Hydrophobic Length Research Articles

Occurrence, Bioaccumulation, and Trophic Transfer of Short-Chain Chlorinated Paraffins (SCCPs) in a Marine Food Web from Laizhou Bay, Bohai Sea (Eastern China)

Short-chain chlorinated paraffins (SCCPs) are a persistent organic pollutant, and limited information is available on their bioaccumulation and trophic transfer, which would be affected by carbon chain length, chlorine content, and hydrophobicity. In this study, relevant data on SCCPs in water, sediments, and organisms collected from Laizhou Bay were analyzed to investigate the specific distribution of SCCPs and their bioaccumulation and trophic transfer. In water and sediments, the average SCCP concentrations (ΣSCCPs) were 362.23 ± 81.03 ng/L and 609.68 ± 90.28 ng/g d.w., respectively. In 28 species of organisms, the ΣSCCPs varied from 70.05 to 47,244.13 ng/g l.w. (average = 648 ± 7360) and the predominant homologs were C13 (average = 34.91%) and Cl5–7 (average = 93.13%), differing from those in water (average = C11 32.75% and average = Cl5–7 88%) and sediments (average = C13 31.60% and average = Cl6–8 87.16%). The logarithm bioaccumulation factors (BAFs) of ΣSCCPs were 1.18–2.74 and were positively correlated with the log Kow. A significant negative linear relationship was observed between biota-sediment accumulation factors (BSAFs) and log Kow. It is suggested that the hydrophobicity may affect the bioaccumulation of SCCPs. SCCPs demonstrated a trophic magnification factor (TMF) ranging from 2.19 to 3.00 (average = 2.51) and exhibited a significant linear correlation with carbon chain length (p < 0.05) and log Kow values (p < 0.05), suggesting that SCCPs have biomagnification potential in Laizhou Bay that is affected by hydrophobicity and carbon chain length.

Gemini surfactant-engineered di-Schiff bases: Tailoring hydrophobicity to enhance catalytic and biological activities

This study explores the enhancement of catalytic performance of silver nanoparticles (AgNPs) using a series of gemini surfactants based on di-azomethine with varying hydrophobic tail lengths: DSGO, DSGD, and DSGH. By fine-tuning the molecular structure of these surfactants, we aim to develop more effective catalysts for purifying polluted water sources. The high surface energy of AgNPs often results in their aggregation, reducing their catalytic efficacy. However, increasing the surfactant tail length from 8 (DSGO) to 16 (DSGH) carbon atoms improves the stability and dispersibility of AgNPs, as confirmed by DLS, TEM, and UV analyses. DSGH, with its longer carbon tail, facilitates AgNPs synthesis with superior stability and smaller particle size, indicated by a higher zeta potential of +55.6 mV and a reduced size of 15.1 nm. This is attributed to the increased surface activity and hydrophobicity of the surfactants. As the tail length increases from 8 to 16, the investigated surfactant’s tendency for micellization and adsorption rises. Notably, DSGH exhibits the lowest critical micelle concentration (CMC) of 406 μM and the highest adsorption Gibbs free energy (ΔG°ads) of −59.08 kJ·mol−1 at 20 °C, enabling strong adsorption onto AgNPs. By modulating surfactant hydrophobicity, we effectively regulated AgNP catalytic activity. The DSGH/AgNPs composite shows enhanced catalytic activity, efficiently converting p-nitrophenol (p-NP) and methylene blue (MB) into less toxic species with apparent rate constants (kapp) of 0.368 and 0.537 min−1, respectively. Additionally, the AgNP-incorporated gemini surfactants exhibit promising antimicrobial activity against tested bacteria and fungi. Remarkably, the DSGD/AgNPs hybrid system surpasses commonly used commercial antimicrobial agents in efficacy. This study underscores the potential of manipulating surfactant structure to control the catalytic and antimicrobial activity of AgNPs.

Promoted lignocellulose fractionation and improved enzymatic hydrolysis of corn stalks through cationic surfactant combined with deep eutectic solvent pretreatment

The efficient conversion of lignocellulose relies on the implementation of an effective pretreatment strategy. Cationic surfactants combined with deep eutectic solvent ([Betaine][LA] was employed as a novel pretreatment strategy for treating corn stalks. Valuable insights were provided on the impact of the surfactant hydrophobic segment length on pretreatment efficacy. The specific pretreatment conditions were optimized by single factor and orthogonal experiment. Octadecyl trimethyl ammonium bromide (OTAB, 1.5 wt%) with the longest hydrophobic part combined with [Betaine][LA] (Betaine-to-LA molar ratio 1:4) achieved the best pretreatment effect (delignification 92.8 %, xylan elimination 91.1 %) when severity factor reached 4.26, meanwhile, 1.7 g/L xylo-oligosaccharides and 4.4 g/L furfural were detected in pretreatment liquid due to the hydrolysis of hemicellulose in corn stalks with acidic deep eutectic solvent [Betaine][LA]. The relative saccharification activity reached 2.7 times of raw material, while the lignin surface area significantly decreased, leading to enhanced cellulose accessibility. Additionally, molecular perspective provided by molecular dynamics showed the elimination of lignin and xylan was facilitated by strong interaction of hydrogen-bond and van der Waals force between lignin and hemicellulose with [Betaine][LA] + OTAB. Overall, the effectiveness and potential of cationic surfactant combined deep eutectic solvent pretreatment strategy for lignocellulose pretreatment was revealed.

The Dsc ubiquitin ligase complex identifies transmembrane degrons to degrade orphaned proteins at the Golgi

The Golgi apparatus is essential for protein sorting, yet its quality control mechanisms are poorly understood. Here we show that the Dsc ubiquitin ligase complex uses its rhomboid pseudo-protease subunit, Dsc2, to assess the hydrophobic length of α-helical transmembrane domains (TMDs) at the Golgi. Thereby the Dsc complex likely interacts with orphaned ER and Golgi proteins that have shorter TMDs and ubiquitinates them for targeted degradation. Some Dsc substrates will be extracted by Cdc48 for endosome and Golgi associated proteasomal degradation (EGAD), while others will undergo ESCRT dependent vacuolar degradation. Some substrates are degraded by both, EGAD- or ESCRT pathways. The accumulation of Dsc substrates entails a specific increase in glycerophospholipids with shorter and asymmetric fatty acyl chains. Hence, the Dsc complex mediates the selective degradation of orphaned proteins at the sorting center of cells, which prevents their spreading across other organelles and thereby preserves cellular membrane protein and lipid composition.

Structural determinants of parabens in inhibiting human and rat gonadal 3β-hydroxysteroid dehydrogenase

This study delved into the impacts of 10 parabens on the activity of human and rat gonadal 3β-hydroxysteroid dehydrogenase (3β-HSD) within human KGN cell and rat testicular microsomes, as well as on the secretion of progesterone in KGN cells and the inhibitory potency was compared between human and rats. Intriguingly, the outcomes revealed that ethyl, propyl, butyl, hexyl, heptyl, nonyl, phenyl, and benzyl parabens displayed varying IC50 values for human 3β-HSD2, from 4.15 to 139.96 μM, demonstrating characteristics of mixed inhibitors. Notably, within KGN cells, all examined parabens, excluding nonyl and phenyl parabens, significantly inhibited progesterone secretion at 5–50 μM. In the case of rats, the IC50 values for these parabens on gonadal 3β-HSD1 fluctuated between 7.15 and 110.76 μM, likewise functioning as mixed inhibitors. Through docking analysis, it was proposed that most parabens effectively bind to NAD+ and/or steroid binding site. Moreover, bivariate correlation analysis unveiled an inverse correlation between IC50 values and structural characteristics such as LogP, molecular weight, heavy atom number, and carbon number within the alcohol moiety of parabens. 3D-QSAR elucidated pivotal regions, comprising hydrogen bond donor, hydrogen bond acceptor, and hydrophobic region, with the most potent inhibitor nonyl paraben engaging with all regions, while the weakest inhibitor ethyl paraben interacted with the regions except for the hydrophobic region. In conclusion, this investigation underscored the inhibitory effects imparted by several parabens on both human and rat gonadal 3β-HSD activity, with their inhibitory potency being modulated by aspects of hydrophobicity and carbon chain length.

Structural and dynamic behaviour of concentrated aqueous solutions of (poly)ethylene glycols: Insight into the impact of hydrophobicity, hydrogen bonding and chain length

Understanding the delicate interplay between hydrophobicity/hydrophilicity, hydrogen bonding ability and solute size in modulating the chemico-physical properties of aqueous solutions with increasing solute concentration is a challenging task. Here, we focus on how bulk properties, such as diffusion and aggregation behaviour, are affected by the different hydration patterns observed for differently concentrated aqueous solutions of (poly)ethylene glycols, and their corresponding methoxyethers, of various lengths. Using a combined experimental and computational approach, we analyse solutions of ethylene glycol (EG), dimethoxyethane (DME), polyethylene glycol with 4 repeating units capped with either hydroxyl (PEG200) or methoxyl (PEG250DME) tails, and polyethylene glycol with 9 repeating units (PEG400). By disentangling the contributions of hydrophobicity, hydrogen bonding ability, and chain length, we observe that for the smaller solutes electristriction and hydrophobic hydration are the main phenomena occurring. Instead, as the solute becomes larger, these effects give way to the non-trivial conformational flexibility that can either favour or disfavour intermolecular interactions which lead to the formation of water-rich regions excluded from the solute.

Enhanced degradation of post-consumer polyethylene terephthalate (PET) wastes by fusion cutinase: Effects of anchor and linker peptides

Enzymatic degradation of poly(ethylene terephthalate) (PET) into its corresponding monomers provides an attractive route for green plastic recycling and environmental remediation applications. However, the binding of PET hydrolases toward the PET surface is a rate-limiting step in PET degradation. Hence, we selected three anchor peptides and four linker peptides to fuse the previously engineered leaf-branch compost cutinase for facilitating enzyme binding and improving degradation of real post-consumer PET wastes of Coca Cola and C′eastbon PET bottles, with using the amorphous PET as a control. The systematical characterization of the seven cutinases revealed that the anchor peptide with moderate hydrophobicity plus chaperone activity and the flexible linker peptide with small hydrophobicity but long length were more suitable for each domain to serve its own role, affording the facilitated PET binding affinities and enhanced PET degradation performance. Thus, the optimal fusion cutinase possessed up to 3.3 times higher catalytic efficiency (kcat/Km) and 76 % increased long-term degradation performance than the parental cutinase, respectively. Further, complete degradation of C′eastbon PET wastes and 77 % degradation of Coca Cola PET wastes were achieved by the optimal cutinase of 33.3 nmol·g−1PET in 96 h, proving its superiority against the real post-consumer PET wastes.

Self-assembling properties of mono and di-rhamnolipids characterized using small-angle X-ray scattering

Rhamnolipids are glycolipid surfactants composed by a hydrophilic head of either one (mono-RL) or two (di-RL) rhamnose moieties coupled to hydroxyaliphatic chains that can be of different lengths. In spite of their importance in different fields of applications, as bioremediation processes for instance, self-aggregation physico-chemical properties of RLs are not unique. This because a variety of aggregates morphologies (shape and size) can either exist or coexist in aqueous dispersion due to mono-RL:di-RL molar ratio, hydrophobic tails length, pH and the presence of co-surfactants and additives. Recently, a theorethical approach reported the self-assembling morphologies of either pure mono or di-RL in aqueous environment, predicting the formation of spherical to ellipsoidal micelles to worm-like and disk-like aggregates depending on RL concentration and fatty acid chain length. In order to add new information to those previously available, the present work investigated the self-assembling properties of mono-RL-C10-C10 and di-RL-C10-C10 separately in aqueous dispersion by small angle X-Ray scattering (SAXS). A novel approach was applied to the data analysis coupling the scattering length density profiles of the RLs chemical groups and Monte Carlo simulations. Such an approach allowed us to infer about the preferred mono-RL and di-RL conformations that fit better in the self-assembling morphologies. In this way, we show that mono-RL-C10-C10 self-assembles into lamella-like aggregates coexisting with 30 % of multi-lamella aggregates (circa of 5 closed stacked lamella) from a concentration ranging from 10 to 50 mM, with hydrophobic thickness of about 12 Å, a hydrated polar head thickness of 10 Å, and an area per glycolipid of 76 Å2. On the other hand, di-RL prefers to self-associate into flexible cylinder-like aggregates, from 70 mM to 110 mM concentration, with hydrophobic radius on the order of 7.5 Å, a hydrated polar shell of 21.5 Å, with hydropobic/polar interface of 110 Å2 per glycolipid. Interestingly, the parameters obtained from the best fitting to the experimental data associated to the volume fraction distribution of the chemical groups within the aggregates revealed that the hydrophobic chains are more disordered in mono-RL planar aggregates than in di-RL worm-like aggregates, as well as the hydration properties. Further, the addition of 100 mM NaCl in di-RL aqueous dispersion leads to the formation of longer worm-like aggregates. Taking together, this work opens a new avenue regarding characterization of biosurfactants self-assembling properties by using SAXS, also contributing to prepare more efficient biosurfactant dispersions depending on the desired applications in industrial sectors and bioremediation.

Synthesis of homologous series of surfactants from renewable resources, structure–properties relationship, surface active performance, evaluation of their antimicrobial and anticancer potentialities

Sugar esters display surface-active properties, wetting, emulsifying, and other physicochemical phenomena following their amphipathic nature and recognize distinct biological activity. The development of nutritional pharmaceuticals and other applications remains of great interest. Herein, three novel homologous series of several N-mono-fatty acyl amino acid glucosyl esters were synthesized, and their physicochemical properties and biological activities were evaluated. The design and preparation of these esters were chemically performed via the reaction of glucose with different fatty acyl amino acids as renewable starting materials, with the suggestion that they would acquire functional characteristics superior and competitive to certain conventional surfactants. The synthesized products are characterized using FTIR, 1H-NMR, and 13C-NMR spectroscopy. Further, their physicochemical properties, such as HLB, CMC, Γmax, γCMC, and Amin, were determined. Additionally, their antimicrobial and anticancer efficiency were assessed. The results indicate that the esters' molecular structure, including the acyl chain length and the type of amino acid, significantly influences their properties. The measured HLB ranged from 8.84 to 12.27, suggesting their use as oil/water emulsifiers, wetting, and cleansing agents. All esters demonstrate promising surface-active characteristics, with moderate to high foam production with good stability. Notably, compounds 6-O-(N-dodecanoyl, tetradecanoyl cysteine)-glucopyranose (34, 35), respectively and 6-O-(N-12-hydroxy-9-octadecenoyl cysteine)-glucopyranose (38) display superior foamability. Wetting efficiency increased with decreasing the chain length of the acyl group. The storage results reveal that increasing the fatty acyl hydrophobe length enhances the derived emulsion's stability for up to 63 days. Particularly, including cysteine in these glucosyl esters improves wetting, foaming, and emulsifying potentialities. Furthermore, the esters exhibit antibacterial activity against several tested Gram-positive and Gram-negative bacteria and fungi. On the other hand, they show significant antiproliferative effects on some liver tumor cell lines. For instance, compounds 6-O-(N-12-hydroxy-9-octadecenoylglycine)-glucopyranose (28), 6-O-(N-dodecanoyl, hexadecanoyl, 9-octadecenoyl and 12-hydroxy-9-octadecenoylvaline)- glucopyranose (29, 31, 32 and 33), respectively in addition to the dodecanoyl, hexadecanoyl, 9-octadecenoyl and 12-hydroxy-9-octadecenoyl cysteine glucopyranose (34, 36, 37 and 38), respectively significantly inhibit the examined cancer cells.

Influence of structural variations in polysarcosine functionalized lipids on lipid nanoparticle‐mediated mRNA delivery

AbstractLipid nanoparticles (LNPs) have been demonstrated to be potent and well‐tolerated vehicles for delivering mRNA in vaccination and therapeutics. However, the presence of anti‐poly(ethylene glycol) (PEG) antibodies in the body resulted in the problems of hypersensitivity reaction, accelerated blood clearance and high systemic reactogenicity after repeated dosing of PEG lipid‐contained LNPs, thus limiting the utility for in vivo messenger RNA (mRNA) delivery. Here, we synthesized well‐defined polysarcosine functionalized lipids (pSar‐lipids) with various hydrophobic tail lengths and molecular weights by the accelerated ring‐opening polymerization of sarcosine N‐carboxyanhydride (NCA). The obtained pSar‐lipids were utilized as PEG lipid alternatives to explore structure–activity relationships of pSar‐lipid‐based LNPs. The results demonstrated that pSar‐lipid‐based LNPs by intravenous administration represented higher mRNA delivery efficiency in the liver and spleen with the increased hydrophobic tail length of pSar‐lipids. Importantly, more significant preference for mRNA delivery into the liver was identified by increasing the molecular weight of pSar segments. As a result, this work elucidated the effect of structural variations in pSar‐lipids on LNP‐mediated in vivo mRNA delivery, providing clues to optimize pSar‐lipids as potential alternatives to PEG lipids for developing next‐generation of LNP delivery systems.

Synthesis and emulsion stability of salt resistant viscosity reducer for heavy oil reservoirs with varying salinities

To address the inadequate salt resistance of viscosity reducers and their limited applicability to reservoirs with single salinity, we synthesized salt-resistant viscosity reducers PANxAn in this study. These compounds were derived from fatty alcohol polyoxyethylene ether acrylate, N-alkyl acrylamide, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid. The structures were identified using nuclear magnetic hydrogen spectroscopy. We investigated the effects of the hydrophilic group ethoxy-chain length (n = 14, 16, 18, 20 and 22) and hydrophobic group alkyl-chain length (x = 12, 14, 16, and 18) on the salt resistance, interfacial activity, wettability, interfacial viscoelasticity and emulsification viscosity reduction performance of the viscosity reducers. Futher, the structures of the viscosity reducers which can adapt to different salinities were determined. Based on the emulsification viscosity reduction effect, PAN14A16, PAN12A16, PAN12A18, PAN12A20/PAN16A16 and PAN12A22/PAN18A16 adapted to salinities range of 2 × 104-6 × 104, 4 × 104-8 × 104, 6 × 104-10 × 104, 8 × 104-12 × 104 and 10 × 104-14 × 104 mg/L, respectively. At the optimal salinity, PANxAn reduced the oil–water interfacial tension from 28.3 to 5.0 mN/m, dynamic contact angle from 130.0° to 61.0°, and heavy oil viscosity from 454.6 to 60.0 mPa·s with a viscosity reduction rate of 86.80 %. The synthesis of salt-resistant PANxAn provides theoretical guidance and application value for enhancing the recovery efficiency of viscosity-reducer flooding in high-salinity heavy oil reservoirs.

Responsive Microgels through RAFT-HDA Dynamic Covalent Bonding Chemistry.

This paper developed a method for preparing ultrasound-responsive microgels based on reversible addition fragmentation chain transfer-hetero Diels-Alder (RAFT-HAD) dynamic covalent bonding. First, a styrene cross-linked network was successfully prepared by a Diels-Alder (DA) reaction between phosphoryl dithioester and furan using double-ended diethoxyphosphoryl dithiocarbonate (BDEPDF) for RAFT reagent-mediated styrene (St) polymerization, with a double-ended dienophile linker and copolymer of furfuryl methacrylate (FMA) and St as the dienophile. Subsequently, the microgel system was constructed by the HDA reaction between phosphoryl disulfide and furan groups using the copolymer of polyethylene glycol monomethyl ether acrylate (OEGMA) and FMA as the dienophore building block and hydrophilic segment and the polystyrene pro-dienophile linker as the cross-linker and hydrophobic segment. The number of furans in the dienophile chain and the length of the dienophile linker were regulated by RAFT polymerization to investigate the effects of the single-molecule chain functional group degree, furan/dithioester ratio, and hydrophobic cross-linker length on the microgel system. The prepared microgels can achieve the reversible transformation of materials under force responsiveness, and their preparation steps are simple and adaptive to various potential applications in biomedical materials and adaptive electrical materials.

Factors influencing the fate of chemical food safety hazards in the terrestrial circular primary food production system-A comprehensive review.

Food safety is recognized as a major hurdle in the transition toward circular food production systems due to the potential reintroduction and accumulation of chemical contaminants in these food systems. Effectively managing these hazardous contaminants in a risk-based manner requires quantitative insights into the factors influencing the presence and fate of contaminants in the entire circular food chain. A systematic literature review was performed to gain an up-to-date overview of the known factors and their influence on the transfer and accumulation of contaminants. This review focused on the terrestrial circular primary food production system, including the pathways between waste- or byproduct-based fertilizers, soil, crops, animal feed, and farmed animals. This review revealed an imbalance in research regarding the different pathways: studies on the soil-to-crop pathway were most abundant. The factors identified can be categorized as compound-related (intrinsic) factors, such as hydrophobicity, molecular weight, and chain length, and extrinsic factors, such as soil organic matter and carbon, pH, milk yield of cows, crop age, and biomass. Quantitative data on the influence of the identified factors were limited. Most studies quantified the influence of individual factors, whereas only a few studies quantified the combined effect of multiple factors. By providing a holistic insight into the influential factors and the quantification of their influence on the fate of contaminants, this review contributes to the improvement of food safety management for chemical hazards when transitioning to a circular food system.

Influences of hydrophobic tail length tuning of linear aliphatic di-cation functioned anion exchange membrane on electrodialysis desalination

We successfully prepared a series of highly ionized anion exchange membranes (AEMs) with the equivalent modifications of the linear aliphatic di-cation appending different flexible and hydrophobic alkyl tails (named QPT-Cn, n is the number of carbon atoms in the tails). Due to the synergistic interaction between the domain-limiting of the intermediate unit ethyl group of the di-cation and the hydrophobicity of the tails, QPT-Cn membranes are endowed with different microphase separation structures and exhibit various mechanical and electrochemical properties. The well complement of the C12 tails and the dense di-cations offer QPT-C12 the well-tuned microphase structure, manifesting better mechanical and electrochemical properties at the wet state. Owing to the greatly improve electrochemical properties, QPT-C12 shows the comprehensive ED performances significantly better than those of commercial AMX with an increase of 7.97 % in current efficiency (η), a reduction of 21.70 % in energy consumption, and η remaining rates of more than 98.76 %. The above results confirm that the complementary enhancement strategy of combining appropriately sized hydrophobic alkyl tails with dense linear aliphatic di-cation is an effective method to develop the advanced ED AEMs. The excellent ED performances of QPT-C12 are of competitive in the ED desalination applications.

Fabrication and enzymatic dissociation of long-chain alkanoylcholine-based worm-like micelles

In order to elucidate the possibility of the formation and enzymatic dissociation of worm-like micelles (WLMs) from long-chain alkanoylcholines (LCACs), strategies of fabrication and butyrylcholine esterase (BChE)-catalyzed dissociation of LCAC-based WLMs have been developed. Three LCACs with different hydrophobic tail lengths, namely dodecanoylcholine bromide (DCB), myristoylcholine bromide (MCB), and palmitoylcholine bromide (PCB), have been used as model cationic surfactants. It was demonstrated that the hydrophobic tail length of an LCAC played an important role in the formation of WLMs. With the assistance of sodium salicylate (NaSal), DCB proved to be incapable of efficiently forming WLMs, whereas MCB and PCB performed well. PCB-based WLMs have also been fabricated with the aid of NaNO3. To fabricate WLMs at a surfactant concentration of 0.1 mol L−1, the optimal molar ratio of the additive (NaSal and NaNO3) to the surfactant (MCB and PCB) was around 0.83 (NaSal/MCB), 0.63 (NaSal/PCB) and 20 (NaNO3/PCB), respectively. The respective average diameters of the WLMs were about 4.11 nm (MCB-NaSal), 4.82 nm (PCB-NaSal), and 4.51 nm (PCB-NaNO3). Meanwhile, the respective zero-shear viscosities of the WLMs were about 5.38 × 102 mPa s (MCB-NaSal), 1.81 × 105 mPa s (PCB-NaSal), and 7.35 × 104 mPa s (PCB-NaNO3). Jelly-like PCB-NaSal and PCB-NaNO3 WLMs underwent efficient dissociation through a BChE-catalyzing strategy under mild conditions of pH 7.4 and 37 °C. Its chemical principle was a hydrolysis reaction of PCB catalyzed by BChE.

Post-synthetic modification of NH2-MIL-101(Al)@SiO2 with different non-polar ligands for improving HPLC separation performance of estrogens

Due to the excellent pore structure, MOFs as the stationary phase was playing an important part in chromatography. In this work, the shell-core MIL-101(Al)@SiO2 composites post-synthetic modified by ligands with different polarities were fabricated for separation of estrogens. The structure and morphology of these materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET). In order to investigate the influence of the ligand polarity on chromatographic separation performance of estrogens, alkyl molecules with different chain length were introduced as the ligands. With the hydrophobicity and chain length of the ligands increasing, the resolutions of the MIL-101(Al)@SiO2 columns for the separation of estrogens exhibited the tendency of a parabola. Best result was achieved on the C4-MIL-101(Al)@SiO2 column. On that basis, the possible retention mechanism on C4-MIL-101(Al)@SiO2 column was elucidated by studying the mobile phase effect on separation behavior.

Design, Synthesis, and Structure-Activity Relationship Studies of New Quinone Derivatives as Antibacterial Agents.

Resistance to antibacterial agents is a growing global public health problem that reduces the efficacy of available antibacterial agents, leading to increased patient mortality and morbidity. Unfortunately, only 16 antibacterial drugs have been approved by the FDA in the last 10 years, so it is necessary to develop new agents with novel chemical structures and/or mechanisms of action. In response to this, our group takes up the challenge of designing a new family of pyrimidoisoquinolinquinones displaying antimicrobial activities against multidrug-resistant Gram-positive bacteria. Accordingly, the objective of this study was to establish the necessary structural requirements to obtain compounds with high antibacterial activity, along with the parameters controlling antibacterial activity. To achieve this goal, we designed a family of compounds using different strategies for drug design. Forty structural candidates were synthesized and characterized, and antibacterial assays were carried out against high-priority bacterial pathogens. A variety of structural properties were modified, such as hydrophobicity and chain length of functional groups attached to specific carbon positions of the quinone core. All the synthesized compounds inhibited Gram-positive pathogens in concentrations ranging from 0.5 to 64 µg/mL. Two derivatives exhibited minimum inhibitory concentrations of 64 µg/mL against Klebsiella pneumoniae, while compound 28 demonstrated higher potency against MRSA than vancomycin.

Chemico-Physical Properties of Some 1,1'-Bis-alkyl-2,2'-hexane-1,6-diyl-bispyridinium Chlorides Hydrogenated and Partially Fluorinated for Gene Delivery.

The development of very efficient and safe non-viral vectors, constituted mainly by cationic lipids bearing multiple charges, is a landmark for in vivo gene-based medicine. To understand the effect of the hydrophobic chain's length, we here report the synthesis, and the chemico-physical and biological characterization, of a new term of the homologous series of hydrogenated gemini bispyridinium surfactants, the 1,1'-bis-dodecyl-2,2'-hexane-1,6-diyl-bispyridinium chloride (GP12_6). Moreover, we have collected and compared the thermodynamic micellization parameters (cmc, changes in enthalpy, free energy, and entropy of micellization) obtained by isothermal titration calorimetry (ITC) experiments for hydrogenated surfactants GP12_6 and GP16_6, and for the partially fluorinated ones, FGPn (where n is the spacer length). The data obtained for GP12_6 by EMSA, MTT, transient transfection assays, and AFM imaging show that in this class of compounds, the gene delivery ability strictly depends on the spacer length but barely on the hydrophobic tail length. CD spectra have been shown to be a useful tool to verify the formation of lipoplexes due to the presence of a "tail" in the 288-320 nm region attributed to a chiroptical feature named ψ-phase. Ellipsometric measurements suggest that FGP6 and FGP8 (showing a very interesting gene delivery activity, when formulated with DOPE) act in a very similar way, and dissimilar from FGP4, exactly as in the case of transfection, and confirm the hypothesis suggested by previously obtained thermodynamic data about the requirement of a proper length of the spacer to allow the molecule to form a sort of molecular tong able to intercalate DNA.

Stereochemistry-activity relationship of ceramide-induced exosome production to clear amyloid-β in Alzheimer's disease.

Stereochemistry has a substantial impact on the biological activity of various drugs. We investigated the role of stereochemistry of ceramides in inducing the production of exosomes, a type of extracellular vesicle, from neuronal cells, with a potential benefit in improving the clearance of amyloid-β (Aβ), a causal agent of Alzheimer's disease. A stereochemical library of diverse ceramides with different tail lengths was synthesized with the purpose of varying stereochemistry (D-erythro: DE, D-threo: DT, L-erythro: LE, L-threo: LT) and hydrophobic tail length (C6, C16, C18, C24). The exosome levels were quantified using TIM4-based exosome enzyme-linked immunosorbent assay after concentrating the conditioned medium using centrifugal filter devices. The results revealed a pivotal role of stereochemistry in determining the biological activity of ceramide stereoisomers, with the superiority of those based on DE and DT stereochemistry with C16 and C18 tails, which demonstrated significantly higher exosome production, without a significant change in the particle size of the released exosomes. In transwell experiments with Aβ-expressed neuronal and microglial cells, DE- and DT-ceramides with C16 and C18 tails significantly decreased extracellular Aβ levels. The results reported here are promising in the design of non-classic therapies for the treatment of Alzheimer's disease.

Effect of ratio of hydrophilic and hydrophobic ligand length on the adsorption behaviors of amphiphilic gold nanoparticles at the liquid-liquid interface

Amphiphilic gold nanoparticles (AuNPs) covered with hydrophobic and hydrophilic ligands assemble at the interface between hexane and water into monolayer structures, forming microdroplets that are covered with amphiphilic AuNPs. Here, we focused on the effect of the ratio of hydrophilic to hydrophobic ligand lengths on the assembly of amphiphilic AuNPs at the interface surface. By controlling the ratio, the extent of amphiphilic AuNPs migrating to the interface was examined. The amphiphilic AuNPs tended to migrate to the interface with an increase in the length of hydrophobic ligands. More importantly, diverse adsorption isotherm models were applied to the systems to examine the adsorption behavior of amphiphilic AuNPs at the interface. Adsorption parameters such as equilibrium constant and maximum uptake depending on the ratio of ligand length were obtained from data fitting, and they had high values with an increase in the hydrophobic ligand length. These results suggest that the adsorption behavior of amphiphilic AuNPs at the interface can be controlled by adjusting the ligand length ratio. Furthermore, the closest distance between amphiphilic AuNPs at the interface by using the obtained maximum uptake values was estimated, and it also was confirmed by the small-angle X-ray scattering (SAXS) technique.