Hydrophobic Groups Research Articles

Strengthening the π-conjugation of lignin by constructing its ordered supramolecular structure

The π-conjugation system of lignin makes it one kind of multifunctional biopolymer with many remarkable features such as ultraviolet-shielding properties, photothermal conversion capability, and fluorescence performance. The quest for effective strategies to strengthen the π-conjugation of lignin is significantly important to the design and production of outstanding lignin-based materials. In this work, we strengthen the π-conjugation of lignin by transforming lignin raw materials from disordered aggregates into ordered lignin colloidal spheres (LCSs) through supramolecular self-assembly. Moreover, we explore the relationship between the conjugation of lignin and its supramolecular structure by comparing the LCSs with different sizes, functional group arrangements, and compactness. Results demonstrate that the conjugation is stronger in the LCSs that have more hydrophobic groups inside and higher density. The primary strengthening mechanism of lignin conjugation is that the ordered and compact supramolecular structure results in a shorter average distance between benzene rings and stronger π-π interaction compared with that of disordered and loose supramolecular structure. We further demonstrate the great ultraviolet-shielding property and photothermal conversion capability of LCSs in polymer films, in which LCSs exhibit improved application performances than that of lignin raw materials due to their strengthened conjugation.

Biotinylated polyaminoacid-based nanoparticles for the targeted delivery of lenvatinib towards hepatocarcinoma

In this work, we describe the development of targeted polymeric nanoparticles loaded with lenvatinib for the treatment of hepatocellular carcinoma (HCC). A synthetic brush copolymer (PHEA-g-BIB-pButMA-g-PEG-biotin) was synthesized from α-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) by a three-step reaction involving atom transfer radical polymerisation (ATRP) to graft hydrophobic polybutylmethacrylate pendant groups and further conjugation with biotinylated polyethylene glycol via carbonate ester. Subsequently, lenvatinib-loaded nanoparticles were obtained and characterized demonstrating colloidal size, negative zeta potential, biotin exposure on the surface and the ability to release lenvatinib in a sustained manner. Lenvatinib-loaded nanoparticles were tested in vitro on HCC cells to evaluate their anticancer efficacy compared to free drug. Furthermore, the enhanced in vivo efficacy of lenvatinib-loaded nanoparticles on nude mice HCC xenograft models was demonstrated by evaluating tumor burdens, apoptotic markers and histological scores after administration of lenvatinib-nanoparticles via intraperitoneal or oral route. Finally, in vivo biodistribution studies were performed, demonstrating the ability of the prepared drug delivery systems to significantly accumulate in the solid tumor by active targeting, due to the presence of biotin on the nanoparticle surface.

Design, synthesis, and biological evaluation of RSL3-based GPX4 degraders with hydrophobic tags

Ferroptosis is a new type of programmed cell death characterized by iron-dependent lipid peroxidation, during which glutathione peroxidase 4 (GPX4) plays an essential role and is well-recognized as a promising therapeutic target for cancer treatment. Although some GPX4 degradation molecules have been developed to induce ferroptosis, the discovery of GPX4 degraders with hydrophobic tagging (HyT) as an innovative approach is more challenging. Herein, we designed and synthesized a series of HyT degraders by linking the GPX4 inhibitor RSL3 with a hydrophobic and bulky group of adamantane. Among them, compound R8 is a potent degrader (DC50, 24h = 0.019 μM) which can effectively degrade GPX4 in a dose- and time-dependent manner. Furthermore, compound R8 exhibited superior in vitro antitumor potency against HT1080 and MDA-MB-231 cell lines with IC50 values of 24 nM and 32 nM respectively, which are 4 times more potent than parental compound RSL3. Mechanistic investigation evidenced that R8 consumes GPX4 protein mainly through the ubiquitin proteasome (UPS) and enables to induce the accumulation of LPO, thereby triggering ferroptosis. Our work presented the novel GPX4 degrader of R8 by HyT strategy, and provided a promising pathway of degradation agents for the treatment of ferroptosis relevant diseases.

Co-encapsulation of vitamin E and quercetin by soybean lipophilic proteins based on pH-shifting and ultrasonication: Focus on interaction mechanisms, structural and physicochemical properties

This study explored the mechanism of interaction of pH-shifting combined ultrasonication and its effect on soybean lipophilic proteins (SLP) and the potential of modified SLP as the carrier for vitamin E (VE) and quercetin (QU). The spectroscopy results revealed that both VE and QU changed the SLP conformation and exposed hydrophobic groups. The loading rates of VE and QU by SLP with alkaline pH-shifting combined with ultrasonication (300 w,20 min) were 86.91% and 75.99%, respectively. According to the antioxidant analysis, with an increase in the ultrasonication power, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging capacity of the samples increased, where the DPPH and ABTS radical scavenging capacity of sample SQV-6 were 70.90% and 63.43%, respectively. The physicochemical properties, microstructure, and stability of the SLP–VE–QU complex improved significantly. Overall, the present findings broadened the application of simple structural carriers for co-encapsulating functional factors.

A study on the structure-functionality relationship of Solenaia oleivora protein under high-intensity ultrasonication processing

Solenaia oleivora is a valuable freshwater mussel endemic to China with a high content of high-quality proteins, but the lack of structural information and limited functionality of Solenaia oleivora proteins constrained their application in the food industry. This study investigates the changes in structural characteristics and functionality of Solenaia oleivora protein under ultrasound processing at power from 200 to 600 W. The ultrasound treatment caused increased contents of β-turn and α-helix, and the exposure of interior hydrophobic groups, resulting in the increased hydrophobicity by around 3 folds. The ultrasound treatment could significantly decrease particle size and increase surface charges of Solenaia oleivora proteins, facilitating the increase of hydrosolubility from 10.2% to 81.7%. These structural changes and increased hydrosolubility contributed to the enhancement of emulsifying and foaming properties, and in vitro digestibility. The results suggested that the ultrasound-treated Solenaia oleivora proteins possessed the potential as an alternative protein in food applications.

Effect of organic matter with various carbon chain lengths on methane hydrate formation: Kinetic, thermodynamic, and microstructural studies

Organic matter is a pivotal component in methane hydrate (MH) deposition and plays a crucial role in the MH formation process due to its intricate chain structures. In this study, organic matters (OMs) with varying carbon chain lengths, including glycine, alanine, phenylalanine, 12-amino dodecanoic acid, dodecyl amine, and dodecanoic acid, were selected to investigate their impacts on the kinetics, thermodynamics, and microstructure of MH. Kinetic experimental findings reveal that long carbon chain OMs and OMs containing hydrophobic functional groups promote MH formation, with a more pronounced effect at higher concentrations. Conversely, short carbon chain OMs and OMs with hydrophilic functional groups exhibit kinetic inhibition of MH. Thermodynamic experiments show that the effect of OMs on the thermodynamics of MH at low concentrations (<1 wt%) is negligible. At higher concentrations, 12-aminododecanoic acid and dodecyl amine at 5 wt% make the phase equilibrium conditions of MH more moderate, while glycine at 3 wt% shows an inhibiting effect. Furthermore, the interaction between OMs functional groups, water and methane molecules influences MH crystals, alters crystal size and increases the proportion of large and small cages of MH. This study helps to understand the role of OMs in MH formation and promots an in-depth understanding and utilization of MH resources.

Glucose-induced glycation enhances the foaming properties of Trichosanthes kirilowii seed protein isolate: Insights into structure, interfacial behavior, and proteomics

Improving the foaming properties of plant proteins has recently attracted particular interest. The foaming properties of Trichosanthes kirilowii seed protein isolate (TPI) after glucose glycation (wet heating) were investigated by structural characterization, interfacial behavior evaluation, and quantitative proteomics analysis. The results showed that the highest degree of grafting of TPI (45.54%) with glucose was observed at a reaction time of 2 h. Grafting with glucose unfolded the structure of TPI, which was confirmed by increased molecular flexibility, loss of α-helices, and exposure of hydrophobic groups. The foaming capacity and foaming stability of the TPI was greatly improved after glycation. The bubbles in the TPI–glucose conjugate foams were smaller in size, more uniform, and denser than those in the TPI foams. Moreover, the deterioration rate of the conjugate foams was significantly slower than that of the TPI foams. Mechanistically, the improved foam properties were mainly attributed to increased surface activity, accelerated air/water interfacial adsorption, and enhanced interfacial film thickness. The results of quantitative proteomics indicated that several proteins involved in foam stability and elasticity were upregulated in the initial foams of the conjugates, which partly explains the improved foam properties. Overall, G2 showed the most superior foam properties and interfacial behavior among all the samples. This study offers further insights into the mechanisms by which glycation improves the foaming properties of plant proteins and will be useful for the development of foamed foods from TPI.

Surface Modification of Silk Fabric by Polysaccharide Derivatives towards High-Quality Printing Performance Using Bio-Based Gardenia Blue Ink.

Ink-jet-printed silk, a premium textile material, was achieved by utilizing a bio-based gardenia blue dye. However, the sharpness of the printing pattern is difficult to control due to the limited water-retention capacity of silk. To address this issue, three polysaccharide derivatives, namely, sodium alginate (SA), low-viscosity hydroxypropyl methyl cellulose (HPMC-I), and high-viscosity hydroxypropyl methyl cellulose (HPMC-II), were employed as thickeners to modify the silk by the dipping-padding method. Firstly, the preparation of the gardenia blue ink and the rheology assessment of the thickener solution were conducted. Furthermore, the impacts of different thickeners on the micro-morphology, element composition, and hydrophilicity of the silk, along with the wetting behavior of the ink on the silk, were analyzed comparatively in order to identify an appropriate thickener for preserving pattern outlines. Lastly, the color features, color fastness, and wearing characteristics of the printed silk were discussed to evaluate the overall printing quality. Research results showed that the optimized ink formulation, comprising 12% gardenia blue, 21% alcohols, and 5.5% surfactant, met the requirements for ink-jet printing (with a viscosity of 4.48 mPa·s, a surface tension of 34.12 mN/m, and a particle size of 153 nm). The HPMC-II solution exhibited prominent shear-thinning behavior, high elasticity, and thixotropy, facilitating the achievement of an even modification effect. The treatment of the silk with HPMC-II resulted in the most notable decrease in hydrophilicity. This can be attributed to the presence of filled gaps and a dense film on the fibers' surface after the HPMC-II treatment, as observed by scanning electron microscopy. Additionally, X-ray photoelectron spectroscopy analysis confirmed that the HPMC-II treatment introduced the highest content of hydrophobic groups on the fiber surface. The reduced hydrophilicity inhibited the excessive diffusion and penetration of gardenia blue ink, contributing to a distinct printing image and enhanced apparent color depth. Moreover, the printed silk demonstrated qualified color fastness to rubbing and soaping (exceeding grade four), a soft handle feeling, an ignorable strength loss (below 5%), and a favorable air/moisture penetrability. In general, the surface modification with the HPMC-II treatment has been proven as an effective strategy for upgrading the image quality of bio-based dye-printed silk.

The conformational modification of myofibrillar protein by magnetic field improves its emulsification properties

This study investigated the effect of different magnetic field treatments (0, 3, 6, 9, 12 mT) on the structure and emulsification properties of myofibrillar protein (MP). The results showed that the emulsion stabilized by MP with 3, 6, 9 mT magnetic field treatments possessed higher emulsifying ability, storage stability and apparent viscosity, since magnetic field induced the structural unfolding of MP and exposed the hydrophobic groups (the surface hydrophobic increased from 30.10 to 43.73 μg). Meanwhile, the magnetic field treatments decreased the MP particle size from 1752.00 to 1278.67 nm, which was favorable for the diffusion and adsorption of proteins at the oil-water interface, thus improving the MP emulsification ability and stability. Furthermore, the 9 mT magnetic field-treated MP had the best ability to emulsify oil droplets with a more uniform and smaller emulsion size from 28.593 to 23.443 μm. However, high-intensity magnetic field treatment (12 mT) caused MP particles to aggregate and the hydrophobic binding sites to be buried, which was not conducive to encapsulating oil droplets.

Nondestructive frozen protein ink: Antifreeze mechanism, processability, and application in 3D printing

Antifreeze peptide (AFP) including in frozen protein ink is an inevitable trend because AFP can make protein ink suitable for 3D printing after freezing. AFP-based surimi ink (ASI) was firstly investigated, and the AFP significantly enhanced 3D printability of frozen surimi ink. The rheological and textural results of ASI show that the τ0, K, and n values are 321.14 Pa, 2.2259 × 105 Pa·sn, and 0.19, respectively, and the rupture strength of the 3D structure is up to 217.67 g. Circular dichroism, intermolecular force, and differential scanning calorimeter show ASI has more undenatured protein after freezing when compared that surimi ink (SI), which was denatured, and the α-helix changed to a β-sheet due to the destruction of hydrogen bonds and the exposure of hydrophobic groups. The water distribution, water holding capacity, and microstructure indicate that ASI effectively binds free water after freezing, while SI has weak water binding capacity and a large amount of free water is formed. ASI is suitable for 3D printing, and can print up to 40.0 mm hollow isolation column and 50.0 mm high Wuba which is not possible with SI. The application of AFP provides guidance for 3D printing frozen protein ink in food industry.

Effects of sodium tripolyphosphate on the quality and digestion properties of PSE pork

This study aimed to examine the impact of sodium tripolyphosphate (STPP) on the quality and digestive characteristics of PSE pork. The results showed a notable decrease in cooking loss of PSE pork from 29.11% to 25.67% with increasing STPP concentration (P < 0.05). Additionally, the gastric digestibility of PSE pork decreased significantly from 52.01% to 45.81% (P < 0.05). The particle size of digesta decreased significantly after gastrointestinal digestion (P < 0.05). These changes were primarily due to the enhanced cross-linking of proteins through ionic interactions, hydrogen bonds and hydrophobic interactions, and resulted in the embedding of hydrophobic groups and endogenous fluorophores. Furthermore, denser network was formed. These findings give a new insight into considering the impact of STPP on meat nutrition when used to enhance texture and water holding capacity.

Study of the perturbed hydrogen-bonded water structure of the hydration shell of N-Methyl-Acetamide by Raman multivariate curve resolution spectroscopy

In this work, Raman scattering measurement combined with multivariate curve resolution (Raman-MCR) technique has been used to obtain the solute correlated spectra (SC) of N-methyl-acetamide (NMA) in an aqueous medium. The SC spectra is composed of NMA intramolecular vibrations and NMA induced-perturbations of water OH stretch vibrations. The SC spectra obtained for different mole-fractions of NMA reveal that as the mole-fraction of NMA increases the perturbed water interacting with the amide group is retained whereas it gets depleted from the hydrophobic hydration shell of the methyl group of NMA. The high wavenumber region of the OH spectrum shows that the fraction of the weakly hydrogen-bonded population is higher in the bulk water compared to perturbed water. The Raman spectra of perturbed OH spectral features due to hydration of the hydrophobic methyl group of NMA have been extracted from SC spectra obtained at low mole-fraction of NMA by the MCR technique. Its spectral feature resembles the SC-OH spectra of hydrophobic hydration of the methyl group of methanol.

Study on preparation and properties of antifreeze compound road dust suppressant

Open-pit mine pavement dust dries and breaks easily. As such, a composite pavement dust suppressant with good wettability, moisturizing, coagulation, and antifreezing properties in winter was investigated. Monomer screening and orthogonal experiments were conducted, using evaporation rate, permeability rate, viscosity, and freezing point as evaluation indexes. Consequently, a dust suppressant solution is a mixture of glycerol (GLY), sodium dodecylbenzene sulfonate (SDBS), polyacrylamide (PAM), compound propylene glycol (PG), and potassium acetate (PA). The characteristics of the dust suppressant and its interaction mechanism with road dust were measured and analyzed. The results showed that the optimal ratio of the antifreeze-type composite dust suppressant is 3%GLY, 0.30%SDBS, 0.07% PAM, and 50%PG + 10%PA; the contact angle is 27.62°, which can effectively wet coal dust. Moreover, it easily forms hydrogen bonds with water molecules to release free -OH, which increases the oxygen-containing functional groups in the dust. The maximum viscosity is 25.4 mPa·s, and the hydrophobic groups adsorbed on the surface of the dust can condense and agglomerate the dust to form large particles, and effectively inhibit the occurrence of dust. It freezes at − 34.2 ℃, resists a temperature of − 30 ℃ without freezing, and improves dust suppression efficiency and antifreezing effect in cold areas.

Effect of dry- and moist-heat treatment processes on the structure, solubility, and in vitro digestion of macadamia protein isolate.

This study aimed to enhance the solubility and digestibility of macadamia protein isolate (MPI) for potential utilization in the food industry. The impact of dry- and moist-heat treatments at various temperatures (80, 90, and 100°C) and durations (15 and 30min) on macadamia protein's microstructure, solubility, molecular weight, secondary and tertiary structure, thermal stability, and digestibility were investigated and evaluated. The heating degree was found to cause roughening of the MPI surface. The solubility of MPI after dry-heat treatment for 15 min at 100°C reached 290.96±2.80% relative to that of untreated protein. Following heat treatment, the bands of protein macromolecules disappeared, while MPI was stretched by vibrations of free and hydrogen-bonded hydroxyl groups. Additionally, an increase in thermal stability was observed. After heat treatment, hydrophobic groups inside the protein are exposed. Heat treatment significantly improved the in vitro digestibility of MPI, reaching twice that of untreated protein. The results also demonstrated that dry- and moist-heat treatments have distinct impacts on MPI, while heating temperature and duration affect the degree of modification. With a decreased ordered structure and increased random coil content, the dry-heat treatment significantly enhanced the in vitro digestibility of MPI. The digestibility of MPI after dry-heat treatment for 30 min at 90°C increased by 77.82±2.80% compared to untreated protein. Consequently, compared to moist-heat treatment, dry-heat treatment was more effective in modifying macadamia protein. Dry-heat treatment of 30 min at 90°C was determined as the optimal condition. PRACTICAL APPLICATION: Heat treatment enhances MPI characteristics, potentially advancing macadamia-derived food production, including plant-based beverages and protein supplements.

Self-cleaning and anti-corrosion superhydrophobic coatings of PA-TiO2@SiO2 copolymerized hetero compound

Inspired by leaf lotus effect, superhydrophobic surfaces have developed rapidly in recent years. In this paper, anatase nano TiO2 with particles size of about 70 nm was successfully loaded on the surface of SiO2 by sol-gel method. SiO2 and TiO2 were chemically bonded by Ti-O-Si and constructed a certain micro- and nano-composite structure. After superhydrophobic composite PA-TiO2@SiO2 was obtained by copolymerizing with acrylate and other monomers. The coating was prepared by drop coating plus spraying coating on glass substrates with water contact angles >160° and excellent self-cleaning properties, which could maintain the performance of the superhydrophobic coating by immersion in acidic solutions or water for 2 days. Meanwhile, the coating on the surface of the glass plate at −20 °C significantly delayed the freezing time of the ice. The rough structure of the surface and the presence of fluorine-containing hydrophobic groups gave the superhydrophobic coating an advantage over acrylate polymers in reducing the corrosion rate of steel surfaces.

Effects of pH and temperature on the properties of acid-induced commercial soy protein isolate gel

The goals of this study were to investigate the effect of preheating conditions on the formation of thermal aggregates of commercial soy isolate protein (SPI) and to characterize the textural properties and microstructure of acid-induced SPI gels. SPI was subjected to preheating treatments at different temperatures (85 °C, 95 °C) and pH values (7.0, 7.5, 8.5, 9.5), and the treated SPI was then used to form acid-induced gels. Characterization of the different gels showed that lower temperatures and pH values favored protein aggregation and the formation of larger aggregates, while higher temperatures and pH values led to a lower degree of aggregation and the formation of smaller aggregates. The lowest average particle size (340.77 nm) and turbidity (0.063), and the highest solubility (81.79 %) were obtained when the preheating temperature of the thermal aggregates was 95 °C and the pH was 9.5. Higher preheating temperature and pH values caused the unfolding of SPI’s tertiary structure, decreased the content of β-sheet structure, and increased the exposure of hydrophobic groups and free sulfhydryl groups. These exposed groups facilitated protein–protein interactions during network assembly, resulting in denser and stronger gel networks. Notably, SPI subjected to higher temperatures and pH values exhibited greater binding capacity for water molecules, higher water holding capacity, and gel strength. Overall, the results showed that modification of preheating temperature and pH can control the formation state of SPI thermal aggregates, ultimately impacting the properties of SPI acid-induced gels.

Unveiling the Failure Mechanism of Zn Anodes in Zinc Trifluorosulfonate Electrolyte: The Role of Micelle-like Structures.

Zinc trifluorosulfonate [Zn(OTf)2] is considered as the most suitable zinc salt for aqueous Zn-ion batteries (AZIBs) but cannot support the long-term cycling of the Zn anode. Here, we reveal the micelle-like structure of the Zn(OTf)2 electrolyte and reunderstand the failing mechanism of the Zn anode. Since the solvated Zn2+ possesses a positive charge, it can spontaneously attract OTf- with the hydrophilic group of -SO3 and the hydrophobic group of -CF3 via electrostatic interaction and form a "micelle-like" structure, which is responsible for the poor desolvation kinetics and dendrite growth. To address these issues, an antimicelle-like structure is designed by using ethylene glycol monomethyl ether (EGME) as a cosolvent for highly reversible AZIBs. The modified electrolyte shows lower dissociation ability to Zn(OTf)2 and higher coordination tendency with Zn2+ compared to the Zn(OTf)2 electrolyte, resulting in the unique solvation structure of Zn2+(H2O)1.2(OTf-)2(EGME)2.8, which significantly reduces the charge of micelle, damages the micelle-like structure, and boosts the desolvation kinetics. Moreover, the reduction of EGME and OTf- can form a robust dual-layered SEI with high Zn2+ ion conductivity. Consequently, the Zn/Cu asymmetric coin cell using ZT-EGME can work at a high rate and a capacity of 50 mA cm-2 and 5 mA h cm-2 for more than 120 cycles, while its counterparts using ZT can barely work. Moreover, a 505.1 mA h pouch cell with practical parameters including a lean electrolyte supply of 15 mL A h-1 and an N/P ratio of ∼3.5 can work for 50 cycles.

Vesicles exhibit high-performance removal of per-and polyfluoroalkyl substances (PFAS) depending on their hydrophobic groups

The removal of per- and polyfluoroalkyl substances (PFAS) from drinking water is urgently needed. Here, we demonstrated high performance of vesicles on PFAS adsorption. Vesicles used in this study were enclosed amphiphile bilayers keeping their hydrophobic groups inside and their hydrophilic groups outside in water. The distribution coefficient Kd of perfluorooctane sulfonic acid (PFOS) for vesicles was 5.3 × 105 L/kg, which is higher than that for granulated activated carbon (GAC), and Kd of perfluorooctanoic acid (PFOA) for vesicles was 103–104 L/kg. The removal efficiencies of PFOA and PFOS adsorption on DMPC vesicles were 97.1 ± 0.1% and 99.4 ± 0.2%, respectively. The adsorption behaviors of PFOA and PFOS on vesicles were investigated by changing the number of cis-double bonds in the hydrophobic chains of the vesicle constituents. Moreover, vesicles formed by membranes in the different phases were also tested. The results revealed that, when vesicles are formed of a membrane in the liquid-crystalline (liquid-like) phase, the adsorption amounts of both PFOA and PFOS increased as the cis-double bond in the hydrocarbon chains decreased, which is considered due to molecular shape similarity. When vesicles are formed of a membrane in the gel (solid-like) phase, they do not adsorb PFAS as much as in the liquid-crystalline phase, even though the hydrocarbon chains do not have any cis-double bond. Our findings demonstrate that vesicles can be utilized as PFAS adsorbents by optimizing the structure of vesicle constituents and their thermodynamical phase. Indeed, the vesicles (DMPC) were demonstrated that they can adsorb PFOA and PFOS, and be coagulated by a coagulant even in environmental water. The coagulation will enable the removal of PFOA and PFOS from the water after adsorption.

Insight into the Binding Interaction between PEDCs and hERRγ Utilizing Molecular Docking and Molecular Dynamics Simulations.

Phenolic environmental endocrine-disrupting chemicals (PEDCs) are persistent EDCs that are widely found in food packaging materials and environmental media and seriously threaten human health and ecological security. Human estrogen-related receptor γ (hERRγ) has been proposed as a mediator for the low-dose effects of many environmental PEDCs; however, the atomic-level descriptions of dynamical structural features and interactions of hERRγ and PEDCs are still unclarified. Herein, how three PEDCs, 4-(1-methylpropyl)phenol (4-sec-butylphenol), 5,6,7,8-tetrahydro-2-naphthol (tetrahydro-2-napthol), and 2,2-bis(4-hydroxy-3,5-dimethoxyphenyl)propane (BP(2,2)(Me)), interact with hERRγ to produce its estrogenic disruption effects was studied. Molecular docking and multiple molecular dynamics (MD) simulations were first conducted to distinguish the detailed interaction pattern of hERRγ with PEDCs. These binding structures revealed that residues around Leu271, Leu309, Leu345, and Phe435 are important when binding with PEDCs. Furthermore, the binding energies of PEDCs with hERRγ were also characterized using the molecular mechanics/Poisson Boltzmann surface area (MM-PBSA) and solvated interaction energy (SIE) methods, and the results showed that the interactions of CH-π, π-π, and hydrogen bonds are the major contributors for hERRγ binding to these three PEDCs. What is striking is that the methoxide groups of BP(2,2)(Me), as hydrophobic groups, can help to reduce the binding energy of PEDCs binding with hERRγ. These results provide important guidance for further understanding the influence of PEDCs on human health problems.

Effect of the structure of chitosan quaternary ammonium salts with different spacer groups on antibacterial and antibiofilm activities

In this study, three types of dodecyl chitosan quaternary ammonium salts, each with different spacer groups were synthesized. These chitosan derivatives are N′,N′-dimethyl-N′-dodecyl-ammonium chloride-N-amino-acetyl chitosan (DMDAC), N′-dodecyl-N-isonicotinyl chitosan chloride (DINCC) and N′,N′-dimethyl-N′-dodecyl-ammonium chloride-N-benzoyl chitosan (DMDBC). The synthesized products were characterized using Fourier transform infrared spectrometers, nuclear magnetic resonance, thermogravimetric analysis, and elemental analysis. The antibacterial and antibiofilm activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were investigated. The experimental results indicated that the introduction of hydrophobic groups of spacer groups could enhance the antibacterial and antibiofilm activities of the chitosan derivatives. The antibacterial rates of the chitosan derivatives were over 90 % for both E. coli and S. aureus at a concentration of 0.5 mg/mL. The chitosan derivatives removed >50 % of the mature biofilm of E. coli and over 90 % of the mature biofilm of S. aureus at a concentration of 2.5 mg/mL. Further, the synthesized chitosan derivatives were determined to be non-toxic to L929 cells. Among them, DMDBC exhibited the most promising overall performance and show potential for wide-ranging applications in food preservation, disinfectants, medical, and other fields.