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The coupled dynamics of colloidal nanoparticle spreading and self-assembly at a fluid-fluid interface
摘要： We investigated the physicochemical and transport phenomena governing the self-assembly of colloidal nanoparticles at the interface of two immiscible fluids. By combining in-situ grazing incidence small-angle X-ray scattering (GISAXS) with a temporal resolution of 200 ms and electron microscopy measurements we gained new insights into the coupled effects of solvent spreading, nanoparticle assembly and recession of the vapor-liquid interface on the morphology of the self-assembled thin films. We focus on oleate-passivated PbSe nanoparticles dispersed across an ethylene glycol subphase as a model system and demonstrate how solvent parameters such as surface tension, nanoparticle solubility, aromaticity and polarity influence the mesoscale morphology of the nanoparticle superlattice. We discovered that a nanoparticle precursor monolayer film spreads in front of the bulk solution and influences the fluid spreading across the subphase. Improved understanding of the impact of kinetic phenomena (i.e., solvent spreading and evaporation) on superlattice morphology is important to describe the formation mechanism and ultimately enable assembly of high-quality superlattices with long range order.
关键词： self-assembly,interfacial phenomena,in-situ GISAXS,nanoparticle superlattice,spreading dynamics
更新于2025-09-23 15:21:01
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Total Internal Reflection-based Extinction Spectroscopy of Single Nanoparticles
摘要： Here we report a reflection-mode total internal reflection microscopy (TIRM) to measure the extinction spectrum of individual dielectric, plasmonic or light-absorbing nanoparticle, and to differentiate absorption and scattering components from the total optical output. These capabilities were enabled via illuminating the sample with evanescent wave of which the lightpath length was comparable with the size of single nanoparticles, leading to a dramatically improved reflectance change (ΔI/I0) up to tens of percent. It was further found that scattering and absorption of light contributed to bright and dark centroids, respectively, in the optical patterns of single nanoparticles, allowing for distinguishing scattering and absorption components from the extinction spectrum by the use of an appropriate image processing method. In addition, wide-field feature of TIRM enabled the studies on tens of nanoparticles simultaneously with gentle illumination. The present work not only provides a promising and complementary tool for understanding the light-matter interactions at single nanoparticle level, but also expands the applicable scope of total internal reflection-based spectroscopy and microscopy.
关键词： total internal reflection,single nanoparticle spectroscopy,extinction spectroscopy
更新于2025-09-23 15:21:01
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Surface-plasmon-coupled chemiluminescence amplification of silver nanoparticles modified immunosensor for high-throughput ultrasensitive detection of multiple mycotoxins
摘要： A novel surface-plasmon-coupled chemiluminescent immunosensor was developed for the detection of multiplex mycotoxins with ultrahigh sensitivity, high throughput and simplicity. The immunosensor was constructed by immobilizing carboxyl modified silver nanoparticles (AgNPs) and bovine serum albumin combined antigens sequentially on the glass chip modified with amino groups. The optical properties of AgNPs could amplify the chemiluminescence (CL) generated on the chip through the surface plasmon resonance phenomenon. Using a competitive immunoassay, the CL signals from all the sensing sites on the chip were collected simultaneously by a charge-coupled device for ultrasensitive analysis of multiple mycotoxins. Citrinin, aflatoxin B1 and ochratoxins A were selected as model analytes. Under optimal conditions, the surface-plasmon-coupled chemiluminescent immunosensor-based method presented wide linear ranges over 4 orders of magnitude and much lower limits of detection than previous work. The assay results of mycotoxins in red yeast rice samples using the proposed method were in good agreement with that using the liquid chromatography-mass spectrometry method. Its high selectivity, high throughput, acceptable stability and accuracy showed broad prospects in mycotoxin monitoring and evaluation of safety on Traditional Chinese Medicine.
关键词： Immunosensor array,Signal amplification,Silver nanoparticle,Multiplex immunoassay,Mycotoxins,Surface-plasmon-coupled chemiluminescence
更新于2025-09-23 15:21:01
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Silicon Nanoparticle Films Infilled with Al <sub/>2</sub> O <sub/>3</sub> using Atomic Layer Deposition for Photosensor, Light Emission and Photovoltaic Applications
摘要： Solution-processed thin films of crystalline silicon nanoparticles (Si NPs) have a great potential for a wide variety of electronic and optoelectronic applications. However, such films are inherently unstable due to their huge surface-to-volume ratios and high surface energies, making them prone to degradation associated to spontaneous oxidation in ambient conditions. In this work, we explore the use of atomic layer deposition (ALD) as a means to stabilize and potentially functionalize solution-processed thin films of Si NPs for (opto)electronics e.g. thin-film transistors, photosensors, light-emitting devices, and photovoltaics. We prepared films of randomly distributed Si NPs with ultrashort surface ligands (Si-H termination) using wet-chemistry and spray-coating and then use ALD to infill the films with Al2O3. Through microscopy and optical structural/morphological analysis, we demonstrate the achievability of ALD infilling of films of Si NPs and probe the stability of these films against oxidation. Moreover, we show that the ALD infilling leads to changes in the light emission properties of the Si NP films, including a relative quenching of disorder-related emission features and variations in surface-related dielectric confinement effects. Our studies reveal ALD as a relevant technique toward manufacturing de facto robust, functional nanomaterials based on Si NPs and on nanoscale silicon materials more generally.
关键词： Photoluminescence properties,Nanoparticle film infilling,Silicon nanocrystal films,Air stability,Atomic layer deposition
更新于2025-09-23 15:21:01
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ZnO Nanosheets Modified with Graphene Quantum Dots and SnO2 Quantum Nanoparticles for Room-Temperature H2S Sensing
摘要： Overcoming the low selectivity issue of semiconductor oxide (SMO)-based gas sensors at room temperature and realizing the accurate detection of trace disease biomarkers are highly desirable for widespread deployments of sensors in exhaled breath. Here, a self-assembly strategy is proposed to create a graphene quantum dot (GQD) functionalized porous and hierarchical SnO2 quantum nanoparticles (SnO2QNP)/ZnO nanostructure. SnO2QNP/ZnO nanosheets self-assembled directly on the digital integrated electrodes with a post-synthetic humidity treatment (psHT), the construction of GQD and SnO2QNP loaded ZnO nanosheet heterostructure is highly controllable and reproducible. The strong synergistic effect and p-n heterojunction between the p-type GQD and n-type SnO2 and ZnO effectively enlarged the resistance variation due to the change in oxygen adsorption. In comparison with pristine ZnO and SnO2/ZnO sensors, the GQD modified hierarchical SnO2QNP/ZnO nanostructure exhibited a remarkably high response (S=15.9 for 0.1 ppm H2S) and rapid response/recovery time (14/13s), and good selectivity towards H2S against other interfering gases. In particular, we applied principal component analysis (PCA) to analyze the sensing performance of GQD-SnO2QNP/ZnO sensor and found that the combined effects of GQD/SnO2QNP/ZnO heterointerfaces contributed to the improvement of selectivity of sensors. The results demonstrate that the GQD modified SMO with the hierarchical structure has a high potential in the non-invasive exhaled diagnosis.
关键词： graphene quantum dot,principal component analysis,exhaled diagnosis,gas sensor,zinc oxide nanosheet,tin dioxide quantum nanoparticle
更新于2025-09-23 15:21:01
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Recent advances of plasmonic nanoparticle-based optical analysis in homogeneous solution and at the single-nanoparticle level
摘要： Plasmonic nanoparticles with special localized surface plasmon resonance (LSPR) characters have been widely applied for optical sensing of various targets. With the combination of single nanoparticle imaging techniques, dynamic information of reactions and biological processes is obtained, facilitating the deep understanding of their principle and design of outstanding nanomaterials. In this review, we summarize the recently adopted optical analysis of diverse analytes based on plasmonic nanoparticles in both homogeneous solution and single-nanoparticle level. A brief introduction of LSPR is first discussed. Colorimetric and fluorimetric homogeneous detection examples by using different sensing mechanisms and strategies are provided. Single plasmonic nanoparticle-based analysis is concluded in two aspects: visualization of chemical reactions and understanding of biological processes. The basic sensing mechanisms and performances of these systems are introduced. Finally, this review highlights the challenges and future trend of plasmonic nanoparticle-based optical analysis system.
关键词： Plasmonic nanoparticles,Single-nanoparticle level,Fluorimetric assays,Chemical reactions,Localized surface plasmon resonance (LSPR),Optical analysis,Homogeneous solution,Colorimetric assays,Biological processes
更新于2025-09-23 15:21:01
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Photoactive ZnO nanosuspension for intensification of organics contaminations decomposition
摘要： In this work the photoactive properties of the aqueous suspension containing ZnO nanoparticles and zinc nitrate have been studied. The mechanism of organics photodecomposition at the presence of prepared suspension was studied by the measurements of spectral dependencies of Chicago Sky Blue dye photodecomposition. It was found that dye photodecomposition proceeds in three different photochemical processes: 1) the direct photodecomposition of organic molecules; 2) oxidation of dye molecules by reactive oxygen species which are the product of nitrate anions photodecomposition; 3) photocatalytic action of ZnO nanoparticles.
关键词： ZnO,Nanoparticle,Photocatalytic properties,Zinc nitrate
更新于2025-09-23 15:21:01
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Mesoporous black TiO2 array employing sputtered Au cocatalyst exhibiting efficient charge separation and high H2 evolution activity
摘要： The separation and transfer of photogenerated carriers are the key issue in the design of high performance TiO2 photocatalysts. In order to overcome the kinetic limitations and achieve rapid charge transfer, TiO2-related multi-component catalysts have been extensively studied. Among all the TiO2 supports, the impressive black TiO2 (BT) with broad visible light absorption spectrum and oxygen vacancies are preferable, but still suffers from low quantum efficiency. Meanwhile, poor control of cocatalyst placement by conventional loading method can also severely impede photocatalytic efficiency. Herein a fast and simple metal magnetron sputter approach was used to place highly-uniformed Au nanoparticles cocatalyst on the top of the mesoporous TiO2-BT nanotube array fabricated by in situ electrochemical anodization approach on a Ti film. This confined plasmonic photocatalyst with highly uniformly distributed Au cocatalysts exhibited greatly enhanced charge-separation and charge-transfer behavior, and a remarkable 10 times enhancement of the photocatalytic H2 evolution reactivity over conventional TiO2 nanotube. The TiO2-BT-Au electron transfer cascade structure is proposed in which black TiO2 acts as a buffer layer for TiO2 conduction band electrons, allowing efficient photogenerated electrons to be transferred to Au nanoparticles and then into the TiO2 pores that suitable for H2 generation. Since the nanotube walls themselves are curved upwards, the short diffusion length allows electrons to be easily transferred to the cocatalyst, where recombination of photogenerated electron pairs is limited. The metal magnetron sputter technique for noble metal cocatalyst immobilization and the unique TiO2-BT-Au electron-transfer system are promising and can be extended to the design of other supported catalysts.
关键词： Metal magnetron sputter,TiO2 nanotube arrays,Oxygen vacancies,Hydrogen evolution,Au nanoparticle,Black TiO2
更新于2025-09-23 15:21:01
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Au nanoparticle preconcentration coupled with CE-electrochemiluminescence detection for sensitive analysis of fluoroquinolones in European eel ( <i>Anguilla anguilla</i> )
摘要： In this work, a novel method based on gold nanoparticle preconcentration coupled with CE for electrochemiluminescent detection of ciprofloxacin, enrofloxacin, ofloxacin, and norfloxacin in European eels was developed. The addition of gold nanoparticles induced the rapid enrichment of fluoroquinolones, which was simpler than the conventional enrichment approaches such as solid phase extraction and solid-phase microextraction. More than 100 times enrichment was observed after gold nanoparticle aggregation-based preconcentration. The CE-electrochemiluminescent parameters that affected the separation and detection were optimized. Under the optimized conditions, the linear ranges for the four fluoroquinolones were 0.090—8.0 μmol/L with the detection limits between 0.020 to 0.050 μmol/L. The proposed approach showed the advantages of high sensitivity, high selectivity, wide linear range, and low detection limit. It was used to analyze fluoroquinolones in European eel, and the results showed that the developed method can satisfy the detection requirements for fluoroquinolones determination in aquatic products set by China and European Union.
关键词： Capillary electrophoresis,fluoroquinolones,preconcentration,European eel,gold nanoparticle
更新于2025-09-23 15:21:01
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Optical Trapping of Nanoparticles Using All-Silicon Nanoantennas
摘要： The ability to optically trap nanoscale particles in a reliable and noninvasive manner is emerging as an important capability for nanoscience. Different techniques have been introduced, including plasmonic nanostructures. Nano-optical tweezers based on plasmonics face the problem of Joule heating however due to high losses in metals. Here we experimentally demonstrate the optical trapping and transport of nanoparticles using a non-plasmonic approach, namely a silicon nanoantenna. We trap polystyrene nanoparticles with diameters of 20 and 100 nm, and use fluorescence microscopy to track their positions as a function of time. We show that multiple nanoparticles can be trapped simultaneously with a single nanoantenna. We show that the infrared trapping laser beam also produces fluorescent emission from trapped nanoparticles via two-photon excitation. We present simulations of the nanoantenna that predict enhanced optical forces with insignificant heat generation. Our work demonstrates that silicon nanoantennas enable nanoparticles to be optically trapped without deleterious thermal heating effects.
关键词： Optical trapping,silicon nanoantenna,thermal effect,optical force,nanoparticle
更新于2025-09-23 15:21:01