4,4′-[(2,7-Dibromo­fluorene-9,9-di­yl)dimethyl­ene]dipyridinium bis­(perchlorate)

In the crystal of the title compound, C25H20Br2N2 2+·2ClO4 −, inter­molecular N—H⋯O and C—H⋯O hydrogen bonds, along with C—H⋯π inter­actions, stabilize the crystal structure

A glutathione-responsive silica-based nanosystem capped with in-situ polymerized cell-penetrating poly(disulfide)s for precisely modulating immuno-inflammatory responses

International audienceHypothesisPrecise modulation of immuno-inflammatory response is crucial to control periodontal diseases and related systemic comorbidities. The present nanosystem with the controlled-release and cell-penetrating manner enhances the inflammation modulation effects of baicalein in human gingival epithelial cells (hGECs) for better oral healthcare.ExperimentsWe constructed a red-emissive mesoporous silica nanoparticle-based nanosystem with cell-penetrating poly(disulfide) (CPD) capping, through a facile in-situ polymerization approach. It was featured with a glutathione-responsive manner and instant cellular internalization capacity for precisely delivering baicalein intracellularly. Laboratory experiments assessed whether and how the nanosystem per se with the delivered baicalein could modulate immuno-inflammatory responses in hGECs.FindingsThe in-situ polymerized CPD layer capped the nanoparticles and yet controlled the release of baicalein in a glutathione-responsive manner. The CPD coating could facilitate cellular internalization of the nanosystem via endocytosis and thiol-mediated approaches. Notably, the intracellularly released baicalein effectively downregulated the expression of pro-inflammatory cytokines through inhibiting the NF-κB signaling pathway. The nanosystem per se could modulate immuno-inflammatory responses by passivating the cellular response to interlukin-1β. This study highlights that the as-synthesized nanosystem may serve as a novel multi-functional vehicle to modulate innate host response via targeting the NF-κB pathway for precision healthcare

Variation in global chemical composition of PM2.5: emerging results from SPARTAN

The Surface PARTiculate mAtter Network (SPARTAN) is a long-term project that includes characterization of chemical and physical attributes of aerosols from filter samples collected worldwide. This paper discusses the ongoing efforts of SPARTAN to define and quantify major ions and trace metals found in fine particulate matter (PM2.5). Our methods infer the spatial and temporal variability of PM2.5 in a cost-effective manner. Gravimetrically weighed filters represent multi-day averages of PM2.5, with a collocated nephelometer sampling air continuously. SPARTAN instruments are paired with AErosol RObotic NETwork (AERONET) sun photometers to better understand the relationship between ground-level PM2.5 and columnar aerosol optical depth (AOD). We have examined the chemical composition of PM2.5 at 12 globally dispersed, densely populated urban locations and a site at Mammoth Cave (US) National Park used as a background comparison. So far, each SPARTAN location has been active between the years 2013 and 2016 over periods of 2-26 months, with an average period of 12 months per site. These sites have collectively gathered over 10 years of quality aerosol data. The major PM2.5 constituents across all sites (relative contribution±SD) are ammoniated sulfate (20%±11%), crustal material (13.4%±9.9%), equivalent black carbon (11.9%±8.4%), ammonium nitrate (4.7%±3.0%), sea salt (2.3%±1.6%), trace element oxides (1.0%±1.1%), water (7.2%±3.3%) at 35% RH, and residual matter (40%±24%). Analysis of filter samples reveals that several PM2.5 chemical components varied by more than an order of magnitude between sites. Ammoniated sulfate ranges from 1.1μg m-3 (Buenos Aires, Argentina) to 17μg m-3 (Kanpur, India in the dry season). Ammonium nitrate ranged from 0.2μg m-3 (Mammoth Cave, in summer) to 6.8 μg m-3 (Kanpur, dry season). Equivalent black carbon ranged from 0.7μg m-3 (Mammoth Cave) to over 8μg m-3 (Dhaka, Bangladesh and Kanpur, India). Comparison of SPARTAN vs. coincident measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network at Mammoth Cave yielded a high degree of consistency for daily PM2.5 (r2 = 0.76, slope = 1.12), daily sulfate (r2 = 0.86, slope = 1.03), and mean fractions of all major PM2.5 components (within 6%). Major ions generally agree well with previous studies at the same urban locations (e.g. sulfate fractions agree within 4% for 8 out of 11 collocation comparisons). Enhanced anthropogenic dust fractions in large urban areas (e.g. Singapore, Kanpur, Hanoi, and Dhaka) are apparent from high Zn:Al ratios. The expected water contribution to aerosols is calculated via the hygroscopicity parameter κv for each filter. Mean aggregate values ranged from 0.15 (Ilorin) to 0.28 (Rehovot). The all-site parameter mean is 0.20±0.04. Chemical composition and water retention in each filter measurement allows inference of hourly PM2.5 at 35% relative humidity by merging with nephelometer measurements. These hourly PM2.5 estimates compare favourably with a beta attenuation monitor (MetOne) at the nearby US embassy in Beijing, with a coefficient of variation r2 = 0.67 (n = 3167), compared to r2 = 0.62 when κv was not considered. SPARTAN continues to provide an open-access database of PM2.5 compositional filter information and hourly mass collected from a global federation of instruments.Fil: Snider, Graydon. Dalhousie University Halifax; CanadáFil: Weagle, Crystal L.. Dalhousie University Halifax; CanadáFil: Murdymootoo, Kalaivani K.. Dalhousie University Halifax; CanadáFil: Ring, Amanda. Dalhousie University Halifax; CanadáFil: Ritchie, Yvonne. Dalhousie University Halifax; CanadáFil: Stone, Emily. Dalhousie University Halifax; CanadáFil: Walsh, Ainsley. Dalhousie University Halifax; CanadáFil: Akoshile, Clement. University Of Ilorin; NigeriaFil: Anh, Nguyen Xuan. Vietnamese Academy Of Science And Technology; VietnamFil: Balasubramanian, Rajasekhar. National University Of Singapore; SingapurFil: Brook, Jeff. University of Toronto; CanadáFil: Qonitan, Fatimah D.. Institut Teknologi Bandung; IndonesiaFil: Dong, Jinlu. Tsinghua University; ChinaFil: Griffith, Derek. The Council For Scientific And Industrial Research; SudáfricaFil: He, Kebin. Tsinghua University; ChinaFil: Holben, Brent N.. National Aeronautics and Space Administration. Goddart Institute for Space Studies; Estados UnidosFil: Kahn, Ralph. National Aeronautics and Space Administration. Goddart Institute for Space Studies; Estados UnidosFil: Lagrosas, Nofel. Manila University; FilipinasFil: Lestari, Puji. Institut Teknologi Bandung; IndonesiaFil: Ma, Zongwei. Nanjing University; ChinaFil: Misra, Amit. Indian Institute Of Technology; IndiaFil: Norford, Leslie K.. Massachusetts Institute of Technology; Estados UnidosFil: Quel, Eduardo Jaime. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Salam, Abdus. University Of Dhaka; BangladeshFil: Schichtel, Bret. State University of Colorado - Fort Collins; Estados UnidosFil: Segev, Lior. Weizmann Institute Of Science Israel; IsraelFil: Tripathi, Sachchida. Indian Institute Of Technology; IndiaFil: Wang, Chien. Massachusetts Institute of Technology; Estados UnidosFil: Yu, Chao. University Of Emory. Rollins School Of Public Health; Estados UnidosFil: Zhang, Qiang. Tsinghua University; ChinaFil: Zhang, Yuxuan. Tsinghua University; ChinaFil: Brauer, Michael. University of British Columbia; CanadáFil: Cohen, Aaron. Health Effects Institute; Estados UnidosFil: Gibson, Mark D.. Dalhousie University Halifax; CanadáFil: Liu, Yang. University Of Emory. Rollins School Of Public Health; Estados UnidosFil: Martins, J. Vanderlei. University of Maryland; Estados UnidosFil: Rudich, Yinon. Weizmann Institute Of Science Israel; IsraelFil: Martin, Randall V.. Dalhousie University Halifax; Canadá. Harvard-Smithsonian Center for Astrophysics; Estados Unido