Tungsten Disulfide Quantum Dots Research Articles

Unraveling the impact of tungsten disulfide quantum dots on human serum albumin conformational dynamics and fibrillation pathways: An integrated multi-spectroscopic, biochemical, and molecular docking investigation

Herein, the intricate molecular interplay between human serum albumin (HSA) and tungsten disulfide quantum dots (WS2 QDs) was probed using spectroscopic techniques and sophisticated molecular simulation methods. Fluorescence spectroscopy demonstrated that under physiological conditions, WS2 QDs forge a non-fluorescent ground-state complex with HSA, facilitated by hydrogen bonding and van der Waals forces, ultimately resulting in the static quenching of the protein's intrinsic fluorescence. Complementary site competition experiments and molecular docking simulations reinforced a precise 1: 1 binding stoichiometry, predominantly targeting HSA's Site I. Three-dimensional fluorescence spectroscopy revealed that WS2 QDs perturb the HSA polypeptide backbone, subtly modifying the microenvironment surrounding aromatic amino acid residues. This alteration was further corroborated by circular dichroism spectroscopy, marked by a decrease in helical content and a transition towards irregular peptide conformations. Thermal stability assays illuminated the reduced thermal resilience of the HSA − WS2 QD complex. Laser confocal microscopy coupled with thioflavin T staining yielded compelling evidence that WS2 QDs effectively inhibit amyloid fibril formation in both HSA and lysozyme, underscoring their potential as potent anti-amyloidogenic agents. This comprehensive study offers pivotal insights into multifaceted impact of WS2 QDs on protein structure and function, thereby expanding their horizon of potential applications within the burgeoning field of nanomedicine.

Chitosan-coated iron(III) oxide nanoparticles and tungsten disulfide quantum dots-immobilized Fiber-based WaveFlex Biosensor for Staphylococcus Aureus bacterial detection in real food samples

The research proposes and investigates an extraordinarily sensitive, label-free WaveFlex biosensor utilizing optical fiber technology for the detection of Staphylococcus aureus (S. aureus), a common foodborne bacterium. The WaveFlex biosensor (plasmon Wave based Flexible optical fiber Biosensor) is based on a novel flexible tapered single-mode fiber structure, utilizing gold nanoparticles (AuNPs) to trigger the phenomenon of localized surface plasmon resonance (LSPR). Additionally, the sensitivity is further enhanced using chitosan-coated iron(III) oxide nanoparticles (Fe3O4–CS NPs) and tungsten disulfide quantum dots (WS2-QDs). The optical fiber surface is functionalized with antibodies to achieve specific detection of S. aureus. For S. aureus concentrations at 1 × 108 CFU/mL (colony-forming units per milliliter), the sensor's maximum sensitivity of 2.74 nm/lg (CFU/mL), and a detection limit (LOD) of 6.67 CFU/mL. This ultra-sensitive biosensor holds great potential for widespread applications in various fields, including disease detection, medical diagnostics, and food safety inspection.

Cost-efficient and ultrasensitive sensor for electrochemical detection and cytotoxicity assessment of tetracyclines

The uncontrolled overuse of tetracyclines (TCs) has contributed to a significant rise in the levels of not only antibiotic residues in the environmental but also drug- and multidrug-resistant bacteria, necessitating a convenient, sensitive, and rapid assay for the quantitative determination and health risk assessment of TCs. This study presents the development of a nanocomposite sensor which integrates hydroxylated multiwalled carbon nanotubes (MWCNTs-OH), tungsten disulfide quantum dots (WS2QDs), and prussian blue (PB). This sensor was capable of measuring the concentrations of tetracycline (TC), oxytetracycline (OTC), doxycycline (DC), and tigecycline (TEC) at levels ranging from 0.10 to 125.00 μM, with detection limits of 0.010, 0.015, 0.020, and 0.060 μM, respectively (S/N = 3). The excellent electrochemical performance enabled the sensor to measure TC concentrations in real water samples. Importantly, the sensor was also used to evaluate the cytotoxicity of TCs on human hepatocarcinoma (HepG2) cells. The 48 h half-inhibitory concentrations (IC50) for TC, OTC, DC, and TEC were 344.91 μM, 365.14 μM, 349.59 μM, and 604.66 μM, respectively, indicating that TC was the most cytotoxic. The sensing platform described herein not only facilitates the quantitative determination of TCs but also allows for the assessment of their cytotoxicity in the water environment, which greatly simplifies the comprehensive evaluation process and reduces the cost, thus holding great promise for TCs testing.

Role of tungsten disulfide quantum dots in specific protein-protein interactions at air-water interface.

The intriguing network of antibody-antigen (Ab-Ag) interactions is highly governed by environmental perturbations and the nature of biomolecular interaction. Protein-protein interactions (PPIs) have potential applications in developing protein-adsorption-based sensors and nano-scale materials. Therefore, characterizing PPIs in the presence of a nanomaterial at the molecular level becomes imperative. The present work involves the investigation of antiferritin-ferritin (Ab-Ag) protein interactions under the influence of tungsten disulfide quantum dots (WS2 QDs). Isothermal calorimetry and contact angle measurements validated the strong influence of WS2 QDs on Ab-Ag interactions. The interfacial signatures of nano-bio-interactions were evaluated using sum frequency generation vibration spectroscopy (SFG-VS) at the air-water interface. Our SFG results reveal a variation in the tilt angle of methyl groups by ∼12° ± 2° for the Ab-Ag system in the presence of WS2 QDs. The results illustrated an enhanced ordering of water molecules in the presence of QDs, which underpins the active role of interfacial water molecules during nano-bio-interactions. We have also witnessed a differential impact of QDs on Ab-Ag by raising the concentration of the Ab-Ag combination, which showcased an increased inter-molecular interaction among the Ab and Ag molecules and a minimal influence on the methyl tilt angle. These findings suggest the formation of stronger and ordered Ab-Ag complexes upon introducing WS2 QDs in the aqueous medium and signify the potentiality of WS2 QDs relevant to protein-based sensing assays.

A dual-mode fluorometric and smartphone-based colorimetric sensor for cyanide detection using tungsten disulfide quantum dots and silver nanoparticles

In this study, tungsten disulfide quantum dots (WS2 QDs) and silver nanoparticles (AgNPs) were applied to establish a dual-mode fluorometric and smartphone-based colorimetric sensor for the determination of cyanide ions (CN⁻). We indicated that the fluorescence intensity of WS2 QDs was quenched by AgNPs as a result of the inner filter effect (IFE) mechanism. Moreover, the quenched fluorescence intensity of WS2 QDs switched on again in the presence of CN⁻ due to the interaction between AgNPs and CN⁻, leading to destroy AgNPs, diminishing their yellow color and reducing their IFE on WS2 QDs. Based on these facts, we established a turn-off-on fluorometric (with a range of 0.5–30 and detection limits of 0.17 µM) and smartphone-based colorimetric sensor (with 5–500 µM and detection limits of 1.2 µM) for CN⁻ measurement. The sensor was exploited for CN⁻ analysis in water and food samples with satisfactory results. The established dual sensor benefits from both methods advantages such as the high sensitivity of fluorometric sensors as well as simple and visual detection of smartphone-based colorimetric sensors. Additionally, our developed smartphone-based colorimetric sensor can be used as a portable sensor for the sensitive, rapid and low-cost analysis of CN⁻ in the field.

A dual chemiluminescence and ratiometric fluorescence sensor based on WS2 QDs- Fe(II)- S2O82− system for bisphenol A detection

Bisphenol A (BPA) is an environmental containment with toxic and hazardous characteristics towards all organisms. So, introducing a simple and sensitive sensor for its determination in the field is of importance. We applied Fe(II) -S2O82− Fenton-like reaction to design chemiluminescence and fluorescence sensing methods for BPA detection. In the chemiluminescence method, tungsten disulfide quantum dots (WS2 QDs) were used as an enhancer to amplify (around 300-fold) the intensity of the ultra-weak Fe(II) -S2O82− CL reaction. The WS2 QD-enhanced CL system was applied to design a simple and sensitive sensor for monitoring BPA at the range of 1.0–50 μM. Additionally, a ratiometric fluorescence sensor was designed for BPA assay in which WS2 QDs and o-phenylenediamine (OPD) were applied as a reference and a fluorescence reporter, respectively. In the presence of BPA, the fluorescence intensity of ox-OPD, produced from the OPD-Fe(II) -S2O82− reaction, increased while that of WS2 QDs was almost constant. The ratio of reporter fluorescence intensity to that of the reference was linearly proportional to the BPA concentration in the range of 2.5–75 μM. The developed methods were successfully applied for the determination of BPA in water samples.

In situ addition WS2 quantum dots on polymer films for white emission LED applications

This research focuses on the development of simple and low-cost white emission films for LED applications. Tungsten disulfide quantum dots (WS2 QDs) were synthesized using a simple hydrothermal approach and then studied physio-chemical properties. Morphological investigation revealed that the QDs were 3.7 nm in size. The QDs were incorporated into a Polyvinyl Alcohol (PVA) film, yielding stacked films that emitted white light. The stacked film had a color rendering index of 76 % and CIE coordinates of (0.35, 0.34). Through the entrapment of WS2 QDs within PVA films, this study proposes a feasible strategy for lab-scale development of white emission LEDs.

Chemiluminescence signal amplification for determination of tetrachlorobenzoquinone based on acidified tungsten disulfide quantum dots

As a representative intermediate in the migration and transformation of pentachlorophenol (PCP), tetrachlorobenzoquinone (TCBQ) is a carcinogenic halogenated quinone, which can threat human health. Chemiluminescence (CL) is a promising method in environmental analysis due to its high sensitivity, no background interference, and portable features. However, no CL platform for TCBQ determination was developed which may be owing to the weak CL intensity. Herein, a novel CL signal amplification strategy for tungsten disulfide quantum dots (WS2 QDs) via sulfuric acid (SA) activation was proposed. The sulfuric acid-activated WS2 QDs (SA-WS2 QDs) exposed more active sites (W4+) and their CL emission with Na2SO3 was 20 times stronger than that of untreated WS2 QDs. More importantly, the CL emission was significantly enhanced with the introduction of TCBQ through generating electronically excited carbonyl species (λem = 550 nm), and thus a sensitive and selective sensing method for TCBQ in practical water sample was established (linear range: 0.05–1 μM, the limit of detection: 2 nM). This study not only developed a simple, efficient, and sensitive method for TCBQ detection, but also proposed a green and feasible strategy to enhance the CL property of nanoparticles.

One-Step Synthesis of Transition Metal Dichalcogenide Quantum Dots Using Only Alcohol Solvents for Indoor-Light Photocatalytic Antibacterial Activity.

In this study, we report a one-step direct synthesis of molybdenum disulfide (MoS2) and tungsten disulfide (WS2) quantum dots (QDs) through a solvothermal reaction using only alcohol solvents and efficient Escherichia coli (E. coli) decompositions as photocatalytic antibacterial agents under visible light irradiation. The solvothermal reaction gives the scission of molybdenum-sulfur (Mo-S) and tungsten-sulfur (W-S) bonding during the synthesis of MoS2 and WS2 QDs. Using only alcohol solvent does not require a residue purification process necessary for metal intercalation. As the number of the CH3 groups of alcohol solvents among ethyl, isopropyl, and tert(t)-butyl alcohols increases, the dispersibility of MoS2/WS2 increases. The CH3 groups of alcohols minimize the surface energy, leading to the effective exfoliation and disintegration of the bulk under heat and pressure. The bulky t-butyl alcohol with the highest number of methyl groups shows the highest exfoliation and yield. MoS2 QDs with a lateral size of about 2.5 nm and WS2 QDs of about 10 nm are prepared, exhibiting a strong blue luminescence under 365 nm ultraviolet (UV) light irradiation. Their heights are 0.68-3 and 0.72-5 nm, corresponding to a few layers of MoS2 and WS2, respectively. They offer a highly efficient performance in sterilizing E. coli as the visible-light-driven photocatalyst.

A ratiometric fluorescence sensor based on gold silver nanoclusters and tungsten disulfide quantum dots with simple fabrication for the detection of copper ions in river water.

Copper plays a key role in the human body; meanwhile, excess Cu2+ ions can result in various diseases. Nanoclusters (NCs) are often used to measure Cu2+ ions, but there are two difficulties. On the one hand, a single probe of NCs is easily affected by environmental factors. On the other hand, it is difficult to mask the interference of Pb2+ ions and Cd2+ ions in the process of detecting Cu2+ ions. As a new type of quantum dots (QDs), tungsten disulfide quantum dots (WS2-QDs) have some advantages of simple synthesis and stable luminescence properties. Stable WS2-QDs with blue fluorescence are used as a reference probe, while gold silver nanoclusters (AuAgNCs) with red fluorescence are used as a response probe. A ratiometric fluorescent sensor was constructed by mixing the two styles of fluorescent probes, which is abbreviated as NCs/QDs. This nano-sensor can be used to detect the concentration of Cu2+ ions, in which the fluorescence of QDs does not change significantly, while the fluorescence of NCs can be quenched by Cu2+ ions. The concentration of Cu2+ ions can be determined as low as 0.12 μM with a linear range from 0.3 to 3 μM. The common interference caused by Pb2+ and Cd2+ ions can be eliminated by the phosphate buffer solution (PBS). This sensor was used to detect the concentration of Cu2+ in river water with satisfactory results.

Electronic Synaptic Devices with High Thermostability Induced by Embedded Tungsten Disulfide Quantum Dots for Machine Learning

AbstractIf the speed of machine learning is to be improved, devices and systems with strong resistances to various types of internal noise, mainly internal thermal noise, are urgently needed. The successful demonstration of a synaptic device is reported based on a polyimide–tungsten disulfide quantum dot (PI‐WS2 QD) nanocomposite that continued to operate normally after simultaneous exposure of a high temperature of 100 °C. Such excellent performance is attributable to the strong quantum confinement effect of WS2 QDs. The working current of the device and its power consumption are on the orders of nanoamperes and femtojoules, respectively. Undoubtedly, such devices will significantly improve the physical performances of machine learning systems and allow the rapid realization of greatly improving machine learning speed.

Boronic acid-functionalized tungsten disulfide quantum dots as a fluorescence probe for sensitive detection of dopamine

A fluorescence probe comprising boronic acid-functionalized tungsten disulfide quantum dots for the label-free detection of dopamine was developed. The detection method is based on the selective interaction between diols and aminophenylboronic acid. This interaction generates quenching of fluorescence due to aggregation and the inner filter effect of the fabricated fluorescence probe. The proposed method allows the determination of dopamine in the concentration range from 0.05 μM to 100 μM including a correlation coefficient of 0.9925 along with a low detection limit of 0.01 μM. It manifests a better selectivity towards dopamine in the existence of different interfering analytes. Furthermore, the applicability of the proposed method has been utilized in the real sample which showed promising results for diagnostic purposes.

Early stage evaluation of colon cancer using tungsten disulfide quantum dots and bacteriophage nano-biocomposite as an efficient electrochemical platform

BackgroundRecently, biosensors have become popular analytical tools for small analytes due to their high sensitivity and wide analytical range. In the present work, development of a novel biosensing method based on tungsten disulfide quantum dots (WS2 QDs)-Au for rapidly and selectively detecting c-Met protein is introduced. As a proof of concept, M13 bacteriophage-based biosensors were used for the electrochemical detection of c-Met protein as a colon cancer biomarker.MethodThe M13 bacteriophage (virus), as the biorecognition element, was immobilized on glassy carbon electrodes which were modified by WS2 QDs-functionalized gold nanoparticles. The stepwise presence of the WS2 QDs, gold nanoparticles, and immobilized phage on glassy carbon electrodes were confirmed by scanning electron microscope (SEM) and square wave voltammetry (SWV) technique.ResultsThe designed biosensor was applied to measure the amount of c-Met protein in standard solutions, and consequently the desirable detection limit of 1 pg was obtained. Finally, as a proof of concept, the developed platform was used for the evaluation of c-Met protein in serum samples of colon cancer-suffering patients and the results were compared with the results of the common Elisa kit.ConclusionsAs an interesting part of this study, some concentrations of the c-Met protein in colon cancer serum samples which could not be determined by Elisa, were easily analyzed by the developed bioassay system. The developed bioassay system has great potential to application in biomedical laboratories.Graphical

Tungsten disulfide (WS2)/fluorescein ratiometric fluorescent probe for detection of cefixime residues in milk

In this research work, it has been reported a ratiometric fluorescent sensor based on tungsten disulfide quantum dots (WS2 QDs) and fluorescein for the determination of Cefixime (CEF). When excited by radiation of 400 nm wavelength the probe illustrates dual emissions centered at 460 nm and 510 nm. CEF quenches the fluorescence (FL) intensity of fluorescein (510 nm), while it doesn't affect the FL emission of WS2 QDs at 460 nm. The change in the ratio of the two peaks (F460/F510) of the prepared sensor (WS2 QDs/fluorescein) is linearly proportional to the CEF concentration in the range of 200–2.500 ng/mL with a limit of detection (LOD) of 45 ng/mL. Hence, the proposed probe can be successfully used for CEF quantification in the milk samples.

Tungsten disulfide quantum dots (WS2 QDs) as a fluorescence probe for detection of dopamine (DA)

Tungsten disulfide quantum dots (WS2 QDs) as a fluorescence probe for detection of dopamine (DA)

Phosphorescent MoS2 quantum dots as a temperature sensor and security ink.

Currently, few phosphorescent materials (PMs) possess a long phosphorescence lasting time and have potential for application in chemical sensors. Herein, we disclose that the incorporation of few-layer molybdenum disulfide quantum dots (FL-MoS2 QDs) into poly(vinyl alcohol) (PVA) matrices leads to the emission of bright green phosphorescence with a long lasting time of 3.0 s and a phosphorescence quantum yield of 20%. This enhanced phosphorescence originates from the formation of O–H⋯S hydrogen bonding networks between the rich sulfur sites of the FL-MoS2 QDs and the hydroxyl groups of the PVA molecules, which not only rigidifies the vibration modes of the FL-MoS2 QDs but also provides an oxygen barrier. Further investigations reveal that the FL-MoS2 QD/PVA composites exhibit a longer phosphorescence lasting time than N,S-doped carbon dots, few layer tungsten disulfide quantum dots, Rhodamine 6G, and Rhodamine B in PVA matrices. Since heat efficiently induced the removal of water moisture from PVA matrices, the FL-MoS2 QD/PVA composites could be implemented for phosphorescence turn-on and naked-eye detection of temperature variations ranging from 30 to 70 °C. By contrast, the carbon dot/PVA composites were incapable of sensing environmental temperature due to their weak hydrogen bonding with the hydroxyl groups of PVA matrices. Additionally, this study reveals the potential of the FL-MoS2 QD/PVA composites as an advanced security ink for anti-counterfeiting and encryption applications. The given results could open a new direction for potential application of two-dimensional quantum dots in phosphorescence-based sensors and security inks.

Ag@WS2 quantum dots for Surface Enhanced Raman Spectroscopy: Enhanced charge transfer induced highly sensitive detection of thiram from honey and beverages

Novel SERS substrates is urgently in demand for rapid and sensitive analysis of toxic agrochemicals from food. In this work, a monodispersed tungsten disulfide quantum dots modified silver nanosphere (Ag@WS2QD) was prepared and used as SERS substrate. Ag@WS2QD generated uniform and stable SERS signals within 2 min, displaying great promise in “mixing and reading” detection. Compared to unmodified colloidal silver nanoparticles, 4 times higher analytical enhancement factor was found in Ag@WS2QD. Density functional theory calculation verified the enhanced charge transfer within the coupling systems of molecule-Ag@WS2QD. Besides, the unique surface properties are beneficial for the enrichment of specific molecule. Both the chemical extraction and enhanced charge transfer contributes to rapid and sensitive SERS detection of Ag@WS2QD. A “mixing and reading” SERS method for thiram from honey and four kinds of juice was developed from Ag@WS2QD, showing great promise for rapid and direct SERS detection for toxic agrochemicals and further applications.

High sensitive ratiometric fluorescence analysis of trypsin and dithiothreitol based on WS2 QDs

In this paper, a simple tungsten disulfide quantum dots (WS2 QDs)-based ratiometric fluorescence method was established for the detection of trypsin and 1, 4-dithiothreitol. Trypsin can hydrolyze cytochrome c into heme-peptide fragments with peroxidase-like activity. In the presence of hydrogen peroxide, the fragments can generates hydroxyl radicals, which can oxidize o-phenylenediamine (OPD) to form 2,3-diaminophenazine (DAP) with a fluorescence peak at 568 nm. DAP can quench the fluorescence of WS2 QDs at 448 nm via fluorescence resonance energy transfer (FRET). When 1, 4-dithiothreitol was present, it can react with hydroxyl radicals, and less OPD was oxidized, which accompanied by the fluorescence intensity of WS2 QDs increased and the fluorescence intensity of DAP decreased. Therefore, the fluorescence intensity ratio (F568/F448) can be used to monitor trypsin and 1, 4-dithiothreitol. A good linear calibration between fluorescence intensity ratio F568/F448 versus trypsin activity and1, 4-dithiothreitol concentration were obtained within 0.2–140 μg mL−1 and 20–200 μmol L−1, respectively. And the detection limit was 0.09 μg mL−1 for trypsin and 6.8 μmol L−1 for 1, 4-dithiothreitol, respectively. Furthermore, the developed ratiometric fluorescence method was successfully applied for trypsin and 1, 4-dithiothreitol assay in human serum samples.

Highly Stable and Flexible Memristive Devices Based on Polyvinylpyrrolidone: WS2 Quantum Dots

Tungsten disulfide (WS2) quantum dots (QDs) embedded in polyvinylpyrrolidone (PVP) based flexible memristive devices were prepared, and those devices exhibited typical bistable electrical switching and remarkable nonvolatile memristive behaviors. Maximum electricity ON/OFF ratio obtained from the current–voltage (I-V) curves of the device is close to 104. The set voltage of the device is +0.7 V, which effectively reduced the energy consumption. The retention times extracted from data for the devices were as large as 1 × 104 s, which points to these devices having nonvolatile characteristics. Moreover, the highly flexible characteristics of the devices were demonstrated by bending the devices. The carrier transport mechanisms were explained by fitting the I-V curves, and possible operating mechanisms of the devices can be described based on the electron trapping and detrapping processes. WS2 QDs uniformly dispersed in pure transparent N, N-Dimethylformamide (DMF) were obtained by using ultrasonication and a hydrothermal process in this work.

Enhanced photoluminescence of InGaAs/AlGaAs quantum well with tungsten disulfide quantum dots

The pristine and diethylenetriamine (DETA)-doped tungsten disulfide quantum dots (WS2 QDs) with an average lateral size of about 5 nm have been synthesized using pulsed laser ablation (PLA). Introduction of the synthesized WS2 QDs on the InGaAs/AlGaAs quantum wells (QWs) can improve the photoluminescence (PL) of the InGaAs/AlGaAs QW as high as 6 fold. On the basis of the time-resolved PL and Kelvin probe measurements, the PL enhancement is attributed to the carrier transfer from the pristine or DETA-doped WS2 QDs to the InGaAs/AlGaAs QW. A heterostructure band diagram is proposed for explaining the carrier transfer, which increases the hole densities in the QW and enhances its PL intensity. This study is expected to be beneficial for the development of the InGaAs-based optoelectronic devices.