7 × 10 ~ 8.7 × 107cfu/mL, a high coefficient of determination R2 0.9941, and a low limit of determination (LOD) 15.5cfu/mL were established. The method was validated with P. aeruginosa infected foci of mouse wound. The advantage of this aptasensor isthat analysisresults can be obtained within 1.5h, which was much faster than that ofthe standard method (18-24h). Furthermore, combined with a portable instrument, it can be used as a point-of-care testing for the early detection of P. aeruginosa infection, which is useful for selecting the correct antibiotics to achieve good therapeutic effects. Additionally, it also has a broad application prospect in food and environmental areas.

Unveiling Xanthine Presence in Rohu Fish Using Ag+-Doped MoS2 Nanosheets Through Electrochemical Analysis.

Here, we envisage the development of the rapid, reliable, and facile electrochemical sensor for the primary detection of xanthine (Xn) which is significant for the food quality measurement, based on the silver-doped molybdenum disulfide (Ag@MoS2) nanosheets. The structural and compositional properties of the prepared samples were tested through X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photon spectroscopy (XPS). The two-dimensional (2D) MoS2 nanosheets provide the large surface area for the sensing applications and the silver ions help in the enhanced electrochemical response. The fabricated enzymatic biosensor exhibits magnificent cyclic stability with a limit of detection of 27nM. Also, the sensor was tested for rapid, reproducible, specific, and regenerable up to 10 cycles and has a shelf life of 2weeks. The outcomes of this study suggest that the proposed matrix could be employed for the fabrication of devices for early detection of xanthine.

Design of a Novel Electrochemical Aptasensor Based on Molybdenum Disulfide Nanosheets for Lysozyme Detection

Design of a Novel Electrochemical Aptasensor Based on Molybdenum Disulfide Nanosheets for Lysozyme Detection

Aptamer-based flares hybridized with single-stranded DNA-conjugated MoS2 nanosheets for ratiometric fluorescence sensing and imaging of potassium ions and adenosine triphosphate in human fluids and living cells

Addressing the limitations observed in previous studies, where the quantitative range of nanoprobes for detecting K+ and adenosine triphosphate (ATP) did not cover concentrations found within living cells, the present study aimed to develop ratiometric nanoprobes that can accurately sense changes in K+ and ATP levels in living cells and quantify them in human fluids. The proposed nanoprobes consisted of recognition flares modified with 6-carboxyfluorescein (FAM) and 5-carboxytetramethylrhodamine (TAMRA), along with thiolate single-stranded DNA (ssDNA) and molybdenum disulfide nanosheets (MoS2 NSs). The thiolate ssDNA acts as a linker between the flares and the MoS2 NSs, directly forming a functional nanostructure at room temperature. The direct conjugation of labeled flares to the MoS2 NSs simplifies the fabrication process. In the absence of K+ and ATP, the hybridization of flares and thiolate ssDNA caused FAM to move away from TAMRA, suppressing the fluorescence resonance energy transfer (FRET) process. However, upon the introduction of K+ and ATP, the flares undergo a structural transformation via the formation of G-quadruplex formation and the generation of hairpin-shaped structures, respectively. This structural change leads to the release of the flares from the ssDNA-conjugated nanosheet surface. The release of the flares brings FAM and TAMRA into close proximity, allowing FRET to occur, leading to FRET and static quenching. By monitoring the ratio between the fluorescence intensities of FAM and TAMRA, the concentration of K+ (5–100 mM) and ATP (0.3–5 mM) can be accurately determined by the proposed nanoprobes. The advantages of these nanoprobes lie in their ability to provide ratiometric measurements, which enhance the accuracy and reliability of the quantification process. The proposed nanoprobes offer potential applications as ratiometric imaging probes for monitoring K+ and ATP-related reactions in living cells, providing valuable insights into cellular processes. Additionally, they can be employed for determining the levels of K+ and ATP in human fluids, offering potential diagnostic applications in various clinical settings.

Efficient activation of peroxymonosulfate by molybdenum disulfide cocatalysis of Co and N co-doped porous carbon for degrading perfluorooctanoic acid: Synergistic effect of Co and N by molybdenum and its mechanism

In this study, precursor ultrathin molybdenum disulfide nanosheets and ZIF-67 was selected to prepare Co and N co-doped porous carbon by the support of Mo (MoS2/Co@NPC) to activate peroxymonosulfate (PMS) for perfluorooctanoic acid (PFOA) degradation. The morphology, crystal form and composition of MoS2/Co@NPC are studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and other methods. In MoS2/Co@NPC/PMS process, PFOA was completely degraded in 180 min at pH 7, 0.3 g/L catalyst, 0.1 mM PMS and reaction temperature of 25 °C. The degradation efficiency was much higher than that in other systems. The oxidative species for PFOA degradation was studied using free radical quenching experiments and electron paramagnetic resonance (ESR) tests. SO−4 plays a major role in the degradation of PFOA, OH plays an auxiliary role, and 1O2 contributes the least. The effect of different types and positions of cobalt‑nitrogen and molybdenum atoms on the electrocatalytic activity was investigated by density functional theory (DFT) calculations. The co-doping of Co and N into carbon-based materials can synergistically enhance by Mo for the activation of PMS. The unsaturated S atoms on the surface of metal sulfides can trap protons to form H2S while exposing the reducing metal active site, which also accelerates the rate-limiting step of the Co3+/Co2+ conversion. The core-shell structure of Co@NPC doped with Mo has the characteristics of improving the electron transfer ability of carbon, promoting the mass transfer of reactants, and preventing cobalt metal agglomeration and metal dissolution. The degradation pathways of PFOA were investigated and three possible pathways were proposed. In addition to PFOA, MoS2/Co@NPC-800/PMS system can also remove contaminant in pharmaceutical wastewater, indicating that the process has potential application value in practical wastewater treatment.

A Comprehensive Ecotoxicity Study of Molybdenum Disulfide Nanosheets versus Bulk form in Soil Organisms.

The increasing use of molybdenum disulfide (MoS2) nanoparticles (NPs) raises concerns regarding their accumulation in soil ecosystems, with limited studies on their impact on soil organisms. Study aim: To unravel the effects of MoS2 nanosheets (two-dimensional (2D) MoS2 NPs) and bulk MoS2 (156, 313, 625, 1250, 2500 mg/kg) on Enchytraeus crypticus and Folsomia candida. The organisms' survival and avoidance behavior remained unaffected by both forms, while reproduction and DNA integrity were impacted. For E. crypticus, the individual endpoint reproduction was more sensitive, increasing at lower concentrations of bulk MoS2 and decreasing at higher ones and at 625 mg/kg of 2D MoS2 NPs. For F. candida, the molecular endpoint DNA integrity was more impacted: 2500 mg/kg of bulk MoS2 induced DNA damage after 2 days, with all concentrations inducing damage by day 7. 2D MoS2 NPs induced DNA damage at 156 and 2500 mg/kg after 2 days, and at 1250 and 2500 mg/kg after 7 days. Despite affecting the same endpoints, bulk MoS2 induced more effects than 2D MoS2 NPs. Indeed, 2D MoS2 NPs only inhibited E. crypticus reproduction at 625 mg/kg and induced fewer (F. candida) or no effects (E. crypticus) on DNA integrity. This study highlights the different responses of terrestrial organisms to 2D MoS2 NPs versus bulk MoS2, reinforcing the importance of risk assessment when considering both forms.

Effect of UV-O3 treatment on the performance of UV detector based on zinc oxide/molybdenum disulfide nanosheet heterostructures

UV photodetectors based on ZnO nanostructures, using a metal-semiconductor-metal (MSM) configuration, are popular due to their simple fabrication. However, they experience high dark currents and slow photoresponse speeds. This is due to a high recombination rate for photogenerated electrons and holes as well as low charge carrier mobility attributable to ZnO's inherent defects. In this study, MoS2 nanosheets was employed to cover the surface of ZnO nanorods, creating a unique architecture that focuses the impact of MoS2 solely on light absorption and charge transfer on the ZnO surface. Subsequently, a 15-min UV-O3 exposure is applied to the ZnO/MoS2 structure. The ZnO/MoS2UVo heterostructure exhibits remarkable results, including a six-fold increase in sensitivity compared to pure ZnO, Additionally, the Detectivity increases by 265 %, while the Responsivity and Quantum Efficiency rise by up to 102 %. These enhancements are attributed to the reduction of dark current coming from the reduction of oxygen vacancies as sulfur edge atoms from MoS2 fill these vacancies. Furthermore, additional dark current reduction post UV-O3 treatment is due to both the reduced ZnO oxygen vacancies and the formation of a thin MoO3 passivation layer on the ZnO NR surface. Despite these achievements, the study acknowledges the presence of multiple junctions between ZnO, MoS2, and MoO3, which still pose challenges for efficient charge transfer to the electrodes.

Magnetic Prussian blue nanoshells are controllable anchored on the surface of molybdenum disulfide nanosheets for efficient separation of radioactive cesium from water

The rapid development of nuclear energy in China has led to increased attention to the treatment of radioactive wastewaters. Herein, a novel magnetic adsorbent, magnetic Prussian blue‑molybdenum disulfide (PB/Fe3O4/MoS2) nanocomposite, was prepared by a simple in-situ fixation of ferric oxide nanoparticles (Fe3O4 NPs) and Prussian Blue (PB) shell layers on the surface of molybdenum disulfide (MoS2) nanosheets carrier. The prepared PB/Fe3O4/MoS2 nanocomposites adsorbent displayed excellent fast magnetic separation and adsorption capacity of Cs+ (Qm = 80.51 mg/g) from water. The adsorption behavior of Cs+ by PB/Fe3O4/MoS2 conformed to Langmuir isothermal and second-order kinetic model, which belonged to chemical adsorption and endothermic reaction. The equilibrium adsorption capacity of PB/Fe3O4/MoS2 to Cs+ has reached 90 % in less than 110 min. Moreover, the adsorption properties of PB/Fe3O4/MoS2 remained good in the pH range of 2–7. Based on this, PB/Fe3O4/MoS2 complex was a fast and high selectivity adsorption material for Cs+, which was expected to be used in the practical treatment of cesium-containing radioactive wastewater.

Dispersion behaviour of molybdenum disulfide (MoS2) nanosheets in different exposure media and determination of its toxicity using in-vitro and in-silico approaches

MoS2 nanocomposites have been used in a wide range of environmental, biomedical, and energy-related applications due to their unique physicochemical properties. On the contrary, fewer attempts were made to understand its environmental sustainability, fate, and toxicity. The present study reports the synthesis, characterisation, dispersion behaviour, cellular uptake, toxicity, and in-silico docking of trigonal prismatic (2H) defect-rich MoS2 nanosheets. The applicability of a common European approach to the regulatory testing of nanomaterials (NANoREG) was employed to understand the dispersion stability of MoS2 nanosheets. Particle size analysis was used to understand the interaction between MoS2 nanosheets and biomolecules present in the environmental matrices. Prolonged exposure (48 h) of MoS2 nanosheets to HepG2 cells resulted in a significant increase in cellular uptake of Mo compared to that in cells exposed for 1 h. Significant reduction in the cell viability was noticed in HepG2 cells exposed to 500 mg/L (p ≤ 0.05) and HL-60 cells exposed to 1000 mg/L (p ≤ 0.01) and 500 mg/L (p ≤ 0.05) of MoS2 nanosheets concentrations for 48 h. Forward/side scatter plots in flow cytometric assays (apoptosis and mitochondrial permeability) revealed alterations in cellular morphology of HL-60 cells treated with higher concentrations (≥100 mg/L) of MoS2 nanosheets for 48 h. Loss of mitochondrial membrane potential (ΔΨm) was observed in cells treated with higher concentrations (≥100 mg/L) of MoS2 nanosheets. The results obtained by in vitro analysis suggest that MoS2 nanosheets are toxic at higher doses and not at environmentally relevant concentrations. To the best of our knowledge, this is the first study of its kind that demonstrates the cellular and molecular toxicity of MoS2 nanosheets, along with its in silico interactions with the key sixteen macro-molecules involved in programmed cell death.

The therapeutic efficacy of silver loaded rhenium disulfide nanoparticles as a photothermal agent for cancer eradication

Cancer is a life-threatening disease when it is diagnosed at a late stage or treatment procedures fail. Inhibiting cancer cells in the tumor environment is a significant challenge for anticancer therapy. The photothermal effects of nanomaterials are being studied as a new cancer treatment. In this work, rhenium disulfide (ReS2) nanosheets were made by liquid exfoliation with gum arabic (GA) and coated with silver nanoparticles (AgNPs) to produce reactive oxygen species that destroy cancer cells. The synthesized AgNP-GA-ReS2 NPs were characterized using UV, DLS, SEM, TEM, and photothermal studies. According to the DLS findings, the NPs were about 216 nm in size and had a zeta potential of 76 mV. The TEM and SEM analyses revealed that the GA-ReS2 formed single-layered nanosheets on which the AgNPs were distributed. The photothermal effects of the AgNP-GA-ReS2 NPs at 50 μg/mL were tested with an 808 nm laser at 1.2 W cm−2, and they reached 55.8 °C after 5 min of laser irradiation. MBA-MB-231 cells were used to test the cytotoxicity of the newly designed AgNP-GA-ReS2 NPs with and without laser irradiation for 5 min. At 50 μg/mL, the AgNP-GA-ReS2 showed cytotoxicity, which was confirmed with calcein and EtBr staining. The DCFH-DA and flow cytometry analyses demonstrated that AgNP-GA-ReS2 nanosheets under NIR irradiation generated ROS with high anticancer activity, in addition to the photothermal effects.

Constructing a viscoelastic film for enhanced oil recovery via self-adsorption of amphiphilic nanosheets at oil-water interface

Immiscible liquid-liquid interfaces have widespread applications in drug delivery, oil-water separation, oil recovery, emulsion and foam stability, etc. Here, a dense viscoelastic interface film is constructed via the self-adsorption of amphiphilic molybdenum disulfide nanosheets at the oil-water interface, which has significant implications for enhanced oil recovery. The microscopic dispersion characteristics of amphiphilic nanosheets in water phase are characterized using Cryo-EM, and the adsorption regularities of amphiphilic nanosheets in horizontal and vertical directions of oil-water interface are also revealed. Besides the mechanical response and rheological properties of interface adsorption film are systematically studied. Experimental results demonstrate that the amphiphilic nanosheet can self-curl to form a single amphiphilic nanosheet with a size of 30 nm in the water phase as the amphiphilic nanosheets concentration is lower than 50 mg/L. When the amphiphilic nanosheets concentration reaches 100 mg/L, obvious water-phase aggregation behaviors happen. The amphiphilic nanosheets can reduce the oil-water interfacial tension from 18.47 mN/m to 0.27 mN/m by forming multilayer adsorption at the oil-water interface. The adsorption ratio of amphiphilic nanosheets from bulk phase to oil-water interface can reach 97.50 %. In addition, the oil-water interface adsorption film exhibits excellent elastic properties and higher strength because the amphiphilic nanosheets can form a planar network structure at the oil-water interface which can be also directly observed in microfluidic pores. The storage modulus and interface shear viscosity of interface adsorption film are 1.65 Pa and 1.38 mN·s/m, respectively. In theory, the required desorption energy of a single amphiphilic nanosheet from oil-water interface to bulk phase is deduced to be 587 KBT. This work is expected to provide amphiphilic molybdenum disulfide nanosheet as an effective candidate for enhanced oil recovery.

Controllable growth of silver nanoparticles on titanium dioxide/nitrogen-doped carbon nanofiber/molybdenum disulfide: Toward enhanced photocatalytic-activating peroxymonosulfate performance and “memory catalysis”

The combination of photocatalysis and activating peroxymonosulfate (PMS) can generate more active species and degrade pollutants more efficiently. The introduction of “memory catalysis” in the photocatalytic-activating PMS system can further improve the catalytic degradation ability in the dark environment, because the stored electrons (e−1) during photocatalytic process can release in darkness to continue the degradation. In this paper, molybdenum disulfide (MoS2) nanosheets on titanium dioxide/nitrogen-doped carbon nanofibers (T/NC/MoS2 NFs) were prepared by electrospinning and hydrothermal treatment, and then silver (Ag) nanoparticles were deposited by photodeposition (PD) or dark deposition (DD) to form T/NC/MoS2@Ag NFs-PD and T/NC/MoS2@Ag NFs-DD, respectively. The influences of the two samples on the degradation of tetracycline (TC) and “memory catalysis” in photocatalytic-activating PMS systems were explored. The results show that T/NC/MoS2@Ag NFs-DD can remove TC more efficiently and reduce energy consumption. This is because the DD technology can effectively inhibit the growth and aggregation of Ag nanoparticles, thereby improving the e−1 storage capacity and the separation of photogenerated e−1 and holes (h+). Under outdoor solar irradiation, T/NC/MoS2@Ag NFs-DD showed excellent stability and high efficiency in catalytic degradation of a variety of organic pollutants. This study provides a new strategy to realize the efficient and energy-saving degradation of organic pollutants.

Highly water dispersible poly (caffeic acid - L-arginine)-MoS2 nanocomposite modified sensor for effective electrochemical detection of amlodipine drug

The present work applied a facile, green, and versatile approach to preparing self-organized redox polymers on 2D-MoS2 (Molybdenum Disulfide) nanosheets. It was utilized as the modified electrode material for electrochemical determination of 1, 4-dihydropyridine-based antihypertensive drugs viz amlodipine (AMD). Naturally available caffeic acid was used as a precursor, and it was polymerized through a 1, 4-Michael addition reaction with L-arginine. Oxidants and amine functional groups of L-arginine synergistically promote the polymerization of caffeic acid (P (CA-LA)). The P(CA-LA) in the 2D-MoS2 matrix was stabilized via self-assembly by intermolecular interaction between catechol groups and MoS2 sheets. The ultra-sonication process induced the subsequent polymerization and simultaneous exfoliation of MoS2 sheets. The self-assembled P(CA-LA)-MoS2 nanocomposite exhibits a good cyclic voltammetric response with excellent electrochemical oxidation of AMD. The electrochemical response of AMD was explored using a glassy carbon electrode (GCE) modified with P(CA-LA)-MoS2 nanocomposite employing differential pulse voltammetry (DPV). Under the optimized experimental conditions, electrochemical detection of AMD has been performed with a linear correlation between the anodic peak current of AMD observed at 0.8 V. Additionally, the designed self-assembled redox polymer-based nanocomposite sensor exhibited superior selectivity for the detection of AMD with two linear ranges from 0.010 to 16.82 µM and 16.82 to 433.3 µM with good detection limits of 3.6 nM. Moreover, the synergic interactions of polymers and MoS2 and their self-assembly nature can offer a good sensitivity of 0.42 μA μM−1 cm−2. Hence, the electrochemical behavior of self-assembled P(CA-LA)-MoS2/GCE may provide new insights into the recent era of electrodes and sensors.

Preparation and optimization of agarose or polyacrylamide/amino acid-based double network hydrogels for photocontrolled drug release

The high water content and biocompatibility of amino-acid-based supramolecular hydrogels have generated growing interest in drug delivery research. Nevertheless, the existing dominant approach of constructing such hydrogels, the exploitation of a single amino acid type, typically comes with several drawbacks such as weak mechanical properties and long gelation times, hindering their applications. Here, we design a near-infrared (NIR) light-responsive double network (DN) structure, containing amino acids and different synthetic or natural polymers, i.e., polyacrylamide, poly(N-isopropylacrylamide), agarose, or low-gelling agarose. The hydrogels displayed high mechanical strength and high drug-loading capacity. Adjusting the ratio of Fmoc-Tyr-OH/Fmoc-Tyr(Bzl)-OH or Fmoc-Phe-OH/Fmoc-Tyr(Bzl)-OH, we could drastically shorten the gelation time of the DN hydrogels at room and body temperatures. Moreover, introducing photothermal agents (graphene oxide, carbon nanotubes, molybdenum disulfide nanosheets, or indocyanine green), we equipped the hydrogels with NIR responsivity. We demonstrated the light-triggered release of the drug baclofen, which is used in severe spasticity treatment. Rheology and stability tests confirmed the positive impact of the polymers on the mechanical strength of the hydrogels, while maintaining good stability under physiological conditions. Overall, our study contributed a novel hydrogel formulation with high mechanical resistance, rapid gel formation, and efficient NIR-controlled drug release, offering new opportunities for biomedical applications.

Enzymolysis and photothermal-mediated synergistic antimicrobial nanoplatform with programmed EPS degradation and biofilm penetration capabilities for eradication of biofilm wound infections

It is an effective method of eradicating biofilm infection and promoting wound healing by exopolysaccharides (EPS) degradation and penetration of antimicrobial agents into biofilms. In this study, a synergistic antimicrobial nanoplatform (Pec@PLL-MoS2) based on programmed enzymolysis and photothermal therapy was developed. Pectinase (Pec) was modified onto the surface of molybdenum disulfide nanosheets (MoS2 NSs) by ε-poly-L-lysine (PLL) linkage via electrostatic adsorption. With the 808-nm laser irradiation, the activity of Pec was regulated by the photothermal effect produced by the MoS2 NSs. Pec efficiently degraded the EPS and destroyed the structural integrity of the biofilms, thus promoting the penetration of Pec@PLL-MoS2 into the biofilms. With the penetration of Pec@PLL-MoS2, the local hyperthermia produced by the photothermy of the MoS2 NSs further killed the bacteria inside the biofilms, eventually eradicating biofilm infections. In vitro experiments indicated that 81.1 % of Staphylococcus aureus (S. aureus) biofilms and 89.9 % of Escherichia coli (E. coli) biofilms were eradicated within 5 min. The survival rates of the bacteria in the biofilms of S. aureus and E. coli were reduced to 5.1 % and 0.1 %, respectively. In vivo, biofilm infections in wounds were completely eradicated by Pec@PLL-MoS2 under irradiation, thereby reducing inflammation and promoting wound healing. This study demonstrated that Pec@PLL-MoS2 based on programmed enzymolysis and photothermia is a new synergistic treatment strategy for biofilm infections.

Exploring the influence of external electric fields on the mechanical characteristics of zirconium disulfide nanosheets via density functional theory

The density functional theory is utilized to investigate elastic and plastic properties of zirconium disulfide (ZrS2) nanosheet subjected to a uniform external electric field up to 4 VÅ. In this respect, firstly, unit cell dimensions, bond lengths and bond angles are obtained by optimizing the unit cell of ZrS2nanosheet, and the most stable configuration is considered for the nanostructure accordingly. Then, by applying uniaxial and biaxial tensions on the nanosheet under a uniform external electric field, Young's and bulk moduli are computed, respectively. Finally, the applied strain is extended to the plastic region to evaluate the effect of external electric field on the first and second critical strains. It is shown that applying external electric field results in increasing Young's modulus of the nanosheet. However, the bulk modulus increases up to 2 VÅ and deceases afterwards. Besides, the first and second critical strains, which are respectively used to show the end of harmonic and inharmonic regions, decrease in the presence of the external electric field while the difference between them is not affected by the external electric field. Investigating the elastic and plastic properties of zirconium disulfide under an external electric field is important for both fundamental research and practical applications. It can help us develop new materials with tunable properties, optimize their performance in various devices, and contribute to the development of cutting-edge technologies

3D plasmonic SERS aptasensor for rapid detection of aflatoxin B1 combined with Au@Ag bimetallic nanostars and Fe3O4@MoS2 magnetic nanoflowers

As a virulent metabolite, aflatoxin B1 (AFB1) presented in various cereal grain is tightly implicated in severe human diseases. In this study, 3D plasmonic nanohybirds of Raman molecule 4-mercaptobenzoic acid (4-MBA)-embedded and AFB1 aptamer-modified bimetallic nanostars as SERS probes bound to magnetic nanoflowers were fabricated and demonstrated as a high-performance SERS-active aptasensor to quantitatively analyze AFB1. Bimetallic Au@Ag SERS plasmonic nanoprobes with enhanced properties were capable of enhancing discriminative Raman peaks of 4-MBA. Then, the integration of iron tetroxide nanoparticles (Fe3O4 NPs) and molybdenum disulfide nanosheets (MoS2 NShs) with huge specific surface area constituted stable 3D Fe3O4@MoS2 plasmonic nanoflowers, facilitating the bind of numerous aptamer-based SERS probes via the non-covalent interaction between MoS2 NShs and aptamer, which were ideal candidates for SERS-active substrates. Additionally, Fe3O4 NPs as magnetic core endowed 3D nanocomposites with specific magnetic separation characteristic that caused the collected SERS hotspots to exhibit superior signal response, and further strengthening the sensitivity in a complex food matrix. Aptamer-target AFB1 specific recognition triggered linearly diminished 4-MBA signal intensity (I4-MBA) on the substrate to achieve a low detection limit of 58.9 pg/mL. Furthermore, the sensor has the potential to be a promising monitoring tool for other trace contaminants.

Surface modification of tungsten disulfide nanosheets by pH/temperature sensitive polymers for NIR-triggered drug delivery

Stimuli-responsive polymers are attractive nanocarriers for cancer drug delivery due to their biodegradability and precise control of the release of an anti-cancer drug in response to specific triggers. Herein, the tungsten disulfide nanosheet was modified by pH and thermo-responsive polymer as the novel nanocarrier. The physicochemical characteristics of nanoadsorbent were studied by X-ray diffraction, Fourier transform infrared, field emission-scanning electron microscopy, and thermal gravitational analysis. The maximum adsorption capacity in optimal conditions for flutamide with nanoadsorbent (C0 = 20 mg L−1, pH = 5, contact time = 15 min, stirring speed = 500 rpm, and temperature = 25 °C) was obtained 2.43 mg g−1. The Langmuir equilibrium isotherm and the pseudo-second-order kinetic model fit the adsorption mechanism very well. Around 75.26 % of the drug was released from nanocarrier in simulated human fluid at 6 h and 91.48 % in simulated cancer fluid at 45 °C. The near laser irradiation-triggered effective and controllable release of the loaded drug under near laser irradiation is successfully confirmed. Drug releasing 94.77 % under near laser irradiation within 30 min, which was roughly four folds of that without near laser irradiation. Cytotoxicity/cell viability assays using MTT were carried out for samples in PC-3 prostate cancer cells. Based on the cell viability assay on the PC-3 prostate cancer cell line, the drug loaded pH/thermo-responsive nanocarrier indicated better cytotoxic activity than the free drug. According to these results, it is very promising that pH/thermo-responsive nanocarrier can be used as an effective drug delivery system.

WaveFlex biosensor based on S-tapered and waist-expanded technique for detection of glycosylated hemoglobin.

Glycosylated hemoglobin (HbA1c) is considered a new standard for the detection of diabetes mellitus because it is more accurate than regular blood sugar tests and there is no need to take blood on an empty stomach or at a specific time. In this work, we have developed a novel optical fiber biosensor, referred to as the "WaveFlex biosensor," which operates on the principles of localized surface plasmon resonance (LSPR) plasmonic wave. The sensor is fabricated using an innovative S-tapered and waist-expanded technique, enabling it to effectively detect HbA1c. Compared to the HbA1c sensors currently in use, HbA1c optical fiber sensors possess the characteristics of high sensitivity, low cost, and strong anti-interference ability. The gold nanoparticles (AuNPs), cerium oxide (CeO2) nanorods (NRs), and tungsten disulfide (WS2) nanosheets (NSs) are functionalized to improve the effectiveness of the fiber sensor on the probe surface. AuNPs are utilized to generate LSPR by the excitation of evanescent waves to amplify the sensing signal. The CeO2-NRs can have a strong metal-carrier interaction with AuNPs, enhancing the cascade of CeO2-NRs and AuNPs. The WS2-NSs with layered fold structure have a large specific surface area. Therefore, the combination of CeO2-NRs and WS2-NSs is conducive to the binding of antibodies and the addition of sites. The functionalized antibodies on the fiber make the sensor probe capable of specific selection. The developed probe is applied to test the HbA1c solution over concentrations of 0-1000 µg/mL, and the sensitivity and limits of detection of 1.195×10-5 a.u./(µg/mL) and 1.66 µg/mL are obtained, respectively. The sensor probe is also evaluated using assays for reproducibility, reusability, selectivity, and pH. According to the findings, a novel method for detecting blood glucose based on a plasmonic biosensor is proposed.