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Find video protocols related to scientific articles indexed in Pubmed.
Fluorescence lifetime based characterization of active and tunable plasmonic nanostructures.
Opt Express
PUBLISHED: 10-17-2014
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We report a non-contact method that utilizes fluorescence lifetime (FL) to characterize morphological changes of a tunable plasmonic nanostructure with nanoscale accuracy. The key component of the plasmonic nanostructure is pH-responsive polyelectrolyte multilayers (PEMs), which serve as a dynamically tunable "spacer" layer that separates the plasmonic structure and the fluorescent materials. The validity of our method is confirmed through direct comparison with ellipsometry and atomic force microscopy (AFM) measurements. Applying the FL-based approach, we find that a monolayer polycation film responds to pH changes with significantly less hysteresis than a thicker multilayer film with polyelectrolytes of both charges. Additionally, we characterize an active and tunable plasmonic nanostructure composed of self-assembled fluorescent dye (Texas Red), pH-sensitive PEMs, and gold nanospheres adsorbed on the PEM surface. Our results point towards the possibility of using stimulus-sensitive polymers to construct active and tunable plasmonic nanodevices.
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Impact of lithography on the fluorescence dynamics of self-assembled fluorophores.
Opt Express
PUBLISHED: 06-13-2014
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Micro- and nano-patterned fluorescent materials are important for many photonic devices and applications. In this paper, we investigate the impact of three common lithographical techniques, deposition and removal of sacrificial masks, ultraviolet ablation, and focused ion beam milling, on self-assembled fluorophores. We find that different patterning techniques can dramatically change the fluorescence lifetime of the fluorophores and that the degree of modification depends on the patterning techniques.
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A comparative study of nano-scale coatings on gold electrodes for bioimpedance studies of breast cancer cells.
Biomed Microdevices
PUBLISHED: 05-29-2014
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The relative sensitivity of standard gold microelectrodes for electric cell-substrate impedance sensing was compared with that of gold microelectrodes coated with gold nanoparticles, carbon nanotubes, or electroplated gold to introduce nano-scale roughness on the surface of the electrodes. For biological solutions, the electroplated gold coated electrodes had significantly higher sensitivity to changes in conductivity than electrodes with other coatings. In contrast, the carbon nanotube coated electrodes displayed the highest sensitivity to MDA-MB-231 metastatic breast cancer cells. There was also a significant shift in the peak frequency of the cancer cell bioimpedance signal based on the type of electrode coating. The results indicate that nano-scale coatings which introduce varying degrees of surface roughness can be used to modulate the frequency dependent sensitivity of the electrodes and optimize electrode sensitivity for different bioimpedance sensing applications.
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High quality factor silica microspheres functionalized with self-assembled nanomaterials.
Opt Express
PUBLISHED: 10-10-2013
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With extremely low material absorption and exceptional surface smoothness, silica-based optical resonators can achieve extremely high cavity quality (Q) factors. However, the intrinsic material limitations of silica (e.g., lack of second order nonlinearity) may limit the potential applications of silica-based high Q resonators. Here we report some results in utilizing layer-by-layer self-assembly to functionalize silica microspheres with nonlinear and plasmonic nanomaterials while maintaining Q factors as high as 10(7). We compare experimentally measured Q factors with theoretical estimates, and find good agreement.
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Improved performance of micro-fabricated preconcentrators using silica nanoparticles as a surface template.
J Chromatogr A
PUBLISHED: 08-28-2013
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A new approach of enhancing the adsorption capability of the widely used polymer adsorbent Tenax TA poly(2,6-diphenylene oxide) through its deposition on a nano-structured template is reported. The modified Tenax TA-coated silica nanoparticles (SNP) are incorporated as an adsorbent bed in silicon based micro-thermal preconcentrator (?TPC) chips with an array of square microposts embedded inside the cavity and sealed with a Pyrex cover. The interior surface of the chip is first modified by depositing SNP using a layer-by-layer self-assembly technique followed by coating with Tenax TA. The adsorption capacity of the SNP-Tenax TA ?TPC is enhanced by as much as a factor of three compared to the one coated solely with thin film Tenax TA for the compounds tested. The increased adsorption ability of the Tenax TA is attributed to the higher surface area provided by the underlying porous SNP coating and the pores between SNPs affecting the morphology of deposited Tenax TA film by bringing nano-scale features into the polymer. In addition, the adsorption ability of the SNP coating as a pseudo-selective inorganic adsorption bed for polar compounds was also observed. The modified Tenax TA-coated SNP ?TPC is a promising development toward integrated micro-gas chromatography systems.
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Highly stable surface functionalization of microgas chromatography columns using layer-by-layer self-assembly of silica nanoparticles.
Anal. Chem.
PUBLISHED: 08-15-2013
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A controllable and high-yield surface functionalization of silicon microchannels using layer-by-layer (LbL) self-assembly of SiO2 nanoparticles (SNPs) is presented. The application of SNPs (45 nm average diameter) coating as a stationary phase for chromatographic separation is also demonstrated with surface functionalization using chloroalkylsilanes. This method facilitates a simple, low-cost, and parallel processing scheme that also provides homogeneous and stable nanoparticle-based stationary phases with ease of control over the coating thickness. The SNP-functionalized microfabricated columns with either single capillary channels (1 m long, 150 ?m wide, 240 ?m deep) or very narrow multicapillary channels (25 cm long, 30 ?m wide, 240 ?m deep, 16 parallel channels) successfully separated a multicomponent gas mixture with a wide range of boiling points with high reproducibility.
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Demonstration of a cylindrically symmetric second-order nonlinear fiber with self-assembled organic surface layers.
Opt Express
PUBLISHED: 06-07-2011
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We report the fabrication and characterization of a cylindrically symmetric fiber structure that possesses significant and thermodynamically stable second-order nonlinearity. Such fiber structure is produced through nanoscale self-assembly of nonlinear molecules on a silica fiber taper and possesses full rotational symmetry. Despite its highly symmetric configuration, we observed significant second harmonic generation (SHG) and obtained good agreement between experimental results and theoretical predictions.
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Nanoscale patterning of ionic self-assembled multilayers.
Nanotechnology
PUBLISHED: 03-24-2009
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Films that are nanostructured in all three dimensions can be fabricated by the templated growth of ionic self-assembled multilayers (ISAMs) on solids that have been patterned by nanografting. Nanografting was used to controllably pattern -COOH surface groups on a background of -OH groups. Atomic force microscopy (AFM) confirms that ISAM bilayers grow selectively on the -COOH groups and not on the surrounding -OH groups. The patterned area clearly shows an increase in height with an increase in the number of bilayers. As compared with other methods of nanofabrication, nanografting with ISAM deposition provides fast and precise control over the size of the pattern region, which remains stable even after repeated washing. This combination allows the fabricated template to be altered in situ without the need of any kind of mask, expensive probe, or post-lithography processing/cleaning methods. We have demonstrated line widths of 75 nm. Ultimately the line width is limited by the width of the AFM tip that causes desorption of the thiol, which is typically about 25 nm. Smaller line widths should be possible with the use of sharper AFM tips.
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High-contrast solid-state electrochromic devices of viologen-bridged polysilsesquioxane nanoparticles fabricated by layer-by-layer assembly.
ACS Appl Mater Interfaces
PUBLISHED: 01-28-2009
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Water-soluble silsesquioxane nanoparticles (NPs) incorporating viologen groups (PXV; 1,1-bis[3-(trimethoxysilyl)propyl]-4,4-bipyridinium iodide) have been synthesized by sol-gel polymerization. The electrochromic properties of the bulk film fabricated by layer-by-layer (LbL) assembly have been examined, along with their incorporation into solid-state devices. The orange LbL films show high thermal stability and exhibit a maximum UV-vis absorption at 550 nm. Electrochromic switching of the NPs in liquid electrolyte as well as in the solid state was evaluated by a kinetic study via measurement of the change in transmission (% T) at the maximum contrast. Cyclic voltammograms of the PXV NP LbL films exhibit a reversible reduction at -0.6 V vs Ag/AgCl in a 0.1 M NaClO4(aq) solution, revealing good electrochromic stability, with a color change from orange to dark purple-blue at applied potentials ranging from -0.7 to -1.3 V. Cathodically coloring PXV NP solid-state devices exhibit a switching time of a few seconds between the purple-blue reduced state and the orange oxidized state, showing a contrast of 50% at 550 nm and a coloration efficiency of 205 cm2/C. Their solubility and fairly fast electrochromic switching ( approximately 3 s) at low switching voltages (between 0 and 3.0 V), along with their stability under atmospheric conditions, make PXV NPs good candidates for electrochromic displays.
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RAFT synthesis of ABA triblock copolymers as ionic liquid-containing electroactive membranes.
ACS Appl Mater Interfaces
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2-(Dimethylamino)ethyl acrylate (DMAEA) imparts versatile functionality to poly[Sty-b-(nBA-co-DMAEA)-b-Sty] ABA triblock copolymers. A controlled synthetic strategy minimized chain transfer reactions and enabled the preparation of high-molecular-weight ABA triblock copolymers with relatively narrow PDIs between 1.39 and 1.44 using reversible addition-fragmentation chain transfer (RAFT) polymerization. The presence of tertiary amine functionality and their zwitterionic derivatives in the central blocks of the triblock copolymers afforded tunable polarity toward ionic liquids. Gravimetric measurements determined the swelling capacity of the triblock copolymers for ionic liquids (IL) 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIm TfO) and 1-ethyl-3-methylimidazolium ethylsulfate (EMIm ES). A correlation of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and small-angle X-ray scattering (SAXS) results revealed the impact of ionic liquid incorporation on the thermal transitions, thermomechanical properties, and morphologies of the triblock copolymers. IL-containing membranes of DMAEA-derived triblock copolymers and EMIm TfO exhibited desirable rubbery plateau moduli of ~100 MPa and electromechanical actuation to a 4 V electrical stimulus. Maintaining the mechanical ductility of polymer matrices while increasing their ion-conductivity is paramount for future electroactive devices.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.