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Quantitative Understanding of the Ultra-Sensitive and Selective Detection of Dopamine using Graphene Oxide/WS2 Quantum Dot Hybrid
摘要： Herein, we report on the ultra-high sensitive and selective detection of dopamine (DA) at pico-molar level by a low cost sensing platform based on graphene oxide (GO) sheets anchored with tungsten disulfide quantum dots (WS2 QDs). The liquid phase exfoliated WS2 QDs are mostly bilayer type with an average particle size ~2.0 ± 0.3 nm, while the GO sheets are of few-layer thickness. The WS2 QDs are highly luminescent with photoluminescence (PL) quantum yield of ~15% and they exhibit excitation wavelength dependent spectral shift in PL due to the high degree of edge/defect states. In presence of GO, the PL intensity of WS2 QDs partially quenches due to van der Waals interaction and excited-state charge transfer from WS2 to GO. However, in the presence of DA, drastic quenching of PL occurs for WS2/GO hybrid and this enables selective detection of DA as low as 10 pM, which is the lowest among the reported values. We present a new model to quantitatively explain the GO mediated efficient charge transfer and unusual quenching of PL as a function of the DA concentration. Finally, the WS2/GO based sensor is utilized for the detection of DA in the river water and blood serum with a satisfactory recovery, which establishes its practical utility as an efficient environmental/biochemical sensor.
关键词： Fluorescence Quenching,Dopamine,Biosensor,Graphene Oxide,WS2 Quantum Dots
更新于2025-09-23 15:21:01
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Electrochemiluminescent biosensor with DNA link for selective detection of human IgG based on steric hindrance
摘要： A highly selective DNA-based electrochemiluminescence (ECL) based biosensor is described for the detection of human IgG. It is exploiting the effect of steric hindrance that affects the strength of the ECL signal in the presence of IgG. Digoxin-linked signalling DNA was specifically bound to IgG, and this causes steric hindrance which limits the ability of DNA to hybridize with capturing DNA attached to a gold electrode. Europium (II) doped CdSe quantum dots were covalently linked to the DNA in order to generate the ECL signal. Using this steric hindrance hybridization method, the ECL signal of the biosensor were proportional to the concentration of IgG with a wide linear range and a 14 pM detection limit. Conceivably, the method can be expanded to the detection of a wide range of proteins for which homologous recognition elements are available.
关键词： Digoxin-linked signalling DNA,Electrochemiluminescence,Human IgG,Steric hindrance effects,Biosensor,Europium (II) doped CdSe quantum dots
更新于2025-09-23 15:21:01
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Gallium arsenide waveguides as a platform for direct mid-infrared vibrational spectroscopy
摘要： During recent years, mid-infrared (MIR) spectroscopy has matured into a versatile and powerful sensing tool for a wide variety of analytical sensing tasks. Attenuated total reflection (ATR) techniques have gained increased interest due to their potential to perform non-destructive sensing tasks close to real time. In ATR, the essential component is the sampling interface, i.e., the ATR waveguide and its material properties interfacing the sample with the evanescent field ensuring efficient photon-molecule interaction. Gallium arsenide (GaAs) is a versatile alternative material vs. commonly used ATR waveguide materials including but not limited to silicon, zinc selenide, and diamond. GaAs-based internal reflection elements (IREs) are a new generation of semiconductor-based waveguides and are herein used for the first time in direct spectroscopic applications combined with conventional Fourier transform infrared (FT-IR) spectroscopy. Next to the characterization of the ATR waveguide, exemplary surface reactions were monitored, and trace-level analyte detection via signal amplification taking advantage of surface-enhanced infrared absorption (SEIRA) effects was demonstrated. As an example of real-world relevance, the mycotoxin aflatoxin B1 (AFB1) was used as a model analyte in food and feed safety analysis.
关键词： Mid-infrared chem/biosensor,Surface modification,Gallium arsenide,Self-assembled monolayers,Evanescent field absorption,Surface-enhanced infrared absorption
更新于2025-09-23 15:21:01
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Enhancement of cortisol measurement sensitivity by laser illumination for AlGaN/GaN transistor biosensor
摘要： In this study, high electron mobility transistor (HEMT) device was used as an immuno biosensor to measure concentration of a stress hormone, cortisol, by using selective binding on cortisol monoclonal antibody (c-Mab). Also, the HEMT sensor was enhanced in its sensitivity through light illumination to generate photocurrent. The optical pumping could assist the biosensor to discriminate more detailed change, which could result in an increment of limit of detection (LOD) to 1.0 pM cortisol level. It was the lowest level of detection with semiconductor device-based cortisol biosensors and the enhancement of surface potential sensitivity was induced by laser light (532 nm). Output current amplificated by photocurrent was higher than dark original current at about 3.39 % when gate voltage is applied with -3 V. Since the device could be applied to not only standard cortisol solution but also real human salivary sample, it is expected to apply for in vitro direct diagnosis of point-of-care test (POCT).
关键词： HEMT,biosensor,cortisol,AlGaN/GaN,laser illumination
更新于2025-09-23 15:21:01
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Ultrasensitive Detection of MicroRNA with a Bismuthene-enabled Fluorescence Quenching Biosensor
摘要： Bismuthene, a monoelemental two-dimensional material, has shown promise in the biomedicine, electronic, and energy fields due to its high carrier mobility and stability at room temperature. However, its use in biosensing applications is restricted due to the undefined quenching mechanism for dye molecules. Herein, we develop a novel ultrathin bismuthene-based sensing platform for microRNA (miRNA)-specific detection that even discriminates single-base mismatches. The detection limit can reach 60 pM. Excitingly, the fluorescence quenching mechanism of bismuthene, ground state weakly fluorescent charge transfer, is determined via femtosecond pump-probe spectroscopy. This finding provides a proof-of-concept platform to i) fundamentally explore the quenching mechanism of bismuthene and ii) sensitively detect miRNA molecules for early cancer.
关键词： biosensor,Bismuthene,microRNA,charge transfer,fluorescence quenching
更新于2025-09-23 15:21:01
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High-sensitivity biosensor for identification of protein based on terahertz Fano resonance metasurfaces
摘要： Terahertz metasurface biosensors have gained significant attention in biological field due to its label-free, real-time and in-situ detection properties. In this paper, a planar array of Fano asymmetric split ring resonators (ASRs) fabricated on 25 μm flexible polyimide substrate was proposed for new terahertz metasurface biosensors. It is shown that 160 GHz/RIU and 240 GHz/RIU refractive index sensitivity can be severally obtained near 0.81 and 1.13 THz transmission dips of the proposed system. Correspondingly, for biosensor samples that protein A/G, A/G + IgG were spotted on ASRs surface in our experiment, shifts of 8.9 GHz and 11.7 GHz, 17.6 GHz and 52.9 GHz toward low frequency were observed, respectively. These results illustrate high-sensitivity and label-free detection of proteins, implying a new feasible way of sensing in terahertz domain.
关键词： Fano resonance,Terahertz,Biosensor,Metasurface
更新于2025-09-23 15:21:01
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Three-core photonic crystal fiber surface plasmon resonance sensor
摘要： A three-core photonic crystal fiber (PCF) surface plasmon resonance (SPR) biosensor with high performance is presented. The structure of the biosensor is easy to implement and has good repetition. The outer layer of the fiber structure is gold film. The analyte is placed on the surface of the gold film. The Full vector finite element method is used to numerical simulation and analysis the transmission mode and characteristics of the three-core PCF-SPR biosensor. The influence of sensor structure parameters on sensing performance is investigated. The structure parameters are optimized. The optimum structure parameters are given. The refractive index (RI) sensitivity of the sensor is discussed there. The results show that the average refractive index sensitivity of the sensor is 3435 nm/RIU in the sensing range of 1.33–1.40, and the resolution is 2.91 × 10?6 RIU. The sensor has the advantages of high sensitivity and high resolution. And it can be applied to real-time detection of the bio-molecules and small drug-molecules.
关键词： Photonic crystal fiber,Biosensor,Surface plasmon resonance,Refractive index sensitivity,Finite element method
更新于2025-09-23 15:21:01
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Two-dimensional transition metal dichalcogenides mediated long range surface plasmon resonance biosensors
摘要： Two-dimensional transition metal dichalcogenides (TMDCs), as promising alternative plasmon supporting materials to graphene, exhibit potential applications in sensing. Here, we propose a TMDCs-mediated long range surface plasmon resonance (LRSPR) imaging biosensor, which shows tremendous improvements in both imaging sensitivity (> ×2) and detection accuracy (> ×10) as compared to conventional surface plasmon resonance (cSPR) biosensor. It is found that the imaging sensitivity of the LRSPR biosensor can be enhanced by the integration of TMDC layers, which is di?erent from the previously reported graphene-mediated cSPR imaging sensor whose imaging sensitivity decreases with the number of graphene layers. This imaging sensitivity enhancement e?ect for the TMDCs-mediated LRSPR sensor originates from the propagating nature of the LRSPR at both interfaces of sensing medium/gold and gold/cytop layer (with matching refractive index as sensing medium). By tuning the thickness of gold ?lm and cytop layer, it is possible to achieve optimized imaging sensitivity for LRSPR sensor with any known integrated number of TMDC layers and the analyte refractive index. The proposed TMDCs-mediated LRSPR imaging sensor could provide potential applications in chemical sensing and biosensing applications.
关键词： detection accuracy,biosensor,long range surface plasmon resonance,Two-dimensional transition metal dichalcogenides,imaging sensitivity
更新于2025-09-23 15:21:01
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Label-free Thrombin Detection Using a Tapered Fiber-optic Interferometric Aptasensor
摘要： Aptamer biosensor for label-free thrombin detection based on a tapered fiber-optic interferometer has been proposed and demonstrated. The biosensor probe can be easily fabricated by tapering a commercial double-cladding fiber down to 5 μm in diameter and it provides a high refractive index sensitivity of 1660 nm/RIU. The changes are determined by tracing the wavelength shift of the dip in the transmission spectrum with variable surrounding refractive index. With the help of surface functionalization of thrombin-binding aptamers, the proposed fiber-optic biosensor proves its capability in label-free detection of thrombin with a lowest detectable concentration of 0.1 μM, together with high specificity in various concentrations of pure and mixed thrombin solutions.
关键词： Fiber-optic biosensor,tapered fiber interferometer,aptamer,thrombin detection
更新于2025-09-23 15:21:01
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - The mechanical simulation of a special biosensor
摘要： Cantilever-based sensor is kind of the most popular MEMS sensor. In this paper, by taking an example the process of analyzing a transducer is explained, such as building models and performing mathematic operations on result data to get the performance parameters of a cantilever-based sensor. We also state the principle of the cantilever bio-sensor. In the meantime we explain the theory of the operating of cantilever, and a cantilever sensor design guided by mechanical simulation.
关键词： simulation,ANSYS,biosensor,cantilever,MEMS
更新于2025-09-23 15:21:01