- 标题
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- 实验方案
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A Turn-On Fluorescent Probe for Sensitive Detection of Cysteine in a Fully Aqueous Environment and in Living Cells
摘要： We reported here a turn-on fluorescent probe (1) for the detection of cysteine (Cys) by incorporating the recognition unit of 2,4-dinitrobenzenesulfonyl ester (DNBS) to a coumarin derivative. The structure of the obtained probe was confirmed by NMR and HRMS techniques. The probe shows a remarkable fluorescence off-on response (～52-fold) by the reaction with Cys in 100% aqueous buffer. The sensing mechanism was verified by the HPLC test. Probe 1 also displays high selectivity towards Cys. The detection limit was calculated to be 23 nM. Moreover, cellular experiments demonstrated that the probe is highly biocompatible and can be used for monitoring intracellular Cys.
关键词： living cells,aqueous environment,fluorescent probe,turn-on,cysteine
更新于2025-09-19 17:15:36
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Extension of the range of profile surface roughness measurements using metrological atomic force microscope
摘要： The calibration service of profile surface roughness by using a metrological atomic force microscope is now available at National Metrology Institute of Japan (NMIJ), AIST. The calibration method is designed by referring to ISO 19606: 2017 (JIS R 1683: 2014). The scope of the ISO 19606: 2017, however, is limited to roughness measurements of surfaces with an arithmetical mean roughness, Ra, in the range of about 1 nm–30 nm. Currently there is strong demand for the measurement of surface roughness of more than 30 nm in the precision machining industry and for the measurement of surface roughness of sub-nanometer order in the semiconductor industry. In order to meet such demand, it is necessary to extend the range of surface roughness measurements in the NMIJ's calibration service. In this study, authors performed surface roughness measurements using a metrological AFM and evaluated their uncertainties. As a result of a series of measurements and evaluation of their uncertainties, it has been found that the calibration range can be extended to surfaces with an arithmetical mean roughness, Ra, in the range of about 0.2 nm–100 nm. The measurement results and the future challenges are reported in this paper.
关键词： Probe-tip diameter evaluation,Calibration,Metrological AFM,Surface roughness
更新于2025-09-19 17:15:36
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A highly selective and sensitive fluorescent probe for simultaneously distinguishing and sequentially detecting H <sub/>2</sub> S and various thiol species in solution and in live cells
摘要： A novel dual-channel fluorescent probe (NCR) based on differences in reactivity among H2S, Cys/Hcy, and GSH was rationally designed for simultaneously distinguishing and sequentially sensing H2S, Cys/Hcy, and GSH using two emission channels, which also demonstrated that NCR can be used for targeting mitochondria in mammalian cells.
关键词： live cells,thiol species,fluorescent probe,mitochondria-targeted,H2S
更新于2025-09-19 17:15:36
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Hybrid gate dielectrics: a comparative study between polyvinyl alcohol/ $$\hbox {SiO}_{2}$$ SiO 2 nanocomposite and pure polyvinyl alcohol thin-film transistors
摘要： Polyvinyl alcohol (PVA) thin films as polymer gate dielectrics, with and without SiO2 nanoparticles were fabricated using spin-coating. Surface roughness and hydrophilicity of PVA and PVA/SiO2 thin films were studied by contact-angle measurements and atomic force microscopy. The dielectric properties were characterized via capacitance and leakage-current measurements on metal–insulator–metal structures. In order to further investigate the application potential of such materials as a replacement for conventional inorganic dielectrics such as SiO2 in organic thin-film transistors, devices were fabricated based on these polymers using α, ω-dihexylquaterthiophene as an active layer. Performance of the devices was realized by electrical measurements and Kelvin probe force microscopy. All transistors showed hole and electron mobilities in the low-voltage range. PVA/SiO2 films showed larger capacitance, less hydrophilicity, rougher surfaces and considerable leakage currents compared with those with neat PVA. Although integrating nanoparticles modified surface electronic properties and showed a shift in surface potential as observed in Kelvin probe force measurements, it appears that non-polymeric and neat polymeric dielectric materials could still be a privilege to nanocomposite polymeric dielectrics for optoelectronic applications.
关键词： ambipolar thin-film transistor,scanning probe microscopy (SPM),surface chemistry,electrical and structural properties,Polymer dielectrics
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - A Miniature Fiber-Optic Photoacoustic Probe Coated with MoS<inf>2</inf>-PDMS for Water Level and Oil-Water Interface Detection*
摘要： We demonstrate a miniature broadband (~13.3 MHz) fiber-tip photoacoustic probe with ~68.32-μm thick MoS2-polydimethylsiloxane (PDMS) composite for accurate measurement of water and oil-water interface levels. The composite was applied to the tip of a double-clad fiber with an outer diameter of 125 μm using dip coating. The propagation time of an ultrasonic wave generated by a 5-ns pulsed laser excitation in liquids was extracted to determine water level or silicone oil-water interface in a glass tube. An excellent goodness of fit (R2≈0.996) was achieved with a high accuracy of ~1.5 μm in the tested water-level range of 0-218 μm. Then the proposed technique exhibited an average relative error of 0.68% for the oil-water interface detection, along with a good fitting coefficient of 98.7% in the range of 0-8 mm. The presented photoacoustic probe therefore shows a great potential in compact accurate liquid level monitoring.
关键词： photoacoustic probe,2D nanomaterials,optical fiber tip,ultrasonic liquid level measurement
更新于2025-09-19 17:15:36
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RECENT ADVANCES IN ULTRAFAST TIME-RESOLVED SCANNING TUNNELING MICROSCOPY
摘要： Making smaller and faster functional devices has led to an increasing demand for a microscopic technique that allows the investigation of carrier and phonon dynamics with both high spatial and temporal resolutions. Traditional optical pump–probe methods can achieve femtosecond temporal resolution but fall short in the spatial resolution due to the diffraction limit. Scanning tunneling microscopy (STM), on the contrary, has realized atomic-scale spatial resolution relying on the high sensitivity of the tunneling current to the tip-sample distance. However, limited by the electronics bandwidth, STM can only push the temporal resolution to the microseconds scale, restricting its applications to probe various ultrafast dynamic processes. The combination of these two methods takes advantages of optical pump–probe techniques and highly localized tunneling currents of STM, providing one viable solution to track atomic-scale ultrafast dynamics in single molecules and low-dimensional materials. In this review, we will focus on several ultrafast time-resolved STM methods by coupling the tunneling junctions with pulsed electric waves, THz, near-infrared and visible laser. Their applications to probe the carrier dynamics, spin dynamics, and molecular motion will be highlighted. In the end, we will present an outlook on the challenges and new opportunities in this field.
关键词： terahertz technique,femtosecond laser,Scanning tunneling microscopy,pump-probe technique,ultrafast dynamics.
更新于2025-09-19 17:15:36
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Variations of the elastic modulus perpendicular to the surface of rubrene bilayer films
摘要： Investigations exploring the inherent mechanical properties of electronic materials have grown rapidly in recent years largely because they are important in developing flexible electronics, organic displays and sensors. However, our understanding of the mechanical properties of organic semiconductors with a thin-film form remains limited. We report herein on an investigation of the structures and related elastic moduli perpendicular to the surface of a rubrene thin film. A rubrene/Si(100) film typically has a cluster-type morphology mainly comprised of crystalline nanodomains within the film. We propose a structural bilayer model that can be used to explain the layered nature or characteristics of the rubrene films. As the film thickness is increased, the enhancement in elastic modulus can be attributed to the presence of a soft surface layer on a hard underlayer. Based on four-point probe measurements, the bilayered nature of such materials can be used to characterize their electrical resistive behavior while interfacial roughness is sensitive to the transport paths of conduction electrons. This information is valuable for future applications of organic semiconductors in flexible devices.
关键词： four-probe measurement,atomic force microscopy,rubrene,stress
更新于2025-09-19 17:15:36
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Towards Detection of Glycoproteins Using Molecularly Imprinted Nanoparticles and Boronic Acid-Modified Fluorescent Probe
摘要： Glycoproteins represent a group of important biomarkers for cancer and other life-threatening diseases. Selective detection of specific glycoproteins is an important step for early diagnosis. Traditional glycoprotein assays are mostly based on lectins, antibodies, and enzymes, biochemical reagents that are costly and require special cold chain storage and distribution. To address the shortcomings of the existing glycoprotein assays, we propose a new approach using protein-imprinted nanoparticles to replace the traditional lectins and antibodies. Protein-imprinted binding sites were created on the surface of silica nanoparticles by copolymerization of dopamine and aminophenylboronic acid. The imprinted nanoparticles were systematically characterized by dynamic light scattering, scanning and transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and elemental analysis. A boronic acid-modified fluorescent probe was used to detect the target glycoprotein captured by the imprinted nanoparticles. Using horseradish peroxidase as a model glycoprotein, we demonstrated that the proposed method can be applied to detect target protein containing multiple glycosylation sites. Because of their outstanding stability and low cost, imprinted nanoparticles and synthetic probes are attractive replacements of traditional biochemical reagents to develop simpler, faster, and more cost-effective analytical methods for glycoproteins.
关键词： glycoprotein,molecular imprinting,boronic acid,fluorescent probe
更新于2025-09-19 17:15:36
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Gold Nanoparticle-Based Fluorescent Theranostics for Real-Time Image-Guided Assessment of DNA Damage and Repair
摘要： Chemotherapeutic dosing, is largely based on the tolerance levels of toxicity today. Molecular imaging strategies can be leveraged to quantify DNA cytotoxicity and thereby serve as a theranostic tool to improve the efficacy of treatments. Methoxyamine-modified cyanine-7 (Cy7MX) is a molecular probe which binds to apurinic/apyrimidinic (AP)-sites, inhibiting DNA-repair mechanisms implicated by cytotoxic chemotherapies. Herein, we loaded (Cy7MX) onto polyethylene glycol-coated gold nanoparticles (AuNP) to selectively and stably deliver the molecular probe intravenously to tumors. We optimized the properties of Cy7MX-loaded AuNPs using optical spectroscopy and tested the delivery mechanism and binding affinity using the DLD1 colon cancer cell line in vitro. A 10:1 ratio of Cy7MX-AuNPs demonstrated a strong AP site-specific binding and the cumulative release profile demonstrated 97% release within 12 min from a polar to a nonpolar environment. We further demonstrated targeted delivery using imaging and biodistribution studies in vivo in an xenografted mouse model. This work lays a foundation for the development of real-time molecular imaging techniques that are poised to yield quantitative measures of the efficacy and temporal profile of cytotoxic chemotherapies.
关键词： Cy7MX-loaded gold nanoparticles,DNA repair mechanism,AP-targeted delivery,chemotheranostic,molecular probe,real-time imaging
更新于2025-09-19 17:15:36
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A selective and sensitive azido near-infrared fluorescent probe for tris(2-carboxyethyl)phosphine quantitative detection and its application for <i>E. coli</i> determination
摘要： We developed a sensitive near-infrared fluorescent probe, azido hemicyanine (HC-N3), for the detection of tris(2-carboxyethyl)phosphine (TCEP) with the lowest LOD (92 nM) so far. HC-N3 has good selectivity for TCEP among thiols and 20 kinds of natural amino acid. The quantification of E. coli (101–103 cfu mL?1) demonstrated its practicability in complicated biosystems.
关键词： E. coli determination,near-infrared fluorescent probe,selectivity,sensitivity,TCEP detection
更新于2025-09-19 17:15:36