Citrate-Regulated Surface Morphology of SiO₂@Au Particles To Control the Surface Plasmonic Properties

In this work, SiO₂@Au core–shell particles under ambient conditions were prepared by using 120 nm SiO₂ spheres with ca. 4 nm Au nanoparticles decorated on the surfaces as seeds, the aqueous solutions of sodium citrate/HAuCl₄ mixtures as growth solutions, and hydroxylamine as reducing agent. The morphology of the Au shells obtained on the SiO₂ spheres was readily regulated only by the citrate-to-HAuCl₄ molar ratio; no deliberate adjustment of the temperature and pH of the reaction media was needed. When the citrate-to-HAuCl₄ molar ratio in the growth solution was below 4:1, the surfaces of the SiO₂ spheres were covered with sparsely packed Au nanoparticles with sizes in the range of 20–40 nm, depending on the citrate-to-HAuCl₄ molar ratio. When the citrate-to-HAuCl₄ molar ratio in the growth solution was above 8:1, the surfaces of the SiO₂ spheres were coated by complete, uniform Au nanoshells. Concomitant with this citrate-regulated morphology, the localized surface plasmon resonance peaks of the resulting SiO₂@Au particles shifted from 611 nm for the sparse Au nanoparticle coating to 784 nm for the complete Au nanoshell coating. Furthermore, the sparsely packed Au nanoparticle coating showed stronger surface enhancement Raman spectroscopic signals than the uniform Au nanoshell coating, while the latter exhibit higher photothermal efficiency than the former

Syntheses and Characterization of Nearly Monodispersed, Size-Tunable Silver Nanoparticles over a Wide Size Range of 7–200 nm by Tannic Acid Reduction

Nearly monodispersed spherical silver nanoparticles (Ag NPs) were synthesized by using tannic acid (TA) as both reductant and stabilizer in a 30 °C water bath. The size of the as-prepared Ag NPs could be tuned in a range of 7–66 nm by changing the molar ratio of TA to silver nitrate and pH of the reaction solutions. UV–vis spectra, TEM observations, and temporal evolution of the monomer concentrations for the reactions carried out at different experimental conditions showed that the improved size distribution and size tunability of the Ag NPs were mainly attributed to the use of TA, which could promote the balance of nucleation and growth processes of the NPs effectively. The size of the Ag NPs was extendable up to 200 nm in one-pot fashion by the multi-injection approach. The size-dependent surface-enhanced Raman scattering (SERS) activity of the as-prepared Ag NPs was evaluated, and the NPs with size around 100 nm were identified to show a maximum enhanced factor of 3.6 × 10⁵. Moreover, the as-prepared TA-coated Ag NPs presented excellent colloidal stability compared to the conventional citrate-coated ones

High-Performance Integrated rGO-[Polymeric Ionic Liquid] [Heteropolyanions] for Catalytic Degradation of Azo Dyes

Polymeric ionic liquid (such as poly[ViEtIm]Br)-modified reduced graphene oxide (rGO), rGO-poly[ViEtIm]Br, was nominated as an open carrier to construct a degradation platform. The large specific surface of rGO together with the anion-exchange property of poly[ViEtIm]Br terminals led to the wide growth of heteropolyanions (like [PW12O40]3–, [PMo12O40]3–, and [SiW12O40]4–), thus assembling the integrated catalyst rGO-poly[ViEtIm][heteropolyanions]. The grafted poly[ViEtIm]Br provided an anchor point to interlink the polar heteropolyanions and the nonpolar rGO substrate, endowing this graphene-based catalyst with excellent dispersibility. The adequate exposure of heteropolyanions further promoted the decolorization capability during the degradation procedure. Morphology, structure, and properties of materials were confirmed and monitored via transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–vis) spectroscopy, etc. rGO-poly[ViEtIm][PW12O40] was selected as the optimal catalyst with degradation efficiency toward methyl orange reaching 98.7% in 3 h. In addition, the excellent structural stability of the catalyst improved the decolorization efficiency, which reached 95% after recycling five times

Validation of <i>PsnSuSy2</i> integration into tobacco genome and expression in transgenic tobacco lines.

<p>a. Validation of <i>PsnSuSy2</i> tobacco transgenic lines using PCR amplification. Genomic DNA was extracted from the leaves of one-month-old transgenic tobacco. The PCR products were electrophoresed on a 1.2% agarose gel with DL15000 DNA marker (first lane). b. Relative expression of <i>PsnSuSy2</i> in two month-old stem segments of plastichron index (PI) 3–5 determined by real-time RT-PCR. C. SuSy enzyme activity of in two month-old stem segments of PI3–5. Expressed levels in both <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120669#pone.0120669.g003" target="_blank">Fig. 3b and 3c</a> were averaged from five different samples per line ± S.E. The <i>t</i>-test was used to examine the significance of difference between <i>PsnSusy2</i> transgenic and wildtype lines, and *denotes significance at <i>p</i> < 0.05. WT represents wildtype tobacco while all others labeled with line numbers are of different <i>PsnSusy2</i> transgenic lines.</p

Changes in lignocellulosic components in <i>PsnSusy2</i> tobacco transgenic lines.

<p>a. Cellulose contents in the plastichron index (PI) 5~8 stem tissues of three-month-old <i>PsnSusy2</i> transgenic tobacco lines. b. Hemicellulose contents in the PI5~8 stem tissues of three-month-old <i>PsnSusy2</i> transgenic tobacco lines. c. Lignin contents in the stem the PI5~8 stem tissues of three-month-old <i>PsnSusy2</i> transgenic tobacco lines. d. Fiber length in the PI5~8 stem tissue of three-month-old <i>PsnSusy2</i> transgenic tobacco lines. All measurements are the means of five different samples ± S.E. The <i>t</i>-test was used to examine the significance of difference between <i>PsnSusy2</i> transgenic and wildtype lines, and *denotes significance at <i>p</i> < 0.05. The WT represents wildtype tobacco plants, whereas all the others are different <i>PsnSusy2</i> transgenic lines.</p

Tissue-specific expression of the <i>PsnSuSy2</i> in one-year-old hybrid <i>Populus simonii</i> × <i>Populus nigra</i> propagated from two years old hybrid trees.

<p>a. Tissue-specific expression pattern characterized by RT-PCR. b. Tissue-specific expression pattern characterized by real-time quantitative PCR. The expression levels for real-time quantitative PCR were averaged from three replicates.</p

Phenotypic changes in <i>PsnSusy2</i> transgenic lines.

<p>a. Phenotypic comparison of three-month-old tobacco transgenic line of L38 and wildtype tobacco. CK represents wildtype tobacco while T represents L38 transgenic line. b. Comparison of heights of three-month-old tobacco transgenic lines and wildtype. c. Stem diameters of three-month-old tobacco transgenic lines at 3 cm height above the root collar. d. Puncture strength of stem segments (plastichron index 5) in three-month-old transgenic lines. All measurements shown in a, b, and c were averaged from five different samples per line ± S.E. The <i>t</i>-test was used to examine the significance of difference between <i>PsnSusy2</i> transgenic and wildtype lines, and *denotes significance at <i>p</i> < 0.05. The WT represents wildtype tobacco while the others lines labeled with line numbers are of different <i>PsnSusy2</i> tobacco transgenic lines.</p

Changes in chlorophyll contents and biomass of <i>PsnSusy2</i> tobacco transgenics.

<p>a. Chlorophyll contents of the third, fourth and fifth functional leaves of different <i>PsnSuSy2</i> tobacco transgenic lines of two-month-old plants. b. Fresh weights of three-month-old <i>PsnSuSy2</i> tobacco transgenic lines. c. Dry weights of three-month-old <i>PsnSuSy2</i> tobacco transgenic lines. d. Ratios of dry vs. fresh weight for of three-month-old <i>PsnSuSy2</i> tobacco transgenic lines. All measurements shown in 5a, 5b, and 5c were averaged from five different samples per line ± S.E. The <i>t</i>-test was used to examine the significance of difference between <i>PsnSusy2</i> transgenic and wildtype lines, and *denotes significance at <i>p</i> < 0.05. The WT represents wildtype tobacco while the others lines labeled with line numbers are of different <i>PsnSusy2</i> tobacco transgenic lines.</p

Scanning electron micrographs of the PI5–8 stem transverse sections of three-month-old tobacco transgenic lines.

<p>a. and c were from wildtype tobacco plants. b. and d are the L15 <i>PsnSusy2</i> tobacco transgenic line. Short red lines in Figure c and d depict the difference between the cell wall thickness in the tobacco transgenic lines and the wildtype plants. The magnification factor is 100X for Fig. 7a and 7b, and 3000X for 7c and 7d.</p

Changes in carbohydrates (sugars) in <i>PsnSusy2</i> tobacco transgenics.

<p>a. Total soluble sugar contents of stem tissues in different <i>PsnSuSy2</i> tobacco transgenic lines. b. Sucrose contents of stem tissues in different <i>PsnSuSy2</i> tobacco transgenic lines. c. Glucose contents of stem tissues in different <i>PsnSuSy2</i> tobacco transgenic lines. d. Fructose contents of stem tissue in different <i>PsnSuSy2</i> tobacco transgenic lines. All samples in 6a, 6b and 6c were harvested from tissues between PI3 and PI5. All measurements shown in 6a-d were averaged from five different samples per line ± S.E. The <i>t</i>-test was used to examine the significance of difference between <i>PsnSusy2</i> transgenic and wildtype lines, and *denotes significance at <i>p</i> < 0.05. The WT represents wildtype tobacco while the others lines labeled with line numbers are of different <i>PsnSusy2</i> tobacco transgenic lines. Note that the total soluble sugar contents were measured using two-month-old plants, whereas sucrose, glucose, and fructose were measured one week later.</p