Low Concentrations Of Chemicals Research Articles

Cellular Sensing Governs the Stability of Chemotactic Fronts.

In contexts ranging from embryonic development to bacterial ecology, cell populations migrate chemotactically along self-generated chemical gradients, often forming a propagating front. Here, we theoretically show that the stability of such chemotactic fronts to morphological perturbations is determined by limitations in the ability of individual cells to sense and thereby respond to the chemical gradient. Specifically, cells at bulging parts of a front are exposed to a smaller gradient, which slows them down and promotes stability, but they also respond more strongly to the gradient, which speeds them up and promotes instability. We predict that this competition leads to chemotactic fingering when sensing is limited at too low chemical concentrations. Guided by this finding and by experimental data on E. coli chemotaxis, we suggest that the cells' sensory machinery might have evolved to avoid these limitations and ensure stable front propagation. Finally, as sensing of any stimuli is necessarily limited in living and active matter in general, the principle of sensing-induced stability may operate in other types of directed migration such as durotaxis, electrotaxis, and phototaxis.

Thermochemical Conversion of Untreated and Pretreated Biomass for Efficient Production of Levoglucosenone and 5-Chloromethylfurfural in the Presence of an Acid Catalyst

Levoglucosenone (LGO) and 5-chloromethyl furfural (5-CMF) are two bio-based platform chemicals with applications in medicines, green solvents, fuels, and the polymer industry. This study demonstrates the one-step thermochemical conversion of raw and pretreated (delignified) biomass to highly-valuable two platform chemicals in a fluidized bed reactor. Hydrochloric acid gas is utilized to convert biomass thermochemically. The addition of hydrochloric acid gas facilitates the formation of LGO and CMF. Acid gas reacts with biomass to form 5-CMF, which acts as a catalyst to increase the concentration of LGO in the resulting bio-oil. The presence of higher cellulose content in delignified biomass significantly boosts the synthesis of both platform chemicals (LGO and CMF). GC-MS analysis was used to determine the chemical composition of bio-oil produced from thermal and thermochemical conversion of biomass. At 350 °C, the maximum concentration of LGO (27.70 mg/mL of bio-oil) was achieved, whereas at 400 °C, the highest concentration of CMF (19.24 mg/mL of bio-oil) was obtained from hardwood-delignified biomass. The findings suggest that 350 °C is the optimal temperature for producing LGO and 400 °C is optimal for producing CMF from delignified biomass. The secondary cracking process is accelerated by temperatures over 400 °C, resulting in a low concentration of the target platform chemicals. This work reveals the simultaneous generation of LGO and CMF, two high-value commercially relevant biobased compounds.

Enhanced hyperspectral tomography for bioimaging by spatiospectral reconstruction

Here we apply hyperspectral bright field imaging to collect computed tomographic images with excellent energy resolution (~ 1 keV), applying it for the first time to map the distribution of stain in a fixed biological sample through its characteristic K-edge. Conventionally, because the photons detected at each pixel are distributed across as many as 200 energy channels, energy-selective images are characterised by low count-rates and poor signal-to-noise ratio. This means high X-ray exposures, long scan times and high doses are required to image unique spectral markers. Here, we achieve high quality energy-dispersive tomograms from low dose, noisy datasets using a dedicated iterative reconstruction algorithm. This exploits the spatial smoothness and inter-channel structural correlation in the spectral domain using two carefully chosen regularisation terms. For a multi-phase phantom, a reduction in scan time of 36 times is demonstrated. Spectral analysis methods including K-edge subtraction and absorption step-size fitting are evaluated for an ex vivo, single (iodine)-stained biological sample, where low chemical concentration and inhomogeneous distribution can affect soft tissue segmentation and visualisation. The reconstruction algorithms are available through the open-source Core Imaging Library. Taken together, these tools offer new capabilities for visualisation and elemental mapping, with promising applications for multiply-stained biological specimens.

Tracing the movement of electronic cigarette flavor chemicals and nicotine from refill fluids to aerosol, lungs, exhale, and the environment

BackgroundGiven the high concentrations of nicotine and flavor chemicals in EC (electronic cigarette) fluids, it is important to determine how efficiently they transfer to aerosols, how well they are retained by users (exposure), and if they are exhaled into the environment where they settle of surfaces forming ECEAR (EC exhaled aerosol residue). ObjectivesTo quantify the flavor chemicals and nicotine in refill fluids, inhaled aerosols, and exhaled aerosols. Then deduce their retention and contribution to ECEAR. MethodsFlavor chemicals and nicotine were identified and quantified by GC-MS in two refill fluids, smoking machine-generated aerosols, and aerosols exhaled by 10 human participants (average age 21; 7 males). Machine generated aerosols were made with varying puff durations and two wattages (40 and 80). Participants generated exhale ad libitum; their exhale was quantified, and chemical retention and contribution to ECEAR was modeled. Results“Dewberry Cream” had five dominant (≥1 mg/mL) flavor chemicals (maltol, ethyl maltol, vanillin, ethyl vanillin, furaneol), while “Cinnamon Roll” had one (cinnamaldehyde). Nicotine transferred well to aerosols irrespective of topography; however, transfer efficiencies of flavor chemicals depended on the chemical, puff volume, puff duration, pump head, and EC power. Participants could be classified as “mouth inhalers” or “lung inhalers” based on their exhale of flavor chemicals and nicotine and retention. Lung inhalers had high retention and exhaled low concentrations of EC chemicals. Only mouth inhalers exhaled sufficient concentrations of flavor chemicals/nicotine to contribute to chemical deposition on environmental surfaces (ECEAR). ConclusionThese data help distinguish two types of EC users, add to our knowledge of chemical exposure during vaping, and provide information useful in regulating EC use.

Unraveling the molecular effects of oxybenzone on the proteome of an environmentally relevant marine bacterium

The use of Benzophenone-3 (BP3), also known as oxybenzone, a common UV filter, is a growing environmental concern in regard to its toxicity on aquatic organisms. Our previous work stressed that BP3 is toxic to Epibacterium mobile, an environmentally relevant marine α-proteobacterium. In this study, we implemented a label-free quantitative proteomics workflow to decipher the effects of BP3 on the E. mobile proteome. Furthermore, the effect of DMSO, one of the most common solvents used to vehicle low concentrations of lipophilic chemicals, was assessed to emphasize the importance of limiting solvent concentration in ecotoxicological studies. Data-independent analysis proteomics highlighted that BP3 induced changes in the regulation of 56 proteins involved in xenobiotic export, detoxification, oxidative stress response, motility, and fatty acid, iron and amino acid metabolisms. Our results also outlined that the use of DMSO at 0.046% caused regulation changes in proteins related to transport, iron uptake and metabolism, and housekeeping functions, underlining the need to reduce the concentration of solvents in ecotoxicological studies.

Miniaturized probe on polymer SU-8 with array of individually addressable microelectrodes for electrochemical analysis in neural and other biological tissues.

An SU-8 probe with an array of nine, individually addressable gold microband electrodes (100μm long, 4μm wide, separated by 4-μm gaps) was photolithographically fabricated and characterized for detection of low concentrations of chemicals in confined spaces and in vivo studies of biological tissues. The probe's shank (6mm long, 100μm wide, 100μm thick) is flexible, but exhibits sufficient sharpness and rigidity to be inserted into soft tissue. Laser micromachining was used to define probe geometry by spatially revealing the underlying sacrificial aluminum layer, which was thenetched to free the probes from a silicon wafer. Perfusion with fluorescent nanobeads showed that, like a carbon fiber electrode, the probe produced no noticeable damage when inserted into rat brain, in contrast to damage from an inserted microdialysis probe. The individual addressability of the electrodes allows single and multiple electrode activation. Redox cycling is possible, where adjacent electrodes serve as generators (that oxidize or reduce molecules) and collectors (that do the opposite) to amplify signals of small concentrations without background subtraction. Information about electrochemical mechanisms and kinetics may also be obtained. Detection limits for potassium ferricyanide in potassium chloride electrolyte of 2.19, 1.25, and 2.08μM and for dopamine in artificial cerebral spinal fluid of 1.94, 1.08, and 5.66μM for generators alone and for generators and collectors during redox cycling, respectively, were obtained.

Characterisation of (anti-)progestogenic and (anti-)androgenic activities in surface and wastewater using high resolution effectdirected analysis

The quality of surface waters is threatened by pollution with low concentrations of bioactive chemicals, among which those interfering with steroid hormone systems. Induced by reports of anti-progestogenic activity in surface waters, a two-year four-weekly survey of (anti-)progestogenic activity was performed at three surface water locations in the Netherlands that serve as abstraction points for the production of drinking water. As certain endogenous and synthetic progestogenic compounds are also potent (anti-)androgens, these activities were also investigated. Anti-progestogenic and anti-androgenic activities were detected in the majority of the monitoring samples, sometimes in concentrations exceeding effect-based trigger values, indicating the need for further research. To characterize the compounds responsible for the activities, a high resolution Effect-Directed Analysis (hr-EDA) panel was combined with PR and AR CALUX bioassays, performed in agonistic and antagonistic modes. The influent and effluent of a domestic wastewater treatment plant (WWTP) were included as effluent is a possible emission source of active compounds. As drivers for androgenic and progestogenic activities several native and synthetic steroid hormones were identified in the WWTP samples, namely androstenedione, testosterone, DHT, levonorgestrel and cyproterone acetate. The pesticides metolachlor and cyazofamid were identified as contributors to both the anti-progestogenic and anti-androgenic activities in surface water. In addition, epiconazole contributed to the anti-progestogenic activities in the rivers Rhine and Enclosed Meuse. This study showed the strength of hr-EDA for the identification of bioactive compounds in environmental samples and shed light on the drivers of (anti-)progestogenic and (anti-)androgenic activities in the aquatic environment.

Clustering and prioritization to design a risk-based monitoring program in groundwater sources for drinking water

BackgroundThe number of chemical parameters included in monitoring programs of water utilities increased in the last decade. In accordance with the European Drinking Water Directive, utilities aim at a tailored risk-based monitoring (RBM) program. Here, such a RBM program was developed for the largest Dutch water utility, mostly using groundwater as a source. Data from target analyses and high-resolution mass spectrometry-based suspect screening was used to cluster the different source waters. Targets were prioritized based on (preliminary) drinking water guideline values or the threshold of toxicological concern. Suspects were prioritized for further identity confirmation based on semi-quantitative occurrence concentrations combined with in vitro toxicity information. Finally, a RBM program was suggested for each cluster of source waters.ResultsOut of 731 target chemicals, 153 were detected at least once over a 5-year period. Roughly 10% of the detected non-target screening features matched to suspects. 108 source waters were clustered into 7 clusters. Source waters with low numbers and concentrations of organic chemicals were located in areas with all land-use types, while clusters of source waters with higher numbers of chemicals were related to infiltrated surface water. For perfluorinated chemicals, 25 suspects matched features detected in source waters and 7 features detected in drinking water. For the target chemicals, simple treatment showed the lowest and sorption-based techniques relatively high removal efficiencies. The chemical composition of all drinking waters related to non-contaminated source waters. (Preliminary) guideline values were available for 45 of the retrieved target chemicals, and used for prioritization for monitoring frequencies. These chemicals individually posed no appreciable concern to human health. Suspects were prioritized for further identity confirmation based on semi-quantitative occurrence in produced water, detection frequencies and information on toxic potency. Once confirmed and assessed as relevant, the suspects could be added to target monitoring.ConclusionThis approach provided a feasible workflow for RBM of target chemicals for clusters of groundwater sources, connected to a feed of new relevant chemicals based on suspect screening.

A Comparative Study on Sorption Characteristics by Corn Stalk Pith Using Green Modification with Different Polycarboxylic Acids

In this study, an efficient and economical modification with low chemical concentration process was used for preparing biosorbent. Corn stalk pith (CP) was esterified with different polycarboxylic (tartaric, citric, and malic) acids, and then the resultant modified products were applied as sorbents to remove methylene blue (MB) via sorption. Compared with the raw materials, the esterification led to some variation in the specific surface area, pore volume and structure, which thereby affected the sorption efficacy of MB. The pseudo-second-order kinetic model and the Langmuir model well described the MB sorption for all modified CPs. Following modification, sorption capacity increased by 290.1 % for tartaric acid modified-CP, 759.0 % for citric acid modified-CP and 658.2 % for malic acid modified-CP, and the maximum MB sorption were 208.3, 458.7 and 404.9 mg/g, respectively. The mechanisms of MB sorption via modified CP involve electrostatic interaction, π-π interaction, and hydrogen bonds interaction. The substantial enhancement on MB sorption by the CP esterified with polycarboxylic acids provides a novel means for dyes removal from wastewater.

Environmental Chemicals Disrupted Lipid/Fatty Acid Contents of Rat Organs and Reversed by Treatment With Citrus Lime Nano‐particle

The environment is rich with trace concentrations of toxicants, these toxicants in the living system can disrupt biological homeostasis. We had reported that trace concentrations of emerging contaminants dysregulate antioxidant systems. In the present study we investigated the effects of these cellular defense disrupting chemicals on organs’ fatty acids and lipids contents and evaluated effects of Citrus lime conjugated nano‐particles. Rats were treated with environmental chemicals (EC) consisting of mixture of atrazine, dieldrine, endrine, endosulfan, anthracene, 17‐alpha ethynyl estradiol, diethylstilbestrol, estradiol, estrone, testosterone and estriol at a concentration of 1–10 ug/L in drinking water for 6 weeks along with control. Another group was treated with synthesized 2 μM Citrus lime nano‐particle alone or in combination with EC. At the end of the treatment, rats were euthanized, and organs collected. Samples were extracted for determination of fatty acids and lipids using Agilent 7890B/5977B GC/MSD System with SQ detector with HP‐5 MS capillary column. Results shows treatment with environmental toxicants dysregulated fatty acid species in the heart, liver, lung, spleen, brain, and fat with changes that varied up to 7.0×108 % when compared to the control. Similarly, cholesterol contents were severely dysregulated with the range of changes varying from −68 to 2.0×1010 %. The highest dysregulation occurred in the fat tissues. All these changes were reversed in the group treated with synthesized Citrus lime nano‐particle. Our results indicate that environmental chemicals in trace concentrations disrupts fatty acids species and cholesterol contents of different organs. The disrupted fatty acids are Hexadexcanoic acid methyl ester; n‐Hexadecanoic acid, 10‐methyl‐, methyl ester; 9,12‐Octadecadienoic acid; Heptadecanoic acid; Eicosatetraenoic acid, methyl ester, Methyl stearate. These disruptions by environmental chemicals were reversed by nano‐particle conjugated to alkaloid from Citrus lime. These fatty acid species possess antioxidants, anti‐inflammatory, and other cellular defense and regulatory functions. Thus, our results suggest that low concentrations of environmental chemicals’ disruptions of these functions is the hallmark of slow and long‐term developing health altering conditions such as diabetes, Alzheimer’s, rheumatoid arthritis etc. possibly mediated by inflammatory processes and induced oxidative stress. Our results further suggest that nano‐particle conjugated alkaloid could serve as an antidote to long term effects of exposure to trace concentrations of environmental chemicals.Support or Funding InformationThis research is supported by Tittle III under the Award Number P031B090216;Title III, Part B, HBGI (CFDA No. 84.031B).

Emerging Advanced Technologies Developed by IPR for Bio Medical Applications ‑.A Review.

Over the last decade, research has intensified worldwide on the use of low-temperature plasmas in medicine and healthcare. Researchers have discovered many methods of applying plasmas to living tissues to deactivate pathogens; to end the flow of blood without damaging healthy tissue; to sanitize wounds and accelerate its healing; and to selectively kill malignant cancer cells. This review paper presents the latest development of advanced and plasma-based technologies used for applications in neurology in particular. Institute for Plasma Research (IPR), an aided institute of the Department of Atomic Energy (DAE), has also developed various technologies in some of these areas. One of these is an Atmospheric Pressure Plasma Jet (APPJ). This device is being studied to treat skin diseases, for coagulation of blood at faster rates and its interaction with oral, lung, and brain cancer cells. In certain cases, in-vitro studies have yielded encouraging results and limited in-vivo studies have been initiated. Plasma activated water has been produced in the laboratory for microbial disinfection, with potential applications in the health sector. Recently, plasmonic nanoparticle arrays which allow detection of very low concentrations of chemicals is studied in detail to allow early-stage detection of diseases. IPR has also been developing AI-based software called DeepCXR and AIBacilli for automated, high-speed screening and detection of footprints of tuberculosis (TB) in Chest X-ray images and for recognizing single/multiple TB bacilli in sputum smear test images, respectively. Deep Learning systems are increasingly being used around the world for analyzing electroencephalogram (EEG) signals for emotion recognition, mental workload, and seizure detection.

SCORE EXPOSITION OF CHEMICAL LOADS AND THEIR ASSOCIATION WITH OCCUPATIONAL RISKS IN THE MODERN MANUFACTURE OF POLYVINYL CHLORIDE

Introduction. In the modern production of polyvinyl chloride (PVC), despite relatively low levels of air pollution of the working zone of the harmful substances, the problem of the negative effects of chemical factors on organism remains topical In this regard, the objective of the present study was the quantitative estimation of exposure of chemical loads (ECL) priority toxicants in PVC production and the identification of associated links with health indices. Material and methods. In the work of the applied methods of hygienic studies using a methodology for assessing occupational risks of the method of calculation of exposure to the chemical load. To justify a connection with the profession of morbidity used method of correlation analysis. Results. In PVC production average settlement values of ECL priority substances (vinyl chloride and 1.2 dichloroethane) for the 10-year period were was shown to gradually decrease and be statistically significantly higher: during the first five-year period in comparison with the second, at mechanics in comparison with bureaucrats, in the shop of production of PVC in comparison with the shop of production of VH (р <0.01; р <0.001). When studying the health state of workers, the high prevalence of occupational risks was also noted rather functional violations of a cardiovascular system (31.2±5.1), neurologic frustration (28.0±3.2), functional violations of a digestion system (26.3±3.4). At medical examination diseases of a cardiovascular system (43.4±5.9), the nervous system (29.5±4.9), the system of digestion had the greatest prevalence (19.7±4.0). Correlation relationships between separate indices of the violation of health and quantitative indices of ECL are revealed. Conclusion. For example, in employees of a modern PVC production, the results demonstrate it to be possible to identify an association between health and ECL, reflecting the cumulative impact of chemical pollutants production media after years of work at the enterprise. There was confirmed the usefulness of calculations specified ECL for linking disease with an occupation, particularly in the context of the effects of low concentrations of chemicals.

Coagulation/flocculation of textile effluent using a natural coagulant extracted from Dillenia indica.

The aim of this study was to assess the efficiency of mucilage extracted from the fruit of Dillenia indica for enhancing coagulation in the treatment of textile effluent. The mucilage extraction was carried out in water at room temperature. The pH, concentration of coagulant FeCl3.6H2O, and concentration of mucilage solution were optimized with star-type central composite design (CCD). We were able to analyze the synergistic effects between the FeCl3.6H2O and mucilage concentrations: the process of coagulation/flocculation (CF) for chemical oxygen demand (COD) removal was more efficient at a low chemical coagulant concentration (8.00 mg L-1) and a higher natural coagulant (NC) concentration (15.00 mg L-1). This demonstrated the potential of this mucilage to treat textile effluents, with 67.66%% COD removal, 96.86% turbidity removal and 91.12% apparent color reduction. The characterization of the mucilage of Dillenia indica was done using Fourier transform infrared spectroscopy (FTIR) and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR), and the signals obtained indicated the presence of polysaccharides, which are responsible for enhancing the CF process.

Three patients with probable aerotoxic syndrome

Introduction: “Aerotoxic syndrome” is a debated entity. Regulatory authorities consider long-term health effects to be an unlikely consequence of exposure to contaminated air because several air quality monitoring studies report low concentrations of toxic chemicals in cabin air. We describe two pilots and one flight attendant, who developed ill health during their flying career which improved after cessation of flying.Case details: The most frequently reported symptoms were headache, balance problems, fatigue, gastro-intestinal complaints and cognitive impairment. One of these patients had reduced levels of butyrylcholinesterase after a flight suggesting exposure to organophosphate compounds had occurred. All three were found to have elevated neuronal and glial auto-antibodies, biomarkers of central nervous system injury, and all three had genetic polymorphisms of paraoxonase (PON-1) and two of cytochrome P450, leading to a reduced ability to metabolize organophosphate compound (OPs).Discussion: A similar constellation of symptoms has been described in other studies of aircrew, although objective evidence of exposure is lacking in most of these studies. Reduced levels of butyrylcholinesterases in one of our cases is suggestive of causation and elevated neuronal and glial autoantibodies provide objective evidence of damage to the central nervous system. We consider further research is warranted.

Multiple Persistent Environmental Chemicals at Low Concentrations Differentially Regulates Fatty Acids/Lipids in Wild Type and PPARAa−/− Mice

Many chemicals are detected in the environment at very low levels, they were viewed as being incapable of causing harm. Their risks to human health and associated environment are now emerging. But effects of their multiple interactions at cellular and molecular levels is unknown. We have investigated the effects of treatment of wild type and PPARα knockout mice on fatty acid contents in different organs. Mice were treated with low concentrations of multiple persistent environmental chemicals: atrazine, dieldrin, endrin, endosulfan and anthracene (1–100ng/L) in drinking water for six weeks and brain, liver, kidney, heart and spleen were collected, processed for fatty acid/lipid contents determination by GC/MS. The percentage changes in the levels of the fatty acid following treatment were calculated for wild type (WT) and PPARα −/− (KO). The changes (WT and KO) were compared to find the effects of treatment and the genetic (PPARα) influence on the regulation of fatty acid levels. Our results show differential presence of fatty acids: hexadecanoic acid, hexadecanoic acid methyl ester, hexadecanamide, 9‐octadecanemaide, pentadecanoic acid, octadecanoid acid, arachidonic acid, and cholesterol in the different organs as well as their differential regulation in the WT and KO. Results are summarized in Tables 1 and 2. Briefly, treatment increased 9‐octadecanemaide by 145% (WT) and 38% (KO) in the heart, reduced in the kidney 17% (WT), 29% (KO); hexadecanoic acid, octadecanoic acid was increased 0% (WT) but by 178% and 110% respectively (KO) (kidney), octadecanoic acid went up by 334% (KO) with not change in WT, hexadecanamide increased by 92% in KO Liver with 5% in WT. Generally, more perturbations in the regulation of the levels of fatty acid species in the KO than in the WT. These results indicate that multiple persistent environmental chemicals at low concentrations have limited effects on fatty acid dynamics in the WT but enhanced possible dysregulations in the PPARAα−/− mice.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Identification and quantification of electronic cigarette exhaled aerosol residue chemicals in field sites

BackgroundElectronic cigarette (EC) users may exhale large clouds of aerosol that can settle on indoor surfaces forming ECEAR (EC exhaled aerosol residue). Little is known about the chemical composition or buildup of this residue. ObjectiveOur objective was to identify and quantify ECEAR chemicals in two field sites: an EC user's living room and a multi-user EC vape shop. MethodsWe examined the buildup of ECEAR in commonly used materials (cotton, polyester, or terrycloth towel) placed inside the field sites. Materials were subjected to different lengths of exposure. Nicotine, nicotine alkaloids, and tobacco-specific nitrosamines (TSNAs) were identified and quantified in unexposed controls and field site samples using analytical chemical techniques. ResultsNicotine and nicotine alkaloids were detected in materials inside the EC user's living room. Concentrations of ECEAR chemicals remained relatively constant over the first 5 months, suggesting some removal of the chemicals by air flow in the room approximating a steady state. ECEAR chemicals were detected in materials inside the vape shop after 6 h of exposure and levels continually increased over a month. By 1 month, the nicotine in the vape shop was 60 times higher than in the EC user's living room. ECEAR chemical concentrations varied in different locations in the vape shop. Control fabrics had either no detectable or very low concentrations of chemicals. ConclusionsIn both field sites, chemicals from exhaled EC aerosols were deposited on indoor surfaces and accumulated over time forming ECEAR. Non-smokers, EC users, and employees of vape shops should be aware of this potential environmental hazard.

Improved thermal stability of regenerated cellulose films from corn (Zea mays) stalk pith using facile preparation with low-concentration zinc chloride dissolving

In this study, an improved facile cellulose dissolution with low chemical concentration process was used for preparing corn stalk pith regenerated cellulose (RC) films. The conventional method usually requires 68% zinc chloride solution for cellulose dissolution. The objective of this study is produced corn stalk pith RC films by using a low-concentration zinc chloride solution with improved thermal stability. The major weight loss peak temperature of RC films was increased from 231 °C to 307 °C as the crystallinity indexes increased from 48.30% to 53.19% by decreased the concentration of zinc chloride solution from 65% to 45%, respectively. The increased thermal stability can create new opportunities for the development of RC films dissolving by zinc chloride solution.

Structural characterization of recombinant streptokinase following recovery from inclusion bodies using different chemical solubilization treatments

Circular dichroism (CD) in far-UV region was employed to study the extent of changes occurred in the secondary structures of recombinant streptokinase (rSK), solubilized from inclusion bodies (IBs) by different chemicals and refolded/purified by chromatographic techniques. The secondary structure distribution of rSK, obtained following different chemical solubilization systems, was varied and values in the range of 12.4–14.5% α-helices, 40–51% β-sheets and 35.5–48.3% turns plus residual structures were found. With reducing the concentration of chemicals during IB solubilization, the content of turns plus random coils was diminished and simultaneously the amounts of α- and β-sheets were increased. These changes in the secondary structures would lower the hydrophobicity along with the chance of protein aggregation and expose the hydrophilic regions of the protein. Therefore, these alterations in the secondary structures, occurred following efficient IBs solubilization by low concentration of chemicals, could be related to enhancement in rSK biological potency previously observed.

Adjustable thermal barrier of cotton fabric by multilayer immobilization of PCM nanocapsules

Poly(diallyldimethylammonium chloride) encapsulated n-octadecane nanocapsules (Cap+) were facilely immobilized on cationized cotton at ambient temperature by stepwise coating with poly-4-styrenesulfonic acid (PSS) binder and Cap+ nanocapsules via layer-by-layer technique. The negative molecules of PSS binder spontaneously attached on the cationized cotton and then acted as negative sites for further immobilization of positively charged Cap+ nanocapsules through electrostatic interaction. The increase of quantity of immobilized Cap+ nanocapsules could be obtained by increasing the number of PSS/Cap+ treatment cycles. The prolonged duration of thermoregulating action was obtained when increasing the quantity of Cap+ immobilized on the cotton fabric, resulting in the adjustable thermal barrier property of cotton fabric. The cotton sample immobilized with 5 cycles of PSS/Cap+ treatment exhibited the highest reduction of surface temperature, i.e. ~ 2.5 °C for longer than 10 min when the surrounding temperature was about 50 °C. In addition, this sample could retain about 77% of original quantity of immobilized Cap+ after 15 washing cycles. The facile polyelectrolyte assisted nanoencapsulation and immobilization of PCM nanocapsules on the cotton fabrics proposed in this study were effectively performed using low concentrations of non-toxic chemicals, in which they might be incorporated into the conventional fabric finishing system.

Solubilization of inclusion body proteins using low and very low concentrations of chemicals: implications of novel combined chemical treatment designs in enhancement of post‐solubilization target protein purity and biological activity

AbstractBACKGROUNDSolubilization of inclusion body (IB) proteins by conventional methods (i.e. high concentrations of denaturants such as chaotropes) is a challenging process due to denaturation of the native‐like secondary structures and subsequently low recovery into bioactive forms. The main objective of this work was to study the effect of a range of chemicals at low and very low concentrations on the solubilization of IB proteins produced in Escherichia coli and the enhancement of the target protein biological activity subsequent to refolding.RESULTSPerformance of chemical combinations at low and very low concentrations through the solubilization process of recombinant streptokinase (rSK) from IBs isolated from E. coli was appraised based on values pertinent to three parameters including target protein solubilization yield, purity and biological activity. In comparison with the conventional IBs' solubilization method (i.e. 4 mol L‐1 urea), combinations of 0.5–1 mol L‐1 urea with very low to low concentrations (0.05–1%) of detergents resulted in considerable target protein solubilization (by 100%), very high post‐solubilization target protein purities (up to 100%) and biological activities (up by 360%).CONCLUSIONOwing to the improvements in the abovementioned integral parameters, these chemical treatments are good candidates to be considered for more efficient and cost‐effective recovery of recombinant target proteins from IBs. © 2017 Society of Chemical Industry