- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A microfluidic paper-based laser-induced fluorescence sensor based on duplex-specific nuclease amplification for selective and sensitive detection of miRNAs in cancer cells
摘要： MicroRNAs (miRNAs) are considered as the potential biomarkers for many cancers. To determine miRNAs in cancer cells is significant for realizing these diseases. In this work, a microfluidic paper-based laser-induced fluorescence sensor based on duplex-specific nuclease (DSN) amplification was developed and applied to selectively and sensitively determine miRNAs in cancer cells. An interface for laser-induced fluorescence detection was firstly applied to perform the sample detection on the paper-based chip. Under the optimal conditions, DSN (3 μL 0.10 U) and Taqman probes (2 μL 2.5 × 10?7 M) were preserved on the circles (Diameter 4 mm) of the folded paper chip. When miRNA solution was added, the mixed solution could trigger fluorescence signal amplification by cyclically digesting hybrids of miRNAs and Taqman probes by DSN. The whole determination, including sample heating process, could be accomplished within 40 min. The detection limits for miRNA-21 and miRNA-31 were 0.20 and 0.50 fM respectively, corresponding to only 1.0 and 1.5 zmol consumption of miRNAs. The testing of mismatched miRNAs showed that the method had good specificity. Finally, the method was applied to determine miRNA-21 and miRNA-31 in lysates of cancer cells of A549 and HeLa, and hepatocyte LO2. MiRNA-21 and miRNA-31 could be successfully found from the two cancer cells. The concentrations for miRNA-21 and miRNA-31 were 1.74 × 10?13 M and 6.29 × 10?14 M in HeLa cell lysate (3.75 × 104 cells/mL), 3.07 × 10?15 M and 3.28 × 10?15 M in A549 cell lysate (8.33 × 106 cells/mL) respectively. The recoveries ranged from 87.30% to 111.83%, indicating the results were reliable. The developed method was effective, selective and sensitive in the determination of miRNAs in cancer cells.
关键词： microRNA,Duplex-specific nuclease,Paper-based sensor,Laser-induced fluorescence,Cancer cell
更新于2025-09-23 15:19:57
-
Data on eosin Y solutions for laser-induced fluorescence in water flows
摘要： Dye tracing techniques involve the tagging of a sample of water with dye, providing important qualitative and quantitative information. This article presents physical and fluorescence properties of dye solutions obtained by diluting a pharmaceutical aqueous solution of eosin Y with distilled water. Sample solutions with eosin concentrations ranging from 0 to 20 g/L were examined under various temperatures and laser powers. The data include measurements of dynamic viscosity, surface tension and pH. Fluorescence emission spectra as well as laser beam attenuation and photobleaching measurements are also reported. The datasets provide guidelines for obtaining optimal dye mixtures and suitable optical configurations to implement eosin fluorescence techniques.
关键词： Dye-water solution,Surface tension,Viscosity,Laser-induced fluorescence,pH
更新于2025-09-23 15:19:57
-
Direct measurement of the ionization source rate and closure of the particle balance in a helicon plasma using laser induced fluorescence
摘要： A detailed study of the ?ows of ion and neutral argon populations in a helicon plasma was carried out. Understanding the principle ion sinks and sources of neutral fueling is essential to understanding the ability of helicon wave heating to create high density plasmas. This heating mechanism and the neutral fueling required to sustain it and perhaps manipulate the axial density pro?le in long cylindrical plasmas are an active research topic for advanced plasma wake?eld accelerator concepts. Using laser induced ?uorescence (LIF) of ion and neutral argon species, an ion ?ux of up to 2:5 (cid:2) 1021 m(cid:3)2 s(cid:3)1 was measured leaving the core of a helicon plasma with a peak electron density of 4:0 (cid:2) 1018 m(cid:3)3. Taking the divergence of the axial ion ?ux pro?le yields a minimum ionization rate estimate of 2 (cid:2) 1021 m(cid:3)3 s(cid:3)1, and including the radial divergence increases the estimated ionization rate to approximately 1022 m(cid:3)3 s(cid:3)1. Neutral ?ow velocities measured using LIF reveal a circulatory fueling and loss mechanism with distinct zones where radial or axial sources and sinks dominate.
关键词： laser induced fluorescence,ionization source rate,argon,helicon plasma,particle balance
更新于2025-09-23 15:19:57
-
Laser-induced fluorescence velocimetry for a hypersonic leading-edge separation
摘要： Two-dimensional mapping of the velocity distribution for a hypersonic leading-edge separation flowfield generated by a “tick” shaped geometry is presented for the first time. Discrete measurements of two velocity components were acquired at a flow condition having a total specific enthalpy of 3.8 MJ/kg by imaging nitric oxide fluorescence over numerous runs of the hypersonic tunnel at the Australian Defence Force Academy (T-ADFA). The measured freestream velocity distribution exhibited some non-uniformity, which is hypothesized to originate from images acquired using a set of ultraviolet specific mirrors mounted on the shock tunnel deflecting under load during a run of the facility, slightly changing the laser sheet orientation. The flow separation point was measured to occur at 1.4 ± 0.2 mm from the model leading edge, based on the origin of the free shear layer emanating from the expansion surface. Reattachment of this free shear layer on the compression surface occurred at 59.0 ± 0.2 mm from the model vertex. Recirculating the flow bound by the separation and reattachment points contained supersonic reverse flow and areas of subsonic flow aligned with the location of three identified counter-rotating vortices. A comparison of the recirculation flow streamline plots with those computed using Navier–Stokes and direct simulation Monte Carlo (DSMC) codes showed differences in flow structures. At a flow time close to that produced by the facility, flow structures generated by the DSMC solution were seen to agree more favorably with the experiment than those generated by the Navier–Stokes solver due to its ability to better characterize separation by modeling the strong viscous interactions and rarefaction at the leading edge. The primary reason for this is that the no-slip condition used in the Navier–Stokes solution predicts a closer separation point to the leading edge and structures when compared to the DSMC solution, which affects surface shear stress and heat flux, leading to a difference in flow structures downstream of the separation.
关键词： velocimetry,laser-induced fluorescence,hypersonic,leading-edge separation,Navier–Stokes,DSMC,Doppler-shift
更新于2025-09-23 15:19:57
-
Characterization of tracers for two-color laser-induced fluorescence liquid-phase temperature imaging in sprays
摘要： The variation of the fluorescence spectral signature of tracer solutions with temperature enables temperature imaging measurements in liquids and sprays by simultaneously recording and rationing the fluorescence intensity detected in two separate wavelength channels. In this work, we recorded fluorescence spectra of ethanol-based solutions of nine laser dyes used as tracers (PTP, stilbene 1, coumarin 152, coumarin 153, rhodamine B, rhodamine 101, pyrromethene 597, DCM, and pyridine 1) after excitation at either 266, 355, or 532 nm (depending on the dye) for temperatures between 298 and 348 K (close to the boiling point of the solvent), and for concentrations (depending on dye) around 10 mg/l (i.e., ~ 10–5 mol/l). The influence of signal self-absorption was investigated for the tracers best suited for thermometry, rhodamine B and coumarin 152, where the latter is almost unaffected due to its large Stokes shift. In thin-film (100 μm) cells, possible concentration effects on the fluorescence spectrum were investigated in the absence of signal self-absorption in the 0.1–10 and 0.5–50 mg/l range for rhodamine B and coumarin 152, respectively. Sensitivities of the two-color intensity ratios were determined for two selected color detection channels for each tracer characterized by their center wavelength and spectral half width and conditioned on averaged intensities of larger than 10% of the spectral peak of their respective fluorescence spectrum. The use of coumarin 152 that showed the overall best spectroscopic properties was demonstrated for temperature imaging in a burning ethanol spray.
关键词： coumarin 152,rhodamine B,sprays,temperature imaging,two-color laser-induced fluorescence,tracers
更新于2025-09-23 15:19:57
-
Interaction of Zinc Oxide and Copper Oxide Nanoparticles with Chlorophyll: A Fluorescence Quenching Study
摘要： The present study aims to investigate the interactions of zinc oxide nanoparticles and copper oxide nanoparticles with the major photosynthetic pigment chlorophyll using ultraviolet-visible, steady state, and time resolved laser induced fluorescence spectroscopy. The steady state fluorescence measurements show that zinc oxide and copper oxide nanoparticles quench the fluorescence of chlorophyll in concentration-dependent manner. The Stern-Volmer plot for the chlorophyll-zinc oxide nanoparticles is linear, and the value of quenching constant has been observed to increase with temperature indicating the possibility of dynamic quenching. A decrease in the lifetime of chlorophyll with increase in the concentration of zinc oxide nanoparticles confirms the involvement of dynamic quenching in the chlorophyll–zinc oxide nanoparticle interaction. In the case of copper oxide nanoparticles, the Stern-Volmer plot deviates from linearity observed in the form of upward curvature depicting the presence of both static and dynamic quenching. In addition, the lifetime of chlorophyll decreases with increase in the concentration of copper oxide nanoparticles displaying the dominance of dynamic quenching in the chlorophyll-copper oxide nanoparticle interaction. The decrease observed in the value of binding constant with increasing temperature and negative values of change in enthalpy, entropy, and Gibb’s free energy indicates that van der Waal and hydrogen bonding are the prominent forces during the interaction of chlorophyll with both zinc oxide and copper oxide nanoparticles and that the process is spontaneous and exothermic. The interaction of zinc oxide and copper oxide nanoparticles with chlorophyll occurs through electron transfer mechanism. The obtained results are useful in understanding the sensitization processes involving chlorophyll and zinc oxide and copper oxide nanoparticles.
关键词： chlorophyll and nanoparticles,molecular interaction,ultraviolet-visible spectroscopy,laser-induced fluorescence spectroscopy,Attenuated total reflectance–Fourier transform infrared spectroscopy,steady state and time resolved fluorescence,X-ray diffraction
更新于2025-09-19 17:15:36
-
The RbSr <sup>2</sup> Σ <sup>+</sup> ground state investigated <i>via</i> spectroscopy of hot and ultracold molecules
摘要： We report on spectroscopic studies of hot and ultracold RbSr molecules, and combine the results in an analysis that allows us to fit a potential energy curve (PEC) for the X(1)2S+ ground state bridging the short-to-long-range domains. The ultracold RbSr molecules are created in a mK sample of Rb and Sr atoms and probed by two-colour photoassociation spectroscopy. The data yield the long-range dispersion coefficients C6 and C8, along with the total number of supported bound levels. The hot RbSr molecules are created in a 1000 K gas mixture of Rb and Sr in a heat-pipe oven and probed by thermoluminescence and laser-induced fluorescence spectroscopy. We compare the hot molecule data with spectra we simulated using previously published PECs determined by three different ab initio theoretical methods. We identify several band heads corresponding to radiative decay from the B(2)2S+ state to the deepest bound levels of X(1)2S+. We determine a mass-scaled high-precision model for X(1)2S+ by fitting all data using a single fit procedure. The corresponding PEC is consistent with all data, thus spanning short-to-long internuclear distances and bridging an energy gap of about 75% of the potential well depth, still uncharted by any experiment. We benchmark previous ab initio PECs against our results, and give the PEC fit parameters for both X(1)2S+ and B(2)2S+ states. As first outcomes of our analysis, we calculate the s-wave scattering properties for all stable isotopic combinations and corroborate the locations of Fano–Feshbach resonances between alkali Rb and closed-shell Sr atoms recently observed [V. Barbé et al., Nat. Phys., 2018, 14, 881]. These results and more generally our strategy should greatly contribute to the generation of ultracold alkali–alkaline-earth dimers, whose applications range from quantum simulation to state-controlled quantum chemistry.
关键词： spectroscopy,laser-induced fluorescence,thermoluminescence,ultracold molecules,photoassociation,potential energy curve,Fano-Feshbach resonances,RbSr molecules
更新于2025-09-19 17:15:36
-
Laser-induced fluorescence and dispersed-fluorescence spectroscopy of the ?2E?X?2A1 transition of jet-cooled calcium methoxide (CaOCH <sub/>3</sub> ) radicals
摘要： Laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectra of the ?A2E ? ?X2A1 electronic transition of the calcium methoxide (CaOCH3) radical have been obtained under jet-cooled conditions. Complete active space self-consistent field and coupled-cluster calculations on the free radical were performed to aid the assignment of vibronic transitions observed in the LIF/DF spectra. In addition to dominant spectral features that are well reproduced by vibrational frequencies and Franck-Condon (FC) factors calculated ab initio, the FC matrix for the ?A2E ? ?X2A1 electronic transition contains considerable off-diagonal elements that connect (i) the CaO-stretch (ν4) mode and non-CaO stretch modes and (ii) the asymmetric CaOC stretch (ν3) and the CaOC bending (ν8) modes. The Jahn-Teller and pseudo-Jahn-Teller interactions involving the ?2E state as well as the spin-orbit interaction induce additional vibronic transitions that are not allowed under the Born-Oppenheimer approximation. Additionally, anharmonic vibrational terms in the ground state induce transitions that are forbidden in the harmonic-oscillator approximation. Spin-orbit splitting has been observed for several vibrational levels of the ?2E state, and an essentially constant value was measured at all levels accessed in the LIF experiment. Implications of the present spectroscopic investigation to the proposed schemes of laser-cooling MOCH3 (M = alkaline earth metals) molecules and detection of time-reversal-symmetry-violating interactions are discussed.
关键词： calcium methoxide,laser cooling,spin-orbit interaction,Jahn-Teller effect,Franck-Condon factors,vibronic transitions,CaOCH3,Laser-induced fluorescence,pseudo-Jahn-Teller effect,dispersed-fluorescence spectroscopy
更新于2025-09-19 17:13:59
-
Simultaneous measurement of CO and OH in flames using a single broadband, femtosecond laser pulse
摘要： In this short communication, we report simultaneous measurement of CO and OH in flames using a single femtosecond (fs)-duration laser source. Two-photon excitation of CO A 1 (cid:2) ←← X 1 ?+ (3,0), (4,0) and (5,0) bands and single-photon excitation of OH A 2 ?+ ← X 2 (cid:2) (1,0) band are achieved simultaneously using one fs-duration laser pulse near 283 nm. Subsequently, crosstalk-free, laser-induced fluorescence (LIF) emissions are detected from the v’ = 3, 4 and 5 upper vibrational levels of CO in the 200–230 nm region, and (1,1) and (0,0) bands of OH near the 310-nm region. A detailed spectroscopic investigation of CO in a gas cell is followed by simultaneous detection of CO and OH in C 2 H 4 /air flames. The measured CO and OH profiles as a function of flame equivalence ratio agree well with equilibrium calculations. The present study extends the applicability of broadband fs-LIF imaging of OH in flames, and reveal an alternate method to obtain heat release rate in turbulent flames via simultaneous OH and CO measurements.
关键词： Femtosecond diagnostics,Carbon monoxide,Laser-induced fluorescence,Hydroxyl radical
更新于2025-09-19 17:13:59
-
Investigation on ion behavior in magnetically shielded and unshielded Hall thrusters by laser-induced fluorescence
摘要： Non-intrusive characterization of the ion velocity distribution functions at several points of interest in 600 W magnetically shielded MSHT-600 and unshielded USHT-600 Hall thrusters plume by laser-induced fluorescence was conducted. Several visual clues supporting the magnetic shielding effect of MSHT-600 were presented. The measured ion axial velocity distribution functions show that the ion axial velocity is higher and observed to reach the maximum at nearer location to the exit plane on the centerline in the magnetically shielded Hall thruster than that in the unshielded one under the same operating conditions but uniformly distributed in the radial direction when ignoring the slower population for both thrusters. These results are in accordance with the higher specific impulse measured in several other shielded Hall thrusters. Moreover, the ion axial velocity on the centerline is higher than the average axial velocity at other radial locations for the same axial distance downstream of the exit plane in USHT-600, while the higher plume divergence or the inner pole erosion causes the velocity on the centerline to decrease in MSHT-600. The downstream shift of the accelerating potential and electric field distribution are also the typical features in magnetically shielded Hall thrusters as reported in other studies. Finally, the xenon ion velocity vector fields show that the ion population starts to meet and diverge further downstream of the exit plane in MSHT-600 than that in USHT-600, which may be associated with the difference of the plume divergence.
关键词： magnetically shielded Hall thrusters,unshielded Hall thrusters,laser-induced fluorescence,ion velocity distribution functions,ion behavior
更新于2025-09-19 17:13:59