Evaluation of genipin-crosslinked chitosan hydrogels as a potential carrier for silver sulfadiazine nanocrystals

In the present study genipin crosslinked chitosan (CHI) hydrogels, which had been constructed and reported in our previous studies (Lei Gao, et al. Colloids Surf. B Biointerfaces. 2014, 117: 398), were further evaluated for their advantage as a carrier for silver sulfadiazine (AgSD) nanocrystal systems. Firstly, AgSD nanocrystals with a mean particle size of 289 nm were prepared by wet milling method and encapsulated into genipin crosslinked CHI hydrogels. AgSD nanocrystals displayed a uniform distribution and very good physical stability in the hydrogel network. Swelling-dependent release pattern was found for AgSD nanocrystals from hydrogels and the release profile could be well fitted with Peppas equation. When AgSD nanocrystals were encapsulated in hydrogels their fibroblast cytotoxicity decreased markedly, and their antibacterial effects against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were still comparable to unencapsulated AgSD nanocrystals. In vivo evaluation in excision and burn cutaneous wound models in mice showed that AgSD nanocrystal hydrogels markedly decreased the expression of inflammatory cytokine IL-6, but increased the levels of growth factors VEGF-A and TGF-β1. Histopathologically, the wounds treated by hydrogels containing AgSD nanocrystals showed the best healing state compared with commercial AgSD cream, hydrogels containing AgSD bulk powders and blank hydrogels. The wounds treated by AgSD nanocrystal hydrogels were dominated by marked fibroblast proliferation, new blood vessels and thick regenerated epithelial layer. Sirius Red staining assay indicated that AgSD nanocrystal hydrogels resulted in more collagen deposition characterized by a large proportion of type I fibers. Our study suggested that genipin-crosslinked CHI hydrogel was a potential carrier for local antibacterial nanomedicines

Effect of SO₂ on CO₂ Absorption in Flue Gas by Ionic Liquid 1‑Ethyl-3-methylimidazolium Acetate

Significant efforts are being made to develop several novel solvents or materials for postcombustion CO₂ capture technology. Traditional amine solvents suffer from mass loses due to its volatility and poisoning by flue gas impurities. Ionic liquids (ILs) are considered to be promising alternatives for CO₂ capture due to their unique features, such as negligible vapor pressure. Despite the extensive research on CO₂ capture by ILs, few studies have investigated the effect of flue gas components on CO₂ absorption performance. Because of the large differences between CO₂ and SO₂ in the absorption capacity and partial pressure in flue gas, it is essential to study the role of SO₂ in CO₂ capture using ILs. This work focused on studying the effect of SO₂ with low concentration on postcombustion CO₂ capture by 1-ethyl-3-methylimidazolium acetate [C₂mim]­[OAc] and explaining the microscopic mechanism through quantum chemical calculation. Results showed that the CO₂ absorption capacity was largely decreased by 25% in the presence of SO₂. After 5 cycles of regeneration, the initial absorption capacity of CO₂ in [C₂mim]­[OAc] remarkably decreased by 48%. Thus, the ionic liquid lost its excellent reversibility and regeneration property for CO₂ capture under continuous exposure to SO₂. The quantum chemical calculation indicated that CO₂ could hardly compete with SO₂ for the main active sites in [C₂mim]­[OAc]. In addition, the net charge transfer amount from acetate anion to CO₂ significantly decreased from −0.537 to −0.039 e in the presence of SO₂, which explained the decreased absorption capacity of CO₂ in [C₂mim]­[OAc]

Synthesis of Mg-Doped Ordered Mesoporous Pd–Al₂O₃ with Different Basicity for CO, NO, and HC Elimination

Employing NH₄HCO₃ as pore-enlarging agent and P123 as a template agent, ordered mesoporous Mg-doped γ-Al₂O₃ with different basicity and large surface area have been successfully synthesized by a facile sol–gel approach by adjusting the content of magnesium and pH value. Specifically, the result alumina calcined at 1000 °C with large specific surface area (234.4 m² g^–1) and high pore volume (0.72 cm³ g^–1) was obtained when the Mg content was 9 wt %. These materials with ordered mesostructure and advantageous structural properties were utilized as carriers of Pd–Al₂O₃ catalysts for the catalytic reaction of simulated exhaust automobile gases including CO, NO, and hydrocarbon (HC). The results revealed that the high catalytic performance of Pd/9Mg-OMA originated from its more appropriate basicity, greater PdO dispersion, and higher surface area

Inhibitors of cathepsin B reduce caspase-1 activation in macrophages infected with KIM5.

<p>BMDMs were left untreated or treated with 25 µM of E64d or CA-074 Me (CA) for 1 hr. Following infection with <i>Y. pestis</i> strains expressing YopJ^KIM in the absence or presence of the inhibitors, supernatants were collected (A, B) or microscopic assay was performed (C). IL-1β ELISA (A) and LDH release assay (B) was done on supernatants collected 24 hr post-infection. Results shown are the averages from three independent experiments. Error bars represent standard deviations. (★★, <i>P</i><0.01 as determined by one way ANOVA as compared to infection in absence of inhibitor) (C) Infected BMDMs on coverslips were incubated with FAM-YVAD-FAM 9 hr post-infection stained for active caspase-1 (green) for 1 hr and PI uptake (red) immediately before observation. Representative images of phase, green and red signals were captured by digital photomicroscopy.</p

Caspase-3/7 activity is low in KIM5-infected macrophages.

<p>(A) BMDMs were left uninfected (U) or infected with <i>Y. pestis</i> strains expressing YopJ^KIM or YopJ^C172A in 96-white walled tissue culture plates. Caspase-3/7 activity was measured 4, 8, 12 or 24 hr post-infection with fluorometer. The results from three independent experiments were averaged and are shown as fold change compared to uninfected cells. Error bars represent standard deviations. Differences in caspase-3/7 activities between uninfected and infected cells were not significant as determined by two way ANOVA (B) BMDMs were left uninfected (U) or infected with <i>Y. pestis</i> strains expressing YopJ^KIM or YopJ^C172A or treated with 1 µM of staurosporine (STS) for 16 hr. Macrophage lysates were collected and analyzed by PARP immunoblotting. Sizes of molecular weight standards (kDa) are shown on the left. Positions of full length PARP and cleaved PARP (c-PARP) are showed on right.</p

HMGB1 is released from KIM5-infected macrophages.

<p>BMDMs were infected with <i>Y. pestis</i> strains expressing YopJ^KIM or YopJ^C172A or left uninfected (U). Medium from infected macrophages was collected at 24 hr post infection and immunoblotted for HMGB1. Total cell lysate (Lys) was used as a positive control. Position of molecular weight standard (kDa) is shown on the left.</p

Caspase-1 is not required for innate host protection against <i>Yersinia</i> endowed with enhanced cytotoxicity.

<p>(A) Six to eight-week old Casp1<i>^+/+</i> (wild type, WT) or Casp1<i>^−/−</i> (Casp1-) C57BL/6J mice were infected orogastrically with 1×10⁹ CFU of <i>Y. pseudotuberculosis</i> IP26 carrying pACYC184 encoding YopP or YopJ^YPTB. Mouse survival was monitored for 21 days. Results shown are pooled from two independent experiments. Total numbers of mice infected are shown in parenthesis. (B) Data from (A) are reformatted by grouping mice according to infecting strain. Significant difference between survival curves was determined by log rank test.</p

Enhanced YopP-mediated macrophage cell death is associated with elevated levels of IL-1β release.

<p><i>Y. pseudotuberculosis</i> IP26 (<i>ΔyopJ</i>) carrying the empty pACYC184 plasmid (pACYC) or pACYC184 encoding the indicated YopP or YopJ isoforms was used to infect BMDMs. Twenty four hours post-infection, medium was collected for IL-1β ELISA (A) and LDH release assay (B). Results shown are the averages from three independent experiments. Error bars represent standard deviations (★★, <i>P</i><0.01; ★★★, <i>P</i><0.001 as determined by one way ANOVA as compared to pACYC condition).</p

KIM5-infected necrotic macrophages contain active caspase-1.

<p>BMDMs were seeded on glass coverslips in a 24-well plate and left uninfected (U) or infected with <i>Y. pestis</i> strains expressing YopJ^KIM or YopJ^C172A. FAM-YVAD-FMK was added at 9 hr post infection to stain for active caspase-1 and PI uptake assay was performed immediately before microscopic analysis. (A) Representative images of phase, active caspase-1 (green) and PI uptake (red) signals captured by digital photomicroscopy are shown in a-c and e-g, respectively. Panels d and h show merged images of green and red signals. (B) Average percentages of BMDMs positive for active caspase-1, PI or both signals was calculated (∼100–300 cells per field) from three random fields in three independent experiments. Error bars represent standard deviations.</p

RIP1 is not required for YopJ^KIM-induced cell death or IL-1β secretion.

<p>BMDMs were treated with 30 µM RIP1 inhibitor necrostatin-1 (Nec) or vehicle 1 hr prior to and during infection. BMDMs were infected with <i>Y. pestis</i> strains expressing YopJ^KIM or YopJ^C172A or left uninfected (U). Supernatants were collected and LDH release (A) and secreted IL-1β (B) were measured at 8 hr or 24 hr post-infection from three independent experiments. Results shown are averages and error bars represent standard deviations (★★, <i>P</i><0.01 as determined by one way ANOVA as compared to YopJ^KIM no inhibitor).</p