Combination Of Hydrophobicity Research Articles

Exploring complexity of class-A Beta-lactamase family using physiochemical-based multiplex networks

The Beta-lactamase protein family is vital in countering Beta-lactam antibiotics, a widely used antimicrobial. To enhance our understanding of this family, we adopted a novel approach employing a multiplex network representation of its multiple sequence alignment. Each network layer, derived from the physiochemical properties of amino acids, unveils distinct insights into the intricate interactions among nodes, thereby enabling the identification of key motifs. Nodes with identical property signs tend to aggregate, providing evidence of the presence of consequential functional and evolutionary constraints shaping the Beta-lactamase family. We further investigate the distribution of evolutionary links across various layers. We observe that polarity manifests the highest number of unique links at lower thresholds, followed by hydrophobicity and polarizability, wherein hydrophobicity exerts dominance at higher thresholds. Further, the combinations of polarizability and volume, exhibit multiple simultaneous connections at all thresholds. The combination of hydrophobicity, polarizability, and volume uncovers shared links exclusive to these layers, implying substantial evolutionary impacts that may have functional or structural implications. By assessing the multi-degree of nodes, we unveil the hierarchical influence of properties at each position, identifying crucial properties responsible for the protein’s functionality and providing valuable insights into potential targets for modulating enzymatic activity.

Combination of hydrophobicity and codon usage bias determines sorting of model K+ channel protein to either mitochondria or endoplasmic reticulum.

When the K+ channel-like protein Kesv from Ectocarpus siliculosus virus 1 is heterologously expressed in mammalian cells, it is sorted to the mitochondria. This targeting can be redirected to the endoplasmic reticulum (ER) by altering the codon usage in distinct regions of the gene or by inserting a triplet of hydrophobic amino acids (AAs) into the protein's C-terminal transmembrane domain (ct-TMD). Systematic variations in the flavor of the inserted AAs and/or its codon usage show that a positive charge in the inserted AA triplet alone serves as strong signal for mitochondria sorting. In cases of neutral AA triplets, mitochondria sorting are favored by a combination of hydrophilic AAs and rarely used codons; sorting to the ER exhibits the inverse dependency. This propensity for ER sorting is particularly high when a common codon follows a rarer one in the AA triplet; mitochondria sorting in contrast is supported by codon uniformity. Since parameters like positive charge, hydrophobic AAs, and common codons are known to facilitate elongation of nascent proteins in the ribosome the data suggest a mechanism in which local changes in elongation velocity and co-translational folding in the ct-TMD influence intracellular protein sorting.

A Water-soluble polymeric surfactant with thickening water and emulsifying oil simultaneously for heavy oil recovery

For enhanced heavy oil recovery, either a conventional polymer for thickening water or a surfactant for emulsifying heavy oil has its limitation when each of two is used alone. The former can not effectively drive oil out while the latter could be inefficient in the low swept area. So, a Polymer surfactant with both good viscoelasticity and emulsification of heavy oil is of great significance. Here, by means of polyvinyl alcohol (PVA) grafting with acrylamide (AM) and 2-acrylamide-2-methyl propanesulfonic acid (AMPS), a novel polymeric surfactant PVA-g-P(AM-co-AMPS) was synthesized and the viscosity of PVA-g-P(AM-co-AMPS) aqueous solution can be as much as 27 times more than that of unmodified PVA. The degree of viscosity reduction for the four typical heavy oils can reach to above 85%. The “quasi crosslinking” structure formed by hydrophobic combination with the original hydrophilic groups may be the reason for such a result. The findings of this study can help for better understanding to a construct two-phase viscosity regulator. This polymeric surfactant could be applied in enhanced heavy oil recovery.

Exploring the kinetic selectivity of drugs targeting the β1 -adrenoceptor.

In this study, we report the β1‐adrenoceptor binding kinetics of several clinically relevant β1/2‐adrenoceptor (β1/2AR) agonists and antagonists. [3H]‐DHA was used to label CHO‐β1AR for binding studies. The kinetics of ligand binding was assessed using a competition association binding method. Ligand physicochemical properties, including logD7.4 and the immobilized artificial membrane partition coefficient (K IAM), were assessed using column‐based methods. Protein Data Bank (PDB) structures and hydrophobic and electrostatic surface maps were constructed in PyMOL. We demonstrate that the hydrophobic properties of a molecule directly affect its kinetic association rate (k on) and affinity for the β1AR. In contrast to our findings at the β2‐adrenoceptor, K IAM, reflecting both hydrophobic and electrostatic interactions of the drug with the charged surface of biological membranes, was no better predictor than simple hydrophobicity measurements such as clogP or logD7.4, at predicting association rate. Bisoprolol proved kinetically selective for the β1AR subtype, dissociating 50 times slower and partly explaining its higher measured affinity for the β1AR. We speculate that the association of positively charged ligands at the β1AR is curtailed somewhat by its predominantly neutral/positive charged extracellular surface. Consequently, hydrophobic interactions in the ligand‐binding pocket dominate the kinetics of ligand binding. In comparison at the β2AR, a combination of hydrophobicity and negative charge attracts basic, positively charged ligands to the receptor's surface promoting the kinetics of ligand binding. Additionally, we reveal the potential role kinetics plays in the on‐target and off‐target pharmacology of clinically used β‐blockers.

Multiplexed Covalent Patterns on Double-Reactive Porous Coating.

We have conceptualized and demonstrated an approach based on the combination of hydrophobicity, a substrate‐independent dip coating as porous material with double residual chemical reactivities for implementing multiplexed, miniaturized and unclonable bulk‐infused patterns of different fluorophores following distinct reaction pathways. The embedded hydrophobicity (∼102°) restricted the unwanted spreading of beaded aqueous ink on the coating. The constructions of micropatterns on porous dip‐coating via ink‐jet printing or microchannel cantilever spotting offered orthogonal read‐out and remained readable even after removal of the exterior of the coating.

Effects of Succinylation on the Physicochemical Properties and Structural Characteristics of Edible Rapeseed Protein Isolate Films

AbstractThis study described the manufacture and characterization of different levels of succinic anhydride (0–15%, w/w) on rapeseed protein isolate (RPI) films. Mechanical, barrier, optical, surface, microstructure, and thermal properties were investigated. Results showed that 5% succinylated rapeseed protein isolate (SRPI) film revealed the overall optimal properties. The mechanical and barrier properties of 5% SRPI film were enhanced significantly compared to the RPI film. The water vapor permeability values of RPI and 5% SRPI films were 0.77 and 0.32 g mm/[hour m2 kPa], respectively. Succinylation improved the color of RPI. The contact angle of 5% SRPI film was 108.68° and was the most hydrophobic combination. Moreover, scanning electron microscopy images revealed that 5% SRPI showed a dense, homogenous, and smooth microstructure. Thermogravimetric analysis results verified a low level of succinylation strengthened the thermal resistance of SRPI films. The content of β‐sheet was almost half of all secondary structures after succinylation, which was supported by analyses of Fourier transform infrared spectroscopy. Results demonstrated that succinylation could be employed to improve the properties of rapeseed protein and SRPI films have great potential to be used as edible films.

Mono and co-immobilization of imidazolium ionic liquids on silica: effects of the substituted groups on the adsorption behavior of 2,4-dinitrophenol.

Ionic liquid modified silicas with high adsorption capacity for phenols prompt us to deeply explore the contribution of interactions between the adsorbent and adsorbate, with a particular focus on hydrophobicity, π–π, electrostatic and acid–base interactions. Herein, by introducing a series of typical substituent groups including N,N-dimethylaminopropyl (A), benzyl (B), dodecyl (D) and naphthylmethyl (N) in an imidazole ring (Im), three mono-immobilized and two co-immobilized imidazolium ionic liquid modified silicas, namely SilprAImCl, SilprBImCl, SilprNImCl, SilprDBImCl and SilprDAImCl, werre synthesized for removal and recovery of 2,4-dinitrophenol (2,4-DNP) from aqueous solutions. Adsorption kinetics, isotherms, thermodynamic analysis and desorption experiments have been carried out. The experimental results reveal that the substituent groups such as N,N-dimethylaminopropyl, benzyl and naphthylmethyl on the imidazole ring can significantly enhance the adsorption of 2,4-DNP via the acid–base interaction or π–π interaction and the adsorption capacity of 2,4-DNP follows the order: SilprNImCl > SilprAImCl > SilprBImCl. Furthermore, SilprDBImCl exhibits the largest adsorption capacity and SilprDAImCl has the lowest among the five adsorbents. These interesting finds indicate that the combination of hydrophobicity and π–π interactions lead to enhanced adsorption performance towards 2,4-DNP, while the combination of the hydrophobicity and acid–base interactions can restrain greatly adsorption of 2,4-DNP from aqueous medium. Adsorption mechanisms of 2,4-DNP on the five adsorbents have been clarified. These results will provide a deeper insight for efficient removal of phenols from water environments.

Effect of dissolved gas on bubble growth on a biphilic surface: A diffuse-interface simulation approach

In this paper, we numerically study pool boiling of a binary (water and nitrogen) mixture on a surface endowed with a combination of hydrophobicity and hydrophilicity (i.e., the so called biphilic surface). Here we adopt a numerical approach based on the phase field theory, where the vapor-liquid interface is assumed to be of a finite thickness (hence diffusive in nature) and requires no explicit tracking schemes. The theoretical modeling of two-phase heat and mass transfer in water diluted with nitrogen demonstrates the significant impact of impurities on bubble dynamics. The simulations show that locally high concentrations of nitrogen gas within the vapor bubble is essential to weakening the condensation effect, which results in sustained bubble growth and ultimately (partial) departure from the surface under the artificially enlarged gravity. Simply increasing the solubility of nitrogen in water, however, turns out to be counterproductive because possible re-dissolution of the aggregated nitrogen by the bulk water could deprive the bubble of vital gas contents, leading instead to continuous bubble shrinkage and collapse. Additionally, it is found that with the significant accumulation of nitrogen, the bubble interface is increasingly dominated by a strong interfacial thermocapillary flow due to the Marangoni effect.

Designing composite films of SiO2/TiO2/PDMS with long lasting invariable colors and enhanced mechanical robustness

Structurally colored films with invariable color, excellent mechanical robustness and liquids impermeable property have received extensive attentions due to its great advantages in practical application. However, colored films from the same opal or inverse opal structure always have different colored appearances. This character makes the color controlling become very complicated. This study presents an effective approach for fabricating PCs films with invariable colors by infiltrating TiO2 and PDMS into PCs of hollow SiO2 and followed with a curing process. The obtained films exhibit several advantages, such as enhanced color saturation, the same color with its original PS@SiO2 PCs templates, widen full-width-at-half-maximum (FWHM), long lasting invariable colors and enhanced mechanical robustness. Additionally, the combination of hydrophobicity and tunable stop-bands is significant for potential application in paint and external decoration of architectures. The present results open new vistas for the research of functional films.

Simple fabrication of colloidal crystal structural color films with good mechanical stability and high hydrophobicity

Weak mechanical stability and low hydrophobicity have been considered as major obstacles for actual applications of structural color films from colloidal crystals. This paper presents these films with good mechanical properties and high hydrophobicity by employing a simple preparation strategy. With this strategy, the mechanical property of the structural color films was remarkably improved by the structure lock effect of polyacrylate adhesive when its latex was used as a co-assembly component with polystyrene microspheres. Likewise, the hydrophobicity of structural color films was enhanced by using cationic surfactant. Furthermore, the obtained films exhibited several unique characteristics, such as good mechanical stability, high hydrophobicity, and bright structural color. Therefore, the combination of hydrophobicity and mechanical stability was significant for potential architectural applications of paint and external decoration.

Atmospheric plasma-polymerization of hydrophobic and wear-resistant coatings on glass substrates

In order to find a coating that promotes both the wear resistance and the hydrophobicity of glass, a non-thermal atmospheric jet plasma-polymerization system with mixtures of two precursors at different proportions were used. (Heptadecafluoro-1,1,2,2-tetrahydrodecyl)trimethoxysilane (FLUSI) was used to promote the hydrophobicity, due to its fluorocarbon chain. Aminopropyltriethoxysilane (APTES) was used to enhance the wear resistance of the surface. The key aspect of the present work consists of determining the optimal mixture of precursors that produces a satisfactory coating in both characteristics; since coatings based on FLUSI have a low wear resistance and those based on APTES have a hydrophilic character. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), lap-shear tests, static water contact angle (WCA), tribological tests, profilometry measurements and energy dispersive X-ray spectroscopy (EDX) were used to analyze the coatings. It is believed that the upper limit of hydrophobicity that can be attained by modifying of the surface chemistry (WCA of ∼120°) has been achieved. It was observed that the wear resistance depends on the thickness and the SiOSi content of the coatings. These appear to be directly related to the proportion of APTES in the mixture. The sample that was coated with 50% of APTES and 50% of FLUSI provided the best combination of hydrophobicity and wear resistance. It showed the highest WCA (123.2°±1.5) because it has a high fluorocarbon content and the highest CF3 content. Its wear resistance is considerably better than that of the uncoated glass and is one of the highest exhibited by the hydrophobic samples.

Magnetic solid sulfonic acid decorated with hydrophobic regulators: a combinatorial and magnetically separable catalyst for the synthesis of α-aminonitriles.

A three-component, Strecker reaction of a series of aldehydes or ketones, amines, and trimethylsilyl cyanide for the synthesis of α-aminonitriles in the presence of a catalytic amount of a magnetic solid sulfonic acid catalyst, Fe3O4@SiO2@Me&Et-PhSO3H under solvent-free conditions have been investigated. This catalyst, with a combination of hydrophobicity and acidity on the Fe3O4@SiO2 core-shell of the magnetic nanobeads, as well as its water-resistant property, enabled easy mass transfer and catalytic activity in the Strecker reaction. The catalyst was easily separated by an external magnet and the recovered catalyst was reused in 6 successive reaction cycles without any significant loss of activity.

Development of GoSlo-SR-5-69, a potent activator of large conductance Ca2+-activated K+ (BK) channels

We have designed, synthesised and characterised the effects of a number of novel anthraquinone derivatives and assessed their effects on large conductance, Ca2+ activated K+ (BK) channels recorded from rabbit bladder smooth muscle cells using the excised, inside/out configuration of the patch clamp technique. These compounds are members of the GoSlo-SR family of compounds, which potently open BK channels and shift the voltage required for half maximal activation (V1/2) negatively. The efficacy of the anilinoanthraquinone derivatives was enhanced when the size of ring D was increased, since the cyclopentane and cyclohexane derivatives shifted the V1/2, by −24 ± 6 mV and −54 ± 8 mV, respectively, whereas the cycloheptane and cyclooctane derivatives shifted the V1/2 by −61 ± 6 mV and −106 ± 6 mV. To examine if a combination of hydrophobicity and steric bulking of this region further enhanced their ability to open BK channels, we synthesised a number of naphthalene and tetrahydro-naphthalene derivatives. The tetrahydro-2-naphthalene derivative GoSlo-SR-5-69 was the most potent and efficacious of the series since it was able to shift the activation V1/2 by greater than −100 mV when applied at a concentration of 1 μM and had an EC50 of 251 nM, making it one of the most potent and efficacious BK channel openers synthesised to date.

Hydrophobic structural color films with bright color and tunable stop-bands

Hydrophobic structural color films have attracted a special attention due to the great advantages in application, which currently become a research hot-spot. This study presents a convenient approach to fabricate hydrophobic structural color films by modifying self-assembled polymer opal from cross-linked polystyrene microspheres and polydimethylsiloxane. The obtained films exhibited several unique characteristics, such as a high water contact angle of 137°, bright structural color, and tunable stop-bands. Additionally, the combination of hydrophobicity and tunable stop-bands was significant for potential application in paint and external decoration of architectures. The present result opens new vistas for the research of functional films, using thermal-assisted self-assembly as a simple method that is cheap and commonly available.

<i>In Situ</i> Growth of Carbon Nanotubes on Carbon Foam for Enhanced Oil Adsorption

This work presents a facile approach to grow carbon nanotubes (CNTs) on the surface of carbon foams (CFs) for the fabrication of hierarchical CNTs/CF composites, which exhibit enhanced oil adsorption capability. The preparation of CFs is carried out by using commercially available polyurethane (PU) foams as hard template and resol as carbon precursor. Fe/Mg/Al layered double hydroxide (LDHs) is used as catalyst precursor for the efficient growth of CNTs on CFs via chemical vapor deposition (CVD), in which CNTs are controllably grown onto the strut of CFs. The presence of CNTs in the CFs can significantly improve the hydrophobicity of the composites and enable the selective separation of oil from water with the combination of hydrophobicity and capillary action. Such well-designed hierarchical nanostructures are benefit for maximum utilization of cell structure and surface property of the composites and display good oil adsorption performance. The synthesis procedure paves the way for the exploitation of the CFs as adsorbent for the removal of spill oil and environmental protection.

Synthesis of a carbon nanofiber/carbon foam composite from coal liquefaction residue for the separation of oil and water

A carbon nanofiber (CNF)/carbon foam composite was fabricated from coal liquefaction residue (CLR) through a procedure involving template synthesis of carbon foam and catalytic chemical vapor deposition (CCVD) treatment. The high solubility and high pyrolysis yield make CLR a promising carbon precursor for the synthesis of carbon materials using the template method. The carbon foam has cell size of about 500μm and a porosity as high as 95vol.%. Fe species naturally present in the CLR disperse homogeneously on the surface of the carbon foam acting as a catalyst in the CCVD process. After the CCVD treatment, the whole surface of the carbon foam is covered by entangled CNFs with external diameters of 20–100nm and lengths of several tens of micrometers. The obtained CNF/carbon foam composites are effective selective adsorbents in the separation of oil and water, through a combination of hydrophobicity and capillary action.

Hot embossing of thermoplastic multilayered stacks

The combination of different polymer materials during replication offers additional opportunities for fabrication and functionality of microsystems. Different surface and structural properties of polymers allow for improvements in microsystems for example by means of hydrophilic and hydrophobic combinations in microfluidic devices. Due to its high flexibility and precision hot embossing as one of the established micro replication processes facilitates processing of several polymer layers in one single process step. By this multi-component process micro structured systems consisting of thin layers of different polymers with adapted surface properties are fabricated. In this paper we describe the challenge of molding different types of polymers and some applications for multi-component micro systems.

Destabilizing Alzheimer’s Aβ42Protofibrils with Morin: Mechanistic Insights from Molecular Dynamics Simulations

Alzheimer's disease is a progressive, neurodegenerative disorder that is the leading cause of senile dementia, afflicting millions of individuals worldwide. Since the identification of the amyloid beta-peptide (Abeta) as the principal toxic entity in the progression of Alzheimer's disease, numerous attempts have been made to reduce endogenous Abeta production and deposition, including designing inhibitors of the proteases that generate the peptide, generating antibodies against Abeta aggregates, utilizing metal chelators, and identifying small molecules that target the peptide during the aggregation pathway. The last approach is particularly attractive, as Abeta is normally present in vivo, but aggregation is a purely pathological event. Studies conducted in vitro and in vivo have suggested that administration of flavonoids, compounds naturally present in many foods, including wine and tea, can prevent and reverse Abeta aggregation, but mechanistic details are lacking. In this work, we employ atomistic, explicit-solvent molecular dynamics (MD) simulations to identify the mechanism of Abeta fibril destabilization by morin, one of the most effective anti-aggregation flavonoids, using a model of the mature Abeta fibril. Through the course of 24 simulations totaling 4.3 mus, we find that morin can bind to the ends of the fibrils to block the attachment of an incoming peptide and can penetrate into the hydrophobic core to disrupt the Asp23-Lys28 salt bridges and interfere with backbone hydrogen bonding. The combination of hydrophobicity, aromaticity, and hydrogen bonding capacity of morin imparts the observed behavior.

Assembly of N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer films with catechol sensing selectivity

The highly water insoluble N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate is synthesised and investigated for sensor applications. This amphiphilic molecule is immobilised by evaporation of an acetonitrile solution at a basal plane pyrolytic graphite (HOPG) electrode surface and is shown to provide a monolayer film. By varying the amount of deposit partial or full coverage can be achieved. The N-hexadecyl-pyridinium-4-boronic acid hexafluorophosphate monolayer acts as an active receptor for 1,2-dihydroxy-benzene (catechol) derivatives in aqueous media. The ability to bind alizarin red S is investigated and the Langmuirian binding constant determined as a function of pH. It is shown that the immobilised boronic acid monolayer acts as sensor film for a wider range of catechols. A comparison of Langmuirian binding constants for alizarin red S (1.4 × 105 mol−1 dm3), catechol (8.4 × 104 mol−1 dm3), caffeic acid (7.5 × 104 mol−1 dm3), dopamine (1.0 × 104 mol−1 dm3), and L-dopa (8 × 103 mol−1 dm3) reveals that a combination of hydrophobicity and electrostatic interaction causes considerable selectivity effects.

Use of soil moisture dynamics and patterns at different spatio-temporal scales for the investigation of subsurface flow processes

Abstract. Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes, especially in data scarce or previously ungauged catchments. The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes) than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture response allows for visualization of flow processes in the unsaturated zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale) and binary indicator maps (for the long-term and hillslope scale). Annual dynamics of soil moisture and decimeter-scale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a data-scarce catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. The most likely explanation for preferential flow in this catchment is a combination of hydrophobicity, small scale heterogeneity in rainfall due to redistribution in the canopy and strong gradients in unsaturated conductivities leading to self-reinforcing flow paths.