Glycol Chain Length Research Articles

Impact of side chain length on the properties and alkaline fuel cell performance of OEG-grafted poly(terphenyl piperidinium) anion exchange membranes

In designing comb-shaped anion exchange membranes (AEMs), replacing alkyl side chains with ethylene glycol (EG)-based ones significantly enhances membrane properties and boosts AEM fuel cell performance. Although much research has focused on optimizing the placement of EG segments within the polymer matrix, the effect of EG chain length remains less explored. In this work, a series of poly(terphenyl piperidinium) AEMs with N-oligo(ethylene glycol) (OEG) terminal pendants having two to five EG repeating units were prepared by simple post-polymerization quaternization. The membrane properties showed a strong correlation with the length of the OEG side chains, influenced by both chemical composition and phase behavior. Among the OEG-grafted AEMs, PTP-OEG3 with moderate three EG repeating units, exhibited the best properties due to a careful balance between EG and cationic groups, leading to a favorable microphased separation. It achieved high hydroxide conductivity (114 mS cm−1 at 80 °C in water), robust mechanical strength (tensile strength >52 MPa), and good ex situ alkaline stability. As a result, the AEM fuel cells with the property-balanced PTP-OEG3 membrane achieved the highest peak power density of 976 mW cm−2. The in situ stability of these AEMs was also investigated. Evidently, understanding the optimal EG side chain length is an important criterion for designing AEM materials for alkaline fuel cells.

Modulating Surface Cation Concentration via Tuning the Molecular Structures of Ethylene Glycol-Functionalized PEDOT for Improved Alkaline Hydrogen Evolution Reaction.

The sluggish catalytic kinetics of nonprecious metal-based electrocatalysts often hinder them from achieving efficient hydrogen evolution reactions (HERs). Poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have been promising materials for various electrochemical applications. Nevertheless, previous studies have demonstrated that PEDOT coatings can be detrimental to HER performance. In this study, we investigated the alkaline HER efficiency of nickel foam coated with three types of ethylene glycol (EG)-functionalized EDOT. Specifically, EDOT derivatives bearing hydroxyl (-OH) and methoxy (-OCH3) end groups on the EG side chain and molecules containing two EDOT units are interconnected via EG moieties. EG groups are selected due to their strong interaction with alkali metal cations. Intriguingly, improved HER performance is observed on all electrodes coated with EG-functionalized EDOTs. Electrochemical impedance spectroscopy, electrochemical quartz crystal microbalance with dissipation, and XPS analysis are employed to explore the origin of enhanced HER efficiency. The results suggest the EG moieties can induce locally concentrated ions near the electrode surface and facilitate water dissociation through noncovalent interactions. The influence of EG chain length is systematically investigated by synthesizing molecules with di-EG, tetra-EG, and hexa-EG functionalities. This study highlights the importance of molecular design in modifying electrode surface properties to promote alkaline HER.

Sol-gel synthesized porous Yb-K2Ti6O13(n) for photocatalytic degradation of azophloxine: effect of polyethylene glycol chain length

Sol-gel synthesized porous Yb-K2Ti6O13(n) for photocatalytic degradation of azophloxine: effect of polyethylene glycol chain length

Ethylene glycol derivative-pendanted quaternary ammonium antibacterial polymers with low cytotoxicity

Cationic poly(quaternary ammonium) (pQA) polymers exhibit excellent antibacterial efficacy but high cytotoxicity (thus low selectivity), hampering their widespread use as antibacterial agents. Herein, we systematically synthesized a series of pQA polymers (pQA−EG) containing biocompatible ethylene glycol (EG) derivative pendant groups with different chain lengths and connectivities (acyclic/cyclic). The antibacterial efficacy of pQA−EG was optimized by a moderate EG chain length, which endowed the polymer with balanced hydrophobicity/charge density. The high chain flexibility of the EG derivative combined with its good hydrophilicity was critical for significantly lowering the cytotoxicity of pQA−EG. Hence, compared with pQA polymers containing alkyl pendant groups, the pQA−EG polymer containing a long flexible EG derivative pendant group exhibited significantly lower cytotoxicity and higher selectivity as well as satisfactory antibacterial activity and kinetics. Our study offers a rational platform for synthesizing low-toxicity antibacterial polymers and provides fundamental insights into their structure−biological activity relationships.

The effects of chain length of polyethylene glycol on porous Na2Ti6O13 for photocatalytic degradation of ofloxacin

The effects of chain length of polyethylene glycol on porous Na2Ti6O13 for photocatalytic degradation of ofloxacin

Degradation of oligo[poly(ethylene glycol) fumarate] hydrogels through stimulus-mediated pendent group cyclization

Hydrogels are of interest for a wide range of applications including drug delivery, regenerative medicine, agriculture, and personal care products. Among the water-soluble synthetic polymers that can be processed to form hydrogels, oligo[poly(ethylene glycol) fumarate] (OPF) has attracted significant attention. The degradation of OPF can be tuned to some extent based on the poly(ethylene glycol) chain length and amount of cross-linker incorporated, but the degradation is generally quite slow, occurring over several months. Here we introduce a new approach to tune and trigger the degradation of OPF. Fumarate alkenes were functionalized to introduce protected pendent amines, that after deprotection could cyclize to 6-membered lactams, thereby cleaving the polymer backbone. Using light as a model stimulus, we demonstrated that the cleavage of an o-nitrobenzyl carbamate protecting group led to more rapid polymer degradation. Remaining unfunctionalized fumarates allowed the functionalized OPF to be cross-linked, forming a hydrogel. Treatment with light led to breakdown of the hydrogels, as indicated by a substantial reduction in the compressive modulus. The functionalization and stimulus-responsive cleavage mechanism should be applicable to other stimuli, providing a versatile approach to control OPF degradation for various applications.

The Characteristics of the Metal-Free and Non-Conjugated Polymer Film with Self-Assembled Nanoparticles.

It is shown in this paper that a polymer, MA-PEG 1000-DGEBA (MP1D), exhibits antireflection, substrate-dependent photoluminescence (SDP), wide band-gap, and photoconduction characterization. MP1D was synthesized from maleic anhydride, polyethylene glycol 1000, and bisphenol-A diglycidyl ether. Self-assembled nanoparticles embedded in MP1D film and ranging from 2.5 to 31.6 nm are observed, which could be expected as scatterers to enhance light trapping and extraction. The size of the nanoparticle increases with the concentration of the MP1D solution. Besides solution concentration, the nanoparticle dimension could be modified by the chain length of polyethylene glycol in the polymer synthesis. The effects of solution concentration, annealing temperature, annealing period, and substrate on the photoluminescence (PL) of MP1D films are examined. Increasing solution concentration increases PL intensity. However, aggregation-caused quenching is explicit as the solution concentration exceeds 100 mM. PL intensity increases with annealing temperature, which could be attributed to crystallinity improvement. PL intensity increases with increasing the annealing period from 0.5 to 2 h. Nonetheless, as the annealing period exceeds 2 h, PL quenching is emerging, which could be due to aggregation. It is expected that MP1D could be a promising candidate for host materials and MP1D film could play a multifunctional role (antireflective and light-trapping functions) in optoelectronics.

Influence of PEG Chain Length of Functionalized Magnetic Nanoparticles on the Cytocompatibility and Immune Competence of Primary Murine Macrophages and Dendritic Cells.

A major drawback of nanoparticles (NPs) for biomedical applications is their preferential phagocytosis in immune cells, which can be avoided by surface modifications like PEGylation. Nevertheless, examinations of different polyethylene glycol (PEG) chain lengths on the competence of immune cells as well as possible immunotoxic effects are still sparse. Therefore, primary murine macrophages and dendritic cells were generated and incubated with magnetic nanoporous silica nanoparticles (MNPSNPs) modified with different mPEG chains (2 kDa, 5 kDa, and 10 kDa). Cytotoxicity, cytokine release, and the formation of reactive oxygen species (ROS) were determined. Immune competence of both cell types was examined and uptake of MNPSNPs into macrophages was visualized. Concentrations up to 150 µg/mL MNPSNPs showed no effects on the metabolic activity or immune competence of both cell types. However, ROS significantly increased in macrophages incubated with larger PEG chains, while the concentration of cytokines (TNF-α and IL-6) did not indicate a proinflammatory process. Investigations on the uptake of MNPSNPs revealed no differences in the onset of internalization and the intensity of intracellular fluorescence. The study gives no indication for an immunotoxic effect of PEGylated MNPSNPs. Nevertheless, there is still a need for optimization regarding their internalization to ensure an efficient drug delivery.

Halogen-Bonding Heteroditopic [2]Catenanes for Recognition of Alkali Metal/Halide Ion Pairs.

The first examples of halogen bonding (XB) heteroditopic homo[2]catenanes were prepared by discrete Na+ template-directed assembly of oligo(ethylene glycol) units derived from XB donor-containing macrocycles and acyclic bis-azide precursors, followed by a CuI -mediated azide-alkyne cycloaddition macrocyclisation reaction. Extensive 1 H NMR spectroscopic studies show the [2]catenane hosts exhibit positive cooperative ion-pair recognition behaviour, wherein XB-mediated halide recognition is enhanced by alkali metal cation pre-complexation. Notably, subtle changes in the catenanes' oligo(ethylene glycol) chain length dramatically alters their ion-binding affinity, stoichiometry, complexation mode, and conformational dynamics. Solution-phase and single-crystal X-ray diffraction studies provide evidence for competing host-separated and direct-contact ion-pair binding modes. We further demonstrate the [2]catenanes are capable of extracting solid alkali-metal halide salts into organic media.

Halogen‐Bonding Heteroditopic [2]Catenanes for Recognition of Alkali Metal/Halide Ion Pairs

AbstractThe first examples of halogen bonding (XB) heteroditopic homo[2]catenanes were prepared by discrete Na+ template‐directed assembly of oligo(ethylene glycol) units derived from XB donor‐containing macrocycles and acyclic bis‐azide precursors, followed by a CuI‐mediated azide‐alkyne cycloaddition macrocyclisation reaction. Extensive 1H NMR spectroscopic studies show the [2]catenane hosts exhibit positive cooperative ion‐pair recognition behaviour, wherein XB‐mediated halide recognition is enhanced by alkali metal cation pre‐complexation. Notably, subtle changes in the catenanes’ oligo(ethylene glycol) chain length dramatically alters their ion‐binding affinity, stoichiometry, complexation mode, and conformational dynamics. Solution‐phase and single‐crystal X‐ray diffraction studies provide evidence for competing host‐separated and direct‐contact ion‐pair binding modes. We further demonstrate the [2]catenanes are capable of extracting solid alkali‐metal halide salts into organic media.

Probing Surface and Interfacial Tension of Ionic Liquids in Vacuum with the Pendant Drop and Sessile Drop Method.

We report on the surface and interface tension measurements of the two ionic liquids (ILs) [C8C1Im][PF6] and [m(PEGn)2Im]I (n = 2, 4, 6) in a surface science approach. The measurements were performed in a newly developed and unique experimental setup, which allows for surface tension (ST) measurements using the pendant drop method and for contact angle measurements using the sessile drop method under the well-defined conditions of a high vacuum (from 10-7 mbar). The setup also allows for in vacuum transfer to an ultrahigh vacuum system for surface preparation and analysis, such as in angle-resolved X-ray photoelectron spectroscopy. For [C8C1Im][PF6], we observe a linear decrease in the surface tension with increasing temperature. The ST measured under high vacuum is consistently found to be larger than under ambient conditions, which is attributed to the influence of water uptake in air by the IL. For [m(PEGn)2Im]I (n = 2, 4, 6), we observe a decrease in the ST with increasing polyethylene glycol chain length in a vacuum, similar to very recent observations under 1 bar Argon. This decrease is attributed to an increasing enrichment of the PEG chains at the surface. The ST data obtained under these ultraclean conditions are essential for a fundamental understanding of the relevant parameters determining ST on the microscopic level and can serve as a benchmark for theoretical calculations, such as molecular dynamic simulations. In addition to the ST measurements, proof-of-principle data are presented for sessile drop measurements in HV, and a detailed description and characterization of the new setup is provided.

Exploring Carbonyl Chemistry in Non-aqueous Mg Flow Batteries.

Non-aqueous redox flow batteries (RFBs) are emerging electrochemical technologies for grid energy storage. Non-aqueous Mg RFBs that use Mg metal as the anode are especially promising due to various benefits of the Mg metal anode, including its low potential, high volumetric capacity, SEI-free, highly reversible operation and low cost. Despite the potential, there are rarely any studies on developing non-aqueous Mg RFBs. Herein, a non-aqueous Mg redox flow battery using a polymer catholyte is reported. Through rational molecular engineering, a carbonyl-based moiety is combined with a polyethylene glycol moiety to achieve a polymer with high voltage and high solubility in the ether-based electrolyte. A series of polymers with different polyethylene glycol chain lengths are synthesized and their performances are measured first at the molecular level, and then at the device level in a Mg redox flow battery using a Mg foil as the anode, the polymer solution as the catholyte and a porous membrane as the separator. The flow battery delivers a voltage of 1.8 V, a maximum capacity of 475 mAh/L, an average Coulombic efficiency of 90.5%, an average voltage efficiency of 67.4%, an energy efficiency of 61.0%, and an energy density of 0.855 Wh/L. Systematic mechanistic studies are performed to understand the performance decay mechanism and possible strategies for future improvement are discussed. This work opens a new avenue for the development of energy storage technologies for grid electricity storage.

Synthesis and Immunological Activity of Novel Oligo(ethylene glycol) Analogues of α-Galactosylceramide.

CD1d-arbitrated activation of i-NKT cells by α-galactosylceramide results in the effective secretion of Th1 and Th2 cytokines, with adjuvanticity skewed toward Th2 immunity. However, the polarization of immune response could be achieved by suitable modification of the glycolipid structure. In the current study, novel glycolipids with an amphiphilic oligo ethylene glycol lipid moiety bearing the benzyloxy group at the terminus on the acyl arm of sphingosine, exhibited CD1d ligand binding as quantified by IL-2 cytokine production. When immunized with quadrivalent split influenza virus in BALB/c mice, the novel ceramide analogues with a longer oligo (ethylene glycol) chain length induced significant levels of antibody (IgG) with Th1-polarized immune response.

Surfactant chemistry and polymer choice affect single-wall carbon nanotube extraction conditions in aqueous two-polymer phase extraction

Quantitative determination of the effects of surfactant chemistry and polymer chain length on the concentration conditions necessary to yield extraction of specific single-wall carbon nanotube (SWCNT) species in an aqueous two-polymer phase extraction (ATPE) separation are reported. In particular, the effects of polyethylene glycol (PEG) chain length, surfactant ratios, and systematic structural variations of alkyl surfactants and bile salts on the surfactant ratios necessary for extraction were investigated using a recently reported fluorescence-based method. Alkyl surfactant tail length was observed to strongly affect the amount of surfactant necessary to cause PEG-phase extraction of nanotube species in ATPE, while variation in the anionic sulfate/sulfonate head group chemistry has less impact on the concentration necessary for extraction. Substitution of different bile salts results in different surfactant packings on the SWCNTs, with substitution greatly affecting the alkyl surfactant concentrations required for (n,m) extraction. Finally, distinct alkyl-to-bile surfactant ratios were found to extract specific (n,m) SWCNTs across the whole effective window of absolute concentrations, supporting the hypothesized competitive adsorption mechanism model of SWCNT sorting. Altogether, these results provide valuable insights into the underlying mechanisms behind ATPE-based SWCNT separations, towards further development and optimization of the ATPE method for SWCNT chirality and handedness sorting.

Impact of PEGylation on an antibody-loaded nanoparticle-based drug delivery system for the treatment of inflammatory bowel disease

Nanoparticle-based oral drug delivery systems have the potential to target inflamed regions in the gastrointestinal tract by specifically accumulating at disrupted colonic epithelium. But, delivery of intact protein drugs at the targeted site is a major challenge due to the harsh gastrointestinal environment and the protective mucus layer. Biocompatible nanoparticles engineered to target the inflamed colonic tissue and efficiently penetrate the mucosal layer can provide a promising approach for orally delivering monoclonal antibodies to treat inflammatory bowel disease. The study aims to develop mucus-penetrating nanoparticles composed of poly(lactic-co-glycolic acid, PLGA) polymers with two different polyethylene glycol (PEG) chain lengths (2 kDa and 5kDa) to encapsulate monoclonal antibody against tumor necrosis factor-α (TNF-α). The impact of different PEG chain lengths on the efficacy of the nanosystems was evaluated in vitro, ex vivo, and in vivo. Both PLGA-PEG2k and PLGA-PEG5k nanoparticles successfully encapsulated the antibody and significantly reduced TNF-α secretion from activated macrophages and intestinal epithelial cells. However, only antibody-loaded PLGA-PEG2k nanoparticles were able to alleviate the experimental acute colitis in mice demonstrated by improved colon weight/length ratio, histological score, and reduced tissue-associated myeloperoxidase activity and expression of proinflammatory cytokine TNF-α levels compared with the control group. The results suggest that despite having no significant differences in the in vitro cell-based assays, PEG chain length has a significant impact on the in vivo performance of the mucus penetrating nanoparticles. Overall, PLGA-PEG2k nanoparticles were presented as a promising oral delivery system for targeted antibody delivery to treat inflammatory bowel disease. Statement of significanceThere is an unmet therapeutic need for oral drug delivery systems for safe and effective antibody therapy of inflammatory bowel disease. Therefore, we have developed PEGylated PLGA-based nanoparticulate drug delivery systems for oral targeted delivery of anti-TNF-α antibody as a potential alternative treatment strategy. The PEG chain length did not affect encapsulation efficiency or interaction with mucin in vitro but resulted in differences in in vitro release profile and in vivo efficacy study. We demonstrated the superiority of anti-TNF-α mAb-PLGA-PEG2k over mAb-PLGA-PEG5k nanoparticles to effectively exhibit anti-inflammatory responses in an acute murine colitis model. These nanoparticle-based formulations may be adjusted to encapsulate other drugs that could be applied to a number of disorders at different mucosal surfaces.

Control of Specific/Nonspecific Protein Adsorption: Functionalization of Polyelectrolyte Multilayer Films as a Potential Coating for Biosensors.

Control of nonspecific/specific protein adsorption is the main goal in the design of novel biomaterials, implants, drug delivery systems, and sensors. The specific functionalization of biomaterials can be achieved by proper surface modification. One of the important strategies is covering the materials with functional coatings. Therefore, our work aimed to functionalize multilayer coating to control nonspecific/specific protein adsorption. The polyelectrolyte coating was formed using a layer-by-layer technique (LbL) with biocompatible polyelectrolytes poly-L-lysine hydrobromide (PLL) and poly-L-glutamic acid (PGA). Nonspecific protein adsorption was minimized/eliminated by pegylation of multilayer films, which was achieved by adsorption of pegylated polycations (PLL-g-PEG). The influence of poly (ethylene glycol) chain length on eliminating nonspecific protein adsorption was confirmed. Moreover, to achieve specific protein adsorption, the multilayer film was also functionalized by immobilization of antibodies via a streptavidin bridge. The functional coatings were tested, and the adsorption of the following proteins confirmed the ability to control nonspecific/specific adsorption: human serum albumin (HSA), fibrinogen (FIB), fetal bovine serum (FBS), carcinoembryonic antigen human (CEA) monitored by quartz crystal microbalance with dissipation (QCM-D). AFM imaging of unmodified and modified multilayer surfaces was also performed. Functional multilayer films are believed to have the potential as a novel platform for biotechnological applications, such as biosensors and nanocarriers for drug delivery systems.

Amphifunctional Mesoporous Silica Nanoparticles with “Molecular Gates” for Controlled Drug Uptake and Release

AbstractIt is demonstrated that the uptake and release of hydrophobic drugs/dyes by mesoporous silica nanoparticles (MSN) is critically dependent on the functional groups present on their outer surfaces. For this, amphifunctional MSNs are synthesized, possessing hydrophobic pores and hydrophilic functional groups on the outer surface. Further, the outer surface is modified with a different chain length of molecules, e.g., propargyl alcohol, triethylene glycol, and PEG (2000) via azide–alkyne click chemistry. The effect of these different surface functional groups on uptake of drug/dye is demonstrated with Nile red, proflavine (free base form), and rhodamine 6G. The uptake of these molecules is found to be inversely proportional to the bulkiness of surface functionality. To counter this effect, an alternate method of loading is proposed and demonstrated. Finally, the effect of these different functional groups on the release of loaded drug proflavine is studied, which supports the hypothesis that bulkier outer surface groups also hinder the release of drugs loaded in the porous MSN.

Magnetic black phosphorus microbubbles for targeted tumor theranostics

Abstract Black phosphorus (BP) is attracting more and more interest for the biomedical application. The absorption in a wide spectral range and high photothermal conversion efficiency make BP suitable for photothermal therapy. However, BP alone is hard to realize the targeted therapy, which limits the precision and efficiency of the therapy. Magnetic microbubbles (MBs) are favored drug carriers because they can resist the sheer force of blood flow in a magnetic field, which improves the efficiency of MBs adhesion to the vascular wall for targeted ultrasound diagnosis and therapy. This study first optimized the magnetic MBs configurations through controlling the connecting polyethylene glycol (PEG) chain length. The magnetic MBs with PEG2000 have been chosen for targeted BP nanosheets delivery due to the better stability and magnetic responsiveness. The magnetic black phosphorus microbubbles (MBBPM) can realize the targeted tumor theranostics in vitro and in vivo. They could be applied for the targeted ultrasound imaging with an enhanced echogenicity by three times when accumulated at the target site where the magnetic field is applied. As the NIR laser irradiation was applied on the accumulated MBBPM, they dynamited and the temperature increased rapidly. It improved the cell membrane permeability, thus accelerating and enhancing a precision photothermal killing effect to the breast cancer cells, compared to BP alone.

The effect of the polyethylene glycol chain length of a lipopolymer (DSPE-PEGn) on the properties of DPPC monolayers and bilayers

Due to the growing importance of controlled drug delivery systems (DDS), the main task of nanotechnology is to develop stable, effective and non-toxic nanocarriers in which the drug can be encapsulated and delivered to a specific diseased site in the patient's body. Currently, one of the most popular ways to improve the pharmacokinetic and physicochemical properties of liposomes is introducing into their structure poly(ethylene glycol) chains conjugated with 1,2-disteroil-sn-glycero-3-phosphoethanolamine (DSPE) molecules. Because the research so far does not give an unequivocal answer which length of PEG chains is more beneficial for liposomes properties, the aim of this work was to investigate the influence of this parameter (DSPE-PEG350, DSPE-PEG750 and DSPE-PEG2000) on model DPPC membrane. The studies were performed on monolayer and bilayer systems and were related to the surface pressure measurements, Brewster angle microscopy experiments, Grazing Incidence X-ray Diffraction studies, dynamic light scattering and zeta potential measurements and the experiments with the calcein release and steady-state fluorescence anisotropy of DPH. The obtained results proved that the molecular organization of the DPPC membrane strongly depends on the length of poly(ethylene glycol) chains conjugated with DSPE. Moreover, the addition of different lengths of polymer chains changes the properties of formulated liposomes, especially their stability, permeability, size and surface charge.

Fullerene derivatives with oligoethylene-glycol side chains: an investigation on the origin of their outstanding transport properties.

For many years, fullerene derivatives have been the main n-type material of organic electronics and optoelectronics. Recently, fullerene derivatives functionalized with ethylene glycol (EG) side chains have been showing important properties such as enhanced dielectric constants, facile doping and enhanced self-assembly capabilities. Here, we have prepared field-effect transistors using a series of these fullerene derivatives equipped with EG side chains of different lengths. Transport data show the beneficial effect of increasing the EG side chain. In order to understand the material properties, full structural determination of these fullerene derivatives has been achieved by coupling the X-ray data with molecular dynamics (MD) simulations. The increase in transport properties is paired with the formation of extended layered structures, efficient molecular packing and an increase in the crystallite alignment. The layer-like structure is composed of conducting layers, containing of closely packed C60 balls approaching the inter-distance of 1 nm, that are separated by well-defined EG layers, where the EG chains are rather splayed with the chain direction almost perpendicular to the layer normal. Such a layered structure appears highly ordered and highly aligned with the C60 planes oriented parallel to the substrate in the thin film configuration. The order inside the thin film increases with the EG chain length, allowing the systems to achieve mobilities as high as 0.053 cm2 V−1 s−1. Our work elucidates the structure of these interesting semiconducting organic molecules and shows that the synergistic use of X-ray structural analysis and MD simulations is a powerful tool to identify the structure of thin organic films for optoelectronic applications.