共查询到20条相似文献，搜索用时 15 毫秒
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Visualizing the 3D chemical profiles of individual aerosols is crucial to understand their formation and aging processes, yet remains technically challenging. Here, the first application of stimulated Raman scattering (SRS) microscopy on 3D chemical imaging of individual aerosols in a nondestructive manner is demonstrated. SRS is capable of mapping chemical components of aerosols at a speed four orders of magnitude faster than conventional spontaneous Raman microscopy. Spatially resolved distributions of nitrates and sulfates reveal the fine structures and different mixing states of atmospheric particles. Moreover, high‐throughput quantifications of chemical compositions and particle size distributions are realized by large‐area imaging and statistical analysis. Its high‐speed and 3D chemical quantification capabilities promise SRS microscopy as a unique tool for studying the properties of single atmospheric particles, and ultimately their impacts on climate and human health. 相似文献
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Pu Wang Owen Liang Wei Zhang Thomas Schroeder Ya‐Hong Xie 《Advanced materials (Deerfield Beach, Fla.)》2013,25(35):4918-4924
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Biswajit Sen 《Journal of Modern Optics》2013,60(11):1697-1711
Coherent light coupled to a third-order nonlinear medium is responsible for spontaneous and for stimulated Raman processes. The analytical solutions up to second order in coupling constants of various field modes for spontaneous Raman and for stimulated Raman processes are utilized to obtain the amplitude-squared and amplitude-cubed squeezing of the input coherent light. The amplitude-squared and amplitude-cubed squeezing are completely ruled out for all modes for spontaneous Raman processes. For stimulated Raman processes, we observe that the squeezing for amplitude-squared and amplitude-cubed are possible for pump and for vibrational phonon modes. It is found that the percentage of higher ordered amplitude squeezing decreases with the increase of the orders. The squeezing in Stokes and in anti-Stokes modes are ruled out even for stimulated Raman processes. 相似文献
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Optical Microresonators: Chip‐Scale Fabrication of High‐Q All‐Glass Toroidal Microresonators for Single‐Particle Label‐Free Imaging (Adv. Mater. 15/2016) 
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下载免费PDF全文 Kassandra A. Knapper Kevin D. Heylman Erik H. Horak Randall H. Goldsmith 《Advanced materials (Deerfield Beach, Fla.)》2016,28(15):2944-2944
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A simple, convenient, and efficient method for highly sensitive Raman detection is made by using a Au nanoparticle (AuNP)-embedded polydimethylsiloxane (PDMS) elastomer, referred to as AuNP-PDMS. When this AuNP-PDMS layer is applied to a surface, it can dramatically enhance the Raman signal of detected molecules. Moreover, it can be used for sensitive chemical imaging on solid substrates. As a proof of concept, patterned chemical images of p-aminothiophenol and methylene blue on a Ag substrate are obtained after this chemically patterned Ag substrate is covered by AuNP-PDMS. 相似文献
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Qi Li Yuanyuan Jiang Rongcheng Han Xiaolan Zhong Siyun Liu Zhi‐Yuan Li Yinlin Sha Dongsheng Xu 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(6):927-932
Molecular imaging techniques based on surface‐enhanced Raman scattering (SERS) face a lack of reproducibility and reliability, thus hampering its practical application. Flower‐like gold nanoparticles have strong SERS enhancement performance due to having plenty of hot‐spots on their surfaces, and this enhancement is not dependent on the aggregation of the particles. These features make this kind of particle an ideal SERS substrate to improve the reproducibility in SERS imaging. Here, the SERS properties of individual flower‐like gold nanoparticles are systematically investigated. The measurements reveal that the enhancement of a single gold nanoparticle is independent of the polarization of the excitation laser with an enhancement factor as high as 108. After capping with Raman signal molecules and folic acid, the gold nanoflowers show strong Raman signal in the living cells, excellent targeting properties, and a high signal‐to‐noise ratio for SERS imaging. 相似文献
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Xuezhi Qiao Zhenjie Xue Lu Liu Keyan Liu Tie Wang 《Advanced materials (Deerfield Beach, Fla.)》2019,31(4)
Although the strength of Raman signals can be increased by many orders of magnitude on noble metal nanoparticles, this enhancement is confined to an extremely short distance from the Raman‐active surface. The key to the development of Raman spectroscopy for applications in diagnosis and detection of cancer and inflammatory diseases, and in pharmacology, relies on the capability of detecting analytes that are noninteractive with Raman‐active surfaces. Here, a new Raman enhancement system is constructed, superficial‐layer‐enhanced Raman scattering (SLERS), by covering elongated tetrahexahedral gold nanoparticle arrays with a superficial perovskite (CH3NH3PbBr3) film. Plasmonic decay is depressed along the vertical direction away from the noble metal surface and the penetration depth is increased in the perovskite media. The vertical penetration of SLERS is verified by the spatial distribution of the analytes via Raman imaging in layer‐scanning mode. 相似文献
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Shiyu Sun Ruimin Wang Yida Huang Jiale Xu Kuan Yao Wanshan Liu Yimei Cao Kun Qian 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(34)
Defined hierarchical materials promise cell analysis and call for application‐driven design in practical use. The further issue is to develop advanced materials and devices for efficient label‐free cell capture with minimum instrumentation. Herein, the design of hierarchical beads is reported for efficient label‐free cell capture. Silica nanoparticles (size of ≈15 nm) are coated onto silica spheres (size of ≈200 nm) to achieve nanoscale surface roughness, and then the rough silica spheres are combined with microbeads (≈150–1000 µm in diameter) to assemble hierarchical structures. These hierarchical beads are built via electrostatic interaction, covalent bonding, and nanoparticle adherence. Further, after functionalization by hyaluronic acid (HA), the hierarchical beads display desirable surface hydrophilicity, biocompatibility, and chemical/structural stability. Due to the controlled surface topology and chemistry, HA‐functionalized hierarchical beads afford high cell capture efficiency up to 98.7% in a facile label‐free manner. This work guides the development of label‐free cell capture techniques and contributes to the construction of smart interfaces in bio‐systems. 相似文献
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Xihui Gao Qi Yue Zining Liu Mengjing Ke Xingyu Zhou Sihan Li Jianping Zhang Ren Zhang Liang Chen Ying Mao Cong Li 《Advanced materials (Deerfield Beach, Fla.)》2017,29(21)
Surgical resection is a mainstay in the treatment of malignant brain tumors. Surgeons, however, face great challenges in distinguishing tumor margins due to their infiltrated nature. Here, a pair of gold nanoprobes that enter a brain tumor by crossing the blood–brain barrier is developed. The acidic tumor environment triggers their assembly with the concomitant activation of both magnetic resonance (MR) and surface‐enhanced resonance Raman spectroscopy (SERRS) signals. While the bulky aggregates continuously trap into the tumor interstitium, the intact nanoprobes in normal brain tissue can be transported back into the blood stream in a timely manner. Experimental results show that physiological acidity triggers nanoparticle assembly by forming 3D spherical nanoclusters with remarkable MR and SERRS signal enhancements. The nanoprobes not only preoperatively define orthotopic glioblastoma xenografts by magnetic resonance imaging (MRI) with high sensitivity and durability in vivo, but also intraoperatively guide tumor excision with the assistance of a handheld Raman scanner. Microscopy studies verify the precisely demarcated tumor margin marked by the assembled nanoprobes. Taking advantage of the nanoprobes' rapid excretion rate and the extracellular acidification as a hallmark of solid tumors, these nanoprobes are promising in improving brain‐tumor surgical outcome with high specificity, safety, and universality. 相似文献
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Sesha L. A. Paluri John D. Ryan Nhi H. Lam Dhriti Nepal Ioana E. Sizemore 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(23)
The clinical applications of silver nanoparticles (AgNPs) remain limited due to the lack of well‐established methodologies for studying their nanokinetics. Hereby, the primary goal is to adapt a suite of analytical‐based methodologies for examining the in vitro absorption, distribution, metabolism, and elimination of AgNPs. Vero 76 and HEK 293 cells are exposed to ≈10‐nm spherical AgNPs+ and AgNPs? at relevant concentrations (0–300 µg mL?1) and times (4–48 h). Absorption: Inductively coupled plasma optical emission spectroscopy (ICP‐OES) demonstrates that the two AgNP formulations are not bioequivalent. For example, different bioavailabilities (C maximum < 20.7 ± 4% and 6.82 ± 0.4%), absorption times (T maximum > 48 and ≈24 h), and absorption rate laws (first‐ and zeroth‐order at 300 µg mL?1) are determined in Vero 76 for AgNPs+ and AgNPs?, respectively. Distribution: Raman and CytoViva hyperspectral imaging show different cellular localizations for AgNPs+ and AgNPs?. Metabolism: Cloud point extraction (CPE)‐tangential flow filtration (TFF) reveal that ≤ 11% ± 4% of the administered, sublethal AgNPs release Ag+ and contribute to the observed cytotoxicity. Elimination: ICP‐OES‐CPE suggests that AgNPs are cleared via exocytosis. 相似文献
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Brett H. Hokr Gary D. Noojin Georgi I. Petrov Hope T. Beier Robert J. Thomas Benjamin A. Rockwell 《Journal of Modern Optics》2014,61(1):53-56
Remote chemically specific detection of trace impurities in the atmosphere from distances on the order of kilometers is an important problem from both an environmental and a national defense viewpoint. A new scheme is discussed consisting of the remote generation of a backward propagating stimulated Raman pulse. This pulse is then used to drive a coherent anti-Stokes Raman scattering scheme, resulting in a strong chemically specific signal propagating back to the detector. 相似文献
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Wi JS Sengupta S Wilson RJ Zhang M Tang M Wang SX 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(23):3276-3280
A two-tiered Ag nanoparticle containing a cavity at the center of each nanoparticle is generated by two simple steps of nano-imprinting and metal vacuum deposition. It enables sub-zeptomole detection of organic molecules and five orders of the dynamic sensing range. 相似文献
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Jiuxing Li Zhi Zhu Fang Liu Bingqing Zhu Yanli Ma Jinmao Yan Bingqian Lin Guoliang Ke Rudi Liu Leiji Zhou Song Tu Chaoyong Yang 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(39):5449-5487
It is demonstrated that DNA can be used to control the synthesis of silver nanoplates with different morphologies using spherical silver seeds. UV–vis spectroscopy, transmission electron microscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, and Raman spectroscopy are used to characterize the synthesized nanoparticles. Silver nanoprisms are encoded by poly C and poly G, while silver flower bouquets and silver nanodiscs are synthesized using poly A and poly T, respectively. The length of DNA is found to have little effect on the morphology of silver nanoparticles. Moreover, the synthesized silver nanoplates are found to have high surface enhanced Raman scattering enhancement ability, good antibacterial activity, and good biocompatibility. These discoveries will broaden the application of DNA in nanoscience and will provide a new platform to investigate the interaction between DNA sequences and silver nanoparticles. 相似文献
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Jianing Chen Pablo Albella Zhaleh Pirzadeh Pablo Alonso‐González Florian Huth Stefano Bonetti Valentina Bonanni Johan Åkerman Josep Nogués Paolo Vavassori Alexandre Dmitriev Javier Aizpurua Rainer Hillenbrand 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(16):2341-2347
The fundamental optical properties of pure nickel nanostructures are studied by far‐field extinction spectroscopy and optical near‐field microscopy, providing direct experimental evidence of the existence of particle plasmon resonances predicted by theory. Experimental and calculated near‐field maps allow for unambiguous identification of dipolar plasmon modes. By comparing calculated near‐field and far‐field spectra, dramatic shifts are found between the near‐field and far‐field plasmon resonances, which are much stronger than in gold nanoantennas. Based on a simple damped harmonic oscillator model to describe plasmonic resonances, it is possible to explain these shifts as due to plasmon damping. 相似文献
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Wei H Håkanson U Yang Z Höök F Xu H 《Small (Weinheim an der Bergstrasse, Germany)》2008,4(9):1296-1300
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Sujin Seo Xiangfei Zhou Gang Logan Liu 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(25):3453-3462
Plasmonic substrates have fixed sensitivity once the geometry of the structure is defined. In order to improve the sensitivity, significant research effort has been focused on designing new plasmonic structures, which involves high fabrication costs; however, a method is reported for improving sensitivity not by redesigning the structure but by simply assembling plasmonic nanoparticles (NPs) near the evanescent field of the underlying 3D plasmonic nanostructure. Here, a nanoscale Lycurgus cup array (nanoLCA) is employed as a base colorimetric plasmonic substrate and an assembly template. Compared to the nanoLCA, the NP assembled nanoLCA (NP‐nanoLCA) exhibits much higher sensitivity for both bulk refractive index sensing and biotin–streptavidin binding detection. The limit of detection of the NP‐nanoLCA is at least ten times smaller when detecting biotin–streptavidin conjugation. The numerical calculations confirm the importance of the additive plasmon coupling between the NPs and the nanoLCA for a denser and stronger electric field in the same 3D volumetric space. Tunable sensitivity is accomplished by controlling the number of NPs in each nanocup, or the number density of the hot spots. This simple yet scalable and cost‐effective method of using additive heterogeneous plasmon coupling effects will benefit various chemical, medical, and environmental plasmon‐based sensors. 相似文献