Rationally Turning the Interface Activity of Mesoporous Silicas for Preparing Pickering Foam and “Dry Water”

We develop a novel protocol to prepare smart, gas/water interface-active, mesoporous silica particles. This protocol involves modification of highly mesoporous silicas with a mixture of hydrophobic octyl organosilane and hydrophilic triamine organosilane. Their structure and compositions are characterized by transmission electron microscopy (TEM), N₂ sorption, solid state NMR, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FT-IR), thermogravimetric analysis (TGA), and elemental analysis. It is demonstrated that our protocol enables the interface activity of mesoporous silica particles to be facilely tuned, so that the stable gas–water interfaces ranging from air bubbles dispersed in water (Pickering foam) and water droplets dispersed in air (“dry water”) can be achieved, depending on the molar ratio of these two organosilanes. The “dry water” is not otherwise attainable for the analogous nonporous silica particles, indicting the uniqueness of the chosen mesoporous structures. Moreover, these particle-stabilized Pickering foams and “dry waters” can be disassembled in response to pH. Interestingly, it was found that aqueous potassium carbonate droplets stabilized by these interface-active mesoporous silica particles (“dry K₂CO₃-containing water”) could automatically capture CO₂ from a simulated flue gas with enhanced adsorption rate and adsorption capacity when compared to the aqueous potassium carbonate bulk solution. This study not only supplies a novel type of efficient, smart, gas/water interface-active mesoporous silica particles but also demonstrates an innovative application of mesoporous materials in gas adsorption

GP73 upregulates APOE and interacts with APOE.

<p>(<b>A</b>) APOE mRNA levels in stable Huh7.5.1 cells were quantified using qRT-PCR. The results are presented as mean ± SEM derived from three experiments (*<i>P</i><0.05). (<b>B</b>) Protein levels of intracellular GP73, APOE, and secreted APOE (sAPOE) in stable Huh7.5.1 cells were detected by western blot. (<b>C</b>) Colocalization analysis of endogenous GP73 and HCV proteins and APOE. For NS5A and APOE, Huh7.5.1 cells were infected with HCV-GFP at 0.02 MOI. The subcellular localizations of GP73, NS5A-GFP and APOE were imaged with indirect immunofluorescence assay. For NS2 and NS4B, Huh7.5.1 cells were transfected with plasmids expressing GFP-tagged NS2 or FLAG-tagged NS4B. The subcellular localizations of GP73, NS2-GFP and NS4B were imaged with indirect immunofluorescence assay. (Bar, 10 µm.) (<b>D</b>) Co-immunoprecipitation analysis of 293T cells cotransfected with plasmids expressing FLAG-tagged GP73 and HA-tagged APOE. Cell lysates were immunoprecipitated with normal mouse IgG (mIgG), anti-Flag and anti-HA, respectively. The cell lysates and immunoprecipitates were analyzed by immunoblotting with antibodies as indicated. (<b>E</b>) Co-immunoprecipitation analysis of secreted GP73 (sGP73) and secreted APOE (sAPOE) in the culture supernatants of Huh7.5.1 cells cotransfected with plasmids expressing FLAG-tagged GP73 and HA-tagged APOE. The supernatants were immunoprecipitated with normal mouse IgG (mIgG), anti-Flag and anti-HA, respectively. The supernatants and immunoprecipitates were analyzed by immunoblotting with antibodies as indicated. (<b>F</b>) Co-immunoprecipitation analysis of 293T cells cotransfected with plasmids expressing FLAG-tagged GP73 truncations and HA-tagged APOE. Cell lysates were immunoprecipitated anti-Flag antibody. The cell lysates and immunoprecipitates were analyzed by immunoblotting with anti-HA antibodies as indicated. (<b>G</b>) Sucrose density gradient analysis of the culture medium of HCV-GFP infected cells. (<i>Upper</i>) Supernatant from infected Huh-7.5.1 cells was fractionated as described in <i>Materials and Methods</i>. The buoyant density of sucrose is plotted with the viral RNA of HCV-GFP measured by qRT-PCR. (<i>Lower)</i> Western blot analysis of GP73, APOE, and core proteins in the fractions of sucrose gradient.</p

GP73 enhances HCV production.

<p>(<b>A</b>)The mRNA levels of GP73 in stable cell lines were detected by qRT-PCR. (<b>B</b>) Infection efficiency of HCV-GFP in Huh7.5.1 stable cells was detected with flow cytometry at the indicated time points after infection at 0.02 MOI. (<b>C</b>) Intracellular viral RNA in Huh7.5.1 cells was quantified by qRT-PCR. The values are normalized to those of 24 h post-infection. (<b>D)</b> HCV-GFP infectivity of the supernatant at 72 h and 96 h post-infection were assayed by flow cytometry. (<b>E</b>) HCVpp infectivity in stable cells. The values are represented relative to naive Huh7.5.1 after normalization with VSVGpp infectivity. (<b>F</b>) HCV RNA levels in stable cells at 96 h post-transfection with pSGR-JFH1. The values are represented relative to those of naive Huh7.5.1 after normalization with HCV RNA level at 6 h post-transfection. The results are presented as mean ± SEM derived from three experiments (*<i>P</i><0.05; **<i>P</i><0.01).</p

GP73 increases the secretion of HCV through the coiled-coil domain.

<p>Huh7.5.1 cells infected with HCV-GFP at 0.02 MOI were transfected with GP73 truncation expression plasmids at 48 h post-infection. At 48 h after transfection, Huh7.5.1 cells were harvested and assayed. (<b>A</b>) Protein expression levels of GP73 truncations were detected by western blot. Infection efficiency (<b>B</b>) and MFI (<b>C</b>) of HCV-infected Huh7.5.1 were assayed by flow cytometry (<b>D</b>) Supernatant HCV-GFP titer was assayed by flow cytometry. (<b>E</b>) HCV viral RNA in the supernatant was quantified by qRT-PCR. (<b>F</b>) HCV-GFP titer of the supernatant from Huh7.5.1 cells transfected with indicated plasmids was assayed by flow cytometry. (<b>G</b>) Intracellular HCV-GFP infectivity was assayed by flow cytometry. (<b>H</b>) Intracellular HCV RNA levels were quantified by qRT-PCR. (<b>I</b>) Diagram of GP73 truncation structure and summary of effects on HCV production. (Y: Yes; N: No; UP: Upregulated). The results are presented as mean ± SEM derived from three experiments (*<i>P</i><0.05; **<i>P</i><0.01).</p

GP73 increases HCV production in the supernatant.

<p>(<b>A</b>) Schematic of the experimental procedure. Huh7.5.1 cells were infected with the lentivirus carrying the coding sequence of GP73 (pRlenti-GP73), vector control (pRlenti), shRNA expression cassette expressing shRNA against GP73 (shGP73-1 and shGP73-2), or non-target control (shNT) for 6 h. After 24 h, Huh7.5.1 cells were infected with HCV-GFP at 0.02 MOI for another 6 h. The GP73 mRNA levels (<b>B</b>), GP73 protein levels (<b>C</b>), the infection efficiency (<b>D</b>), and MFI (<b>E</b>) of Huh7.5.1 cells were assayed 72 h after infection with HCV-GFP. The HCV-GFP titer (<b>F</b>) and HCV viral RNA levels (<b>G</b>) in the supernatant were assayed by flow cytometry or qRT-PCR. The value of pRlenti-GP73 is represented relative to that of pRlenti. The values of shRNAs against GP73 are represented relative to those of shNT. The results are presented as mean ± SEM derived from three experiments (*P<0.05; **P<0.01).</p

GP73 is upregulated by HCV infection.

<p>(<b>A</b>) GP73 mRNA and viral RNA in SGR-harboring and cured cells. The values are represented relative to those of Huh7-SGR. (<b>B</b>) Western blot of GP73 and HCV NS3 proteins in HCV SGR-harboring and cured cells. (<b>C</b>) Huh7.5.1 cells were infected with HCV-GFP at 0.02 MOI. Infection efficiency was detected using a flow cytometer at the indicated time points. (<b>D</b>) Intracellular HCV RNA levels were quantified by qRT-PCR at the indicated time points. The values are represented relative to those of 4 d post-infection. (<b>E</b>) The mRNA level of GP73. The values are represented relative to those of the control. (<b>F</b>) The expression level of GP73 protein and HCV core protein. The results are presented as mean ± SEM derived from three experiments (*<i>P</i><0.05; **<i>P</i><0.01).</p

Multiple HCV infections among 8 drug users.

<p>*Genotyping 6a with core region can not differentiate clusters, because of the high similarity of the nucleotides.</p>¶<p>Not classifiable into clusters. this isolate was close to a reference.</p

HCV genotype distribution.

<p>HCV genotype distribution.</p

Subtype 6a phylogenies estimated from (A) E1 and (B) NS5B region sequences, corresponding to H77 nucleotide positions of 869–1289 and 8276–8615, respectively.

<p>Subtype 6b sequence D84262 was used as an outgroup. Green pies label sequences from our previous studies <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0028006#pone.0028006-Lu1" target="_blank">[8]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0028006#pone.0028006-Fu1" target="_blank">[9]</a>. Red and yellow pies label sequences from this study, in which yellow pies mark isolates from IDUs with multiple HCV infections. Sequences without pies were retrieved from Genbank. In each tree, five rectangles highlight the further classification of 6a isolates into I, II, III, VI, and VII clusters. Scale bar represents 0.02 nucleotide substitutions per site.</p

The overlapped BSPs.

<p>Three indicated solid lines represent the estimated effective population sizes through time under three combination models: BSP + Uncorrected Exponential, BSP + Uncorrected Lognormal, and BSP + Strict Clock, respectively. The colored areas (pink = Exponential, blue = Lognormal, and yellow = Strict) around the solid lines represent the 95% highest posterior density confidence intervals for these estimates. The vertical ruler on the left scales the effective population size while the horizontal ruler on the bottom measures time.</p