Hydrophobic Components Research Articles

Developing Multifunctional Fe-Based Catalysts for the Direct Hydrogenation of CO2 in Power Plant Flue Gas to Light Olefins

The hydrogenation of carbon dioxide (CO2) to produce light olefins is one of the most promising ways to utilize CO2 in power plant flue gas. However, the low concentration of CO2 (~10%) and the existence of water steam in the flue gas pose great challenges for the catalyst design. To address these problems, we introduced a Mg promoter and hydrophobic component into the Fe-based catalyst to improve the CO2 adsorption capacity and weaken the negative effects of water. The yield of light olefins on an optimized multifunctional Fe-based catalyst increased by 37% in low-concentration CO2 hydrogenation with water steam. A variety of characterizations proved that the Mg promoter played critical roles in regulating the adsorption capacity of CO2, increasing the surface electron density of Fe species, and promoting the formation of iron carbide active sites. The hydrophobic component mainly contributed to constraining the oxidation of iron carbides via water steam. It benefited from the rational design of the catalyst, showing how our multifunctional Fe-based catalyst has great potential for practical application in CO2 utilization.

Lipid-Binding Regions within PKC-Related Serine/Threonine Protein Kinase N1 (PKN1) Required for Its Regulation.

PKC-related serine/threonine protein kinase N1 (PKN1) is a protease/lipid-activated protein kinase that acts downstream of the RhoA and Rac1 pathways. PKN1 comprises unique regulatory, hinge region, and PKC homologous catalytic domains. The regulatory domain harbors two homologous regions, i.e., HR1 and C2-like. HR1 consists of three heptad repeats (HR1a, HR1b, and HR1c), with PKN1-(HR1a) hosting an amphipathic high-affinity cardiolipin-binding site for phospholipid interactions. Cardiolipin and C18:1 oleic acid are the most potent lipid activators of PKN1. PKN1-(C2) contains a pseudosubstrate sequence overlapping that of C20:4 arachidonic acid. However, the cardiolipin-binding site(s) within PKN1-(C2) and the respective binding properties remain unclear. Herein, we reveal (i) that the primary PKN1-(C2) sequence contains conserved amphipathic cardiolipin-binding motif(s); (ii) that trimeric PKN1-(C2) predominantly adopts a β-stranded conformation; (iii) that two distinct types of cardiolipin (or phosphatidic acid) binding occur, with the hydrophobic component playing a key role at higher salt levels; (iv) the multiplicity of C18 fatty acid binding to PKN1-(C2); and (v) the relevance of our lipid-binding parameters for PKN1-(C2) in terms of kinetic parameters previously determined for the full-length PKN1 enzyme. Thus, our discoveries create opportunities to design specific mammalian cell inhibitors that disrupt the localization of membrane-associated PKN1 signaling molecules.

Synergistic Augmentation of Beta-Lactams: Exploring Quinoline-Derived Amphipathic Small Molecules as Antimicrobial Potentiators against Methicillin-Resistant Staphylococcus aureus.

The escalation of bacterial resistance against existing therapeutic antimicrobials has reached a critical peak, leading to the rapid emergence of multidrug-resistant strains. Stringent pathways in novel drug discovery hinder our progress in this survival race. A promising approach to combat emerging antibiotic resistance involves enhancing conventional ineffective antimicrobials using low-toxicity small molecule adjuvants. Recent research interest lies in weak membrane-perturbing agents with unique cyclic hydrophobic components, addressing a significant gap in antimicrobial drug exploration. Our study demonstrates that quinoline-based amphipathic small molecules, SG-B-52 and SG-B-22, significantly reduce MICs of selected beta-lactam antibiotics (ampicillin and amoxicillin) against lethal methicillin-resistant Staphylococcus aureus (MRSA). Mechanistically, membrane perturbation, depolarization, and ROS generation drive cellular lysis and death. These molecules display minimal in vitro and in vivo toxicity, showcased through hemolysis assays, cell cytotoxicity analysis, and studies on albino Wistar rats. SG-B-52 exhibits impressive biofilm-clearing abilities against MRSA biofilms, proposing a strategy to enhance beta-lactam antibiosis and encouraging the development of potent antimicrobial potentiators.

Structural and Transport Properties of Hydrophilic and Hydrophobic Modified Ionomers in Proton Exchange Membrane Fuel Cells.

The sluggish commercial application of proton exchange membrane fuel cells (PEMFCs) with low Pt loading is chiefly hindered by concentration polarization loss, particularly at high current density regions. Addressing this, our study concentrates on the ionomer membranes in the cathode catalyst layer (CCL) and explores the potential of incorporating additional hydrophilic or hydrophobic components to modify these ionomers. Therefore, an all-atom model was constructed and for the ionomer and hydrophilic and hydrophobic modifications were implemented via incorporating SiO2 and PTFE, respectively. The investigation was conducted via molecular dynamics (MD) simulations to predict the morphology and structure of the ionomer and analyze the kinetic properties of oxygen molecules and protons. The simulation results elaborate that the hydrophilic and hydrophobic modifications favor the phase separation and the self-diffusion coefficients of oxygen molecules and protons are enhanced. Considering the hydration level of the ionomer films, hydrophilic modification facilitates mass transfer under low-hydration-level conditions, while hydrophobic modification is more effective in optimizing mass transfer as the hydration level increases. The optimal contents of SiO2 and PTFE for each hydration level in this work are 9.6% and 45%, respectively. This work proposes a reliable model and presents a detailed analysis of hydrophilic and hydrophobic modifications, which provides theoretical guidance for quantitative preparations of various composite membranes.

Production of zein nanofibers using an electrospinning technique for the encapsulation of peppermint (Mentha piperita L.) essential oil

Peppermint is a perennial herb with high inhibitory power against bacteria because its chemical profile contains menthol and menthone. In this research, peppermint essential oil (PEO) was encapsulated in various levels (0, 2.5, 5, and 10% w/v) in nanofibers (NFs) obtained from zein using an electrospinning technique. SEM, XRD, TGA, and FTIR tests were performed to investigate the characteristics of NFs after producing them. Also, the resultant NFs were evaluated regarding encapsulation efficiency (EE) and antimicrobial properties via disc-diffusion against Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Salmonella enterica. The results indicated that the morphology was tubular, uniform, and free bead. Fiber diameter increased on average by increasing the amount of PEO (p<0.05). XRD results showed that PEO was amorphous in electrospun zein NFs. TGA and FTIR analyses confirmed the presence of PEO in the electrospun fibers. In addition, the FTIR spectrum showed that the zein protein changed its secondary structure because of the PEO. The results of EE showed that an increase in PEO concentration caused a relevant rise in EE (P<0.05). The electrospun NFs containing PEO showed antimicrobial properties against the target bacteria. According to the current research, NFs obtained from zein via electrospinning can be applied suitably as a substrate to encapsulate PEO as a hydrophobic component.

Peptide-Driven Proton Sponge Nano-Assembly for Imaging and Triggering Lysosome-Regulated Immunogenic Cancer Cell Death.

Triggering lysosome-regulated immunogenic cell death (ICD, e.g., pyroptosis and necroptosis) with nanomedicines is an emerging approach for turning an "immune-cold" tumor "hot"-a key challenge faced by cancer immunotherapies. Proton sponge such as high-molecular-weight branched polyethylenimine (PEI) is excellent at rupturing lysosomes, but its therapeutic application is hindered by uncontrollable toxicity due to fixed charge density and poor understanding of resulted cell death mechanism. Here, a series of proton sponge nano-assemblies (PSNAs) with self-assembly controllable surface charge density and cell cytotoxicity are created. Such PSNAs are constructed via low-molecular-weight branched PEI covalently bound to self-assembling peptides carrying tetraphenylethene pyridinium (PyTPE, an aggregation-induced emission-based luminogen). Assembly of PEI assisted by the self-assembling peptide-PyTPE leads to enhanced surface positive charges and cell cytotoxicity of PSNA. The self-assembly tendency of PSNAs is further optimized by tuning hydrophilic and hydrophobic components within the peptide, thus resulting in the PSNA with the highest fluorescence, positive surface charge density, cell uptake, and cancer cell cytotoxicity. Systematic cell death mechanistic studies reveal that the lysosome rupturing-regulated pyroptosis and necroptosis are at least two causes of cell death. Tumor cells undergoing PSNA-triggered ICD activate immune cells, suggesting the great potential of PSNAs to trigger anticancer immunity.

The amphipathic design in helical antimicrobial peptides.

Amphipathicity is a critical characteristic of helical antimicrobial peptides (AMPs). The hydrophilic region, primarily composed of cationic residues, plays a pivotal role in the initial binding to negatively charged components on bacterial membranes through electrostatic interactions. Subsequently, the hydrophobic region interacts with hydrophobic components, inducing membrane perturbation, ultimately leading to cell death, or inhibiting intracellular function. Due to the extensive diversity of natural and synthetic AMPs with regard to the design of amphipathicity, it is complicated to study the structure-activity relationships. Therefore, this work aims to categorize the common amphipathic design and investigate their impact on the biological properties of AMPs. Besides, the connection between current structural modification approaches and amphipathic styles was also discussed.

Effect of the Formation of Hydrophilic and Hydrophobic-Hydrophilic Associates on the Behavior of Copolymers of N-Vinylpyrrolidone with Methyl Acrylate in Aqueous Solutions.

It has been shown that there exist conditions under which thermosensitive copolymers of N-vinylpyrrolidone with methyl acrylate form hydrophobic-hydrophilic associations, which are unstable dynamic meshes, the bonds in which are continuously broken and created again, and the nature of the formation of such meshes depends significantly on the proportion of the hydrophobic component in the copolymer. It is shown that the interaction of the above copolymers with polyacrylic acid results in the formation of not only classical interpolymer complexes, but also hydrophilic interpolymer associates, which also represent unstable networks existing in a dynamic mode. In such meshes, the molecules of the above copolymers serve as a kind of cross-agent connecting the polyacid molecules. There are also conditions under which such meshes acquire a complex structure, since unstable bonds between macromolecular tangles of both the same and different types take part in their formation. It is shown that the transition from the formation of interpolymer complexes to the formation of hydrophilic interpolymer associates can occur, among other things, due to changes in the acidity or concentration of low-molecular salt in solution.

Hydrophobic Components in Light-Yellow Pulp Sweet Potato (Ipomoea batatas (L.) Lam.) Tubers Suppress LPS-Induced Inflammatory Responses in RAW264.7 Cells via Activation of the Nrf2 Pathway.

Sweet potato is a crop that is widely consumed all over the world and is thought to contribute to health maintenance due to its abundant nutrients and phytochemicals. Previous studies on the functionality of sweet potatoes have focused on varieties that have colored pulp, such as purple and orange, which contain high levels of specific phytochemicals. Therefore, in the present study, we evaluated the anti-inflammatory effects of light-yellow-fleshed sweet potatoes, which have received little attention. After freeze-drying sweet potatoes harvested in 2020, extracts were prepared from the leaves, stems, roots, and tubers in 100% ethanol. Mouse macrophage-like cell line RAW264.7 cells were cultured with 10 µg/mL of the extracts and induced lipopolysaccharide (LPS)-stimulated inflammation. Of the extracts, the tuber extracts showed the highest suppression of LPS-induced interleukin-6 (IL-6) gene expression and production in RAW264.7, which was attributed to the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) oxidative stress response pathway. In addition, preparative high-performance liquid chromatography (HPLC) experiments suggested that hydrophobic components specific to the tuber were the main body of activity. In previous studies, it has been shown that the tubers and leaves of sweet potatoes with colored pulp exhibit anti-inflammatory effects due to their rich phytochemicals, and our results show that the tubers with light-yellow pulp also exhibit the effects. Furthermore, we were able to show a part of the mechanism, which may contribute to the fundamental understanding of the treatment and prevention of inflammation by food-derived components.

Isomerism of Cyclodextrin Tetramer Induced by Alkali Halide Cluster Ions Observed by Ion Mobility Spectrometry-Mass Spectrometry.

Cyclodextrins (CDs) exhibit versatile self-assembly properties due to their hydrophilic and hydrophobic components, with applications such as drug delivery and selective binding. While research on CD self-assembly is extensive, limited studies have explored their aggregation behavior, particularly in interactions with small ionic guests. The present work investigates the structure of β-CD tetramers aggregated with alkali metal chloride clusters using ion mobility spectrometry-mass spectrometry (IMS-MS). The results revealed that diverse structures emerge in the tetramer depending on the alkali metal cluster size. Notably, the doubly charged tetramer exhibits distinct aggregation trends with specific numbers of MCl clusters for Na+ and K+ ions. After initially adopting a bucket-wheel structure with two internal cations, the structure transforms into a new isomer with a tetrahedral configuration upon cluster addition. The formation of the new isomer structure is closely linked to filling the cavity volume with MCl clusters and ionic interactions, which possibly compensate for the weakened hydrogen bonds between CDs. Theoretical calculations further support the structures, showing well-matched collision cross-section (CCS) values compared with the experimental CCS values. This study highlights the role of alkali metal chloride clusters as potential templates, leading to the formation of novel CD assemblies.

Improving Gene Delivery: Synergy between Alkyl Chain Length and Lipoic Acid for PDMAEMA Hydrophobic Copolymers.

In the field of gene delivery, hydrophobic cationic copolymers hold great promise. They exhibit improved performance by effectively protecting genetic material from serum interactions while facilitating interactions with cellular membranes. However, managing cytotoxicity remains a significant challenge, prompting an investigation into suitable hydrophobic components. A particularly encouraging approach involves integrating nutrient components, like lipoic acid, which is known for its antioxidant properties and diverse cellular benefits such as cellular metabolism and growth. In this study, a copolymer library comprising 2-(dimethylamino)ethyl methacrylate (DMAEMA) and lipoic acid methacrylate (LAMA), combined with either n-butyl methacrylate (nBMA), ethyl methacrylate (EMA), or methyl methacrylate (MMA), is synthesized. This enables to probe the impact of lipoic acid incorporation while simultaneously exploring the influence of pendant acyclic alkyl chain length. The inclusion of lipoic acid results in a notable boost in transfection efficiency while maintaining low cytotoxicity. Interestingly, higher levels of transfection efficiency are achieved in the presence of nBMA, EMA, or MMA. However, a positive correlation between pendant acyclic alkyl chain length and cytotoxicity is observed. Consequently, P(DMAEMA-co-LAMA-co-MMA), emerges as a promising candidate. This is attributed to the optimal combination of low cytotoxic MMA and transfection-boosting LAMA, highlighting the crucial synergy between LAMA and MMA.

Solvent-free polyurethane coatings based on an in-situ curing strategy at room temperature with self-cleaning, anti-corrosion and anti-graffiti properties

Anti-smudge coatings have attracted extensive attention in recent years owing to their hydrophobic, self-cleaning, anti-graffiti properties and so on. However, most of the anti-smudge coatings are solvent-based and cured at high temperature or using special curing equipment, which negatively impacts the environment and limits their large-scale application in daily life. Herein, we report a solvent-free anti-smudge coating with potential for large-scale and green manufacturing. In detail, polydimethylsiloxane (PDMS) was used as the hydrophobic component, (3-aminopropyl)triethoxysilane (APTES) and 3-glycidoxypropyltrimethoxysilane (GPTMS) were used as the cross-linking agent, and a solvent-free polyurethane (SFPU) anti-smudge coating was in-situ constructed at room temperature for 24 h without any curing equipment. Due to the enrichment of PDMS chains on the surface and the dense cross-linked network of the coating, the as-prepared coating not only exhibited a high contact angle for water (99.3 ± 1.5°) and diiodomethane (69.5 ± 0.9°), but also excellent anti-smudge to contaminants, with both water and oily liquids were easy to slide off the surface of the coating without leaving any traces. Even after writing with an oil-based marker, the ink on the coated surface could be easily wiped off. Further study reveals that the coating surface maintained its original liquid repellency and stain resistance even after 10 d immersion in a 10 wt% NaCl solution, showing durable anti-corrosion properties. In addition, pigments did not affect the anti-graffiti performance of the coating, providing a multi-color scheme for practical application. This convenient, low-energy, environmentally friendly anti-smudge coating has great potential for widespread application in industry and daily life.

Highly-conductive proton exchange membrane of sulfonated poly(biphenyl alkylene) copolymers for H2/O2 fuel cell with 2.62 W cm-2 power density

Ether-free proton exchange membranes (PEMs) based on aromatic polymers are considered as potential alternatives to perfluorosulfonic acid (PFSA) PEMs due to their low cost, less reactant crossing, exceptional chemical stability and outstanding thermal stability. Herein, a series of high-performance sulfonated poly(biphenyl alkylene) (BPSA-PT-x) membranes with full carbon chain backbones were synthesized to investigate the effect of different ratios of hydrophobic components on membrane properties. Among the prepared membranes, the BPSA-PT-10 % PEM with the highest proton conductivity (311 mS cm-1 at 80 °C water) possessed excellent dimensional stability (in-plane swelling rate ≤19.7 %, through-plane swelling rate ≤24.9 %), mechanical properties (elongation at break: 89.8 % in wet state), thermal stability (glass transition temperature >450 °C) and low H2 crossover (1.80 mA cm-2). Further, the assembled H2/O2 fuel cell based on BPSA-PT-10 % PEM exhibited competitive performance with a peak power density of 2.62 W cm-2. The developed poly(biphenyl alkylene)-based PEMs should have potential applications in hydrogen energy field.

Effect of acetylation on the functional characteristics of lima bean (Phaseolus lunatus)

The limited functionality of native starches and powders in diverse applications necessitates their chemical modification for enhanced use. The effect of acetylation on the functional properties of lima bean (Phaseolus lunatus) powder is presented in this study, and its potential as a modified food ingredient was evaluated. Acetylation was performed at 2.11% (LAA), 2.48% (LAB), 3.40% (LAC), and 3.70% (LAD) levels of acetylation, with unmodified lima bean powder (LCC) serving as a control. The paste clarity, turbidity, sedimentation volume, pasting attributes, starch digestibility, bulk density, and water/oil absorption capacities were evaluated. Acetylation improved yield (64.50% to 72.10%) and pasting properties (1166.0 to 4147.0 RVU), pasting temperatures (84.0 to 88.18 °C), and pasting times (4.67 to 7.0 min). Notably, acetylation increased water absorption capacity while decreasing oil absorption capacity and turbidity, indicating a modified interaction with hydrophilic and hydrophobic components. Light transmittance ranged from 3.3% to 18.7%, demonstrating increased paste clarity in acetylated powders. Acetylation impacted starch digestibility and retrogradation tendencies, with acetylated powders showing a reduced inclination for retrogradation. The solubility and swelling power of the powder were temperature-dependent and increased with elevated temperatures. Therefore, acetylation significantly improves the functional profiles of lima bean powder, suggesting its potential for specialized food formulations, pharmaceuticals, and industrial uses. This study paves the way for the innovative use of modified lima bean powder in formulations where tailored functionality is essential, heralding a new era of application for legume-based powders in food technology.

Enhancing the performance of metallic lithium anode in batteries through water-resistant and air-stable coating

The limited reversibility and high reactivity of lithium metal with the liquid electrolyte in lithium batteries hinder its widespread adoption. The formation of an unstable solid electrolyte interphase layer and the sensitivity of lithium metal to moisture and air are major issues that need to be addressed. To overcome the practical challenges associated with the application of lithium anodes in lithium metal batteries, a well-thought-out design of a protective layer is proposed. Here, we have developed a composite coating comprising polyvinylidene fluoride, fumed colloidal silica, and paraffin wax as a protective layer for lithium metal anodes. The coating exhibits excellent electrochemical stability, high ionic conductivity, and mechanical stability, effectively suppressing dendrite growth and accommodating lithium volume changes during cycling. Moreover, the hydrophobic wax component can mitigate the atmospheric sensitivity of metallic lithium anodes. The coating process employed is facile and economically viable, significantly enhancing the scalability of lithium metal batteries. Experimental characterizations confirm the structure and composition of the coating, and electrochemical measurements demonstrate the improved electrochemical performance and cyclability of the coated lithium metal anodes. The results indicate that the developed composite coating has great potential for enhancing the electrochemical and processing stability of metallic lithium anodes for lithium metal batteries.

Enhancing Zn‐Metal Anode Stability: Key Effects of Electrolyte Additives on Ion‐Shield‐Like Electrical Double Layer and Stable Solid Electrolyte Interphase

AbstractOwing to zinc dendrites and parasitic reactions, aqueous Zn‐metal batteries often suffer from poor reversibility and cyclability. Electrolyte additives present a promising strategy to improve Zn anode stability. However, the ever‐evolving perspectives and mechanisms, paradoxically, complicate battery design, causing a scenario where any electrolyte additive seems to be effective. Herein, it is taken ionic liquid (IL) additives as an example and detailed explored the impact of three typical IL anions, namely OTF−, TFA−, and BF4−. It is identified that the primary determinant of electrolyte additives as their electrical double layer (EDL) structures and their subsequent solid‐electrolyte interface (SEI) composition. An advantageous EDL structure, akin to an ion‐shield, can reduce the absorption of H2O molecules, which further enrich the SEI with zincophilic and hydrophobic components, thereby mitigating parasitic reactions and Zn dendrite formation. As a result, the Zn||Zn cell with optimal [EMIM]OTF additives demonstrates an exceptional cycling life under challenging conditions, its cumulative plated capacity surpasses most previously reported results by utilizing different IL additives. This work extends beyond performance enhancements, representing a valuable exploration of key criteria for electrolyte additives is believed. These insights are expected to offer fundamental guidance for future research and electrolyte design.

Characterization of the mechanical properties of the cortex region of human hair fibers by multiparametric atomic force microscopy mapping

We show the benefit of the use of atomic force microscopy (AFM) in spectroscopy force mode (FV: force volume) for evaluation of the cosmetic active effectiveness in improving the mechanical properties of human hair fibers cortex region. For this, we characterized human hair fibers without and with chemical damage caused by bleaching process. Fiber and resin (embedding material) data were obtained simultaneously in the mapping in order to have the resin data as a reference to ensure a coherent comparison between data from the different fiber groups. Our AFM results, which were evaluated using statistical tests, demonstrated the degradation of fibers after bleaching, corroborating the findings of transmission electron microscopy analysis and the effectiveness of a cosmetic active ingredient in improving the Young's modulus (elastic modulus) (E) of the damaged fibers. We also found a radial decrease in the natural logarithm of Young's modulus ln(E) along the cross-section of the active group fiber, which is compatible with confocal Raman spectroscopy analysis by other authors, demonstrating variation of the active permeation with depth. We note that Young's modulus was also determined by a tensile tester (macro-scale technique), in which it was not possible to obtain statistically significant differences between the groups, evidencing the advantage of the FV-AFM analysis. We also found an increase in ln(E) accompanied by a decrease in maximum adhesion force between tip and sample (negative Pearson correlation coefficient). This result can be explained by the fact that structures composed of hydrophobic components have a higher Young's modulus than structures composed of hydrophilic components.•Bleaching damage and cosmetic hair treatment assessed by AFM, TEM, and tensile tester.•Young's modulus by AFM nanoindentation of hair fibers monitored by sample standard.•Young's modulus changes radially along the cross-section due to the cosmetic active.•AFM data show statistically significant differences among sample groups.•Tensile tester was not able to show statistically significant differences.

Co-encapsulation of organic polymers and inorganic superparamagnetic iron oxide colloidal crystals requires matched diffusion time scales.

Nanoparticles (NPs) that contain both organic molecules and inorganic metal or metal oxide colloids in the same NP core are "composite nanoparticles" which are of interest in many applications, particularly in biomedicine as "theranostics" for the combined delivery of colloidal diagnostic imaging agents with therapeutic drugs. The rapid precipitation technique Flash NanoPrecipitation (FNP) enables continuous and scalable production of composite nanoparticles with hydrodynamic diameters between 40-200 nanometers (nm) that contain hydrophobic superparamagnetic iron oxide primary colloids. Composite NPs co-encapsulate these primary colloids (diameters of 6 nm, 15 nm, or 29 nm), a fluorescent dye (600 Daltons), and poly(styrene) homopolymer (1800, 50 000, or 200 000 Daltons) with NPs stabilized by a poly(styrene)-block-poly(ethylene glycol) (1600 Da-b-5000 Da) block copolymer. Nanoparticle assembly in FNP occurs by diffusion limited aggregation of the hydrophobic core components followed by adsorption of the hydrophobic block of the stabilizing polymer. The hydrodynamic diameter mismatch between the collapsed organic species and the primary colloids (0.5-5 nm versus 6-29 nm) creates a diffusion-aggregation time scale mismatch between components that can lead to nonstoichiometric co-encapsulation in the final nanoparticles; some nanoparticles are composites with primary colloids co-encapsulated alongside organics while others are devoid of the primary colloids and contain only organic species. We use a magnetic capture process to separate magnetic composite nanoparticles from organic-only nanoparticles and quantify the amount of iron oxide colloids and hydrophobic fluorescent dye (as a proxy for total hydrophobic polymer content) in the magnetic and nonmagnetic fractions of each formulation. Analysis of the microstructure in over 1100 individual nanoparticles by TEM imaging and composition measurements identifies the conditions that produce nonstoichiometric composite NP populations without co-encapsulated magnetic iron oxide colloids. Stoichiometric magnetically responsive composite NPs are produced when the ratio of characteristic diffusion-aggregation time scales between the inorganic primary colloid and the organic core component is less than 30 and all NPs in a dispersion contain organic and inorganic species in approximately the same ratio. These rules for assembly of colloids and organic components into homogeneous composite nanoparticles are broadly applicable.

Algae decomposition released dissolved organic matter subfractions on dark abiotic mercury methylation

To understand the mechanism of dark abiotic mercury (Hg) methylation by algae-derived dissolved organic matter (DOM) and effectively manage the environmental risks of mercury methylation in aquaculture areas, we investigated the influence of subfractions of DOM released from algae (Ulothrix sp.) decomposition on mercury methylation. The results showed that the hydrophobic basic component (HOB) in DOM exhibited the most substantial promotion effect on Hg methylation. The methylmercury (MeHg) production in the HOB treatment increased significantly, while the production rate of MeHg (%MeHg represented the concentration ratio of MeHg to THg) in the six subfractions treated solutions decreased significantly with the increase of Hg concentration. The change of the %MeHg was more evident at low Hg concentration, indicating the limited number of binding sites and methyl donors on DOM. As a consequence, Hg(Ⅱ) in the solution could not be converted into MeHg in equal proportion. Furthermore, the production of MeHg in solution was significantly reduced by the decomposed algae DOM, and its concentration was in the range of 0.017–0.085 ng·L−1 (significantly lower than undecomposed algal). The difference between the decomposed and the non-decomposed algae DOM reached a significant level (P < 0.05). When the DOM decayed for 20 and 30 days, the Hg methylation ability of DOM was weakened most obviously. During the decomposition process, considerable variations were observed among the subfractions, with HOB consistently playing a dominant role in Hg methylation. At the same time, the hydrophilic acid component exhibited a significant inhibitory effect on Hg methylation. Generally, the main components (e.g. HOB and HIA (hydrophilic acid component)) of DOM affecting mercury methylation were found in our study, which provided a better understanding of algae-derived DOM subfractions on the Hg methylation, in an attempt to prevent and control water pollution in aquaculture areas.

Effects of concentration of hydrophobic component and swelling in saline solutions on mechanical properties of a stretchable hydrogel.

An elastic biopolymer, resilin possesses exceptional qualities such as high stretchability and resilience. Such attributes are utilized in nature by many species for mechanical energy storage to facilitate movement. The properties of resilin are attributed to the balanced combination of hydrophilic and hydrophobic segments. To mimic the properties of resilin, we developed a hydrogel system composed of hydrophilic acrylic acid (AAc) and methacrylamide (MAM) chains and hydrophobic poly(propylene glycol diacrylate) (PPGDA) chains. The gel was produced through free-radical polymerization in 0.8 M NaCl solutions using KPS as an initiator. In these gels, AAc and MAM can form hydrogen bonds, whereas the association between PPGDA chains can lead to hydrophobic domains. The PPGDA concentration affects the level of hydrogen bonding and gel mechanical properties. Tensile experiments revealed that the elastic modulus increased with a higher PPGDA concentration. Retraction experiments demonstrated increased velocity and acceleration when released from a stretched state with increasing PPGDA concentration. Swelling and deswelling of gels in saline solutions led to a change in mechanical properties and retraction behavior. This study shows that the stretchability and resilience of these hydrogels can be adjusted by changing the concentration of hydrophobic components.