Continuous Synthesis of Highly Uniform Noble Metal Nanoparticles over Reduced Graphene Oxide Using Microreactor Technology

Batch reactors always suffer from inefficient transport properties, discontinuity, and scale-up effects, challenging the particle size control, reproducibility, and large-scale production of noble metal-reduced graphene oxide composites. To address these issues, a microfluidic-based strategy for the continuous synthesis of highly uniform Ag nanoparticles (NPs) over reduced graphene oxide (Ag-rGO composites) was developed in this study. Ag-rGO composites were formed by the coreduction of AgNO₃ and GO with NaBH₄, which was confined inside the dispersed aqueous plugs segmented by octane. By virtue of enhanced mixing and precise control of reaction parameters in the plugs, ultrafine Ag NPs with controlled particle size (1.5–5.6 nm) and narrow particle size distribution (PSD) were evenly deposited on rGO. The average particle size of Ag NPs and relative standard deviation of particle size in Ag-rGO composites synthesized via microfluidic-based strategy were smaller than those via batch method. Moreover, the versatility of this microfluidic-based strategy was further demonstrated in the continuous synthesis of Pt-rGO and Pd-rGO composites

Continuous Synthesis of Ag/AgCl/ZnO Composites Using Flow Chemistry and Photocatalytic Application

Ag/AgCl/ZnO composites were successfully synthesized in a continuous microfluidic system under visible light irradiation, which was employed in situ to reduce a portion of AgCl to metallic Ag. The formation of Ag/AgCl/ZnO composites was confined in small aqueous plugs, which were dispersed by octane as the continuous phase. In this way, enhanced mixing, low risk of channel clogging, and uniform light distribution were achieved. The characterization results revealed that the as-prepared Ag/AgCl/ZnO composites were composed of flowerlike ZnO with Ag/AgCl nanospheres anchored to them. It was found that the synthesis parameters such as water/oil volume flow ratio, total volume flow rate, temperature, and the molar ratio of Zn²⁺ to Ag⁺ had effects on the synthesis of Ag/AgCl/ZnO composites. Furthermore, the as-prepared Ag/AgCl/ZnO composites outperformed Ag/ZnO composites and AgCl/ZnO composites in the visible-light-driven degradation of methyl orange

Facile Synthesis of Co₃O₄ with Different Morphologies via Oxidation Kinetic Control and Its Application in Hydrogen Peroxide Decomposition

Co₃O₄ nanoparticles (NPs) with tubular and hollow structures were successfully synthesized by the formation of CoOOH and subsequent high-temperature calcination in air. The as-synthesized Co₃O₄ retained the morphologies of CoOOH. Therefore, the key step for the synthesis of Co₃O₄ was the controllable preparation of CoOOH NPs with tubular and hollow structures, which were prepared through a facile strategy involving the oxidation of β-Co­(OH)₂ under strong basic conditions (template-free, aqueous solution, and mild temperature). The morphology of CoOOH was tuned by employing air and H₂O₂ as the oxidizing agents which possessed different oxidation abilities and thus resulted in different oxidation kinetics. The plausible formation mechanism of CoOOH NPs with tubular and hollow structures was both related to the Kirkendall effect. In contrast to the commercial Co₃O₄, the as-prepared Co₃O₄ NPs with tubular and hollow structures showed superior catalytic activities for the decomposition of H₂O₂. The reaction rate constants of the as-prepared Co₃O₄ NPs with tubular and hollow structures were over 100 times the value of the commercial one

β-1,3-glucan induces PLD activity in A549 cells.

<p>A549 cells were stimulated with the indicated concentrations of β-1,3-glucan for 30 min (A) or for the indicated duration of time with 50 µg/mL of β-1,3-glucan (B). Thereafter, the PLD activity was determined and differences in [³H] PtdEtOH formation between the control (indicated by “0”) and other groups were compared. In C and D, A549 cells were first incubated with HBSS (Control), HBSS containing 5 µg/mL of isotype control antibody and HBSS containing 5 µg/mL of anti-dectin-1 mAb GE2 (ab82888) for 30 min, respectively. Then, the cells were infected with swollen conidia of <i>A. fumigatus</i> 13073 at an MOI of 10 (C) or stimulated by HBSS and HBSS containing 50 µg/mL of β-1,3-glucan for 30 min, respectively (D). <i>A. fumigatus</i> internalization was analyzed by the nystatin protection assay (C) and the PLD activity (D) was measured. Differences in <i>A. fumigatus</i> internalization and [³H] PtdEtOH formation between the untreated cells (Control) and antibody-treated cells were compared. In E and F, A549 cells were infected with swollen conidia of <i>A. fumigatus</i> 13073 at an MOI of 10 or incubated with PBS (Control) for 30 min. Subsequently, the cells were stained with isotype (IC) antibody or the primary anti-dectin-1 mAb GE2 (ab82888) and analyzed by FACS Calibur flow cytometer. The geometric mean fluorescence intensity was determined by Cell Quest Pro software. Differences between uninfected cells (Control) and conidia-infected cells were compared. G. A549 cells were incubated with swollen conidia of <i>A. fumigatus</i> 13073 at an MOI of 10 or incubated with PBS (Control) for 30 min. Cells were analyzed for dectin-1 expression by immunoblotting using an anti-dectin-1 antibody (sc-26094). FACS profiles and immunoblots shown here are characteristic of 3 independent experiments. Data are represented as mean ± SE (n = 3–4). *P<0.05.</p

Inhibition of <i>A. fumigatus</i> internalization by PLD chemical inhibitors.

<p>A549 cells were incubated for 30 min with 1% (v/v) 1-butanol or tert-butanol (A, B), 2 nM VU0359595 (PLD1-specific inhibitor), 100 nM VU0285655-1 (PLD2-specific inhibitor), or both (C, D). Subsequently, the cells were infected with <i>A. fumigatus</i> 13073 swollen conidia at an MOI of 10. <i>A. fumigatus</i> internalization was analyzed by the nystatin protection assay (A, C) and PLD activities (B, D) were measured. Differences in [³H] PtdEtOH formation or <i>A. fumigatus</i> internalization between the untreated (control) cells and inhibitor-pretreated cells were compared. Data are represented as the mean ± SE (n = 3–4). *P<0.05.</p

Solvent Effect and Hydrogen Bond Interaction on Tautomerism, Vibrational Frequencies, and Raman Spectra of Guanine: A Density Functional Theoretical Study

Stable structures and Raman spectra of guanine have been investigated by density functional theory (DFT). Focusing on solvent effect and hydrogen bonding interaction, we have calculated the two keto-amino tautomers G17K and G19K as well as their guanine–water complexes and tetramers. The results show G17K is more stable than G19K in the gas phase, whereas in polar solvents G19K dominates. The vibrational fundamentals of G17K have been reassigned based on normal-mode analysis, since the previous assignment was limited to the G19K only. In the Raman spectra, the modes of the ring breathing vibration and those in the fingerprint region (from 1000 to 1600 cm^–1) affected by the solvent effect and the hydrogen bonding interaction dramatically. The band at 1163 cm^–1 of G17K in gas has a large blue shift when water molecule forms hydrogen bonds with N₇–H₁₆ and C₆O₁₃ sites. The blue shift can be explained by the influence of hydrogen bonding interaction along with shortening the N₁–C₆ bond distance. In addition, the dominant existing tautomer in polycrystalline and powder guanine is proposed to be G17K, whose calculated vibrational frequencies agree with the experimental Raman spectra reported before

Heat-killed swollen conidia stimulate PLD activity and internalize in A549 cells.

<p>A549 cells were infected with heat-killed (HK) resting conidia, HK swollen conidia (germinated for 6 h), and HK hyphae (germinated for 12 h) of <i>A. fumigatus</i> 13073 (at an MOI of 10 each). The PLD activities were measured (A) and <i>A. fumigatus</i> internalization was determined by immunofluorescent staining (B). Differences in [³H] PtdEtOH formation and in the internalization indices between groups were compared as indicated in the figure. Data are represented as the mean ± SE (n = 3–4). *P<0.05.</p

Interference of endogenous PLD host cell expression reduces the internalization of <i>A. fumigatus</i>.

<p>A549 cells were transfected with non-specific small interfering RNAs (siRNAs) (Control), PLD1-specific siRNAs (A, C), or PLD2-specific siRNAs (B, D). After 48 h, cells were infected with the swollen conidia of <i>A. fumigatus</i> 13073 at an MOI of 10. <i>A. fumigatus</i> internalization was analyzed by the nystatin protection assay (A, B) and PLD activities (C, D) were measured. Differences in [³H] PtdEtOH formation and <i>A. fumigatus</i> internalization between the untransfected cells (Control) and PLD-silenced cells were compared. Data are represented as the mean ± SE (n = 3–4). *P<0.05. The immunoblots represent PLD1 and PLD2 expression in A549 cell lysates.</p

Host cell PLD activity is stimulated by swollen conidia, but not resting conidia.

<p><b>A.</b> A549 cells were infected with the live resting conidia, swollen conidia (germinated for 6 h), and hyphae (germinated for 12 h) of <i>A. fumigatus</i> 13073 at an MOI of 10 for 30 min. B. A549 cells were infected with the swollen conidia of <i>A. fumigatus</i> 13073 for 30 min at the indicated MOI. C. A549 cells were infected with live resting conidia, swollen conidia and hyphae of <i>A. fumigatus</i> AF293 at an MOI of 10 for 30 min. Thereafter, the PLD activity in the A549 cells was measured, and the differences in [³H] PtdEtOH formation between uninfected group (Control) and infected group or between groups were compared as indicated in the figure (A, B, C). D. A549 cells were infected with resting conidia (germinating time = 0), or conidia of <i>A. fumigatus</i> 13073 germinated for the indicated time periods at an MOI of 10 for 60 min. <i>A. fumigatus</i> internalization was determined by immunofluorescent staining. Differences in the internalization index between resting conidia and germinated conidia were compared. Data are represented as the mean ± SE (n = 3–4). *P<0.05.</p

<i>A. fumigatus</i> stimulates PLD activity during its internalization into A549 cells.

<p>A. A549 cells were prelabeled with [³H] oleic acid and infected with the resting conidia of <i>A. fumigatus</i> 13073 at an MOI of 10 for the indicated time periods. Then, ethanol was added to determine the PLD activity. B. A549 cells were infected with the resting conidia of <i>A. fumigatus</i> 13073 at an MOI of 10 for the indicated time periods, and the internalization of <i>A. fumigatus</i> was analyzed by the nystatin protection assay. Differences in [³H] PtdEtOH formation between the 0 h time point and the other time points (A) and differences in the internalization of <i>A. fumigatus</i> between the 2 h time point and the other time points (B) were compared. In parallel, the cells were lysed for immunoblotting with the indicated antibody (C) and the densitometric analysis of immunoblots for three independent experiments is shown (D). Data are represented as the mean ± SE (n = 3–4), and the blots are characteristic of 3 independent experiments. *P<0.05.</p