Physicochemical Properties Of Particles Research Articles

Acute cardiovascular effects of inhaled ambient particulate matter: Chemical composition-related oxidative stress, endothelin-1, blood pressure, and ST-segment changes in Wistar rats

Short-term increases in particulate matter (PM) are associated with heightened morbidity and mortality from cardiovascular causes. Inhalation of PM is known to increase endothelin (ET)-1 levels. Yet, less is known about particle composition-related changes at the molecular level including the endothelinergic system and relationship with cardiovascular function changes. In this work, adult Wistar male rats were exposed for 4 h by nose-only inhalation to clean air, Ottawa urban particles (EHC-93, 48 mg/m3) and water-leached (EHC-93L, 49 mg/m3) particles, to examine the effect of particle compositional changes on oxidative stress, circulating ETs, blood pressure, and heart electrophysiology. Particle deposition in the respiratory compartment was estimated at 85 μg (25 ng/cm2). Lung cell proliferation was low in both treatment groups, indicating absence of acute injury. Inhalation of EHC-93 caused statistically significant elevations (p < 0.05) of oxidative stress markers, ET-1, ET-3, blood pressure, and a decrease of ST-segment duration in the ECG at 1.5 days post-exposure. Leached particles (EHC-93L) caused rapid but transient elevation (p < 0.05) of oxidative stress, ET-1, ET-2, and ET-3 at earlier time points, with no changes in blood pressure or ST-segment. These results demonstrate that inhalation of urban particles at an internal dose inadequate to cause acute lung injury can induce oxidative stress, enhance vasoactive endothelins, leading to vasopressor response, affecting cardiac electrophysiology in Wistar rats, consistent with the cardiovascular impacts of ambient particles in human populations. Change in particle potency after removal of soluble species, notably cadmium, zinc and polar organics suggests that the toxicodynamics of cardiovascular effects can be modified by physicochemical properties of particles.

The roadmap to micro: Generation of micron-sized polymeric particles using a commercial microfluidic system.

Microfluidic-assisted particle fabrication provides a route to circumvent the disadvantages associated with traditional methods of polymeric particle generation, such as low drug loading efficiency, challenges in controlling encapsulated drug release rates, batch-to-batch variability in particle physical properties and formulation instability. However, this approach primarily produces particles with nanometer size dimensions, which limits drug delivery modalities. Herein, we systematically studied parameters for the generation of micron-sized poly(lactic-co-glycolic) acid (PLGA) particles using a microfluidic system, the NanoAssemblr benchtop. Initially, we used two organic solvents that have been reported suitable for the fabrication of PLGA nanoparticles - acetone and acetonitrile. Subsequently, we methodically manipulated polymer concentration, organic: aqueous flow rate ratios, total flow rate, organic phase composition, and surfactant concentration to develop a route for the fabrication of micron-sized PLGA particles. Further, we incorporated hydroxychloroquine (HCQ), a clinically approved drug for malaria and lymphoma, and measured how its incorporation impacted particle physicochemical properties. Briefly, altering the organic phase composition by including ethyl acetate (less polar solvent), resulted in micron-scale particles, as well as increased polydispersity indexes (PDIs). Adjusting the surfactant concentration of poly vinyl alcohol (PVA) after the addition of these solvent mixtures rendered large particles with lower PDI variability. Moreover, encapsulation of HCQ influenced particle hydrodynamic diameter and PDI in a PVA concentration dependent manner. Finally, we demonstrated that unloaded and HCQ-loaded microparticles did not affect the viability of RAW 264.7 macrophages. This study provides an itinerary for fabricating biocompatible, drug-loaded, micron-sized polymeric particles, particularly when the drug of interest is not readily soluble in conventional organic solvents.

Examining the Effects of Microalgal Metabolites on Ciliary Activity of the Eastern Oyster Crassostrea virginica

Suspension-feeding bivalve molluscs have evolved a highly effective mechanism for particle discrimination, which allows them to process efficiently the material to which they are exposed. The mechanisms controlling this preingestive sorting process have been described as either passive or active. Evidence of a passive selection mechanism has been demonstrated in several species of suspension-feeding bivalves. In contrast, to date there has been no evidence that active selection mechanisms underlay particle selection in bivalves, although the possibility of such mechanisms has been hypothesized numerous times. The present study was designed to examine active selection on the gill of the eastern oyster Crassostrea virginica. The gill was chosen for study because in oysters this organ is involved in particle selection. Two in vivo assays were designed in which the gill was exposed to dissolved cell exudate or extracts from the microalga Tetraselmis chuii, and the transport of polystyrene microspheres (25 µm) by the frontal cilia of the ordinary filament quantified by means of video endoscopy. Results demonstrated that the addition of exudates or extracts of T. chuii cells had no significant effect on the percentage of particles being transported dorsally (likely ingested) or ventrally (more likely rejected), and no differences in the number of particles in the ventral groove between control and experimental treatments. Results of follow-up experiments using covalently bound neoglycoproteins commonly found on cell surfaces of microalgal species demonstrated differences in transport of captured microspheres (10 µm, carboxylated) depending on the sugar type. Although chemoreception cannot be completely ruled out, these findings further indicate that physicochemical properties of particles, and not an active behavioral or physiological response (i.e., chemoreception of dissolved metabolites) by the animal, mediate particle selection in oysters.

Immersion Freezing Ability of Freshly Emitted Soot with Various Physico-Chemical Characteristics

The immersion freezing ability of soot particles has in previous studies been reported in the range of low/insignificant to very high. The aims of this study were to: (i) perform detailed physico-chemical characterisation of freshly produced soot particles with very different properties, (ii) investigate the immersion freezing ability of the same particles, and (iii) investigate the potential links between physico-chemical particle properties and ice-activity. A miniCAST soot generator was used to produce eight different soot samples representing a wide range of physico-chemical properties. A continuous flow diffusion chamber was used to study each sample online in immersion mode over the temperature (T) range from −41 to −32 °C, at a supersaturation of about 10% with respect to liquid water. All samples exhibited low to no heterogeneous immersion freezing. The most active sample reached ice-activated fractions (AF) of 10−3 and 10−4 at temperatures of 1.7 and 1.9 K , respectively, above the homogeneous freezing temperature. The samples were characterized online with respect to a wide range of physico-chemical properties including effective particle density, optical properties, particle surface oxidation and soot maturity. We did observe indications of increasing immersion freezing ice-activity with increasing effective particle density and increasing particulate PAH fraction. Hence, those properties, or other properties co-varying with those, could potentially enhance the immersion freezing ice-activity of the studied soot particle types. However, we found no significant correlation between the physico-chemical properties and the observed ice-nucleating ability when the particle ensemble was extended to include previously published results including more ice-active biomass combustion soot particles. We conclude that it does not appear possible in general and in any straightforward way to link observed soot particle physico-chemical properties to the ice-nucleating ability using the online instrumentation included in this study. Furthermore, our observations support that freshly produced soot particles with a wide range of physico-chemical properties have low to insignificant immersion freezing ice-nucleating ability.

Sucrosomial Iron Absorption Involve M Cells Interaction

Introduction: Iron deficiency anemia (IDA) represents a major public health problem. Oral administration has been recognized as the most convenient and safest route for iron treatment. However, most of the traditional iron supplements encounter several obstacles when orally administrated due to their poor solubility and bioavailability. The absorption of commonly used ferrous iron salts is low as the soluble form ferrous iron is easily oxidized to a poorly soluble one ferric iron and also because the absorption of ferrous iron is mediated by the divalent metal transporter 1. In order to overcome gastrointestinal barriers, there is a need for new absorption and protective enhancers acting as carriers and able to promote iron absorption. Microfold cells (M cells) of the Peyer's patches (PP) are found in the gut and mucosa-associated lymphoid tissues. These cells are known for the transport of microbes and particles across the epithelial cell layer from the gut lumen to the lamina propria where interactions with immune cells take place. Previous studies demonstrate that M cells are a common pathway for oral nanoparticles absorption. However physicochemical properties of particles critically influence the efficacy of oral delivery to the lymphatic system. Recently, we have developed a new oral Iron formulation named Sucrosomial® Iron. This oral formulation is an innovative preparation of ferric pyrophosphate, covered by a phospholipids plus sucrester matrix, with high bioavailability, tolerability and gastro-resistance properties that shows an improvement in Hb levels similarly to intravenous iron and without any gastrointestinal side effects; thus, Sucrosomial®Iron can be used as an alternative to common iron salts to improve iron supplementation effectiveness.Aim: to investigate Sucrosomial® Iron absorption pathways using different experimental models.Methods: In order to study the absorption pathways of Sucrosomial® Iron, absorption and transport experiments were performed using in vitro CACO2/RajiB co-culture system and MatTek EpiIntestinalTM human 3D in vitro small intestinal tissue model with epithelialpolarity. Furthermore, the bioavailability of Sucrosomial® Iron was assessed, in terms of tissue distribution and iron metabolism markers expression, using in vivo and ex-vivo models.Results: in vitro transport study using MatTek EpiIntestinalTM model showed a fast increase in iron concentration in the basolateral compartment over time in tissues treated with Sucrosomial® Iron (2,7 ug ±1,7) compare to samples treated with Ferrous Sulfate (1,3 ug ±1,1) or Iron Bisglycinate (1,6 ug ±1,1), indicating an endocytosis mediated uptake confirmed by TEM analysis (Figure 1A-B). M cells involvement was evaluated using in vitro CACO2/RajiB co-culture system. After cells incubation, the iron content in apical media of cells (monocultures and co-cultures) treated with Sucrosomial® Iron was significantly lower compare to cells treated with other iron formulations (Figure 2A). Iron to protein ratio showed a significant iron increase in co-colture cells treated with Sucrosomial® Iron compared to other iron samples (Figure 2B). Sucrosomial® Iron, passed through M cells, was taken up by CD68+ macrophage cells as confirmed by ex-vivo experiments, in which fluorescein tagged Sucrosomial® Iron was added to an isolated rat intestine using Hussing chamber-like model, then analyzed by immunohistochemistry. To study the reticuloendothelial system involvement, tissue distribution and bioavailability of Sucrosomial® Iron were analyzed using anemic newborn piglets. Animals were treated with Sucrosomial® Iron or Iron dextran and piglets treated with Sucrosomial® Iron showed anincreased Hb concentration and a preferential iron accumulation in spleen (Figure 3A-B). Hepcidin and Ferroportin, but not Dmt1 gene expression were induced at duodenum level (Figure 3C).CONCLUSIONS: these results showed that Sucrosomial® Iron can be directly absorbed bypassing the conventional iron absorption pathway and that M cells, through the reticuloendothelial system, may contribute to its absorption and tissue distribution. [Display omitted] DisclosuresBrilli:Pharmanutra S.p.A.: Consultancy. Tarantino:Pharmanutra S.p.A.: Employment.

Recent advances in nano/microparticle-based oral vaccines.

BackgroundVaccines are often recognized as one of the most cost-effective public health interventions in controlling infectious diseases. Most pathogens infiltrate the body from mucosal sites, primarily from the oral and pulmonary region and reach the systemic circulation where disease manifestation starts. Traditional needle-based vaccines are usually not capable of inducing immunity at the mucosal sites where pathogen infiltrates start, but induces systemic immunity. In contrast to needle-based vaccines, mucosally administered vaccines induce immunity at both the mucosal sites and systemically. The oral route of immunization is the most convenient way to administer the vaccines. However, due to the complicated and hostile gastrointestinal structure and environment, vaccines need to overcome major hurdles while retaining their stability and immunogenicity.Area coveredThis review will briefly discuss different barriers to oral vaccine development. It gives a brief overview of different types of nano/microparticle-based oral vaccines and discusses how physicochemical characteristics of the particles influence overall immunity after oral immunization.Expert opinionFormulation strategies using novel lipid and polymer-based nano/microparticle platforms retain stability and antigenicity of vaccines against the harsh gastrointestinal condition. The physicochemical properties of particles can be uniquely tailored to prolong the release of antigens, and attached ligands (M-cells and APC-ligands) can precisely target uptake by immune cells. These represent viable strategies for efficient delivery of oral vaccines.

Preparation and evaluation of vancomycin spray-dried powders for pulmonary delivery

The aim of the current study was to achieve a dry powder formulation of vancomycin by spray drying whilst evaluating the effect of pH and excipient type and percentage used in formulation on particle characteristics and aerosolization performance. A D-optimal design was applied to optimize the formulation comprising vancomycin and two main excipient groups; a carbohydrate bulking agent (lactose, mannitol or trehalose) and a second excipient (hydroxypropyl beta-cyclodextrin or L-leucine) at pH 4 and 7. The physicochemical properties of particles (size, morphology, crystallinity state, residual moisture content), stability, and aerosolization characteristics were investigated. Using the combination of two excipients increased the fine particle fraction of powder emitted from an Aerolizer® device at a flow rate of 60 L/min. Hydroxypropyl beta-cyclodextrin showed more potential than L-leucine in aerosolization capabilities. Stability studies over 3 months of storage in 40 °C and 75% relative humidity suggested a good physical stability of the optimized formulation containing 17.39% hydroxypropyl beta-cyclodextrin along with 29.61% trehalose relative to the amount of drug at pH 4. Use of two excipients including trehalose and hydroxypropyl beta-cyclodextrin with a total weight ratio of 47% relative to the amount of drug is appropriate for the preparation of vancomycin dry powder formulation for inhalation.

Important Oxidants and Their Impact on the Environmental Effects of Aerosols.

Oxidants are central species in the atmosphere, where they not only determine secondary particle formation but also impact human health and climate change. In general, they are unstable, highly reactive, and recyclable and have been studied in field observations, laboratory studies, and model simulations. The most widely investigated oxidants, such as OH radicals, O3, and Cl atom, HONO, NO3, N2O5, and Criegee Intermediates (CIs) have attracted more attention recently. Furthermore, secondary particles formed in the oxidations processes impact the particle physicochemical properties, such as hygroscopicity and optical properties and therefore impact the atmospheric radiation balance. Therefore, the newest investigation results of important oxidants (HONO, NO3, N2O5, and CIs) are reviewed in this manuscript, and the environmental effects of secondary particles formed through corresponding oxidation processes are also stated. Furthermore, some perspectives are further discussed in the article.

Effects of iron-based fuel borne catalyst addition on combustion, in-cylinder soot distribution and exhaust emission characteristics in a common-rail diesel engine

In order to reduce soot emission and assist diesel particulate filter regeneration, iron-based fuel borne catalyst (Fe-FBC) was added into diesel fuel with Fe element mass fractions of 0, 200 and 400 mg/kg in the preparation of FBC fuels (marked as Diesel, Fe200 and Fe400). The in-cylinder soot distribution, pollutant emissions and particle physicochemical properties of FBC fuels were investigated on a visualization modified common-rail engine. The results show that the combustion starting point is advanced with Fe-FBC addition, while the maximum combustion pressure and heat release rate increase. The addition of Fe-FBC in diesel fuel will shorten ignition delay period, accelerate combustion process and lead to the increase of in-cylinder flame temperature, while the in-cylinder soot concentration and soot area occupation ratio are reduced significantly. HC, CO and soot emissions along with the unconventional emissions such as HCHO, CH3CHO and polycyclic aromatic hydrocarbons (PAHs) decrease at each load as the increase of Fe-FBC addition ratio. Compared with Diesel, the peak soot area occupation ratio and soot emissions of Fe400 decrease by 41.6% and 20.4% respectively at full load. It is also found that Fe-FBC addition decreases particle box-counting dimension, which indicates that the polymerization degree between the particles becomes weaker and their arrangement becomes more sparse and loose, so the oxidation characteristic temperature and the activation energy of soot particles decrease significantly. Fe-FBC addition can effectively reduce the type and content of PAHs and the high carbon atom number compounds in soluble organic fraction from exhaust particles.

The settling of resuspended lake sediment related to physicochemical properties of particles of different sizes: Implication for environmental remediation

Sediment resuspension is an important way for shallow lake internal pollution to interact with the overlying water column, and the pollution risks are reasonably related to the retention of resuspended sediment particles in overlying water. In the current study, the settling of resuspended sediment particles was comprehensively investigated under different disturbances using five urban lake sediments. The results show that the particle size distributions of resuspended sediment from different lakes exhibited similar variations during settling with disturbance, although varied settling times were observed under static conditions. During settling with and without disturbance, sediment particle sizes were mainly within 8–63 μm at the initial stage, and were < 8 μm in the later stages of settling. Based on these settling characteristics, the sediment particle size was divided into sand (> 63 μm), silt (8–63 μm), and very fine silt and clay (< 8 μm) fractions. Kinetic analysis suggested that sediment settling for different particle sizes could be well described by the first- and second-order kinetic equations, especially when settling was disturbed (r2 = 0.727–0.999). The retention of resuspended sediment could be enhanced as particle sizes decreased and disturbance intensities increased. Furthermore, a water elutriation method was successfully optimized, with separation efficiencies of 56.1%–83%, to separate sediment particles into the defined three particle size fractions. The chemical compositions of sediment were found to change with different particle sizes. Typically, calcium tended to form large-size sediment, while the total contents of aluminum, iron, magnesium, and manganese showed significantly negative correlations with sediment particle sizes (p < 0.01) and tended to distribute in small-size particles (e.g., < 8 μm). Overall, the sediment particle size related settling dynamics and physicochemical properties suggested the necessity on determining the pollution of resuspended sediment at different particle sizes for restoration of shallow lakes.

Comparative cytotoxic study of silica materials functionalised with essential oil components in HepG2 cells

This work evaluated the cytotoxic effect of different EOCs-functionalised silica particle types. The in vitro toxicity of eugenol and vanillin-immobilised SAS, MCM-41 microparticles and MCM-41 nanoparticles was evaluated on HepG2 cells, and compared to free EOCs and pristine materials. The results revealed that free essential oil components and bare silica had a mild cytotoxic effect on HepG2 cells. However, the comparative study showed that free eugenol and vanillin had a milder cytotoxic effect than the equivalent concentrations of immobilised components on the different silica particles, while differences in cell viability between the bare and functionalised particles relied on the type of analysed material. The most cytotoxic materials were eugenol and vanillin-functionalised MCM-41 micro with IC50 values of 0.19 and 0.17 mg/mL, respectively, at 48 h exposure. Differences in cytotoxicity between functionalised particles may be attributed to the density of the functional components on their surface as a result of the functionalisation reaction performance for different materials. The study of the physico-chemical properties of particles demonstrated that cationic nature and increased hydrophobicity could be responsible for promoting cell-particle interactions for the eugenol and vanillin functionalised silica particles, enhancing their cytotoxic behaviour.

Particle Manipulation with External Field; From Recent Advancement to Perspectives.

Physical forces, such as dielectric, magnetic, electric, optical, and acoustic force, provide useful principles for the manipulation of particles, which are impossible or difficult with other approaches. Microparticles, including polymer particles, liquid droplets, and biological cells, can be trapped at a particular position and are also transported to arbitrary locations in an appropriate external physical field. Since the force can be externally controlled by the field strength, we can evaluate physicochemical properties of particles from the shift of the particle location. Most of the manipulation studies are conducted for particles of sub-micrometer or larger dimensions, because the force exerted on nanomaterials or molecules is so weak that their direct manipulation is generally difficult. However, the behavior, interactions, and reactions of such small substances can be indirectly evaluated by observing microparticles, on which the targets are tethered, in a physical field. We review the recent advancements in the manipulation of particles using a physical force and discuss its potentials, advantages, and limitations from fundamental and practical perspectives.

Generation of High Dose Inhalable Effervescent Dispersions against Pseudomonas aeruginosa Biofilms

PurposeNovel particle engineering approach was used in this study to generate high dose inhalable effervescent particles with synergistic effects against Pseudomonas aeruginosa biofilms.MethodsSpray dried co-amorphous salt of ciprofloxacin (CFX) and tartaric acid (TA) was prepared and coated with external layer of sodium bicarbonate and silica coated silver nanobeads. Design of experiments (DOE) was used to optimize physicochemical properties of particles for enhanced lung deposition.ResultsGenerated particles were co-amorphous CFX/TA showing that CFX lost its zwitterionic form and exhibiting distinct properties to CFX/HCl as assessed by FTIR and thermal analysis. Particles exhibited mass mean aerodynamic diameter (MMAD) of 3.3 μm, emitted dose of 78% and fine particle dose of 85%. Particles were further evaluated via antimicrobial assessment of minimum inhibitory concentrations (MIC) and minimum biofilm eradication concentration (MBEC). MIC and MBEC results showed that the hybrid particles were around 3–5 times more effective when compared to CFX signifying that synergistic effect was achieved. Diffusing wave spectroscopy results showed that the silver containing particles had a disruptive effect on rheological properties as opposed to silver free particles.ConclusionsOverall, these results showed the potential to use particle engineering to generate particles that are highly disruptive of bacterial biofilms.

Microplastics as a Vector for Exposure to Hydrophobic Organic Chemicals in Fish: A Comparison of Two Polymers and Silica Particles Spiked With Three Model Compounds

The role of microplastics as chemical vectors delivering environmental contaminants into biota has been proposed, but their environmental relevance remains an issue of a debate. In this paper we compared the propensity and relative importance of synthetic polymer microparticles (glassy polystyrene (PS) and rubbery polyethylene (PE)) and silica glass particles (SG) to act as vectors for hydrophobic organic chemicals (HOCs) into fish after ingestion. Particles were spiked with three HOCs (17α-ethinylestradiol, chlorpyrifos and benzo(α)pyrene), which differ in hydrophobicity and induce well-known biomarker responses. Three-spined stickleback were exposed to 8 different diets: control diets (1), diets with non-spiked particles (2-4), diets containing a mixture of particles spiked with 3 model contaminants (5-7) and, finally, diets loaded with only the chemical mixture (8), for 14 days. Chemical sorption onto the particles was quantified and chemical transfer into the fish was investigated via biomarkers (CYP1a, ERα, VTG and AChE) in fish intestine, liver and brain and quantification of HOCs in fish muscle. Results demonstrated particle-mediated chemical transfer of moderately hydrophobic contaminants into fish. While PS and PE particles mediated higher chemical transfer and tissue accumulation of 17α-ethinylestradiol and chlorpyrifos than SG, the overall chemical transfer was found to be very low. The present work suggested that chemical sorption, desorption and subsequent transfer of chemicals in vivo depends on multiple interconnected factors, including physicochemical properties of particles and contaminants, as well as toxicokinetic and toxicodynamic interactions. The biomarker approach was, however, suboptimal for assessing chemical transfer when addressing particle-associated chemical mixtures.

Degradation of silica particles functionalised with essential oil components under simulated physiological conditions

In this work, the biodurability of three silica particle types (synthetic amourphous silica, MCM-41 microparticles, MCM-41 nanoparticles) functionalised with three different essential oil components (carvacrol, eugenol, vanillin) was studied under conditions that represented the human gastrointestinal tract and lysosomal fluid. The effect of particle type, surface immobilised component and mass quantity on the physico-chemical properties of particles and silicon dissolution was determined. Exposure to biological fluids did not bring about changes in the zeta potential values or particle size distribution of the bare or functionalised materials, but the in vitro digestion process partially degraded the structure of the MCM-41 nanoparticles. Functionalisation preserved the structure of the MCM-41 nanoparticles after simulating an in vitro digestion process, and significantly decreased the amount of silicon dissolved after exposing different particles to both physiological conditions, independently of the essential oil component anchored to their surface. The MCM-41 microparticles showed the highest solubility, while synthetic amorphous silica presented the lowest levels of dissolved silicon. The study of these modified silica particles under physiological conditions could help to predict the toxicological behaviour of these new materials.

Impact of lubricating base oil on diesel soot oxidation reactivity

In this study, the surface functional groups types and concentrations, graphitization degree, and oxidation reactivity of exhaust soot samples generated by a heavy-duty engine when employing neat diesel and four base oil dosed mixtures as the fuel was compared. Fourier transform infrared (FTIR), Raman spectroscopy and Thermal gravimetric analyzer (TGA) were used to characterize particle physicochemical properties. Four lubricating base oils were blended in diesel at a mass ratio of 0.5% and 1.0% for combustion. It was found that although the chemical compositions of these four base oils were different, the aliphatic CH functional groups content, graphitization degree and oxidation reactivity of exhaust soot exhibited similar trends. The combustion of base oil was found to change the graphitization degree of emitted soot and lead to soot with a more disordered nanostructure. The soot particles derived from base oil blended fuels had higher aliphatic CH groups concentration than those from neat diesel. Soot oxidation reactivity analyses showed that soot generated from base oil blended fuels had lower characteristic temperatures and lower activation energy than that from neat diesel. Besides, there was a clear correlation between the soot graphitization degree, relative concentration of aliphatic CH groups and its oxidation reactivity.

Influence of Ce-based catalytic fuel on exhaust particle physicochemical properties on a common-rail engine

ABSTRACT In order to explore the changes of exhaust particulate matter (PM) with the addition of Ce-based catalyst in diesel, naphthenic acid cerium solution was selected as a fuel borne catalyst (FBC). According to Ce mass fraction of 50, 100, 150, and 300 mg/kg, the solutions were added to diesel fuel and marked as F50, F100, F150, and F300, respectively. The experiments were conducted on a four-cylinder high-pressure common-rail engine fueled with FBC fuel. The particle oxidation characteristics, soluble organic fraction (SOF) components, size distribution, and microstructure with FBC fuel were investigated. The results show that the oxidation reaction of PM shifted to the low-temperature area with increasing FBC blending ratio, and the optimum ratio of Ce element is 150 mg/kg. Compared with diesel particle sample, the number of high-carbon-atom in the SOF of FBC particles decreases and the polycyclic aromatic hydrocarbons (PAHs) decrease by 49.2%, shifting FBC particles to the smaller sizes. The peak number concentration of nucleation-mode particles increases by 8.9%, and the peak mass concentration decreases by 14.5%. The FBC particles contain Ce element mass fraction about 1.23%, and its morphology is loose and porous, besides the degree of bonding is significantly reduced.

An inverse cell culture model for floating plastic particles

Plastic waste has become a major environmental problem. An increasing number of studies investigate microplastic particles with regard to their uptake and effects in cell culture systems. Individual plastic materials vary in their molecular structure, composition, size distribution, material density, and may also differ with respect to their toxicological effects. Plastic particles with lower densities than the cell culture medium, for example polyethylene (PE), pose a particular problem for in vitro assays as they float up during the incubation and thus do not contact the cells located on the bottom of the culture dish. We thus developed a practical and easy-to-use in vitro inverse cell culture model for investigating cellular effects of floating plastic particles. Cytotoxicity tests with floating PE particles were performed to demonstrate the utility of the inverted cell model. PE particles incubated in overhead culture were cytotoxic to HepG2 cells, while under the same cultivation conditions, except for inversion, no cytotoxicity occurred. These positive results demonstrate that inverted cell culture was required to detect the effects of PE particles and underlines the necessity to adapt cell culture conditions to the physicochemical properties of particles in order to obtain a more accurate estimate of the effects of floating particles on cells.

Динамика показателей поглотительной способности почв после пирогенного воздействия

Статья посвящена мониторингу показателей почвенного поглотительного комплекса (ППК)дерново-лесной глеево-элювиальной почвы подвергшейся пожару в 2010 году. В 0-10 см слое произошло уменьшение в содержании илистой фракции на 3.25%, уменьшилось содержание средней пыли на 0.07% и мелкой пыли – на 0.48%.Установлено, что в первый год, после лесного пожара, повысилось значение pHH2O почвенного раствора с 5.21 до 5.93. В 2018 году реакция среды возвращается к исходному значению и составляет 5.34. Гидролитическая кислотность снизилась с 5.08 до 3.14 [ммоль (экв.)/100 г почвы]. Произошло снижение в ППК содержания суммы обменных оснований с 8.99 до 7.90 [ммоль (экв)/100 г почвы]. С 2011 по 2018 год произошло их увеличение с 7.90 до 8.27

Hydrolytic surface erosion of mesoporous silica nanoparticles for efficient intracellular delivery of cytochrome c

Delivery of apoptosis-associated proteins is an attractive approach to treat cancer, but their large molecular sizes and membrane-impermeability require the use of a suitable delivery carrier. As a versatile drug carrier, mesoporous silica nanoparticles (MSNs) have been utilized to transport a variety of therapeutic molecules. However, the use of MSNs for protein delivery has been limited because their conventionally obtainable pore size (ca. 2–3 nm in diameter) is too small to load large-sized biomolecular cargos. In this article, we present surface erosion of MSNs by hydrolytic degradation as a new strategy to obtain a mesoporous colloidal carrier for effective delivery of a bulky apoptosis-inducible protein, cytochrome c (CYT). A series of physicochemical properties of particles were analyzed before and after the hydrolytic surface erosion of pristine small-pored MSNs and the subsequent CYT loading. The results showed that hydrolytic degradation of MSNs imparts beneficial structural features for CYT loading and release, i.e., enlarged pores (up to ~10 nm in diameter) and roughened surface texture, leading to significantly enhanced intracellular delivery of CYT over conventional small-pored MSNs. The present results may offer a useful insight into silica degradability for tuning the internal/external surface characteristics of MSN-based colloidal particles to open a wide range of biomedical applications.