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Control of 1-dimensionally structured tungsten oxide thin films by precursor feed rate modulation in flame vapor deposition
摘要： With the constant tungsten wire feed rate of 4 μm/s, the diameter of nanostructures increases with time and the multi-shell nanostructure and/or branched nanostructure eventually appears and grows. As the diameter and length of 1-D nanostructures increase with time, 1-D nanostructures are easily converted into multi-shell and/or branched nanostructures. The tungsten oxide vapor concentration and flame temperature also affect significantly this conversion of 1-D nanostructures. The increase of tungsten wire feed rate with time accelerated the appearance and growth of multi-shell and/or branched nanostructure, while the decrease of tungsten wire feed rate with time could help prepare the 1-D nanostructured WOX thin film without the growth of multi-shell and/or branched nanostructure. By the modulation of tungsten wire feed rate with time, the thin film thicker than 5μm with single shell nanotube structure could be prepared with almost no increase of nanotube diameter. For the preparation of longer 1-D nanostructured WOX thin film, it is found that the smooth decrease of wire feed rate with time, not the abrupt decrease of feed rate, is required in FVD process to prevent the multi-shell structure growth. We demonstrated that various attractive nanostructures can be prepared quickly by just changing precursor feed rate in FVD process for the first time. The results of this study can provide the basis for many practical applications of FVD process to fast fabrication of several interesting nanostructures.
关键词： nanostructure control,tungsten oxide thin film,precursor feed rate,preparation of 1-D nanostructure,flame vapor deposition
更新于2025-09-23 15:22:29
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Growth of Spherical Gold Satellites on the Surface of Au@Ag@SiO <sub/>2</sub> Core–Shell Nanostructures Used for an Ultrasensitive SERS Immunoassay of Alpha-Fetoprotein
摘要： The identification and detection of cancer biomarkers in early stages is an important issue for the therapy of cancer. However, most methods are time-consuming, limited sensing sensitivity and specificity. In this work, we prepared a novel plasmonic multilayered core–shell-satellite nanostructure (Au@Ag@SiO2-AuNP) consisting of an gold nanosphere with silver coating core (Au@Ag), an ultrathin continuous silica (SiO2) shell and high coverage of gold nanospheres (AuNPs) satellites. Au@Ag core is prominent surface enhanced Raman scattering (SERS) platform and the thin SiO2 layer exhibits a long-range plasmon coupling between Au@Ag core to AuNPs satellites further leading to enhanced Raman scattering. Meanwhile, the outer AuNPs satellites have a high biocompatibility and long-term stability. Combining the above advantages, the well-designed metallic nanoassemblies would be a promising candidate for SERS-based applications in biochemistry. For specific detection of alpha-fetoprotein (AFP), we utilized the SERS-active core-shell-satellite nanostructures modified with AFP antibody as immune probes and nitrocellulose membrane (NC) stabilized captured anti-AFP antibodies as solid substrate. To improve the detection performance, we further systematically optimized the parameters, including silver coating thickness of Au@Ag core, the density and size of satellite AuNPs. Under the optimized conditions, AFP could be detected by the SERS-based sandwich immunoassay with an ultralow detection limit of 0.3 fg/mL, and the method exhibited a wide linear response from 1 fg/mL to 1 ng/mL. The limit of detection (LOD) was considerably lower than conventional methods in literature. This work relies on the unique Au@Ag@SiO2-AuNP nanostructures as immune probe develops a new outlook for the application of multilayered nanoassemblies and demonstrates the great potential in early tumor markers detection.
关键词： surface enhanced Raman scattering (SERS),Au-Ag bimetallic nanospheres,alpha-fetoprotein,core-shell-satellite nanostructure,gold nanospheres
更新于2025-09-23 15:22:29
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Refractive Index Sensor Based on a Gradient Grating Period Guided-Mode Resonance
摘要： In this study, we introduce a novel refractive index sensor based on gradient grating period guided-mode resonance (GGP-GMR). Rather than a constant grating period, as in typical GMR, GGP-GMR comprises a grating period varying in increments of 2 nm. For grating variation from 386 to 392 nm, a detection range of 0.109 RIU with a bulk sensitivity of 1433.7 μm/RIU and theoretical and experimental detection limits of 5.58 × 10?3 and 10?2 RIU, respectively, can be achieved. Several tactics that can be readily adopted are suggested to improve the limit of detection by an order to 10?4 RIU, sufficient for detecting many clinically relevant biomarkers. The readout system requires a narrow band of light and a simple charge-coupled device combined with the compact design of the GGP-GMR sensor, which eases the miniaturization of the system for handheld devices as well as its integration with smartphones.
关键词： Bandstop filter,guided-mode resonance,subwavelength nanostructure.
更新于2025-09-23 15:22:29
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Nano-structural investigations of porous silica coated carbonaceous spheres and dielectric properties of its organosilicone hybrid film
摘要： In this research, a series of carbonaceous spheres samples were synthesized by hydrothermal carbonization of glucose and cyclodextrin, and coated with mesoporous silica. The unique nano-structure of such carbonaceous spheres samples was fully characterized by DLS, XRD, SEM, TEM, Raman spectroscopy and infrared spectroscopy techniques. Such carbonaceous spheres samples were then blended with organosilicone in order to prepare a series of hybrid films. The influence of the added silica coated carbonaceous spheres on the dielectric property of these hybrid film samples was thoroughly investigated. The results indicate that the silica coated carbonaceous spheres are amorphous and have a typical core-shell structure. Such nano-structure and aggregation behavior in the organosilicone matrix can introduce more interfaces into the hybrid organosilicone film samples, and have notably affected the dielectric property of the hybrid organosilicon film samples. The dielectric constant and dielectric loss of the hybrid film samples could be kept relatively low if the introduced interfaces were blurred enough to avoid the interfacial polarity.
关键词： Carbonaceous spheres,Films,Nanostructure,Dielectric properties,Silicones
更新于2025-09-23 15:22:29
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Scanning Surface Plasmon Microscope for Sensing Lipid Array and Au Film Defect
摘要： We demonstrated a scanning radially-polarized surface plasmon microscopy (SSPM) with submicron lateral resolution and high refractive index sensitivity. According to the captured images, SSPM could be used to verify the quality of deposited Au film and Au structure on surface plasmon sensing chip. The defect on the SPR chip, which disturbed the plasmonic wave around the focal point, could be easily detected by our system. Moreover, the application of SSPM in imaging lipid array was showed in this article. The 1, 2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) array was made by dip-pen nanolithography. The results indicated that SSPM system could be used in comparing the thickness of DOPC array. Because of the high sensitivity and high spatial resolution of the system, we expected the SSPM to be used in measuring the properties of nanogold array structures and apply to digital-array biosensors in nanoscale.
关键词： 1,2-Dioleoyl-sn-glycero-3-phosphocholine,Scanning surface plasmon microscope,lipid array,nanostructure
更新于2025-09-23 15:22:29
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Biomimetic fog harvesting surface by photo-induced micro-patterning of zinc-oxide silver hierarchical nanostructures
摘要： As water scarcity has become a major global problem, fog-harvesting technologies are considered an effective sustainable solution for water resources. Here, we report a novel approach to the fog-harvesting technology using zinc oxide-silver hierarchical nanostructures to mimic the Stenocara beetle’s back. Vertically aligned zinc oxide nanowires are first fabricated by a cost-effective and scalable hydrothermal method to produce a super-hydrophilic surface. Silver nanoparticles are then selectively synthesized by an additional photo-induced synthetic process on the zinc oxide nanowire surfaces to form a hydrophobic surface using the hierarchical nanostructures. The fog-harvesting performance was investigated using an artificial fog flow and by measuring the amount of harvested water for efficient fog harvesting. On the superhydrophilic surface, although the water droplets immediately were captured, they formed a puddle at the bottom of the surface due to the high adhesion between water and the surface. In contrast, on the hydrophobic surface, the capturing rate was very low even though the water droplets easily rolled off the surface. Compared to the non-patterned surface, the captured water film on the patterned hydrophilic region grew rapidly into a spherical shape and separated from the surface due to the surrounding hydrophobic regions. As a result, the patterned surface with 0.5 mm pattern size afforded a higher fog collection rate of 1233 mg/h than those of the superhydrophilic and hydrophobic surfaces of 1105 mg/h and 879 mg/h respectively.
关键词： Fog harvesting,Biomimetics,Hierarchical nanostructure,Surface wettability
更新于2025-09-23 15:22:29
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Reduced Graphene Oxide Functionalized with Gold Nanostar Nanocomposites for Synergistically Killing Bacteria through Intrinsic Antimicrobial Activity and Photothermal Ablation
摘要： The exploration of multifunctional photothermal agent is important for antibacterial photothermal lysis, which has emerged as an effective approach to address the problem of pathogenic bacteria infection irrespective of the drug resistant effect. In the present work, a 2D reduced graphene oxide supported Au nanostar nanocomposite (rGO/AuNS) was prepared by the seed mediated growth method for synergistically killing multidrug resistant bacteria. Owing to the prickly and sharp-edge nanostructure, the rGO/AuNS displayed superior antibacterial activity probably due to the damaging of the cell walls or membranes. The cell viability of MRSA was as low as 32% when the MRSA were incubated with rGO/AuNS for 180 min in the absence of light. The 2D structure of the rGO/AuNS facilitated the strong binding affinity towards bacteria. Upon the 808 nm NIR laser irradiation, significant enhancement in bactericidal efficiency (complete death) was obtained due to the localized hyperthermal effect of rGO/AuNS. Moreover, the RGO/AuNS displayed promising biocompatibility. It indicates that the rGO/AuNS can be an alternative and effective dual functional photothermal agent for synergistically killing the multidrug resistant bacteria.
关键词： Reduced Graphene Oxide,Multidrug-resistant bacteria,Antibacterial photothermal lysis,Gold nanostars,Prickly nanostructure
更新于2025-09-23 15:22:29
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Preparation of a Photoactive 3D Polymer Pillared with Metalloporphyrin
摘要： Among the very few efforts for the preparation of stable pillared graphene nanostructures, there is no report of tin porphyrin intercalated between TiO2-graphene (TG) nanosheets. In this study, a nanostructure material of pillared graphene made of tin porphyrin functionalized graphene-TiO2 composite (TG) was successfully synthesized. The prepared compound showed high activity in the photodegradation reaction under irradiation of visible light. Photocatalytic results showed that the composite of graphene-TiO2 containing 3% graphene had the highest photoactivity. The photoactivity of TG (3%) was about 1.5 times higher than that of the pure TiO2. Besides, tin porphyrin-pillared TG composite (TGSP) material exhibited an excellent visible light photocatalytic performance in degradation of methyl orange dye. This compound could destruct 100% of methyl orange dye in 180 min. Such pillared carbon nanostructure exhibited unique photoactivity due to the synergistic effect between the graphene sheets and the SnTCPP pillars. It is found that the highly efficient light-harvesting structure of the SnTCPP pillared TG composite can be attributed to densely embedded porphyrin chromophores with high visible absorptivity within the framework. The investigation of photocatalytic mechanism determined that hydroxyl radical is a main species in photodegradation process of methyl orange over TGSP compound.
关键词： Semiconductors,Nanostructure,Material,Photocatalytic
更新于2025-09-23 15:22:29
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Upconversion of low-energy photons in semiconductor nanostructures for solar energy harvesting
摘要： We explore the status of state-of-the-art upconverter materials in the context of improving solar cell performance. We focus on semiconductor upconversion nanostructures that can harvest two separate bands of the solar spectrum and offer a promising path to rational engineering of improved performance and thus improved overall solar energy harvesting. Photon upconversion is a process in which two low-energy photons are sequentially absorbed and one high-energy photon is emitted. Photon upconversion in both inorganic and organic material platforms has been used to improve solar cell efficiency. Lanthanide-doped salts (inorganic) and triplet–triplet annihilation molecules (organic) have achieved 33% and 60% internal upconversion quantum efficiency, respectively, leading to current density increases of 17 mA/cm2 and 0.86 mA/cm2. However, their performance is limited by their narrow absorption bandwidth (AB) and limited tunability, especially at low photon fluxes. Recently, colloidal semiconductor nanostructures have emerged as a promising material platform for upconversion. The optical absorption in these low-dimensional heterostructures involves both quantum-confined and continuum band states, enabling a much larger AB. Moreover, the techniques of semiconductor heterostructure engineering can be used to optimize performance and to tailor absorption and emission wavelengths. We review the performance and potential impact on solar energy harvesting of upconversion materials, focusing on semiconductor upconverters. We discuss computational models that suggest that semiconductor upconverter nanostructures could have outstanding performance for photovoltaic. We then discuss the current state of the art in semiconductor upconversion morphologies and compositions and provide an outlook on the ways in which nanostructures can be tailored to improve performance for applications.
关键词： nanostructure,photovoltaic,semiconducting
更新于2025-09-23 15:22:29
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Structure and electrochromism of two-dimensional octahedral molecular sieve h’-WO3
摘要： Octahedral molecular sieves (OMS) are built of transition metal-oxygen octahedra that delimit sub-nanoscale cavities. Compared to other microporous solids, OMS exhibit larger versatility in properties, provided by various redox states and magnetic behaviors of transition metals. Hence, OMS offer opportunities in electrochemical energy harnessing devices, including batteries, electrochemical capacitors and electrochromic systems, provided two conditions are met: fast exchange of ions in the micropores and stability upon exchange. Here we unveil a novel OMS hexagonal polymorph of tungsten oxide called h’-WO3, built of (WO6)6 tunnel cavities. h’-WO3 is prepared by a one-step soft chemistry aqueous route leading to the hydrogen bronze h’-H0.07WO3. Gentle heating results in h’-WO3 with framework retention. The material exhibits an unusual combination of 1-dimensional crystal structure and 2-dimensional nanostructure that enhances and fastens proton (de)insertion for stable electrochromic devices. This discovery paves the way to a new family of mixed valence functional materials with tunable behaviors.
关键词： Tungsten oxide,Electrochromism,Octahedral molecular sieves,Proton insertion,Nanostructure
更新于2025-09-23 15:22:29