Mechanism and experimental study on the photocatalytic performance of Ag/AgCl @ chiral TiO2 nanofibers photocatalyst: the impact of wastewater components

© 2014 Elsevier B.V.The effect of the water matrix components of a secondary effluent of a urban wastewater treatment plant on the photocatalytic activity of Ag/AgCl @ chiral TiO2 nanofibers and the undergoing reaction mechanisms were investigated. These effects were evaluated through the water components-induced changes on the net rate of hydroxyl radical (•OH) generation and modeled using a relative rate technique. Dissolved organic matter DOM (k=-2.8×108M-1s-1) scavenged reactive oxygen species, Cl- (k=-5.3×108M-1s-1) accelerated the transformation from Ag to AgCl (which is not photocatalytically active under visible-light irradiation), while Ca2+ at concentrations higher than 50mM (k=-1.3×109M-1s-1) induced aggregation of Ag/AgCl and thus all of them revealed inhibitory effects. In contrast, NO3- (k=6.9×108M-1s-1) and CO32- (k=3.7×108M-1s-1) improved the photocatalytic activity of Ag/AgCl slightly by improving the rate of HO• generation. Other ubiquitous secondary effluent components including SO42- (k=3.9×105M-1s-1), NH3+ (k=3.5×105M-1s-1) and Na+ (k=2.6×104M-1s-1) had negligible effects. 90% of 17-α-ethynylestradiol (EE2) spiked in the secondary effluent was removed within 12min, while the structure and size of Ag/AgCl @ chiral TiO2 nanofibers remained stable. This work may be helpful not only to uncover the photocatalytic mechanism of Ag/AgCl based photocatalyst but also to elucidate the transformation and transportation of Ag and AgCl in natural water

Replacing the 238th aspartic acid with an arginine impaired the oligomerization activity and inflammation-inducing property of pyolysin

<p><i>Trueperella pyogenes</i> (<i>T. pyogenes</i>) is an important opportunistic pathogen. Pyolysin (PLO) importantly contributes to the pathogenicity of <i>T. pyogenes</i>. However, the relationship between the structure and function and the virulence of PLO is not well documented. In the current study, recombinant PLO (rPLO) and three rPLO mutants were prepared. rPLO D238R, a mutant with the 238th aspartic acid replaced with an arginine, showed impairment in oligomerization activity on cholesterol-containing liposome and pore-forming activity on sheep red blood cell membrane. Further study employing the prepared mutants confirmed that the pore-forming activity of PLO is essential for inducing excessive inflammation responses in mice by upregulating the expression levels of IL-1β, TNF-α, and IL-6. By contrast, rPLO P499F, another mutant with impaired cell membrane binding capacity, elicited an inflammation response that was dependent on pathogen-associated molecular pattern (PAMP) activity, given that the mutant significantly upregulated the expression of IL-10 in macrophages and in mice, whereas rPLO did not. Results indicated that domain 1 of the PLO molecule plays an important role in maintaining pore-forming activity. Moreover, the PLO pore-forming activity and not PAMP activity is responsible for the inflammation-inducing effect of PLO. The results of this study provided new information for research field on the structure, function, and virulence of PLO.</p> <p><b>Abbreviations</b>: <i>T. pyogenes: Trueperella pyogenes</i>; PLO: Pyolysin; rPLO: recombinant PLO; PAMP: pathogen-associated molecular pattern; CDCs: cholesterol-dependent cytolysins; PLY: pneumolysin; NLRP3: NLR family pyrin domain containing protein 3; PRRs: pattern recognition receptors; Asp: aspartic acid; TLR4: Toll-like receptor 4; Arg: arginine; Asn: asparagine; IPTG: Isopropyl-β-d-thiogalactoside; PBS: phosphate-buffered saline; sRBCs: sheep red blood cells; TEM: Transmission electron microscopy; RBCM: red blood cell membrane; SDS-PAGE: sodium dodecyl sulfate–polyacrylamide gel electrophoresis; NC membrane: nitrocellulose membrane; SDS-AGE: dodecyl sulfate agarose gel electrophoresis; MDBK cells: Madin–Darby bovine kidney cells; RPMI-1640 medium: Roswell Park Memorial Institute-1640 medium; FBS: fetal bovine serum; BMDMs: bone marrow-derived macrophages; TNF-α: tumor necrosis factor α; IL-1β: interleukin-1β; IFN-γ: interferon-γ; TGF-β: transforming growth factor-β; ELISA: enzyme-linked immunosorbent assay</p

The in vivo tumorgenesis assay and metastasis assay in nude mice.

<p>Nude mice inoculated with SIRT1 si-RNA-transfected cells had markedly reduced tumor volume compared to mice received cells transfected with control si-RNA transfection (730±141vs. 1153±112, mm3 , P<0.001, Figure 5a and 5b).The in vivo metastasis assay shows the inoculation with SIRT1 si-RNA-transfected cells in nude mice had dramatically reduced numbers of metastatic tumors in lung tissues than control si-RNA-transfected cells (4.4±0.9 vs. 2.1±0.5, P<0.001, Figure 5c).</p

Kaplan–Meier survival curves analyses by SIRT1 expression.

<p>Figure 2a: the PFS analyses by SIRT1 expression status (high SIRT1 expression vs. low SIRT1 expression, P<0.001) ; 2b: the OS analyses by SIRT1 expression status ((high SIRT1 expression vs. low SIRT1 expression, P<0.001).</p

The proliferation, migration and invasiveness of NSCLC cells infected with SIRT 1 siRNA and control siRNA.

<p>a. the SRIT1 expression after SIRT1 si-RNA transfection in H292 cells. b the absorbance at 562nm between cells infected with SIRT 1 si-RNA and control si-RNA (P<0.001). c the cell numbers of migrated cells infected with SIRT 1 si-RNA and control si-RNA (P<0.001). d the cell numbers of invasive cells infected with SIRT 1 si-RNA and control si-RNA (P<0.001). </p

Analysis of the sensitivity and reproducibility of UNDP-PCR.

<p>(A) Serial dilutions of PCV2 plasmid DNA were detected by conventional PCR. (B) Serial dilutions of PCV2 plasmid DNA were detected by UNDP-PCR. (C) Serial dilutions of PCV2 serum samples were detected by UNDP-PCR. (D) Serial dilutions of PCV2 serum samples were detected by conventional PCR. (E) Indicated three concentration of PCV2 serum samples were detected by UNDP-PCR in triplicates and in three independent runs. Agarose gel electrophoresis data in upper, middle and lower panels are representative three independent experiments. Lane M: Trans 2000 Plus DNA Marker; lane 1–3∶5×10³; lane 4–6∶5×10²; lane 7–9∶5×10¹; lane10: negative samples.</p

Different serotypes and genotypes of porcine circovirus type 2 used in this study.

<p>Different serotypes and genotypes of porcine circovirus type 2 used in this study.</p

Analysis of the detection breadth of UNDP-PCR.

<p>(A) Functionalized MMP-p5 were incubated with the DNA derived from different PCV2 representative strains in hybridization buffer at 40°C for 30 min, then oligo4 functionalized Au-NPs were added and incubated at 50°C for 30 min with stirring. After washing and magnetic separation, oligo4 were then detected by PCR as described in Methods. (B) PCV2 poly antibodies functionalized magnetic microparticles incubated with different PCV2 representative strains in assay buffer (1% BSA, 1X PBS, 0.2% Tween20 and 2% sheep serum). Antigen-antibody immune complexes were separated magnetically and were washed twice with 1 ml of magnetic-probe solution that contained PBS pH 7.4, 0.1% BSA and 0.05% Tween20. Then viral DNA were extracted by Viral DNA purification Kit, followed by PCV2-specific PCR detection. Lane: M: Trans 2000 Plus DNA Marker; 1: AF381176; 2: DQ104423; 3: AF112862; 4: EU366323; 5: AY579893; 6: AY391729; 7: FJ644927; 8: AY291317; 9: AY484410; 10: AY181947; 11: KC800634; 12: KC800636; 13: KC800639; 14: KC800644; 15: KC800646; 16: AY193712 (PCV1).</p

Comparison of the detection rate of PCV2 infected preclinical samples by conventional PCR, real-time PCR and UNDP-PCR methods.

<p>Comparison of the detection rate of PCV2 infected preclinical samples by conventional PCR, real-time PCR and UNDP-PCR methods.</p

Agarose gel electrophoresis of the relative viral load levels of 11 positive preclinical specimens identified by UNDP-PCR.

<p>Lane M: Trans 2000 Plus DNA Marker; lane 1–11: preclinical specimens; lane 12∶5×10³ Standards; lane 13∶5×10² Standards; lane 14∶5×10¹ Standards; lane15: negative samples.</p