Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

Particulate Matter Ionic and Elemental Composition during the Winter Season: A Comparative Study among Rural, Urban and Remote Sites in Southern Italy

We present an overview of the concentrations and distributions of water-soluble ion species and elemental components in ambient particulate matter for five measurement sites in southern Italy with the aim of investigating the influence of the different site characteristics on PM levels. The sites encompass different characteristics, ranging from urban to coastal and high-altitude remote areas. PM10 and PM2.5 fractions were collected simultaneously using dual channel samplers during the winter period from November 2015 to January 2016 and analyzed for water-soluble ion species, using ion chromatography, and elemental composition, using inductively coupled plasma mass spectrometry (ICP-MS). In all sites, PM2.5 represented the higher contribution to particulate mass, usually more than two times that of the coarse fraction (PM2.5−10). At the coastal site in Capo Granitola (Western Sicily), sea salts constituted about 30% of total PM10 mass. On average, ion species accounted for 30% to 60% of total PM10 mass and 15% to 50% of PM2.5 mass. We found that secondary ion species, i.e., SO42−, NO3− and NH4+ dominated the identifiable components within both PM2.5 and PM10 fractions. The chlorine–sodium ratio was usually lower than that expected from the natural level in sea salt, evidencing aged air masses. At the monitoring site in Naples, a highly urbanized area affected by high levels of anthropogenic source emissions, an increased contribution of ammonium was found, which was imputed to the increased ammonia emissions from industrial combustion sources and road traffic. The concentrations of the investigated elements showed noteworthy differences from one site to another. The PM10 fraction was highly enriched by sources of anthropogenic origin in the samples from the most urbanized areas. In general, the enrichment factors of the elements were similar between the PM10 and PM2.5 fractions, confirming common sources for all elements.

Katabatic Wind and Sea-Ice Dynamics Drive Isotopic Variations of Total Gaseous Mercury on the Antarctic Coast

Clarifying the sources and fates of atmospheric mercury (Hg) in the Antarctic is crucial to understand the global Hg circulation and its impacts on the fragile ecosystem of the Antarctic. Herein, the annual variations in the isotopic compositions of total gaseous Hg (TGM), with 5-22 days of sampling duration for each sample, were presented for the first time to provide isotopic evidence of the sources and environmental processes of gaseous Hg around the Chinese Great Wall Station (GWS) in the western Antarctic. Different from the Arctic tundra and lower latitude areas in the northern hemisphere, positive δ²⁰²Hg (0.58 ± 0.21‰, mean ± 1SD) and negative Δ¹⁹⁹Hg (-0.30 ± 0.10‰, mean ± 1SD) in TGM at the GWS indicated little impact from the vegetation-air exchange in the Antarctic. Correlations among TGM Δ¹⁹⁹Hg, air temperature, and ozone concentrations suggested that enhanced katabatic wind that transported inland air masses to the continental margin elevated TGM Δ¹⁹⁹Hg in the austral winter, while the surrounding marine surface emissions controlled by sea-ice dynamics lowered TGM Δ¹⁹⁹Hg in the austral summer. The oxidation of Hg(0) might elevate Δ¹⁹⁹Hg in TGM during atmospheric Hg depletion events but have little impact on the seasonal variations of atmospheric Hg isotopes. The presented atmospheric Hg isotopes were essential to identify the transport and transformation of atmospheric Hg and further understand Hg cycling in the Antarctic.

Emerging investigator series: influence of marine emissions and atmospheric processing on individual particle composition of summertime Arctic aerosol over the Bering Strait and Chukchi Sea

The Arctic is rapidly transforming due to sea ice loss, increasing shipping activity, and oil and gas development. Associated marine and combustion emissions influence atmospheric aerosol composition, impacting complex aerosol-cloud-climate feedbacks. To improve understanding of the sources and processes determining Arctic aerosol composition, atmospheric particles were collected aboard the Korean icebreaker R/V Araon cruising within the Bering Strait and Chukchi Sea during August 2016. Offline analyses of individual particles by microspectroscopic techniques, including scanning electron microscopy with energy dispersive X-ray spectroscopy and atomic force microscopy with infrared spectroscopy, provided information on particle size, morphology, and chemical composition. The most commonly observed particle types were sea spray aerosol (SSA), comprising ∼60-90%, by number, of supermicron particles, and organic aerosol (OA), comprising ∼50-90%, by number, of submicron particles. Sulfate and nitrate were internally mixed within both SSA and OA particles, consistent with particle multiphase reactions during atmospheric transport. Within the Bering Strait, SSA and OA particles were more aged, with greater number fractions of particles containing sulfate and/or nitrate, compared to particles collected over the Chukchi Sea. This is indicative of greater pollution influence within the Bering Strait from coastal and inland sources, while the Chukchi Sea is primarily influenced by marine sources.

Freezing-Induced Bromate Reduction by Dissolved Organic Matter and the Formation of Organobromine Compounds

The freezing-induced acceleration of bromate reduction by humic substances (HS) contributes to HS bromination and the formation of organobromine compounds (OBCs). Herein, we report the enhanced reduction of bromate by dissolved organic matter and the formation of large amounts of OBCs in freezing solutions. After 48 h of freezing process, 78.1-100% of bromate was reduced by DOM at different initial concentrations of bromate and DOM in acidic solutions (pH 3 and 4). Bromide was one of the main reduction products, and it accounted for 30.9-47.8% of the total bromine content. Except for bromide, a large amount of OBCs formed by brominating DOM with reactive bromine species, like hypobromite, were detected. The conversion of bromate to OBCs, calculated as the total organobromine content to the initial bromate content, ranged from 28.2 to 52.5% and was mainly dependent on the bromate/DOM content. About 110-603 species of OBCs were detected by Fourier transform ion cyclotron resonance mass spectrometry, and they were primarily highly unsaturated and phenolic compounds. By analyzing the spectral variation before and after the freezing process, we found the disappearance of 900 compounds containing only C, H, and O with a low carbon oxidation state that was regarded as the main reductant of bromate. Our findings call for further investigation of the processes and the effects of bromate formation in aqueous environments.

Chemical Constituents of Carbonaceous and Nitrogen Aerosols over Thumba Region, Trivandrum, India

Aerosol filter samples collected at a tropical coastal site Thumba over Indian region were analysed for water-soluble ions, total carbon and nitrogen, organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon/nitrogen and their sources for different seasons of the year. For the entire study period, the order of abundance of ions showed the dominance of secondary ions, such as SO₄^2-, NO₃^-, and NH₄⁺. On average, Mg²⁺ (56%), K⁺ (11%), SO₄^2- (8.8%), and Ca²⁺ (8.1%) contributions were from maritime influence. There was significant chloride depletion due to enhanced levels of inorganic acids, such as SO₄^2- and NO₃^-. Total carbon contributed 21% of the aerosol total suspended particulate matter in which 85% is organic carbon. Primary combustion-generated carbonaceous aerosols contributed 41% of aerosol mass for the entire study period. High average ratios of OC/EC (5.5 ± 1.8) and WSOC/OC (0.38 ± 0.11) suggest that organic aerosols are predominantly comprised of secondary species. In our samples, major fraction (89 ± 9%) was found to be inorganic nitrate in total nitrogen (TN). Good correlations (R ² ≥ 0.82) were observed between TN with NO₃^- plus NH₄⁺, indicating that nitrate and ammonium ions account for a significant portion of TN. The temporal variations in the specific carbonaceous aerosols and air mass trajectories demonstrated that several pollutants and/or their precursor compounds are likely transported from north western India and the oceanic regions.

Global Inorganic Source of Atmospheric Bromine

A few bromine molecules per trillion (ppt) causes the complete destruction of ozone in the lower troposphere during polar spring and about half of the losses associated with the "ozone hole" in the stratosphere. Recent field and aerial measurements of the proxy BrO in the free troposphere suggest an even more pervasive global role for bromine. Models, which quantify ozone trends by assuming atmospheric inorganic bromine (Bry) stems exclusively from long-lived bromoalkane gases, significantly underpredict BrO measurements. This discrepancy effectively implies a ubiquitous tropospheric background level of approximately 4 ppt Bry of unknown origin. Here, we report that I- efficiently catalyzes the oxidation of Br- and Cl- in aqueous nanodroplets exposed to ozone, the everpresent atmospheric oxidizer, under conditions resembling those encountered in marine aerosols. Br- and Cl-, which are rather unreactive toward O3 and were previously deemed unlikely direct precursors of atmospheric halogens, are readily converted into IBr2- and ICl2- en route to Br2(g) and Cl2(g) in the presence of I-. Fine sea salt aerosol particles, which are predictably and demonstrably enriched in I- and Br-, are thus expected to globally release photoactive halogen compounds into the atmosphere, even in the absence of sunlight.