14 research outputs found
Colloidal Assembly in Leidenfrost Drops for Noniridescent Structural Color Pigments
Noniridescent
structural color pigments have great potential as
alternatives to conventional chemical color pigments in many coloration
applications due to their nonbleaching and color-tunable properties.
In this work, we report a novel method to create photonic microgranules
composed of glassy packing of silica particles and small fraction
of carbon black nanoparticles, which show pronounced structural colors
with low angle-dependency. To prepare isotropic random packing in
each microgranule, a Leidenfrost drop, which is a drop levitated by
its own vapor on a hot surface, is employed as a template for fast
consolidation of silica particles. The drop randomly migrates over
the hot surface and rapidly shrinks, while maintaining its spherical
shape, thereby consolidating silica particles to granular structures.
Carbon black nanoparticles incorporated in the microgranules suppress
incoherent multiple scattering, thereby providing improved color contrast.
Therefore, photonic microgranules in a full visible range can be prepared
by adjusting the size of silica particles with insignificant whitening
Colloidal Assembly in Leidenfrost Drops for Noniridescent Structural Color Pigments
Noniridescent
structural color pigments have great potential as
alternatives to conventional chemical color pigments in many coloration
applications due to their nonbleaching and color-tunable properties.
In this work, we report a novel method to create photonic microgranules
composed of glassy packing of silica particles and small fraction
of carbon black nanoparticles, which show pronounced structural colors
with low angle-dependency. To prepare isotropic random packing in
each microgranule, a Leidenfrost drop, which is a drop levitated by
its own vapor on a hot surface, is employed as a template for fast
consolidation of silica particles. The drop randomly migrates over
the hot surface and rapidly shrinks, while maintaining its spherical
shape, thereby consolidating silica particles to granular structures.
Carbon black nanoparticles incorporated in the microgranules suppress
incoherent multiple scattering, thereby providing improved color contrast.
Therefore, photonic microgranules in a full visible range can be prepared
by adjusting the size of silica particles with insignificant whitening
Durable Plasmonic Cap Arrays on Flexible Substrate with Real-Time Optical Tunability for High-Fidelity SERS Devices
Active tunable plasmonic cap arrays
were fabricated on a flexible
stretchable substrate using a combination of colloidal lithography,
lift-up soft lithography, and subsequent electrostatic assembly of
gold nanoparticles. The arrangement of the plasmonic caps could be
tuned under external strain to deform the substrate in reversible.
Real-time variation in the arrangement could be used to tune the optical
properties and the electromagnetic field enhancement, thereby a proving
a promising mechanism for optimizing the SERS sensitivity
Freestanding and Arrayed Nanoporous Microcylinders for Highly Active 3D SERS Substrate
Surface-enhanced Raman scattering (SERS) has been considered as
one of the most promising tools for molecular analysis. To develop
practical platforms, a variety of nanoparticles and two-dimensional
(2D) nanostructures have been prepared. However, low signal intensity
or slow binding kinetics in conventional approaches limits their applications.
To overcome these shortcomings, production and usage of three-dimensional
(3D) nanostructures remain an important yet unmet need. In this paper,
we report novel and effective SERS-active materials by fabricating
hierarchically structured SiO<sub>2</sub> microcylinders decorated
with gold nanoparticles. In order to fully develop 3D nanostructures,
while maintaining fast diffusion of analyte molecules, we used self-assembled
nanostructures of block-copolymers (BCPs) confined in the microholes
of an imprinting mold; the BCPs could provide a template for producing
3D nanostructure composed of nanofibers with sub-100 nm diameter through
their microphase separation, whereas the imprinting technique provided
cylindrical geometry for the local confinement of the BCPs. Microcylinders
with nanodomains were then transformed into microcylinders with 3D
nanopores via reactive-ion etching and, subsequently, their nanopores
were decorated by gold nanoparticles. The resultant 3D nanopores enable
a high loading of gold nanoparticles and formation of abundant hot
spots and microcylinders facilitate the fast diffusion of analyte
molecules through the nanopores, resulting in significant enhancement
of SERS intensity
Droplet-Guiding Superhydrophobic Arrays of Plasmonic Microposts for Molecular Concentration and Detection
Droplet-guiding
superhydrophobic SERS substrates are created by a combinatorial lithographic
technique. Photolithography defines the pattern of a micropillar array
with a radial density gradient, whereas colloidal lithography features
a nanotip array on the top surface of each micropillar. The nanotip
array renders the surface superhydrophobic, and the pattern of micropillars
endows the radial gradient of the contact angle, enabling the spontaneous
droplet migration toward the center of the pattern. Water droplets
containing target molecules are guided to the center, and the molecules
dissolved in the droplets are concentrated at the surface of the central
micropillar during droplet evaporation. Therefore, the molecules can
be analyzed at the predefined position by Raman spectra without scanning
the entire substrate. At the same time, the SERS-active nanotip array
provides high sensitivity of Raman measurement
Droplet-Guiding Superhydrophobic Arrays of Plasmonic Microposts for Molecular Concentration and Detection
Droplet-guiding
superhydrophobic SERS substrates are created by a combinatorial lithographic
technique. Photolithography defines the pattern of a micropillar array
with a radial density gradient, whereas colloidal lithography features
a nanotip array on the top surface of each micropillar. The nanotip
array renders the surface superhydrophobic, and the pattern of micropillars
endows the radial gradient of the contact angle, enabling the spontaneous
droplet migration toward the center of the pattern. Water droplets
containing target molecules are guided to the center, and the molecules
dissolved in the droplets are concentrated at the surface of the central
micropillar during droplet evaporation. Therefore, the molecules can
be analyzed at the predefined position by Raman spectra without scanning
the entire substrate. At the same time, the SERS-active nanotip array
provides high sensitivity of Raman measurement
Scatterplots comparing the expression levels to the mRNA stability states of the expressed genes in RA FLS.
<p>Two biological replicates of RA FLS (derived from two different RA patients) were exposed to a single dose of TNF (10 ng/ml) for 1, 3, 24, or 72 hours. Subsequently, actinomycin D (Act D, 10μg/ml) was added for 3 hours to block active transcription and gene expression was measured by RNA sequencing. RPKM values were generated using CuffDiff2. The mRNA stability status was calculated genome-wide as the ratio of RPKM levels at the TNF+Act D condition divided to the RPKM levels at the TNF condition. This ratio ranges from 0 to 1 and classifies genes to a spectrum from very unstable to very stable transcripts. The genes expressed at 1 (a), 3 (b), 24 (c), and 72 (d) hours of TNF stimulation were plotted based on their expression levels and the mRNA stability states. Shades of blue represent the region of unstable genes, and shades of red represent the zone of stable genes.</p
Genome-wide identification of transcripts stabilized by TNF in RA FLS.
<p>Two biologic replicates of RA FLS (derived from two different RA patients) were exposed to a single dose of TNF (10 ng/ml) for 1 or 72h. Subsequently, Act D was added for 3h and gene expression was measured by RNA sequencing. The degree of TNF-induced mRNA stabilization was calculated as the log<sub>2</sub> difference of TNF+Act D/TNF ratio between 1 and 72h of TNF stimulation and the adjusted p values of TNF-induced stabilization were calculated by RiboDiff. (a), Scatter-plot of the genes displaying TNF-induced mRNA stabilization comparing the degree of mRNA stabilization (y axis) to the adjusted p values of the stabilizing effect of TNF (x-axis). (b), The top 40 genes displaying the highest TNF-induced mRNA stabilization ranked by the degree of stabilization. (c), Enriched biological processes identified by GSEA/MSigDB pathway analysis of the top 10% of the genes (n = 593) displaying the highest degree of TNF-induced mRNA stabilization.</p
Association of expression kinetics with mRNA stability states of TNF-inducible genes in RA FLS.
<p>For (a-b), two biological replicates of RA FLS (derived from two different RA patients) were exposed to a single dose of TNF (10 ng/ml) for 1-72h. Subsequently, Act D (10 μg/ml) was added for 3h and gene expression was measured by RNA sequencing. 386 genes were identified as highly induced (≥5-fold) by TNF at any time point and were clustered into 6 clusters with distinct kinetics of peak expression. (a), Heatmap illustrating the expression kinetics of the 6 clusters (red represents the maximum and blue the minimum expression level across the lane). (b), Stacked bar graphs illustrating the stability states of genes for Cluster 1, Clusters 2 &3, Cluster 4, and Clusters 5 & 6. For (c-f), RA FLS were exposed to a single dose of TNF (10 ng/ml) for 1–72 hours. Primers specific for the eighth intronic region of <i>MMP3</i> and for the first intronic region of <i>CCL5</i> were designed to capture primary transcripts (PT) of <i>MMP3</i> and <i>CCL5</i>. qPCR was used to measure the levels of PT and total mRNA of MMP3 (c-d) and CCL5 (e-f). Cumulative results from six independent experiments are shown. Values were normalized relative to mRNA for GAPDH and are presented as mean ±SEM.</p
Genome-wide evaluation of mRNA stability states of expressed genes in RA FLS.
<p>(a-c), Gene tracks showing sequencing reads from RNA sequencing mapped to <i>CCL20</i> (a), <i>JUN</i> (b) and <i>IRF1</i> (c) genes. The sequencing reads after TNF stimulation for 1 hour without (blue) or with Act D (orange) are shown. (d), Stacked bar graphs illustrating the mRNA stability states of genes expressed in unstimulated (Control) and TNF-stimulated FLS (1, 3, 24 and 72 hours of TNF stimulation). The mRNA stability status was calculated as the ratio of expression levels at the TNF+Act D condition divided to the expression levels at the TNF condition. This ratio ranges from 0 to 1 and classifies genes to a spectrum from very unstable to very stable transcripts. The expressed genes were classified into five groups with distinct stability states and the size of each group is represented as % of total number of expressed genes for each condition.</p