Search Results (77)

Our study develops two configurations of MoS₂ and graphene heterostructures—MoS₂ on graphene (MG) and graphene on MoS₂ (GM)—to investigate biomolecule sensing in field-effect transistor (FET) biosensors. Leveraging MoS₂ and graphene’s distinctive properties, we employ specialized functionalization techniques for each configuration: graphene with MoS₂ on top uses a silane-based method with triethoxysilylbutyraldehyde (TESBA), and MoS₂ with graphene on top utilizes 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE). Our research explores the application of MoS₂–Graphene heterostructures in biosensors, emphasizing the roles of synthesis, fabrication, and material functionalization in optimizing sensor performance. Through our experimental investigations, we have observed that doping MoS₂ and graphene leads to noticeable changes in the Raman spectrum and shifts in transfer curves. Techniques such as XPS, Raman, and AFM have successfully confirmed the biofunctionalization. Transfer curves were instrumental in characterizing the biosensing performance, revealing that GM configurations exhibit higher sensitivity and a lower limit of detection (LOD) compared to MG configurations. We demonstrate that GM heterostructures offer superior sensitivity and specificity in biosensing, highlighting their significant potential to advance biosensor technologies. This research contributes to the field by detailing the creation process of vertical MoS₂–graphene heterostructures and evaluating their effectiveness in accurate biomolecule detection, advancing biosensing technology. Full article

The growing demand for low-cost biosensors has stimulated the study of new technologies and materials like molybdenum disulfide (MoS₂). Due to its electroconductive nature and high surface-to-volume ratio, it allows for the ultra-sensitive detection of biomarkers. The crystal structure of MoS₂ provides it with a unique micrometer thickness, making it appropriate for biosensing in healthcare, environmental monitoring, and food safety. As compared to traditional materials, MoS₂ can work without labels (through field-effect transduction or plasmonic shifts) while maintaining biocompatibility and low-cost fabrication, which fill significant voids in the early diagnosis of diseases. This paper provides an overview of the recent advancements in MoS₂-based biosensors, which are primarily focused on the field-effect transistors and surface plasmon resonance techniques and fabrication methods for MoS₂-based biosensors like mechanical exfoliation, liquid-phase exfoliation, physical vapor deposition, chemical vapor deposition, and chemical exfoliation, applications in various industries, and their characterization techniques to evaluate the quality and functionality of MoS₂ nanosheets in biosensors. While certain challenges remain like improving conductivity and scalability, MoS₂-based biosensors serve as a powerful tool for the precise and reliable detection of biomarkers in environmental, food, and healthcare industries. Full article

In this article, the role of downscaling in boosting the sensitivity of a novel label-free DNA sensor based on sub-10 nm dielectric-modulated transition metal dichalcogenide field-effect transistors (DM-TMD FET) is presented through a quantum simulation approach. The computational method is based on self-consistently solving the quantum transport equation coupled with electrostatics under ballistic transport conditions. The concept of dielectric modulation was employed as a label-free biosensing mechanism for detecting neutral DNA molecules. The computational investigation is exhaustive, encompassing the band profile, charge density, current spectrum, local density of states, drain current, threshold voltage behavior, sensitivity, and subthreshold swing. Four TMD materials were considered as the channel material, namely, MoS₂, MoSe₂, MoTe₂, and WS₂. The investigation of the scaling capability of the proposed label-free gate-all-around DM-TMDFET-based biosensor showed that gate downscaling is a valuable approach not only for producing small biosensors but also for obtaining high biosensing performance. Furthermore, we found that reducing the device size from 12 nm to 9 nm yields only a moderate improvement in sensitivity, whereas a more aggressive downscaling to 6 nm leads to a significant enhancement in sensitivity, primarily due to pronounced short-channel effects. The obtained results have significant technological implications, showing that miniaturization enhances the sensitivity of the proposed nanobiosensor. Full article

The early and accurate detection of cancer remains a critical challenge in biomedical diagnostics. In this work, we propose and investigate a novel surface plasmon resonance (SPR) biosensor platform based on a multilayer configuration incorporating copper (Cu), silicon nitride (Si₃N₄), and molybdenum disulfide (MoS₂) for the optical detection of various cancer types. Four distinct sensor architectures (Sys₁–Sys₄) were optimized through the systematic tuning of Cu thickness, Si₃N₄ dielectric layer thickness, and the number of MoS₂ monolayers to enhance sensitivity, angular shift, and spectral sharpness. The optimized systems were evaluated using refractive index data corresponding to six cancer types (skin, cervical, blood, adrenal, breast T1, and breast T2), with performance metrics including sensitivity, detection accuracy, quality factor, figure of merit, limit of detection, and comprehensive sensitivity factor. Among the configurations, Sys₃ (BK7–Cu–Si₃N₄–MoS₂) demonstrated the highest sensitivity, reaching 254.64 °/RIU for adrenal cancer, while maintaining a low detection limit and competitive figures of merit. Comparative analysis revealed that the MoS₂-based designs, particularly Sys₃, outperform conventional noble-metal architectures in terms of sensitivity while using earth-abundant, scalable materials. These results confirm the potential of Cu/Si₃N₄/MoS₂-based SPR biosensors as practical and effective tools for label-free cancer diagnosis across multiple malignancy types. Full article

Uric acid (UA), the final metabolic product of purines, plays a crucial role in human health monitoring. The UA concentration in biological fluids serves as a diagnostic marker for various disorders, particularly kidney diseases, and represents a potential therapeutic target. Given the growing emphasis on preventive healthcare, developing methods for real-time UA detection has become increasingly significant. Here, we demonstrate the synthesis of novel tumbleweed-like molybdenum diselenide (MoSe₂) nanostructures through a single-step hydrothermal process. The synthesized MoSe₂ was subsequently hybridized with reduced graphene oxide (rGO) to construct electrodes for UA sensing. Differential pulse voltammetry (DPV) measurements revealed that the MoSe₂/rGO-modified glassy carbon electrode (GCE) exhibited excellent UA detection capabilities under optimized conditions. The sensor demonstrated a remarkably low limit of detection (LOD) of 28.4 nM and maintained linearity across a wide concentration range (40 nM to 200 μM). Notably, the sensor showed high selectivity for UA detection even in the presence of common interfering species, including citric acid (CA), dopamine (DA), ascorbic acid (AA), cysteine (Cys), glucose (Glu), oxalic acid (OA), sodium ions (Na⁺), and potassium ions (K⁺). The developed sensor displayed outstanding selectivity, stability, and reproducibility characteristics. This synthetic approach offers promising opportunities for developing MoSe₂-based electrochemical sensing platforms suitable for diverse bioanalytical applications. Full article

This study presents a numerical investigation of surface plasmon resonance (SPR) biosensors incorporating silicon nitride (Si₃N₄) and molybdenum disulfide (MoS₂) for HIV DNA hybridization detection. By optimizing the thickness of Ag and Si₃N₄ and the number of MoS₂ layers, two configurations, Sys₂ (Ag-Si₃N₄) and Sys₃ (Ag-Si₃N₄-MoS₂), were selected for comparative analysis. Performance metrics, including the resonance angle shift, sensitivity, detection accuracy, and quality factor, demonstrated that Sys₂ achieved the highest sensitivity of 210.9°/RIU and an enhanced figure of merit (86.98 RIU⁻¹), surpassing state-of-the-art SPR sensors. Although Sys₃ exhibited a lower sensitivity of 158.1°/RIU due to MoS₂-induced optical losses, it provided a lower limit of detection, suggesting a trade-off between sensitivity and spectral broadening. Compared to previous SPR biosensors, the proposed configurations achieve superior sensitivity while maintaining stability and selectivity, positioning them as promising candidates for next-generation nucleic acid detection platforms. Full article

With the sudden advancement of glucose biosensors for monitoring blood glucose levels for the prevention and diagnosis of diabetes, non-enzymatic glucose sensors have aroused great interest owing to their sensitivity, stability, and economy. Recently, researchers have dedicated themselves to developing non-enzymatic electrochemical glucose sensors for the rapid, convenient, and sensitive determination of glucose. However, it is desirable to explore economic and effective nanomaterials with a high non-enzymatic catalysis performance toward glucose to modify electrodes. Metal oxides (MOs) and metal sulfides (MSs) have attracted extensive interest among scholars owing to their excellent catalytic activity, good biocompatibility, low cost, simple synthesis process, and controllable morphology and structure. Nonetheless, the exploitation of MOs and MSs in non-enzymatic electrochemical glucose sensors still suffers from relatively low conductivity and biocompatibility. Therefore, it is of significance to integrate MOs and MSs with metal/carbon/conducive polymers to modify electrodes for compensating the aforementioned deficiency. This review introduces the recent developments in non-enzymatic electrochemical glucose sensors based on MOs and MSs, focusing on their preparation methods and how their structural composition influences sensing performance. Finally, this review discusses the prospects and challenges of non-enzymatic electrochemical glucose sensors. Full article

The combination of molybdenum disulfide (MoS₂) with plasmonic nanomaterials has opened up new possibilities in biological applications by combining MoS₂’s biocompatibility and high surface area with the optical sensitivity of plasmonic metals. These MoS₂–plasmonic hybrid systems hold great promise in areas such as biosensing, bioimaging, and phototherapy, where their complementary properties facilitate improved detection, real-time visualization, and targeted therapeutic interventions. MoS₂’s adjustable optical features, combined with the plasmon resonance of noble metals such as gold and silver, enhance signal amplification, enabling detailed imaging and selective photothermal or photodynamic therapies while minimizing effects on healthy tissue. This review explores various synthesis strategies for MoS₂–plasmonic hybrids, including seed-mediated growth, in situ deposition, and heterojunction formation, which enable tailored configurations optimized for specific biological applications. The primary focus areas include highly sensitive biosensors for detecting cancer and infectious disease biomarkers, high-resolution imaging of cellular dynamics, and the development of phototherapy methods that allow for accurate tumor ablation through light-induced thermal and reactive oxygen species generation. Despite the promising advancements of MoS₂–plasmonic hybrids, translating these platforms into clinical practice requires overcoming considerable challenges, such as synthesis reproducibility, toxicity, stability in physiological conditions, targeted delivery, and scalable manufacturing. Addressing these challenges is essential for realizing their potential as next-generation tools in diagnostics and targeted therapies. Full article

The integration of a photodetector that converts optical signals into electrical signals is essential for scalable integrated lithium niobate photonics. Two-dimensional materials provide a potential high-efficiency on-chip detection capability. Here, we demonstrate an efficient on-chip photodetector based on a few layers of MoTe₂ on a thin film lithium niobate waveguide and integrate it with a microresonator operating in an optical telecommunication band. The lithium-niobate-on-insulator waveguides and micro-ring resonator are fabricated using the femtosecond laser photolithography-assisted chemical–mechanical etching method. The lithium niobate waveguide-integrated MoTe₂ presents an absorption coefficient of 72% and a transmission loss of 0.27 dB µm⁻¹ at 1550 nm. The on-chip photodetector exhibits a responsivity of 1 mA W⁻¹ at a bias voltage of 20 V, a low dark current of 1.6 nA, and a photo–dark current ratio of 10⁸ W⁻¹. Due to effective waveguide coupling and interaction with MoTe₂, the generated photocurrent is approximately 160 times higher than that of free-space light irradiation. Furthermore, we demonstrate a wavelength-selective photonic device by integrating the photodetector and micro-ring resonator with a quality factor of 10⁴ on the same chip, suggesting potential applications in the field of on-chip spectrometers and biosensors. Full article

The COVID-19 pandemic has highlighted the urgent need for rapid, sensitive, and reliable diagnostic tools for detecting SARS-CoV-2. In this study, we developed and optimized a surface plasmon resonance (SPR) biosensor incorporating advanced materials to enhance its sensitivity and specificity. Key parameters, including the thickness of the silver layer, silicon nitride dielectric layer, molybdenum disulfide (MoS₂) layers, and ssDNA recognition layer, were systematically optimized to achieve the best balance between sensitivity, resolution, and attenuation. The optimized configuration, consisting of a 45 nm silver layer, a 13 nm silicon nitride layer, 2 MoS₂ layers, and a 5 nm ssDNA layer, demonstrated superior performance for detecting SARS-CoV-2 in PBS solution. The biosensor exhibited high sensitivity at low viral concentrations, achieving a sensitivity of 375.01°/RIU, a detection accuracy of 0.002, and a quality factor of 38.34 at 1.0 mM SARS-CoV-2 concentration. Performance metrics validated the sensor’s capability for reliable detection, particularly in early-stage diagnostics where timely intervention is critical. Moreover, the biosensor’s linear response to refractive index changes confirmed its potential for quantitative viral concentration analysis. This study underlines the significance of integrating advanced materials, such as MoS₂ and silicon nitride, to enhance SPR biosensor performance. The findings establish the proposed biosensor as a robust and precise diagnostic tool for SARS-CoV-2 detection, with potential applications in clinical diagnostics and epidemiological monitoring. Full article

Fiber SPR biosensors have low sensitivity and accuracy in detecting biomolecules. In this study, the TRIZ is applied to molecules and optimization. By defining the prototype system, clarifying the components and interacting objects, and adopting a functional model analysis and causal analysis, we deeply explored the key points and root causes of leakage and used a variety of tools, such as technological contradiction, object-field analysis, the HOW-TO model and knowledge effect library, physical contradiction, and the villain method, to come up with different solutions. A novel multimode–single-mode–multimode fiber SPR sensor based on the structure of gold (Au)–molybdenum disulfide (MoS₂)–gold nanoparticles was designed and manufactured by using the TRIZ systematically for the first time. Under the effective guidance of the TRIZ, the sensitivity of the novel sensor is significantly enhanced after the optimization and experimental verification. The new sensor provides an effective reduction in the cost of detection and production and at the same time has excellent stability, ease of preparation, and high reproducibility, which is of significant value and significance for practical applications. Full article

Field-effect transistor (FET) biosensors can be used to measure the charge information carried by biomolecules. However, insurmountable hysteresis in the long-term and large-range transfer characteristic curve exists and affects the measurements. Noise signal, caused by the interference coefficient of external factors, may destroy the quantitative analysis of trace targets in complex biological systems. In this report, a “rectified signal” in the output characteristic curve, instead of the “absolute value signal” in the transfer characteristic curve, is obtained and analyzed to solve these problems. The proposed asymmetric Schottky barrier-generated MoS₂/WTe₂ FET biosensor achieved a 10⁵ rectified signal, sufficient reliability and stability (maintained for 60 days), ultra-sensitive detection (10 aM) of the Down syndrome-related DYRK1A gene, and excellent specificity in base recognition. This biosensor with a response range of 10 aM–100 pM has significant application potential in the screening and rapid diagnosis of Down syndrome. Full article

Graphene and graphene-like two-dimensional layered nanomaterials-based photoelectrochemical (PEC) biosensors have recently grown rapidly in popularity thanks to their advantages of high sensitivity and low background signal, which have attracted tremendous attention in ultrahigh sensitive small molecule detection. This work proposes a non-enzymatic and visible-light-sensitive PEC biosensing platform based on ZIF-67@MoS₂/rGO composite which is synthesized through a facile and one-step microwave-assisted hydrothermal method. The combination of MoS₂ and rGO could construct van der Waals heterostructures, which not only act as visible-light-active nanomaterials, but facilitate charge carriers transfer between the photoelectrode and glassy carbon electrode (GCE). ZIF-67 anchored on MoS₂/rGO heterostructures provides large specific surface areas and a high proportion of catalytic sites, which cooperate with MoS₂ nanosheets, realizing rapid and efficient enzyme-free electrocatalytic oxidation of glucose. The ZIF-67@MoS₂/rGO-modified GCE can realize the rapid and sensitive detection of glucose at low detection voltage, which exhibits a high sensitivity of 12.62 μAmM⁻¹cm⁻². Finally, the ZIF-67@MoS₂/rGO PEC biosensor is developed by integrating the ZIF-67@MoS₂/rGO with a screen-printed electrode (SPE), which exhibits a high sensitivity of 3.479 μAmM⁻¹cm⁻² and a low detection limit of 1.39 μM. The biosensor’s selectivity, stability, and repeatability are systematically investigated, and its practicability is evaluated by detecting clinical serum samples. Full article

The accurate and simultaneous detection of neurotransmitters, such as dopamine (DA) and epinephrine (EP), is of paramount importance in clinical diagnostic fields. Herein, we developed cerium–molybdenum disulfide nanoflowers (Ce-MoS₂ NFs) using a simple one-pot hydrothermal method and demonstrated that they are highly conductive and exhibit significant peroxidase-mimicking activity, which was applied for the simultaneous electrochemical detection of DA and EP. Ce-MoS₂ NFs showed a unique structure, comprising MoS₂ NFs with divalent Ce ions. This structural design imparted a significantly enlarged surface area of 220.5 m² g⁻¹ with abundant active sites as well as enhanced redox properties, facilitating electron transfer and peroxidase-like catalytic action compared with bare MoS₂ NFs without Ce incorporation. Based on these beneficial features, Ce-MoS₂ NFs were incorporated onto a screen-printed electrode (Ce-MoS₂ NFs/SPE), enabling the electrochemical detection of H₂O₂ based on their peroxidase-like activity. Ce-MoS₂ NFs/SPE biosensors also showed distinct electrocatalytic oxidation characteristics for DA and EP, consequently yielding the highly selective, sensitive, and simultaneous detection of target DA and EP. Dynamic linear ranges for both DA and EP were determined to be 0.05~100 μM, with detection limits (S/N = 3) of 28 nM and 44 nM, respectively. This study shows the potential of hierarchically structured Ce-incorporated MoS₂ NFs to enhance the detection performances of electrochemical biosensors, thus enabling extensive applications in healthcare, diagnostics, and environmental monitoring. Full article

An advanced, cost-effective, and portable DNA biosensor capable of detecting multiple bacteria simultaneously has been developed. The biosensor comprises a fast and inexpensive potentiostat that controls the applied potential to a screen-printed electrochemical array platform functionalized with MoS₂ flakes and bacterial DNA probes. The current response obtained by à la carte thionine functionalized carbon nanodots (Ty-CDs) is monitored as an electrochemical indicator of the hybridization event. The design of the potentiostat prioritizes achieving an optimal signal-to-noise ratio and incorporates a user-friendly interface compatible with various devices, including computers, mobile phones, and tablets. The device is compact, lightweight, and manufactured at a low cost. The key components of the potentiostat include a data acquisition board capable of analyzing multiple samples simultaneously and a controller board. The results of this study confirm the ability of the multiplex portable biosensor to successfully detect specific bacterial DNA sequences, demonstrating its reliability and superior performance compared with a traditional, more complex, and laboratory-oriented potentiostat. Full article