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A fluorescent turn-on probe for Hg2+ with a high contrast designed by manipulating functional groups tethered to naphthalimide
摘要： Based on the concept provided by our previous work on a fluorescent Cd2+ probe, a fluorescent turn-on Hg2+ probe with a high contrast was designed through manipulating functional groups tethered to naphthalimide. With carbamoylmethylamino and bis[2-(ethylthio)ethyl]amino groups as tethering functionalities, 1 worked as a useful fluorescent probe in a high selective and sensitive manner over the pH range between 6 and 8 with a detection limit at 2.8 nM (estimated at a pH of 7.2). Comparison of the probe performance of 1 with that of 2 merely with bis[2-(ethylthio)ethyl]amino group suggested that both of the tethering groups exhibited their abilities to chelate with Hg2+, and yet the carbamoylmethylamino group also functioned as a fluorescent off-on switch through a photo-induced electron transfer mechanism. Thus, 1 found a practical utility as an Hg2+ probe in analysis of river as well as tap samples without any tedious pretreatments.
关键词： Carbamoylmethylamino group,Fluorescent probe,Naphthalimide,Fluorescence,Mercury
更新于2025-09-23 15:21:21
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A new fluorescence probe based on diarylethene with a benzothiazine unit for selective detection of Cd2+
摘要： A novel photochromic diarylethene derivative containing a benzothiazine unit has been synthesized. Its photochromism and fluorescent selectivity to metal ions were studied in detail in methanol solution. Under the stimulation of Cd2+ ions, the derivative showed a significant fluorescence enhancement and obvious red shift, accompanied by the fluorescent color changed from dark purple to bright blue. The 1 : 1 stoichiometry between the derivative and Cd2+ was verified by titration experiments and high resolution mass spectrometry. In addition, a molecular logic circuit was designed with the emission intensity at 476 nm as output and the stimuli of Cd2+/EDTA and UV/vis as inputs.
关键词： Fluorescence probe,Cadmium,Logic circuit,Diarylethene
更新于2025-09-23 15:21:21
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Selective and Sensitive Sensing of Hydrogen Peroxide by a Boronic Acid Functionalized Metal–Organic Framework and Its Application in Live-Cell Imaging
摘要： A new boronic acid functionalized Zr(IV) metal?organic framework having the capability of sensing H2O2 in live cells is reported. The Zr-MOF bears a UiO-66 structure and contains 2-boronobenzene-1,4-dicarboxylic acid (BDC-B(OH)2) as a framework linker. The activated Zr-UiO-66-B(OH)2 compound (called 1′) is highly selective for the ?uorogenic detection of H2O2 in HEPES bu?er at pH 7.4, even in the presence of interfering ROS (ROS = reactive oxygen species) and other biologically relevant analytes. The ?uorescent probe was found to display extraordinary sensitivity for H2O2 (detection limit 0.015 μM) in HEPES bu?er, which represents a lower value in comparison to those of the MOF probes documented so far for sensing H2O2 using other analytical methods. Taking advantage of its high selectivity and sensitivity for H2O2 in HEPES bu?er, the probe was successfully employed for the imaging of intracellular H2O2. Imaging studies with MDAMB-231 cells revealed the emergence of bright blue ?uorescence after loading with probe 1′ and subsequent treatment with H2O2 solution.
关键词： Zr(IV) metal?organic framework,boronic acid,live-cell imaging,fluorescent probe,H2O2 sensing
更新于2025-09-23 15:21:21
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Sensors Based on Metal Nanoclusters Stabilized on Designed Proteins
摘要： Among all new nanomaterials, metal nanoclusters (NCs) have attracted special attention due to their interesting optical properties, among others. Metal NCs have been recently studied and used as sensors for different analytes. However, there is a need to explore the potential of these new sensors in a systematic manner and to develop new systems to broaden the possibilities that sensing offers to the industry. In this work, we show the potential use of repeat protein scaffolds as versatile templates for the synthesis and stabilization of various metal NCs, speci?cally Au, Ag, and CuNCs. The resulting protein-metal NCs hybrids are evaluated as sensors for different stimuli such as temperature, ions, or reactive oxygen species (ROS). Among the three protein-metal NCs, all performed nicely as temperature sensors, AuNCs responded to metal ions, and AgNCs were able to detect ROS.
关键词： nanosensor,ROS sensors,metal nanocluster,protein design,temperature sensor,metal sensors,?uorescent probe
更新于2025-09-23 15:21:21
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Hot electron thermoreflectance coefficient of gold during electron-phonon nonequilibrium
摘要： The temperature-dependent reflectivity of metals is quantified by the thermoreflectance coefficient, which is a material dependent parameter that depends on the metallic band structure, electron scattering dynamics, and photon wavelength. After short-pulse laser heating, the electronic sub-system in a metal can be driven to temperatures much higher than that of the lattice, which gives rise to unique non-equilibrium electron and phonon scattering dynamics, leading to a “hot electron” thermoreflectance that is different from the traditionally measured equilibrium coefficient. In this work, we analytically quantify and experimentally measure this hot electron thermoreflectance coefficient through ultrafast pump-probe measurements of thin gold films on silica glass and sapphire substrates. We demonstrate the ability to not only quantify the thermoreflectance during electron-phonon nonequilibrium, but also validate this coefficient’s predicted dependence on the absolute temperature of the electronic subsystem. The approach outlined in this work provides a metrology to further understand and quantify excited-state scattering effects on the dielectric function of metals.
关键词： electron-phonon scattering,Pump-probe,Thermoreflectance,Drude model,electronic temperature
更新于2025-09-23 15:21:21
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[ACS Symposium Series] Gels and Other Soft Amorphous Solids Volume 1296 || Probe Diffusion Dynamic Light Scattering of Polymer solutions and Gels
摘要： Probe diffusion dynamic light scattering technique is a powerful to investigate the dynamics of polymer chains in polymer solutions and gels. Not only the local dynamics and/or local viscosity but also the gel point and the post-gel dynamics can be investigated. In this chapter, we discuss (1) a conventional probe diffusion of radical polymerization of poly(N-isopropylacrylamide) (PNIPAM) aqueous system, (2) an in-situ isorefractive probe diffusion of tetra-arm poly(ethylene glycol) (Tetra-PEG) undergoing sol-gel transition via cross-end-coupling, and (3) of PNIPAM radical polymerization. It is demonstrated that the gel point is determined as a function of the reaction conversion, which is a more universal measure than the reaction time. The post-gel dynamics explored by the probe particles illuminates the local dynamics in a “pool” of the sol phase surrounded by a gel network. Furthermore, comparison in dynamics is made between well-controlled uniform networks (Tetra-PEG gels) and randomly cross-linked more heterogeneous networks (PNIPAM gels) the probe size from the viewpoints of dependence and scattering angle dependence.
关键词： gel point,Tetra-PEG,post-gel dynamics,Probe diffusion,PNIPAM,gels,polymer solutions,dynamic light scattering
更新于2025-09-23 15:21:21
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Vibrational fingerprint of localized excitons in a two-dimensional metal-organic crystal
摘要： Long-lived excitons formed upon visible light absorption play an essential role in photovoltaics, photocatalysis, and even in high-density information storage. Here, we describe a self-assembled two-dimensional metal-organic crystal, composed of graphene-supported macrocycles, each hosting a single FeN4 center, where a single carbon monoxide molecule can adsorb. In this heme-like biomimetic model system, excitons are generated by visible laser light upon a spin transition associated with the layer 2D crystallinity, and are simultaneously detected via the carbon monoxide ligand stretching mode at room temperature and near-ambient pressure. The proposed mechanism is supported by the results of infrared and time-resolved pump-probe spectroscopies, and by ab initio theoretical methods, opening a path towards the handling of exciton dynamics on 2D biomimetic crystals.
关键词： FeN4 center,spin transition,ab initio theoretical methods,excitons,carbon monoxide,infrared spectroscopy,graphene,time-resolved pump-probe spectroscopy,two-dimensional metal-organic crystal
更新于2025-09-23 15:21:21
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Multi-contact switch using double-dressing regularity of probe, fluorescence, and six-wave mixing in a Rydberg atom
摘要： In this paper, we study the realization of a multi-contact switch using the double-dressing regularity of probe, fluorescence, and six-wave mixing signals in a five-level 85Rb atomic system. For the first time, we compare the dressing regularity of Rydberg states by observing electromagnetically induced transparency and signals. With the scanning probe and dressing fields, both large and small line shifts in signals are observed. The small line shifts are induced by double-dressed line shifts. Also, the big line shifts result from the Rydberg dressing. In addition, with an increase in the principal quantum number n of the Rydberg state, all the signals become weaker, while the line shifts of the signals become enhanced. Using the regularity in line shifts of the signals and an acoustic optical modulator to modulate the frequency detuning, we can realize a multi-contact switch action and fast conversion between different contacts.
关键词： six-wave mixing,fluorescence,double-dressing regularity,Rydberg atom,multi-contact switch,probe
更新于2025-09-23 15:21:21
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Electric field strength-dependent accuracy of TiAlN thin film composition measurements by laser-assisted atom probe tomography
摘要： Accurate quantification of absolute concentrations represents a major challenge for atom probe tomography (APT) since the field evaporation process is affected significantly by the measurement parameters. In the present work we investigate systematically the effect of laser pulse parameters on the accuracy of laser-assisted APT for a TiAlN thin film previously quantified by ion beam analysis, combining Rutherford backscattering spectrometry and time-of-flight elastic recoil detection analysis. The electric field strength is estimated from the Al2+/Al+ charge state ratio for all systematically varied measurement parameters. Subsequently, the absolute concentrations from laser-assisted APT are compared to ion beam analysis data. An increase of the electric field strength from approximately 25–28 V nm?1 improves the accuracy of absolute concentrations measured by laser-assisted APT from 11.4 to 4.1 at% for N, from 8.8 to 3.0 at% for Al and from 2.8 to 0.9 at% for Ti. Our data emphasize that the measurement accuracy of laser-assisted APT for TiAlN is governed by the electric field strength. It is shown that the smallest compositional discrepancies between ion beam analysis and APT are obtained for the maximum electric field strength of approximately 28 V nm?1 at 10 pJ laser pulse energy. This can be rationalized by considering the enhanced ionization of neutral fragments caused by the increased electric field strength.
关键词： accuracy,chemical composition,atom probe tomography,TiAlN,electric field strength
更新于2025-09-23 15:21:01
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Influence of magnetic field orientation on laser-induced magnetization precession in Ni-Mn-Sn Heusler alloy film
摘要： Laser-induced magnetization precession is investigated in Ni-Mn-Sn Heulser alloy film using pump-probe all-optical technique. The studies are performed as a function of external magnetic field H applied at various angles with respect to the sample normal. Strong dependence of precession parameters, frequency f, amplitude A and effective damping, two precession modes, identified as Damon-Eshbach (DE) and first-order standing spin wave (PSSW) modes were observed. The values of wave vector for DE mode have been determined. The experimentally obtained exponentially decayed. The dependencies of the magnetization precession parameters have been well simulated in the frame of phenomenological approach, based on Landau-Lifshitz-Gilbert equation.
关键词： standing spin wave mode,pump-probe all-optical technique,Landau-Lifshitz-Gilbert equation,Ni-Mn-Sn Heusler alloy,Damon-Eshbach mode,Laser-induced magnetization precession
更新于2025-09-23 15:21:01