- 标题
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- 实验方案
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Calcium ion assisted fluorescence determination of microRNA-167 using carbon dotsa??labeled probe DNA and polydopamine-coated Fe3O4 nanoparticles
摘要： A selective and sensitive fluorescence biosensor is described for determination of microRNA-167 using fluorescent resonant energy transfer (FRET) strategy. The FRET system comprises carbon dots (CDs, donor) labeled with probe DNA (pDNA) and polydopamine (PDA)-coated Fe3O4 nanoparticles (Fe3O4@PDA NPs, acceptor). The CDs-pDNA can be absorbed onto the surface of Fe3O4@PDA NPs because of the strong π interaction between pDNA and PDA. With the enhanced adsorption ability of Fe3O4@PDA NPs by Ca2+, the fluorescence intensity of CDs at 445 nm (excitation at 360 nm) is quenched. In presence of microRNA-167, the hybridized complex of CDs-pDNA-microRNA-167 will be released from the surface of Fe3O4@PDA NPs due to the weak π interaction of the complex and PDA. This results in the fluorescence recovery of CDs. By application of twice-magnetic separation, the biosensor shows a wide linear range of 0.5–100 nM to microRNA-167 with a 76 pM detection limit. The method was applied to the determination of microRNA-167 in samples of total microRNA extractions from A. thaliana seedlings, and the recoveries ranged from 96.4 to 98.3%.
关键词： Fluorescent resonant energy transfer,Twice-magnetic separation,MicroRNA extractions,Hybridized complex,π interaction,Fluorescence biosensor
更新于2025-09-19 17:13:59
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Establishment of a universal and sensitive plasmonic biosensor platform based on the hybridization chain reaction (HCR) amplification induced by a triple-helix molecular switch
摘要： Herein, we established a universal and sensitive plasmonic sensing strategy for biomolecule assays by coupling the hybridization chain reaction (HCR) strategy and a triple-helix molecular switch. Upon the recognition of the target, a single-stranded DNA as a universal trigger (UT) was released from the triple-helix molecular switch (THMS). Thus, the HCR process can be triggered between two hairpins M1 and M2, resulting in the aggregation of gold nanoparticles (AuNPs) via the hybridization between the tail sequence on M1 (or M2) and a DNA–AuNP probe with a dramatic change in the absorbance at 521 nm. More specifically, the strategy, which was conducted by the introduction of target-specific recognition of THMS and universalized by virtue of altering the aptamer or DNA sequence without changing the triple-helix structure, enables simple design for multiple target detection. By taking advantage of THMS, this strategy could enable stable and sensitive detection of a variety of targets including nucleic acids, small molecules and proteins, which may possess great potential for practical applications.
关键词： gold nanoparticles,biomolecule detection,plasmonic biosensor,triple-helix molecular switch,hybridization chain reaction
更新于2025-09-19 17:13:59
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Graphene assisted terahertz metamaterials for sensitive bio-sensing
摘要： We report that single-stranded deoxyribonucleic acids (ssDNAs) at very low concentrations can be detected using graphene-combined nano-slot-based terahertz (THz) resonance. A combination of the resonant structure and tuned electro-optical properties of graphene can provide unprecedentedly sensitive biomolecule sensing even using very low energy THz photons, overcoming the huge scale di?erence of 10,000:1 between the wavelength and the size of the ssDNAs. Ultrahigh sensitivity is obtained by the signi?cant increase in the absorption cross-section of the graphene sheet with the targeted biomolecules, induced by strong THz ?eld enhancement at the resonance frequency inside the slots. Clearly distinguishable THz optical signals were observed between di?erent species of ssDNAs even at the nano-mole level and analyzed quantitatively in terms of the electro-optical properties of the suspended graphene layer modi?ed by the attached ssDNAs without any molecular-speci?c labeling for the THz regime. Quantitative analysis of ssDNA molecule adsorption was carried based on the change in conductivity using a theoretical THz transmission model.
关键词： Terahertz,Graphene,Metamaterial,Biosensor
更新于2025-09-19 17:13:59
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A Ratiometric Fluorescent Quantum Dot-Based Biosensor for Chlorothalonil Detection via an Inner-Filter Effect
摘要： A new sensitive sensor for detecting chlorothalonil (CHL) based on the inner-filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent quantum dots (RF-QDs) was developed. Here, RF-QDs were designed by two different color CdTe QDs. Based on the IFE, the AuNPs can quench the fluorescence of the RF-QDs. Because of the electrostatic attraction between protamine (PRO) and the AuNPs, the PRO can restore fluorescence effectively. Papain (PAP) can easily hydrolyze PRO and causes the quench of fluorescence quenching. The addition of CHL can inhibit PAP activity and restore the fluorescent signal. Through the characterization of the structural changes of PAP, the inhibition and mechanism of CHL on PAP activity were studied. The ability of CHL to inhibit PAP activity was evaluated by measuring the fluorescence of the RF-QDs. Under the optimal conditions, this sensing platform shows a response to CHL in the range of 0.34-2320 ng/mL and a detection limit of 0.0017 ng/mL. Based on the CHL inhibition of PAP activity, the RF-QDs showed good selectivity for CHL. The practical application of the proposed system was demonstrated by detecting CHL in food and environmental samples with satisfying results.
关键词： ratiometric fluorescent quantum dots,inner-filter effect,biosensor,chlorothalonil,gold nanoparticles
更新于2025-09-19 17:13:59
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Fabrication of Cavity-Sealed Optical Interferometric Surface Stress Biosensor by thin Film Transfer Technique
摘要： We developed a surface stress sensor based on a MEMS Fabry-Perot interferometer with cavity-sealed structure by technique of nanometer-thick parylene sheet for highly sensitive label-free biosensing. The proposed MEMS interferometer can measure the membrane deflection caused by target molecule adsorption as the spectral shift. The proposed cavity-sealed optical interferometer can prevent physical adsorption to the backside of membrane and refractive index drift in the cavity, leading to improvement of sensitivity. We successfully obtained the spectral shift of 77 nm in 10 minutes with the color change associated with the antigen-antibody reaction with a concentration of 1 ng/ml, which improved by 16.7-fold compared with the conventional sensor.
关键词： MEMS biosensor,Surface stress sensor,label-free biosensing,film transfer technique,Fabry-Perot interferometer
更新于2025-09-16 10:30:52
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Introducing Waveguide Loss: Another Way to Realize a High-Sensitivity Microring Biosensor
摘要： Real-time and high-sensitivity biosensors are urgently needed in biochemistry. As one of the candidates, silicon-on-insulator (SOI) sensors exhibits excellent performances. However, there are still some limitations to hinder them to be applied to much wider scenarios. Fabrication tolerance is also required for the generalization of these micro- or nano-structure. In this work, we demonstrate an SOI waveguide biosensor for biochemical sensing with high sensitivity of 1.88×105 dB/RIU. Because of the compact structure and low demand for accuracy of fabrication, this device possesses better applicability and reliability.
关键词： Nanophotonics,Biosensor,SOI,Microring
更新于2025-09-16 10:30:52
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Analysis and simulation of a plasmonic biosensor for hemoglobin concentration detection using noble metal nano-particles resonances
摘要： In this paper, three different shapes (sphere, cubic, and cylinder) silver plasmonic nano-particles for the detection of hemoglobin concentration in blood is analyzed. This work is done to determine the hemoglobin concentration in blood using a sensing feature by changing hemoglobin concentration from 0 to 140g/l. The impact of hemoglobin concentration on refractive index changes in the surrounding medium of nano-particles is considered. Simulated results show that, scattering cross-section has a sharp peak for cubic nano-particles with the full width at half maximum (FWHM) of 50nm. FWHM is 64nm and 94nm for sphere and cylinder nanoparticles, respectively. Exactly, after applying the hemoglobin refractive index in each concentration to the surrounding medium, an increase in resonance wavelength in extinction cross-section is obtained. The wavelength shifts of 3.3nm, 3.7nm, and 5.5nm are obtained for hemoglobin concentration of 140g/l using sphere, cubic, and cylinder shapes nano-particles, respectively. Further, changing the simulated structure parameters can manage the plasmonic resonance wavelength and it is applicable to detect other biological samples.
关键词： hemoglobin detection,Plasmonic biosensor,Surface plasmon resonance,extinction cross-section,noble metal
更新于2025-09-16 10:30:52
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Synergic effect of plasmonic gold nanoparticles and graphene oxide on the performance of glucose sensing
摘要： In this study hybrid nanostructures of Au–graphene oxide (Au–GO) were synthesized via a two-step process and used to modify the glassy carbon electrode (GCE) for electrochemical measurements of glucose. The modified electrode exhibits a fast response less than 4 s, a low detection limit of 0.025 mM and a high signal-to-noise ratio (S/N) of 3.5. The fabricated sensor shows a linear response in a large concentration range from 0.0025 mM to 15 mM with a reproducible sensitivity of 84.53 mA cm?2 mM?1, which is much higher than that of the individual Au, GO and previously reported GO/rGO based sensors. In addition, the biosensor shows excellent results for human serum which agree well with those obtained using a laboratory glucometer. Moreover, the glucose amount in selective commercially available food samples and fresh juices was also successfully measured. The biosensor exhibits excellent selectivity, thermal stability and reproducibility. The enhanced and efficient sensitivity of the developed Au–GO based biosensor may be due to the synergic effects of the plasmonic Au-nanoparticles and GO. The performance of the biosensor suggests that the reported Au–GO hybrid nanostructures can provide a novel platform for developing non-enzymatic biosensors for biomedical and industrial applications.
关键词： hybrid nanostructures,Au–graphene oxide,non-enzymatic biosensor,electrochemical measurements,glucose sensing
更新于2025-09-16 10:30:52
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A label-free RTP sensor based on aptamer/quantum dot nanocomposites for cytochrome <i>c</i> detection
摘要： Given the outstanding room-temperature phosphorescence (RTP) of Mn–ZnS quantum dots (QDs) and the specific recognition performance of the aptamer, we built phosphorescent composites from aptamers conjugated with polyethyleneimine quantum dots (PEI-QDs) and applied them to cytochrome c (Cyt c) detection. Specifically, QDs/CBA composites were generated from the electrostatic interaction between the positively-charged PEI-QDs and the negatively-charged Cyt c binding aptamer (CBA). With the presence of Cyt c, the Cyt c can specifically bind with the QDs/CBA composites, and quench the RTP of QDs through photoinduced electron-transfer (PIET). Thereby, an optical biosensor for Cyt c detection was built, which had a detection range of 0.166–9.96 mM and a detection limit of 0.084 mM. This aptamer-mediated phosphorescent sensor with high specificity and operational simplicity can effectively avoid the interference of scattering light from complex substrates. Our findings offer a new clue for building biosensors based on QDs and aptamers.
关键词： aptamer,quantum dots,biosensor,room-temperature phosphorescence,cytochrome c
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - High sensitivity biosensor for Staphylococcus Aureus detection based on tapered a singlemode-no core-singlemode fiber structure
摘要： A fiber biosensor based on tapered singlemode-no core-singlemode (SNS) fiber structure was investigated for the detection of staphylococcus aureus. The fibre sensor was functionalised by depositing the pig IgG antibodies onto tapered biosensor surface, which has specific binding with staphylococcus aureus. The experimental results showed that transmission spectrum of functionalized sensor undergone wavelength blue shift when it was immersed into Staphylococcus aureus solution, and 1.1 nm wavelength shift was observed with a concentration of 101colony-forming units (CFU)/mL.
关键词： optical fiber sensor,biosensor,staphylococcus aureus,foodborne pathogens,the pig IgG
更新于2025-09-16 10:30:52