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Jianyu Wei, Jinfan Chen, Guozong Yue, Liangsheng Hu, Danqing Zhao, Jing Zhu, Luming Yang, Deshun Huang, Pengxiang Zhao
A novel tridentate ligand nitrilotris(methylene)tris(1,2,3-triazole)triacetate (NTTTA) has been synthesized by click reaction and followed with ester hydrolysis reaction. The silver nanoparticles (AgNPs) were then modified and stabilized by this ligand, and subsequently been employed for the highly selective and sensitive colorimetric detection of Mn2+ in aqueous solution. The presence of Mn2+ can cause the aggregation of AgNPs, which leads to the color change of the dispersion from yellow to brown, as well as the decrease and red-shift of the surface plasmon resonance absorption...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Elizabeth Peterson, Christine Joseph, Hannah Peterson, Rachael Bouwman, Shengzhuang Tang, Jayme Cannon, Kumar Sinniah, Seok Ki Choi
Multivalent ligand-receptor interaction provides the fundamental basis for the hypothetical notion that high binding avidity relates to the strong force of adhesion. Despite its increasing importance in the design of targeted nanoconjugates, an understanding of the physical forces underlying the multivalent interaction remains a subject of urgent investigation. In this study, we designed three vancomycin (Van)-conjugated dendrimers G5(Van)n (n = mean valency = 0, 1, 4) for bacterial targeting with generation 5 (G5) poly(amidoamine) dendrimer as a multivalent scaffold, and evaluated both their binding avidity and physical force of adhesion to a bacterial model surface by employing surface plasmon resonance (SPR) spectroscopy and atomic force microscopy (AFM)...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Aleksander Skuratovsky, Robert J Soto, Marc D Porter
This paper presents a method for immunometric biomarker quantitation that uses standard flow-through assay reagents and obviates the need for constructing a calibration curve. The approach relies on a nitrocellulose immunoassay substrate with multiple physical addresses for analyte capture, each modified with different amounts of an analyte-specific capture antibody. As such, each address generates a distinctly different readout signal that is proportional to the analyte concentration in the sample. To establish the feasibility of this concept, equations derived from antibody-antigen binding equilibrium were first applied in modeling experiments...
May 24, 2018: Analytical Chemistry
Ashish Bhattarai, Andrey Krayev, Alexey Temiryazev, Dmitry Evplov, Kevin Thomas Crampton, Wayne P Hess, Patrick Z El Khoury
Tip-enhanced Raman spectroscopy (TERS) is particularly sensitive to analytes residing at plasmonic tip-sample nanojunctions, where the incident and scattered optical fields may be localized and optimally enhanced. However, the enhanced local electric fields in this so-called gap-mode TERS configuration are nominally orthogonal to the sample plane. As such, any given Raman active vibrational Eigenstate needs to have projections (of its polarizability derivative tensor elements) along the sample normal to be detectable via TERS...
May 23, 2018: Nano Letters
Ji Xu, Nannan Shi, Yilin Chen, Xinyi Lu, Hongyu Wei, Yunqing Lu, Ning Liu, Baifu Zhang, Jin Wang
This study reports on a cylindrical hybrid plasmonic waveguide (CHPW) consisting of a high-index dielectric core, a sandwiched low-index dielectric layer, and a metal cladding. The CHPW supports the TM01 mode with a radially polarized transverse component of the electric field. Optical fields can be significantly enhanced in the sandwiched low-index dielectric region with nanoscale thickness down to 5 nm, and tight mode confinement with the same order of the normalized mode area compared with that of the plasmonic waveguide is achieved...
May 20, 2018: Applied Optics
Bin Ni, Jinbiao Xiao
A compact TE-pass polarizer for silicon-based slot waveguides is numerically proposed based on a directional coupler where an asymmetrical slot waveguide (ASW) and hybrid plasmonic waveguide (HPW) are involved. The input section is linearly tapered to an ASW to markedly enlarge the modal birefringence. Beneficially, only the TM mode can be coupled into the adjacent HPW and attenuated while the injected TE mode just passes through the slot waveguide without coupling by properly choosing the dimensions. As a consequence, an efficient TE-pass polarizer can be implemented...
May 20, 2018: Applied Optics
JunJun Wu, Shuguang Li, Xinyu Wang, Min Shi, Xinxing Feng, Yundong Liu
We propose a D-shaped photonic crystal fiber (PCF) refractive index sensor with ultrahigh sensitivity and a wide detection range. The gold layer is deposited on the polished surface, avoiding filling or coating inside the air holes of the PCF. The influences of the gold layer thickness and the diameter of the larger air holes are investigated. The sensing characteristics of the proposed sensor are analyzed by the finite element method. The maximum sensitivity can reach 31,000  nm/RIU, and the refractive index detection range is from 1...
May 20, 2018: Applied Optics
Yuncai Feng, Youwen Liu, Jinghua Teng
We propose, to the best of our knowledge, a new configuration of a biosensor based on the graphene-MoS2 hybrid structure by adopting the lower refractive index MgF2 prism in order to improve the sensitivity and the figure of merit (FOM). We can obtain an ultrasensitive sensor with values of sensitivity and FOM as high as 540.8°/RIU and 145/RIU, respectively, by modulating the parameters in the configuration and comparatively choosing a different absentee layer material. The proposed structure is applicable in the realization of an integrated device for the surface plasmon resonance biosensor...
May 10, 2018: Applied Optics
Zhao-Yu Ma, Kai Han, Xinxin Dai, Heyou Han
Ignored damage in adjacent normal tissue is fatal especially in some specific tumor therapy such as brain tumor, but it remains a great challenge to conquer it due to random drug diffusion and tumor complexity. Herein, we show the hyperthermia in mitochondria, an interparticle plasmonic coupling effect activated nanoevent, selectively strikes tumor tissue without damaging adjacent normal tissue. Spherical gold nanoparticles with a mitochondria-targeting moiety, triphenyl phosphonium, preferentially accumulated inside tumor mitochondria and reached the threshold to activate interparticle plasmonic coupling effect among gold nanoparticles, realizing selective light-thermal conversion and mitochondrial dysfunction in tumor, whereas little hyperthermia and mitochondrial dysfunction were observed in adjacent normal tissue...
May 23, 2018: ACS Nano
Jingyi Luan, Ting Xu, John Cashin, Jeremiah J Morrissey, Evan D Kharasch, Srikanth Singamaneni
Plasmonic biosensors based on the refractive index sensitivity of localized surface plasmon resonance (LSPR) are considered to be highly promising for on-chip and point-of-care biodiagnostics. However, most of the current plasmonic biosensors employ natural antibodies as biorecognition elements, which are easy to lose their biorecognition ability upon exposure to environmental stressors (e.g., temperature and humidity). Plasmonic biosensors relying on molecular imprints as recognition elements (artificial antibodies) are hypothesized to be an attractive alternative for applications in resource-limited settings due to their excellent thermal, chemical, and environmental stability...
May 23, 2018: Analytical Chemistry
Nestor Gisbert Quilis, Médéric Lequeux, Priyamvada Venugopalan, Imran Khan, Wolfgang Knoll, Souhir Boujday, Marc Lamy de la Chapelle, Jakub Dostalek
The facile preparation of arrays of plasmonic nanoparticles over a square centimeter surface area is reported. The developed method relies on tailored laser interference lithography (LIL) that is combined with dry etching and it offers means for the rapid fabrication of periodic arrays of metallic nanostructures with well controlled morphology. Adjusting the parameters of the LIL process allows for the preparation of arrays of nanoparticles with a diameter below hundred nanometers independently of their lattice spacing...
May 23, 2018: Nanoscale
Justin C W Song
No abstract text is available yet for this article.
May 2018: Nature
Tingting Feng, Peng Liu, Xiao Wang, Jinque Luo, Xuan Zuo, Xinhai Jiang, Chang Liu, Yongzhen Li, Ni Li, Minghua Chen, Ningyu Zhu, Xiaowan Han, Chao Liu, Yanni Xu, Shuyi Si
BACKGROUND AND AIMS: Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent protein deacetylase. Recent studies have demonstrated that enhancing SIRT1 expression or activity may modulate cholesterol and lipid metabolism. However, pharmacological and molecular regulators for SIRT1 are scarce. Here, we aimed to find novel small molecule modulators of SIRT1 to regulate cholesterol and lipid metabolism. METHODS: A high-throughput screening assay was established to identify SIRT1 activators...
April 30, 2018: Atherosclerosis
Mihee Kim, Milan Vala, Christopher Ertsgaard, Sang-Hyun Oh, Timothy P Lodge, Frank S Bates, Benjamin J Hackel
Poloxamer 188 (P188), a poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymer, protects cell membranes against various external stresses whereas polyethylene oxide (PEO; 8,600 g/mol) homopolymer lacks protection efficacy. As part of a comprehensive effort to elucidate the protection mechanism, we used surface plasmon resonance (SPR) to obtain direct evidence of binding of the polymers onto supported lipid bilayers. Binding kinetics and coverage of the P188 and PEO were examined and compared...
May 22, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Jaber Keyvan Rad, Ali Reza Mahdavian, Samideh Khoei, Sakine Shirvalilou
Tumor-selective photodynamic therapy is a successful method for ablation of malignant and cancerous cells. Herein, we introduce the design and preparation of functionalized acrylic copolymer nanoparticles with spiropyran (SP) and imidazole groups through a facile semi-continuous emulsion polymerization. Then, Au3+ ions were immobilized and reduced on their surface to obtain photoresponsive gold-decorated polymer nanoparticles (PGPNPs). The prepared PGPNPs were surface-modified with folic acid as a site-specific tumor cell targeting agent and improve intracellular uptake via endocytosis...
May 22, 2018: ACS Applied Materials & Interfaces
Hao Huang, Huiyi Li, Huaiyu Wang, Jia Li, Penghui Li, Qidan Chen, Yue Chen, Paul K Chu, Bo Li, Xuefeng Yu
We report a modified synthesis route of colloidal gold nanorods (AuNRs) by combining the thermal re-shaping treatment and bi-surfactant modification using hexadecyltrimethylammonium bromide (CTAB) and sodium oleate (NaOL). Aspect ratios down to 1.3 ± 0.1 can be achieved in addition to good monodispersity, uniformity, and chemical stability of the materials. Furthermore, without needing post-treatment, metal ions directly interact with the AuNRs efficiently, allowing rapid and sensitive colorimetric detection of heavy metal ions such as Pb<sup>2+</sup> and Cu<sup>2+</sup> with a low concentration down to 2...
May 22, 2018: Nanotechnology
Min-Zhuo Cheng, Jing Zhang, Dequan Bao, Xiwei Huang
In this communication, we assembled ordered polystyrene (PS) microsphere array as a template with the drop-coating method, and the oxygen plasma was used to etch the template to adjust the spacing between the PS microspheres. Nano-triangular gold array and silver Nano-pyramid array were obtained by ion beam sputtering to deposit precious metal gold and silver. We observed the surface morphology of Au and Au/Ag composite films by scanning electron microscope and characterized the films by X-ray diffraction and Ultraviolet/visible light spectrophotometer...
May 21, 2018: Electrophoresis
Zhi-Qian Wu, Jing-Liang Yang, Nallappagar K Manjunath, Yue-Jiao Zhang, Si-Rui Feng, Yang-Hua Lu, Jiang-Hong Wu, Wei-Wei Zhao, Cai-Yu Qiu, Jian-Feng Li, Shi-Sheng Lin
2D materials hold great potential for designing novel electronic and optoelectronic devices. However, 2D material can only absorb limited incident light. As a representative 2D semiconductor, monolayer MoS2 can only absorb up to 10% of the incident light in the visible, which is not sufficient to achieve a high optical-to-electrical conversion efficiency. To overcome this shortcoming, a "gap-mode" plasmon-enhanced monolayer MoS2 fluorescent emitter and photodetector is designed by squeezing the light-field into Ag shell-isolated nanoparticles-Au film gap, where the confined electromagnetic field can interact with monolayer MoS2 ...
May 22, 2018: Advanced Materials
Mahi R Singh
In this chapter, we explain why metallic nanomaterials are used in nanomedicine. We have shown that the electron density in metallic nanomaterials oscillates and creates electron density waves. When laser light falls on metallic nanoparticles, light interacts with electron density waves. According to Einstein, light, which is electromagnetic waves, consists of particles called photons. Similarly, electron density waves are also made of particles called surface plasmons. Therefore, photons from laser light and surface plasmons from metallic nanostructures interact with each other and create new particles called surface plasmon polaritons...
2018: Advances in Experimental Medicine and Biology
Linhan Lin, Mingsong Wang, Xiaolei Peng, Emanuel N Lissek, Zhangming Mao, Leonardo Scarabelli, Emily Adkins, Sahin Coskun, Husnu Emrah Unalan, Brian A Korgel, Luis M Liz-Marzán, Ernst-Ludwig Florin, Yuebing Zheng
Optical manipulation of plasmonic nanoparticles provides opportunities for fundamental and technical innovation in nanophotonics. Optical heating arising from the photon-to-phonon conversion is considered as an intrinsic loss in metal nanoparticles, which limits their applications. We show here that this drawback can be turned into an advantage, by developing an extremely low-power optical tweezing technique, termed opto-thermoelectric nanotweezers (OTENT). Through optically heating a thermoplasmonic substrate, alight-directed thermoelectric field can be generated due to spatial separation of dissolved ions within the heating laser spot, which allows us to manipulate metal nanoparticles of a wide range of materials, sizes and shapes with single-particle resolution...
April 2018: Nature Photonics
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