Higher PEG Content Research Articles

Determination of the effects of drought stress on Aronia melanocarpa cv. Nero in vitro conditions

Drought stress is a significant threat to plant cultivation in arid and semi-arid regions, negatively affecting growth and leading to plant mortality. This study evaluated the in vitro drought tolerance of Aronia melanocarpa ‘Nero’ by exposing micropropagated plantlets to nutrient media containing different concentrations of PEG-8000 (0%, 1%, and 2%) during the rooting stage. Results showed that increasing PEG concentrations led to a reduction in survival, rooting, plantlet growth, and physiological parameters. The 0% PEG treatment resulted in the highest survival rate (95.83%), root number, and chlorophyll content, while the 2% PEG treatment significantly hindered these parameters. These findings indicate that Aronia melanocarpa 'Nero' is sensitive to drought stress, with reduced growth and physiological activity under higher PEG concentrations.

PEG-crosslinked O-carboxymethyl chitosan films with degradability and antibacterial activity for food packaging

This study developed a kind of PEG-crosslinked O-carboxymethyl chitosan (O-CMC–PEG) with various PEG content for food packaging. The crosslinking agent of isocyanate-terminated PEG was firstly synthesized by a simple condensation reaction between PEG and excess diisocyanate, then the crosslink between O-carboxymethyl chitosan (O-CMC) and crosslinking agent occurred under mild conditions to produce O-CMC–PEG with a crosslinked structure linked by urea bonds. FT-IR and 1H NMR techniques were utilized to confirm the chemical structures of the crosslinking agent and O-CMC–PEGs. Extensive research was conducted to investigate the impact of the PEG content (or crosslinking degree) on the physicochemical characteristics of the casted O-CMC–PEG films. The results illuminated that crosslinking and components compatibility could improve their tensile features and water vapor barrier performance, while high PEG content played the inverse effects due to the microphase separation between PEG and O-CMC segments. The in vitro degradation rate and water sensitivity primarily depended on the crosslinking degree in comparison with the PEG content. Furthermore, caused by the remaining –NH2 groups of O-CMC, the films demonstrated antibacterial activity against Escherichia coli and Staphylococcus aureus. When the PEG content was 6% (medium crosslinking degree), the prepared O-CMC–PEG−6% film possessed optimal tensile features, high water resistance, appropriate degradation rate, low water vapor transmission rate and fine broad-spectrum antibacterial capacity, manifesting a great potential for application in food packaging to extend the shelf life.

Effect of Poly(ethylene glycol) Configuration on Microbubble Pharmacokinetics.

Microbubbles (MBs) hold substantial promise for medical imaging and therapy; nonetheless, knowledge gaps persist between composition, structure, and in vivo performance, especially with respect to pharmacokinetics. Of particular interest is the role of the poly(ethylene glycol) (PEG) layer, which is thought to shield the MB against opsonization and rapid clearance but is also known to cause an antibody response upon multiple injections. The goal of this study was, therefore, to elucidate the role of the PEG layer in circulation persistence of MBs in the naïve animal (prior to an adaptive immune response). Here, we directly observe the number and size of individual MBs obtained from blood samples, unifying size and concentration into the microbubble volume dose (MVD) parameter. This approach enables direct evaluation of the pharmacokinetics of intact MBs, comprising both the lipid shell and gaseous core, rather than separately assessing the lipid or gas components. We examined the in vivo circulation persistence of 3 μm diameter phospholipid-coated MBs with three different mPEG2000 content: 2 mol % (mushroom), 5 mol % (intermediate), and 10 mol % (brush). MB size and concentration in the blood were evaluated by a hemocytometer analysis over 30 min following intravenous injections of 20 and 40 μL/kg MVD in Sprague-Dawley rats. Interestingly, pharmacokinetic analysis demonstrated that increasing PEG concentration on the MB surface resulted in faster clearance. This was evidenced by a 1.6-fold reduction in half-life and area under the curve (AUC) (p < 0.05) in the central compartment. Conversely, the AUC in the peripheral compartment increased with PEG density, suggesting enhanced MB trapping by the mononuclear phagocyte system. This was supported by an in vitro assay, which showed a significant rise in complement C3a activation with a higher PEG content. In conclusion, a minimal PEG concentration on the MB shell (mushroom configuration) was found to prolong circulation and mitigate immunogenicity.

Effects of liquid-to-solid ratio and gamma irradiation on the rheology and cytocompatibility of a beta-tricalcium phosphate-based injectable bone substitute

Injectable bone substitute (IBS) materials are commonly used to fill irregular-shaped bone voids in non-load-bearing areas and can offer greater utility over those which are in prefabricated powder, granule, or block forms. This work investigates the impact of liquid-to-solid ratio (LSR) on the rheology and cytocompatibility of IBSs formulated from bioactive glass particles and β-tricalcium phosphate (β-TCP) in glycerol and poly(ethylene glycol) (PEG). IBS formulations of varying LSR were prepared and packed in 3 cc open-bore syringes and sterilized via gamma irradiation (10 kGy, 25 kGy). Gamma-irradiated formulations with high PEG content required the highest (73 N) mechanical force for injection from syringes. Oscillatory viscosity measurements revealed that the viscosity of samples was directly proportional to glycerol content. PEG and glycerol displayed competing effects on the washout resistance and cohesiveness of samples, which were based on total weight loss in media and Ca2+ ion release, respectively. Cell viability in 24-h extracts of 10 kGy gamma-sterilized and 25 kGy gamma-irradiated samples were 22.94% and 56.53%, respectively. The research highlights the complex interplay of IBS components on IBS rheology and, moreover, the cytotoxicity behaviors of beta-tricalcium phosphate-based injectable bone substitutes by in vitro experiments.

A newly isolated Bacillus pumilus strain SH-9 modulates response to drought stress in soybean via endogenous phytohormones and gene expression (Daegu, South Korea)

Drought stress hampers plant growth and productivity. Some microorganisms mitigate stress in plants; however, the molecular mechanism by which they interact with plants in mitigating stress remains unknown. This study aimed to determine the mechanism by which plant growth–promoting rhizobacteria modulate drought stress in soybean. Results indicated that B. pumilus SH-9 (SH-9) produced indole acetic acid and siderophore, and had capacity for phosphate solubilization. The test for polyethylene glycol 6000 (PEG) tolerance, showed that SH-9 could withstand high PEG concentration (up to 30 %). The isolate was identified a B. pumilus strain using a 16 s ribosomal DNA gene sequence. Inoculation of soybeans with SH-9 enhanced soybean plant growth and biomass by 20 %, even under high drought stress. This was due to a reduction of the endogenous phytohormone (abscisic acid) and upregulation of the antioxidant defense system (SOD, POD, APX, and GSH) by SH-9. Furthermore, the transcription factors GmDREB2, GmbZIP1, and GmNCED3 were involved. Inoculation with SH-9 also improved physio-morphological characteristics such as biomass, chlorophyll, seedling length, and relative water contents in the stressed plant. Overall, the findings of this study indicated that SH-9 enhances plant growth by promoting phosphate solubilization, siderophore, and exopolysaccharides. We, therefore, conclude that SH-9 is a drought-tolerant variant that can improve plant growth even under drought stress via modulation of expression of the phytohormone gene, and antioxidant profile.

The ability of two indigenous bacteria isolated from Moroccan olive tree to promote the growth of olive seedlings in the presence of the pathogen Verticillium dahliae

ABSTRACT The rhizosphere of olive trees (Olea europaea L.) is a source of bacteria with a high potential for biocontrol and plant growth promotion. In the present study, two native olive tree gram-negative bacteria were isolated from the rhizosphere of century-old trees in the region of Zouala (south-eastern Morocco), known for its arid climate and saline soils. The strains Pantoea agglomerans and Enterobacter ludwigii exhibited high tolerance to high PEG and NaCl concentrations, and significant plant growth-promoting (PGP) potential in vitro. The two strains efficiently solubilised phosphate in its two forms (TCP and RP), and Mica as a source of potassium and produced IAA. The two strains exhibited in vitro inhibition ability against Verticillium dahliae with partial inhibition of the growth of the mycelium by the strain P. agglomerans MRC_ZO_17. Greenhouse experiments showed that olive tree seedlings treated with the E. ludwigii MRC_ZO_97 strain significantly improved growth (dry weight) in the presence and absence of the pathogen compared to untreated plants, while the P. agglomerans MRC_ZO_17 strain showed significant effects on seedling growth only in the presence of the pathogen V. dahliae OV1 defoliating pathotype. Both strains showed high exopolysaccharides (EPS) production and good biofilm formation, making them excellent plant growth-promoting rhizobacteria (PGPRs) and Biological Control Agents (BCAs) with great potential to survive in soil under stress conditions.

Plant Growth Promotion and Biocontrol Potentiality of Endophytes Isolated from Root Nodules of Sulla flexuosa L. Plants

Legumes, native to the Mediterranean, harbor reservoirs of endophytes that help plants adapt to various environmental stresses. The current study was carried out to evaluate the plant growth characteristics and antifungal activity of root nodule endophytes as biocontrol agents and plant growth promoters. Eleven bacterial endophytes isolated from root nodules of Sulla flexuosa L. grown in Northwest Morocco were assessed for their plant growth-promoting (PGP), and antifungal properties. Four endophytic bacteria were selected for their efficiency in solubilizing inorganic phosphate. The selected strains were positive for more than 2 PGP traits, including indole acetic acid, ACC deaminase, siderophore, and ammonia production. The screening for lytic enzyme production revealed that all strains were capable of producing chitinase, cellulase, catalase, and protease, while the secretion of amylase and urease was not detected. The HFB11 was the only strain incapable of producing pectinase. In vitro experiments revealed the strains’ potential to withstand salt and drought stresses by being able to grow in high concentrations of NaCl and PEG. Based on 16S rRNA gene sequencing, the strains were identified as Enterobacter and Serratia. The antagonistic activity of the strains against Botrytis cinerea, Aspergillus ochraceus, and Fusarium oxysporum was detected and they were shown to inhibit the fungal growth with various percentages. The highest percentage of inhibition was observed for HFB3 against B. cinerea with 50% inhibition followed by HFB8 which was able to inhibit 47% of F. oxysporum’s growth. In contrast, a weak inhibition was observed against A. ochraceus. All these findings indicate that the chosen endophytes, halotolerant Serratia inhibens HFB8 and Enterobacter hormaechei HFB11, might be used as candidates for effective biocontrol and growth promotion of legumes.

Sensitivity of the Photosynthetic Apparatus in Maize and Sorghum under Different Drought Levels.

Drought is one of the main environmental stress factors affecting plant growth and yield. The impact of different PEG concentrations on the photosynthetic performance of maize (Zea mays L. Mayflower) and sorghum (Sorghum bicolor L. Foehn) was investigated. The activity of the photosynthetic apparatus was assessed using chlorophyll fluorescence (PAM and JIP test) and photooxidation of P700. The data revealed that water deficiency decreased the photochemical quenching (qP), the ratio of photochemical to nonphotochemical processes (Fv/Fo), the effective quantum yield of the photochemical energy conversion in PSII (ΦPSII), the rate of the electron transport (ETR), and the performance indexes PItotal and PIABS, as the impact was stronger in sorghum than in maize and depended on drought level. The PSI photochemistry (P700 photooxidation) in sorghum was inhibited after the application of all studied drought levels, while in maize, it was registered only after treatment with higher PEG concentrations (30% and 40%). Enhanced regulated energy losses (ΦNPQ) and activation of the state transition under drought were also observed in maize, while in sorghum, an increase mainly in nonregulated energy losses (ΦNO). A decrease in pigment content and relative water content and an increase in membrane damage were also registered after PEG treatment. The experimental results showed better drought tolerance of maize than sorghum. This study provides new information about the role of regulated energy losses and state transition for the protection of the photosynthetic apparatus under drought and might be a practical approach to the determination of the drought tolerance of plants.

Effect of Water Deficit on Germination, Growth and Biochemical Responses of Four Potentially Invasive Ornamental Grass Species

Ornamental plant species introduced into new environments can exhibit an invasive potential and adaptability to abiotic stress factors. In this study, the drought stress responses of four potentially invasive ornamental grass species (Cymbopogon citratus, Cortaderia selloana, Pennisetum alopecuroides and P. setaceum) were analysed. Several seed germination parameters were determined under increasing polyethylene glycol (PEG 6000) concentrations. Additionally, plants in the vegetative stage were subjected to intermediate and severe water stress treatments for four weeks. All species registered high germination rates in control conditions (no stress treatment), even at high PEG concentrations, except C. citratus, which did not germinate at -1 MPa osmotic potential. Upon applying the water stress treatments, P. alopecuroides plants showed the highest tolerance, and C. citratus appeared the most susceptible to drought. Stress-induced changes in several biochemical markers (photosynthetic pigments, osmolytes, antioxidant compounds, root and shoot Na+ and K+ contents), highlighted different responses depending on the species and the stress treatments. Basically, drought tolerance seems to depend to a large extent on the active transport of Na+ and K+ cations to the aerial part of the plants, contributing to osmotic adjustment in all four species and, in the case of the most tolerant P. alopecuroides, on the increasing root K+ concentration under water deficit conditions. The study shows the invasive potential of all species, except C. citratus, in dry areas such as the Mediterranean region, especially in the current climate change scenario. Particular attention should be given to P. alopecuroides, which is widely commercialised in Europe as ornamental.

Open-Celled Foams from Polyethersulfone/Poly(Ethylene Glycol) Blends Using Foam Extrusion.

Polyethersulfone (PESU), as both a pristine polymer and a component of a blend, can be used to obtain highly porous foams through batch foaming. However, batch foaming is limited to a small scale and is a slow process. In our study, we used foam extrusion due to its capacity for large-scale continuous production and deployed carbon dioxide (CO2) and water as physical foaming agents. PESU is a high-temperature thermoplastic polymer that requires processing temperatures of at least 320 °C. To lower the processing temperature and obtain foams with higher porosity, we produced PESU/poly(ethylene glycol) (PEG) blends using material penetration. In this way, without the use of organic solvents or a compounding extruder, a partially miscible PESU/PEG blend was prepared. The thermal and rheological properties of homopolymers and blends were characterized and the CO2 sorption performance of selected blends was evaluated. By using these blends, we were able to significantly reduce the processing temperature required for the extrusion foaming process by approximately 100 °C without changing the duration of processing. This is a significant advancement that makes this process more energy-efficient and sustainable. Additionally, the effects of blend composition, nozzle temperature and foaming agent type were investigated, and we found that higher concentrations of PEG, lower nozzle temperatures, and a combination of CO2 and water as the foaming agent delivered high porosity. The optimum blend process settings provided foams with a porosity of approximately 51% and an average foam cell diameter of 5 µm, which is the lowest yet reported for extruded polymer foams according to the literature.

Crowding-induced phase separation and gelling by co-condensation of PEG in NPM1-rRNA condensates

The crowdedness of the cell calls for adequate intracellular organization. Biomolecular condensates, formed by liquid-liquid phase separation of intrinsically disordered proteins and nucleic acids, are important organizers of cellular fluids. To underpin the molecular mechanisms of protein condensation, cell-free studies are often used where the role of crowding is not investigated in detail. Here, we investigate the effects of macromolecular crowding on the formation and material properties of a model heterotypic biomolecular condensate, consisting of nucleophosmin (NPM1) and ribosomal RNA (rRNA). We studied the effect of the macromolecular crowding agent poly(ethylene glycol) (PEG), which is often considered an inert crowding agent. We observed that PEG could induce both homotypic and heterotypic phase separation of NPM1 and NPM1-rRNA, respectively. Crowding increases the condensed concentration of NPM1 and decreases its equilibrium dilute phase concentration, although no significant change in the concentration of rRNA in the dilute phase was observed. Interestingly, the crowder itself is concentrated in the condensates, suggesting that co-condensation rather than excluded volume interactions underlie the enhanced phase separation by PEG. Fluorescence recovery after photobleaching measurements indicated that both NPM1 and rRNA become immobile at high PEG concentrations, indicative of a liquid-to-gel transition. Together, these results provide more insight into the role of synthetic crowding agents in phase separation and demonstrate that condensate properties determined in vitro depend strongly on the addition of crowding agents.

Preparation and characterization of ductile PLA/PEG blend films for eco-friendly flexible packaging application

Poly(lactic acid) (PLA) is the most common biodegradable polymer in the food packaging industry; however, its inherent brittleness limits its applicability. To overcome this limitation, we prepared PLA/poly(ethylene glycol) (PEG) blend films via solvent-free melt extrusion and investigated the effects of different molecular weights (MW) and concentrations of PEG on the thermal, mechanical, barrier, and morphological properties and transparency of the blend films. As the PEG concentration increased, the glass transition and cold crystallization temperatures of the PLA phase in the blend films decreased, i.e., crystallization improved. The tensile strength and elongation of the blend films increased at low PEG concentration, whereas tensile strength decreased and elongation increased at high PEG concentration, indicating an improvement in the ductility of PLA. The oxygen barrier property and transparency of the films improved at high PEG MW and concentration. These PLA/PEG blend films have potential applications as biodegradable flexible packaging materials.

Thermal, spectroscopic characterization and evaluation of antibacterial and cytotoxicity properties of quercetin-PEG-silica hybrid materials

This study reports the characterization of two series of organic-inorganic silica-based hybrid materials with 15 and 20 wt% of quercetin (Q), respectively, and 6, 12, 24 and 50 wt% of polyethylene glycol (P) (for each of them). After the sol-gel synthesis they have been characterized using different techniques (Fourier-Transform Infrared and Micro-Raman spectroscopies, Thermogravimetry, Differential Thermal Analysis). Two tests were also carried out to evaluate their biomedical properties to estimate their antibacterial activity and their cytotoxicity. FT-IR measurements revealed the interaction between the components of the hybrid materials, while Micro-Raman spectra confirmed the presence of quercetin in an oxidized form. Simultaneous Thermogravimetry and Differential Thermal Analysis coupled with Mass Spectrometry enabled to investigate the thermal behavior of the hybrids (up to 800 °C) and to analyze the gas mixtures evolved upon heating in severe inert argon atmosphere. Antibacterial tests showed that an increase of PEG contents results in a decrease of the bacterial growth. Finally, cytotoxicity assessment highlighted that entrapping quercetin in hybrids at high PEG content leads to the constitution of materials that enjoy PEG biocompatibility, while cytotoxic effects are depleted.

Responses of Microstructure, Ultrastructure and Antioxidant Enzyme Activity to PEG-Induced Drought Stress in Cyclocarya paliurus Seedlings

Drought is one of the most important abiotic constraints on agricultural productivity, while global warming leads to the occurrence of more frequent drought events. Cyclocarya paliurus is a multiple-function tree species with medicinal value and timber production, but no information is available on its drought tolerance. In this hydroponic experiment, variations in leaf anatomical morphology, chloroplast ultrastructure, stomatal characteristics, and antioxidant enzyme activities were investigated under six levels of polyethylene glycol 6000 (PEG)-induced drought treatments to assess the drought adaption and physiological response of C. paliurus seedlings. The results showed that PEG-induced drought treatments reduced leaf epidermis, spongy tissue, leaf vein diameter, and spongy ratio, whereas the ratio of palisade tissue to spongy tissue, cell tense ratio, and vein protuberant degree all increased with enhancing the PEG6000 concentrations. Significant differences in stomatal width, stomatal aperture, and stomatal density existed among the treatments (p &lt; 0.01). The stomatal aperture decreased significantly with the increase in PEG6000 concentrations, whereas the greatest stomatal density was observed in the 15% PEG6000 treatment. Compared with the control, higher drought stresses (20% and 25% PEG concentrations) caused damage at the cellular level and chloroplast lysis occurred. PEG6000 treatments also promoted the activities of SOD, POD, and CAT in C. paliurus seedlings, but this increase was insufficient to deal with the membrane lipid peroxidative damage under the high PEG concentrations. Correlation analysis indicated that in most cases there were significant relationships between leaf anatomical characteristics and antioxidant enzyme activities. Our results suggested that C. paliurus seedlings would not survive well when the PEG6000 concentration was over 15% (equal to soil water potential of −0.30 MPa).

Seed Germination Response and Tolerance to Different Abiotic Stresses of Four Salsola Species Growing in an Arid Environment.

Land degradation caused by soil salinization and wind erosion is the major obstruction to sustainable agriculture in the arid region. Salsola species have the potential to prevent land degradation. However, there is limited information about seed germination requirements and tolerance to salinity and drought for representative Salsola species. This study aimed to assess the effects of the winged perianth (seed structural features) and abiotic factors (light, temperature, salinity, and drought) on the seed germination of these species. These Salsola species varied considerably in seed germination characteristics. Compared with naked seeds, winged seeds had lower germination percentages for S. heptapotamica S. rosacea, and S. nitraria species. Darkness decreased the germination percentage of winged and naked seeds of S. rosacea, however, for S. heptapotamica and S. nitraria, decreased seed germination was only when the winged perianth existed. Germination of S. heptapotamica, S. rosacea, and S. nitraria seeds depended on the perianth and light conditions. The naked seeds of these three species could germinate at a wide range of temperatures, especially in light. The presence of perianth, light, and temperature did not significantly influence the germination of S. ruthenica seeds. When cultivating these species, it is beneficial to remove the winged perianth of seeds and sow it on the soil surface when the temperature is above 5/15°C. In addition, seed germination of Salsola displayed high tolerance to salinity and drought. Compared with winged seeds, naked seeds showed lower recovery germination under high salinity but had a similar recovery of germination under high PEG concentration. Our study provides detailed germination information for the cultivation of these four representative Salsola species in degraded saline soils of the arid zone.

PBT/adipic acid modified PEG solid-solid phase change composites

The complicated preparation process and difficulty of recycling were serious obstacles to the widespread use of solid-solid phase change materials (PCMs). Herein, we reported a novel thermoplastic solid-solid PCMs prepared by a facile one-step feeding method. In this study, the esterification and transesterification among the molten mixture of PBT, PEG and adipic acid were conducted to prepare thermoplastic PEG/PBT/Adipic acid copolymer-based PCMs. Adipic acid, as an auxiliary encapsulation agent, could prevent effectively PEG leakage of PEG/PBT/Adipic acid copolymer-based PCMs with high PEG and low PBT content during the phase change process. For PCM-6 containing 91 wt% PEG, 8 wt% PBT and 1 wt% adipic acid, there were no changes in the shape and chemical structure after multiple thermal cycles. The TG results presented that the initial thermal degradation temperature of PCMs-6 was above 200 °C, which was much higher than the processing and working temperature of PCMs-6. The latent heat of PCMs-6 could reach 136.8 J/g, showing great potential for energy storage, especially in the field of green buildings.

Effects of osmotic stress on Chenopodium quinoa seed germination.

Quinoa is a pseudo-cereal native to the Andes known for its exceptional adaptation to extreme soil and climate conditions. The study of the response of Chenopodium quinoa to osmotic stress and the contribution to improving its yield aims to ensure production in arid and semi-arid regions as an alternative crop. The aim of this study is to test the germination capacity of 5 selected varieties; CQ-57, UDEC-2; ICBA-4, ICBA-5 and 115-R subjected to varying osmotic pressures using solutions of PEG-6000 and NaCl. Seeds are incubated at 25 °C for 10 days. Results showed that osmotic stress increases the lag phase but does not affect the germination rate at low concentrations of PEG and NaCl. While for high concentrations the germination rates decrease as compared to controls. Radicale and hypocotyl lengths decreased with increasing the degree of osmotic stress. The effects of osmotic stress are comparable in the 5 varieties. At high concentration of PEG or NaCl, ICBA-5 and CQ-57 exhibited the highest value of germination rate showing the capacity of these varieties to establish itself in regions suffering from salinity or water deficit.

Superior anti-biofouling properties of mPEG-modified polyurethane networks via incorporation of a hydrophobic dangling chain

PEG-modification is a proven method to enhance the hydrophilicity, protein resistance, and anti-biofouling properties of polymer coatings. It is considered as the gold standard interfacial modification technique such that the higher PEG content, the higher hydrophilicity, and lower protein adsorption, i.e., the initial stage of the biofouling process. Nevertheless, increasing the PEG content causes a higher water uptake, which declines the polymer mechanical strength and increases its hydrolytic degradation rate. Thus, an effective strategy to produce a limited-water-absorbing PEG-modified polymer is to force the majority of PEG molecules to migrate towards the interfacial region while the modification takes place. In the current paper, we report the synthesis and characterization of crosslinked polycarbonate-based polyurethanes (PU) containing methoxy polyethylene glycol (mPEG) dangling chains. We show that the simultaneous incorporation of a limited amount of a low-surface-energy dangling chain, i.e., 1-octadecanol (oDEC), along with mPEG, results in a considerably higher mPEG surface concentration, according to X-ray photoelectron spectroscopy (XPS), and a significantly lower water contact angle (WCA), up to 45° lower. We also put forward a reasonable mechanism for our outstanding observation and verified it through extensive experiments, e.g., dynamic WCA, Atomic force microscopy (AFM), and XPS. Moreover, we outline a delicate dynamic WCA experimental protocol, by which the smart and responsive behavior of our coatings is illustrated. Eventually, we examined the mixed hydrophobic/hydrophilic dangling chains strategy for low-protein adsorption applications, in which a great potential has been discovered.

Stress responses of the green microalga, Dunaliella salina to PEG-induced drought

AbstractDrought stress was evaluated with polyethylene glycol 6000 (PEG 6000) treatment in Dunaliella salina, a microalga known for its great ability to withstand salinities of more than 30%. The aim was to explore the acclimation mechanisms used by the microalga to regulate its growth and physiology during coping with drought stress. The microalga was subjected to culture mediums containing 2 and 5% PEG for 25 days and was compared with a control culture medium. Significant decrease in growth parameters such as specific growth rate, biomass and number of divisions per day was demonstrated in PEG-treated algae. During PEG treatment, chlorophylls slightly increased, while β-carotene and total protein were not affected. Osmolytes, as well as carbohydrates, were found to be significantly higher in PEG-treated algae than in control. Increased catalase and ascorbate peroxidase activities were proportionally related to PEG concentrations in the cultures. The PEG-treated cells accumulated a considerable amount of hydrogen peroxide and malondialdehyde, especially at higher PEG concentrations. Electrolyte leakage increased, regardless of the PEG concentrations applied, while DNA fragmentation was not observed after 25 days of treating with PEG. It was concluded that Dunaliella cells could respond to the drought stress, probably by using a higher accumulation of a range of osmolytes and also more stimulation of the antioxidant enzymatic system.

Enzymatic hydrolysis and simultaneous saccharification and fermentation of green coconut fiber under high concentrations of ethylene oxide-based polymers

The present study focuses on elucidating the effects of ethylene oxide-based polymers on cellulosic ethanol production from green coconut fiber (GCF). Data on ethanol production, cell viability, adsorption of cellulases, and enzymatic digestibility were collected from experiments with high concentrations of PEG 4000 and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) 5800 (EOPO 5800). PEG 4000 and EOPO 5800 favored cell viability and ethanol production in simulated experiments with S. cerevisiae CAT-1 and Kluyveromyces marxianus. Enzymatic hydrolysis under 175 g L−1 PEG 4000 increased the sugar release using untreated GCF (702.0%), hydrothermally-pretreated GCF (63.2%), and acid-pretreated GCF (40.1%). However, there were no benefits to using SigmaCell cellulose as the substrate. EOPO 5800 at 100 g L−1 had positive effects on cellulolytic activity preservation and on the sugar release during enzymatic hydrolysis. Both polymers provided higher ethanol titers for simultaneous saccharification and fermentation (SSF) of pretreated GCF compared to polymer-free experiments. A high ethanol yield (89.8%) was reached by the SSF of untreated GCF using 175 g L−1 PEG 4000. This result implies that high polymer concentrations may enable the cellulosic ethanol scheme without the need for pretreatment.