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161.
Annealed Silver-Island Films for Applications in Metal-Enhanced Fluorescence: Interpretation in Terms of Radiating Plasmons 总被引:1,自引:0,他引:1
The effects of thermally annealed silver island films have been studied with regard to their potential applicability in applications
of metal-enhanced fluorescence, an emerging tool in nano-biotechnology. Silver island films were thermally annealed between
75 and 250∘C for several hours. As a function of both time and annealing temperature, the surface plasmon band at ≈420 nm both diminished
and was blue shifted. These changes in plasmon resonance have been characterized using both absorption measurements, as well
as topographically using Atomic Force Microscopy. Subsequently, the net changes in plasmon absorption are interpreted as the
silver island films becoming spherical and growing in height, as well as an increased spacing between the particles. Interestingly,
when the annealed surfaces are coated with a fluorescein-labeled protein, significant enhancements in fluorescence are osbserved,
scaling with annealing temperature and time. These observations strongly support our recent hypothesis that the extent of
metal-enhanced fluorescence is due to the ability of surface plasmons to radiate coupled fluorophore fluorescence. Given that
the extinction spectrum of the silvered films is comprised of both an absorption and scattering component, and that these
components are proportional to the diameter cubed and to the sixth power, respectively, then larger structures are expected
to have a greater scattering contribution to their extinction spectrum and, therefore, more efficiently radiate coupled fluorophore
emission. Subsequently, we have been able to correlate our increases in fluorescence emission with an increased particle size,
providing strong experiment evidence for our recently reported metal-enhanced fluorescence, facilitated by radiating plasmons
hypothesis. 相似文献
162.
Meliha Burcu Gürdere Ali Cemal Emeç Osman Nuri Aslan Yakup Budak Mustafa Ceylan 《合成通讯》2016,46(6):536-545
The triethylamin-mediated addition of 2-aminoethanethiol hydrochloride to chalcone analogs was investigated. This addition, bearing a 2-thienyl group at the 3-position, gave the only addition adduct at room temperature in 3 h, whereas the chalcones bearing the 2-furyl group at the 1-position gave an addition-cyclization product (1, 4-thiazepine) in the same conditions. The effect of the groups to the reaction was investigated by changing the 1- and 3-position groups. The chalcones bearing the 2-thienyl group at the 1-position and the others afforded the mixture of products in different ratio at rt for 0.5–24 h. Moreover, the addition–cyclization products (1,4-thiazepine) were obtained under reflux conditions in 36 h. The structures of the synthesized compounds were elucidated by 1H NMR, 13C NMR, infrared, and elemental analysis. 相似文献
163.
Chip‐Free Microscale‐Incubator‐Based Synthesis of Chitosan‐Based Gene Silencing Nanoparticles
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Noemi Gaglianone Michael Lykke Hvam Hüsnü Aslan Mingdong Dong Kenneth A. Howard Yi‐Ping Ho 《Particle & Particle Systems Characterization》2016,33(5):279-285
The development of polymer‐based nanoparticles to ferry siRNA continues to evolve. It is becoming increasingly apparent that gene silencing nanoparticles produced by conventional bulk manufacturing techniques often exhibit physicochemical heterogeneity within and between batches that can affect the biological performance. Here a new facile and robust “chip‐free” method is presented, termed chip‐free agitation‐generated droplets (CAD) preparation, using chitosan‐based gene silencing nanoparticles as an example. The CAD‐prepared silencing particles, in comparison to the particles prepared by the conventional bulk protocol, exhibit lower surface charge (9 mV vs 21 mV at N/P = 5), higher stability (≈40% higher binding affinity and up to 30% less morphological deformation), and are less prone to aggregation measured by nanoparticle tracking analysis over a period of one month. Furthermore, these physical attributes contribute up to 19% higher in cell viability at N/P = 5, while the gene silencing of enhanced green fluorescent protein remains constant in a human cell line. Control of particle properties is necessary to advance siRNA‐based delivery; the CAD preparation represents a physical complement to chemical design modifications, which can be readily transferred among research labs and utilized for alternative polymer systems. 相似文献
164.
Quaternions are more usable than three Euler angles in the three dimensional Euclidean space. Thus, many laws in different fields can be given by the quaternions. In this study, we show that canal surfaces and tube surfaces can be obtained by the quaternion product and by the matrix representation. Also, we show that the equation of canal surface given by the different frames of its spine curve can be obtained by the same unit quaternion. In addition, these surfaces are obtained by the homothetic motion. Then, we give some results. 相似文献
165.
Beyza Caliskan Aslan Shari Moskow 《Journal of Mathematical Analysis and Applications》2008,341(2):1028-1041
The following generalized eigenproblem is analyzed: Find , u≠0, and λ∈R such that
D〈∇u,∇v〉=λΩ〈∇u,∇v〉 相似文献
166.
The first observation of Metal-Enhanced Fluorescence (MEF) from large gold colloids is presented. Gold colloids, 40 and 200 nm
diameter, were deposited onto glass substrates in a homogeneous fashion. The angular-dependent fluorescence emission of FITC-HSA,
adsorbed onto gold colloids, was measured on a rotating stage which was used to evaluate MEF at all spatial angles. The emission
intensity of FITC-HSA was found to be up to 2.5-fold brighter than the emission on bare glass substrates at an angle of 270
degrees. This is explained by the Radiating Plasmon Model, whereby the combined system, composed of the fluorophore and the
metal colloids, emits with the photophysical characteristics of the fluorophore, after the excitation and the partial radiationless
energy transfer between the excited states of the fluorophore and the surface plasmons of the gold colloids. The fluorescence
enhancement was found to be higher with 200 nm gold colloids as compared to 40 nm colloids due to the increased contribution
of the scattering portion of the 200 nm gold colloid extinction spectrum. These observations suggest that gold colloids could
be used in MEF applications, offering more stable surfaces than the commonly used silvered surfaces, for applications requiring
longer term storage and use. 相似文献
167.
In this paper, we describe an optical geometry that facilitates our further characterization of the temperature changes above
silver island films (SiFs) on sapphire plates, when exposed to microwave radiation. Since sapphire transmits IR, we designed
an optical scheme to capture real-time temperature images of a thin water film on sapphire plates with and without SiFs during
the application of a short microwave pulse. Using this optical scheme, we can accurately determine the temperature profile
of solvents in proximity to metal structures when exposed to microwave irradiation. We believe that this optical scheme will
provide us with a basis for further studies in designing metal structures to further improve plasmonic-fluorescence clinical
sensing applications, such as those used in microwave accelerated metal-enhanced fluorescence (MAMEF). 相似文献
168.
In this Rapid Communication, we present the development of monodisperse core-shell (silver core-silica shell) nanoparticles
with various shell thicknesses featuring a fluorophore, subsequently named Metal-Enhanced Fluorescence (MEF) nanoballs. MEF
nanoballs consist of a ≈130 nm silver nanoparticle core, a silica shell with up to 35 nm thickness and fluorophores doped within the silica shell.
Fluorescent nanobubbles where the silver core is removed by chemical etching are used as control samples to show the benefits
of using silver nanoparticles, i.e, Metal-Enhanced Fluorescence. Finally, we demonstrate the broad potential biological applications
of MEF nanoballs by employing near-infra red emitting probes (Rhodamine 800) within the silica shell, for potential applications
in cellular imaging and solution-based sensing.
Kadir Aslan, Meng Wu, Contributed equally 相似文献
169.
In this paper, we investigated the effects of low-power microwave heating on the components of the recently described new approach to surface DNA hybridization assays, based on the Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF) platform technology. Thiolated oligonucleotides have been linked to surface-bound silver nanostructures which partially coat a glass slide. The addition of a complementary fluorescein-labeled oligonucleotide results in metal-enhanced fluorescein emission as the probe is brought into close proximity to the silver upon hybridization. In addition, the combined use with low-power microwave heating, which is thought to locally heat around the silvered surface, affords for both the assay kinetics and optical amplification to also be localized to the surface. In our model DNA target assay reported here, we can detect 23-mer targets in less than 20 s, up to a 600-fold decrease in the assay run time as compared to control samples hybridized to completion at room temperature. Importantly, the use of MAMEF also reduces the extent of unwanted non-specific DNA absorption, further increasing specific DNA target detection limits. It was also found that low-power microwave heating did not denature DNA and the bulk temperature increase near to silver nanoparticles was only ca. 1 degrees C. 相似文献
170.
The reactions of N‐dichlorophosphoryl‐P‐trichlorophosphazene (Cl3PN POCl2) with phenylmagnesium chloride, o‐tolylmagnesium chloride, p‐tolylmagnesium chloride, p‐chlorophenylmagnesium chloride, 2‐mesitylmagnesium bromide, and 2‐thienyl lithium were studied. The resulting pentaaryl phosphazenes R3PN P(O)R2 were separated by using column chromatography, their structures were defined by IR, elemental analysis, 1H, 13C, 31P NMR, and mass spectroscopy. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:138–143, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10114 相似文献