Long Polyethylene Glycol Chains Research Articles

Modification of crystal growth of NaA zeolite with steric hindrance agents for removing ammonium ion from aqueous solution

The incorporation of steric effects into the hydrothermal synthesis system of NaA zeolite proves to be an effective method for modifying grain size, enhancing grain dispersion and obtaining single crystal products. In this study, three different molecular configurations, namely short-chain ethanolamine (MEA), long-chain polyethylene glycol (PEG), and ring-chain cyclohexanol (CyOH), were employed to investigate the impact of steric effects on the crystal growth of NaA zeolite. The crystal form, morphology, and particle size of NaA zeolite were characterized using XRD, FT-IR, and SEM techniques. The order of steric hindrance in terms of molecular configuration was found to be as follows: CyOH > PEG > MEA. NaA-CyOH exhibited a high dispersion of single crystal particles, the smallest grain size, and the largest specific surface area and pore volume. To evaluate the ammonium ion adsorption performance, NaA-CyOH-31, the zeolite with the best performance, was utilized for studying the reaction kinetics. The results indicated that the adsorption behavior of NaA zeolite towards ammonium ion could be better described by the quasi second-order equation and the Langmuir model. Furthermore, the evaluation of the regeneration ability of NaA-CyOH zeolite demonstrated that the recovered adsorbent still maintained a high level of adsorption performance.

Enhancing hydrogel toughness by uniform cross-linking using modified polyhedral oligomeric silsesquioxane

The use of macro cross-linkers is one of the most effective approaches for developing tough hydrogels. However, the presence of uneven cross-linking and the resulting hydrogel inhomogeneity restrict further improvement. Here, we achieve uniform cross-linking by employing polyhedral oligomeric silsesquioxane (POSS)-grafted acrylated polyethylene glycol (PEG) as a cross-linker to enhance the toughness of hydrogels. The nano-sized hard silica core of POSS facilitates energy dissipation, and its dissolved form ensures uniform cross-linking through molecular-level dispersion. The peripheral acrylate groups introduce multiple interacting points, and the physical entanglements of long-chain PEG contribute to enhanced toughness. Incorporating acrylated POSS-PEG into polyacrylamide hydrogel yields enhanced properties such as toughness of up to 6531 kJ m−3 and break elongation up to 9455%, where the length of PEG chains grafted onto POSS is demonstrated to play a crucial role in facilitating energy dissipation and achieving high toughness.

Tumor acidity-activatable macromolecule autophagy inhibitor and immune checkpoint blockade for robust treatment of prostate cancer.

Immune checkpoint blockade (ICB) antibody such as anti-PD-L1 (aPD-L1) activates cytotoxic T cells (CTLs) to combat cancer, but they showed poor efficacy in prostate cancer (PCa). Lysosome-dependent autophagy is utilized by cancer cells to degrade their MHC-I and to lower their vulnerability to TNF-α and CTLs. Lysosomal pH-sensitive polymeric nanoparticle as a drug delivery carrier may also be a novel autophagy inhibitor to boost immunotherapy, but such an important effect has not been investigated. Herein, we developed a unique tumor acidity-activatable macromolecular nanodrug (called P-PDL1-CP) with the poly(2-diisopropylaminoethyl methacrylate) (PDPA) core and the conjugations of both aPD-L1 and long-chain polyethylene glycol (PEG) coating. The PDPA core was demonstrated to disturb lysosome to block the autophagic flux, thus elevating the cancer cell's MHC-I expression and vulnerability to the TNF-α and CTLs. Long-chain PEG facilitated a good tumor accumulation of P-PDL1-CP nanodrug. Furthermore, P-PDL1-CP nanodrug inhibited tumor autophagy, which synergized with aPD-L1 to promote the tumor-infiltrating CTLs and DCs maturation, to elevate intratumoral TNF-α and IFN-γ levels, and to elicit an anti-tumor immune memory effect in mice for PCa growth inhibition with low side effects. This study verified the synergistic anti-PCa treatment between autophagy inhibition and PD-L1 blockade and meantime broadened the application of pH-sensitive macromolecular nanodrug. STATEMENT OF SIGNIFICANCE: A macromolecular nanodrug, comprising the PDPA core and the surface conjugation of both aPD-L1 antibodies and long-chain PEG coating via a tumor acidity-labile α-carboxy-dimethylmaleic anhydride amine bond, was developed. Tumoral acidity triggered the release of aPD-L1 for immunotherapy. Meantime, the charge switch of the remanent nanodrug enhanced the cancer cell uptake of PDPA, which disturbed the lysosomes to inhibit autophagy. This advanced nanodrug promoted the tumor-infiltrating CTLs and DCs maturation, elevated the intratumoral TNF-α and IFN-γ levels, and elicited the robust anti-tumor immune memory effect. This study demonstrated that the pH-sensitive PDPA macromolecule could serve as a carrier for the aPD-L1 delivery and as an efficient autophagy inhibitor to boost the immunotherapy of prostate cancer.

Modulated integrin signaling receptors of stem cells via ultra-soft hydrogel for promoting angiogenesis

Integrin is a widely distributed adhesion molecule on cell membrane surface, which plays a role in transferring mechanical properties signals of the extracellular matrix into cells during cell adhesion to the extracellular matrix. In this study, by introducing long-chain polyethylene glycol molecules that can be photo-crosslinked into gelatin chains, ultra-soft hydrogel that can simulate soft tissue in vivo is constructed and stimulated by "low matrix stiffness" of the integrin signaling pathway, to promote the vascularization function of stem cells. The storage modulus of the ultra-soft hydrogel at room temperature is as low as 3.24 ± 0.18 Pa and as high as 40.83 ± 1.32 Pa. In vitro experiments showed that the stiffness of hydrogel affects the activation of the phosphorylation of VEGFR by regulating the phosphorylation of integrin and further controls the activation of the ERK pathway, thus regulating the vascularization of ADSCs. In vivo experiments have proved that ADSCs encapsulated in PEG-Gel have excellent performance in repairing skin flaps. The ultra-soft hydrogel can promote the vascularization of ADSCs by activating the "extracellular matrix stiffness-integrin-VEGFR-ERK" regulatory pathway, which is a potential regenerative repair material for promoting the application of stem cells in skin flap repair.

Adjusting the local solvation structures and hydrogen bonding networks for stable aqueous batteries with reduced cost

Exploring low-cost and effective approaches to extend the potentials of aqueous electrolytes is highly desired. Herein, it is found that the activity of H2O in aqueous electrolytes could be intensively manipulated by introducing small urea and long-chain polyethylene glycol (PEG) molecules into LiTFSI-H2O electrolyte systems without super salt concentration. The urea and PEG molecules could exclude partial coordinated H2O out of the inner solvation shell of Li+ and reconstruct hydrogen-bonding network between H2O and PEG molecules outside the solvation sheaths with restricted H2O activity and extended electrochemical window. The bonding competitions in aqueous electrolytes and their correlation to the electrochemical performance of full cells are studied. When the occurrence probability of H2O around Li+ is lower than 40%, stable cycling of 3.1 V LiMn2O4−Li4Ti5O12 full cell is achieved, showing 73% capacity retention after 200 cycles at 1 C rate in optimal electrolytes. This work provides new avenues to understand the role of H2O and explore low-cost and effective approaches for the development of next-generation aqueous lithium-ion batteries.

Intelligent self-assembly prodrug micelles loading doxorubicin in response to tumor microenvironment for targeted tumors therapy

Compared with physical drug-loaded nanocarriers, polymeric prodrug micelles have many advantages such as high drug loading and enhanced stability in blood, so they have great potential in cancer therapy. However, these micelles have a big disadvantage, which cannot achieve long-term circulation in vivo and high absorption of tumor cells simultaneously, resulting in low administration efficiency and poor therapeutic effect on cancer. To solve problems of traditional polymeric prodrug micelles, novel polymeric micelles with tumor microenvironment response were designed in this work. The prodrug formed by covalently linking D-α-tocopherol polyethylene glycol succinate (TPGS 3350 ), peptide (Pep), and doxorubicin (DOX) (TPGS 3350 -Pep-DOX) was self-assembled into micelles by encapsulating DOX physically. When the micelles entered the tumor tissue, the long-chain polyethylene glycol (PEG) was sensitively cut by the matrix metalloproteinase 2/9 (MMP2/9) enzyme, exposing the targeting molecule folate, then it entered the cell through the endocytic pathway mediated by the folate receptor. The drug loading content, encapsulation efficiency, critical micelle concentration, and invitro release of the micelles invented in this study were measured to characterize their properties. The particle size and zeta potential of micelles were characterized by dynamic light scattering. Images were scanned by transmission electron microscopes. In vitro cytotoxicity, cellular uptake, and in vivo antitumor effect evaluation experiments were measured to show that smart micelles have made much progress in material chemistry and drug delivery, making it possible to apply a stimulus–response carrier drug delivery system in clinical application.

Switching ON of Transcription-Translation System Using GUV Fusion by Co-supplementation of Calcium with Long-Chain Polyethylene Glycol.

Giant unilamellar vesicles (GUVs) have been used as a material for bottom-up synthetic biology. However, due to the semi-permeability of the membrane, the need for methods to fuse GUVs has increased. To this aim, methods that are simple and show low leakage during fusion are important. In this study, we report a method of GUV fusion by a divalent cation (Ca2+ ) enhanced with a long chain polyethylene glycol (PEG20k). The methods showed significant GUV fusion without leakage of internal components of GUVs and maintained cell-free transcription-translation ability inside the GUVs without external supplementation of macromolecules. We demonstrate that the Ca-PEG method can be applied for switching ON of transcription-translation in GUVs in a fusion-dependent manner. The method developed here can be applied to extend bottom-up synthetic biology and molecular robotics that use GUVs as a chassis.

Effect of Zwitterionic Surfactant Ligand Monolayer on Magnetic Hyperthermia Properties of Monosize Fe3O4 Nanoparticles

Here Brown relaxation time was altered to enhance magnetic hyperthermia value. Narrow size distributed, hydrophobic Fe3O4 nanoparticles were synthesized by solvothermal reflux method. It is reported that the existing both single step and two-step ligand exchange protocols could not replace hydrophobic surfactant ligand completely. Hence, as-synthesized samples were transferred into hydrophilic by completely removing the hydrophobic surfactant on the nanoparticles by high polar ionic liquids and ligated short-chain bidentate zwitterionic dopamine sulfonate on nanoparticles surface. The short molecules will fast up the Brown relaxation time compared to long molecule surfactant such as polyethylene glycol (PEG). The resultant sample shows magnetic hyperthermia value of 558 Js− 1g− 1 of Fe content at 316 kHz and 35.33 kA/m, at 2 mg/mL. The obtained hyperthermia is very high compared to long-chain PEG ligated Fe3O4 nanoparticles. It is attributed to relaxation time difference of long-chain PEG ligated Fe3O4 and short molecule zwitterion surfactant stabilized Fe3O4. Present hyperthermia results are the first report on zwitterionic dopamine sulfonate anchored Fe3O4 superparamagnetic nanoparticles.

Preparation of a versatile polyethylene glycol-bonded stationary phase based on silica monolith particles and its application in multi-modal separation in high performance liquid chromatography

Silica monolith particles with sizes of 2-5 μm and pore sizes of 20-60 nm were obtained by grinding, flotation, pseudomorphic transformation, and hydrothermal treatment of the silica monolith prepared by the sol-gel method. The pseudomorphic transformation was performed with a dual micellar templating system consisting of Capstone FS-66, a partially fluorinated anion surfactant, and cetyltrimethylammonium bromide (CTAB), a commonly used cation surfactant. Hydrothermal treatment with a sodium carbonate solution was adopted to further expand the pore size. Scanning electron microscopy (SEM) images and N2 adsorption-desorption isotherm measurement results of the silica monolith particles before and after the treatments clearly demonstrated the changes in morphology caused by these treatments. Afterward, a long-chain polyethylene glycol (PEG) containing silane was bonded on the surface of the as-prepared particles, and the resulting products were characterized by elemental analysis and FT-IR spectroscopy analysis, and evaluated by high performance liquid chromatography (HPLC). Elemental analysis and thermogravimetric analysis (TGA) of the bonded stationary phase revealed that the bonding amount of PEG on the silica surface is about 8%. It has been shown that silica monolith particles can be treated and modified for the separation of proteins in size exclusion chromatography mode. It is also demonstrated that the bonded stationary phase can be used for the separation of ribonuclease A and lysozyme in hydrophobic interaction chromatography mode, and for the separation of highly polar compounds (picolinic acid, levodopa, melamine, and catechol) in hydrophilic interaction chromatography mode. The results indicate the versatility of the PEG-bonded stationary phase and its promising application to multi-modal separation in HPLC.

Liberating Native Mass Spectrometry from Dependence on Volatile Salt Buffers by Use of Gábor Transform.

Volatile salts, such as ammonium acetate, are commonly used in buffers for the analysis of intact proteins and protein complexes in native electrospray ionization mass spectrometry. Although these solutions are not technically buffers near pH 7, the volatile nature of the salt minimizes ion adduction to proteins upon transfer to vacuum. Conversely, common biochemical salt buffers, such as Tris/NaCl, are not traditionally used in native mass spectrometry because of the tendency of sodium and other ions to adduct to proteins or form large cluster ions, severely frustrating accurate mass assignment. Here, we demonstrate a Gábor transform method for extracting signal from native-like protein ions even in the presence of a large salt-cluster background. We further show the utility of this method in characterizing polymers and show that the measured average mass of long-chain polyethylene glycol ions from a commercial polymer sample is ∼30 % higher than the manufacturer-estimated average mass. It is expected that this method will enable more widespread use of conventional biochemical buffers in native mass spectrometry and decrease dependence on volatile salts.

Dopamine-induced functionalization of cellulose nanocrystals with polyethylene glycol towards poly(L-lactic acid) bionanocomposites for green packaging

Improving the physical properties of biobased polymers using bionanofillers is essential to preserve its biodegradability. This work presents a dopamine-induced functionalization of cellulose nanocrystals (CNCs) with polyethylene glycol (PEG), to enhance the crystallization, mechanical and barrier properties of poly(L-lactic acid) (PLLA) bionanocomposites. The effect of molecular weight of grafted PEG on the properties of PLLA is also studied. PEGylation of CNCs significantly enhance the crystallization of PLLA, especially for CNCs functionalized with PEG of lower molecular weight, which lead to balanced strength and ductility, and 66.4% reduction in the oxygen permeability coefficient at a low content of 0.5 wt %. Moreover, 168% improvement of ductility for PLLA can be obtained by CNCs functionalized with longer PEG chains. The surface functionalization of CNCs proposed here opens up a green avenue towards designing and fabricating fully bio-based, high-barrier and low-cost polymer nanocomposites for packaging applications.

Introduction of Laser Interference Lithography to Make Nanopatterned Surfaces for Fundamental Studies on Stem Cell Response.

The extracellular matrix (ECM) is a nanostructured environment that provides chemical, mechanical, and topographical stimuli for various cellular functions. Here, we introduce the application of laser interference lithography (LIL) to generate hexagonally arranged gold nanostructures of three different dimensions on silicon to study the effect of feature dimensions on human adipose-derived stem cells (hADSC) in terms of adhesion, growth, and differentiation. Self-assembled monolayers (SAM) were used to passivate the background silicon surface with a long-chain polyethylene glycol (PEG), whereas the gold nanostructures were activated with mercaptoundecanoic acid (MUDA) to direct protein adsorption and cell adhesive structures to them, only. It was possible to show that the size and distance of the nanostructures affected the spreading of hADSC with a decrease of cell size with the increase of feature dimensions, which corresponded also to the expression of focal adhesions and presence of the small GTPase RhoA. Effects of these early events, related to outside-in signal transduction, were visible by an enhanced cell growth on smaller feature dimensions and distinct effects on cell differentiation. Because of the precise control of chemical and topographical cues, the presented system offers great potential to study effects of material topography on stem cell behavior, which may pave the way for applications in tailoring surfaces of implants and tissue engineering scaffolds.

Antibacterial Property of a Polyethylene Glycol-Grafted Dental Material.

Dental materials often cause bacterial adhesion and promote bacterial biofilm formation, which brings a series of long-standing and significant problems in oral health. However, the current development of antibacterial research in dental devices is limited by the lack of materials endowed with good antibacterial properties against oral bacteria. Here, we present a new strategy for reducing the initial adhesion of bacterial on dental biomaterials by chemically bonding long-chain polyethylene glycol. Our work represents an important step toward solving the problem of bacterial accumulation on dental devices.

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

There are successful protocols for dispersing carbon nanotubes and graphene oxide in physiological media by using biocompatible polymers, which enable their use in nanomedicine. However, there is not a clear understanding regarding the mechanisms of the colloidal stabilization manifested (i.e., electric, steric, electrosteric, or through depletion forces). Here we show that the manifestation of a particular mechanism of stabilization for oxidized carbon nanotubes (CNTs) and graphene oxide (GO) in the presence of Pluronic F-127 (PF127) and short- and long-chain polyethylene glycol (PEG 1500 or 35000, respectively) depends on a proper matching between the nanocarbon morphology and the polymer chain length, chemical structure, and concentration. The high aspect ratio one-dimensional morphology of CNTs enables an initial steric and electrosteric stabilization through the nanotube wrapping (i.e., adsorption) by PF127 present in low concentrations (<0.1%). Depletion stabilization for CNTs manifests when PF127 is present in high concentrations (≥1.0%), thus enabling the formation of highly stable CNT colloids even in a 0.9% NaCl saline solution. This depletion stabilization depends little on the CNT structure (i.e., single-walled or multiwalled), surface charge (i.e., ζ potential), oxidation and carboxylation degrees, or nanotube length. On the other hand, large-sized sheets of GO could be colloidally stabilized in 0.9% NaCl only in the presence of PEG 35000 through repulsive depletion forces, whose manifestation occurs with a polymer concentration threshold of 5.0 wt %. Comparatively, in a physiological saline solution, PF127 is able to colloidally stabilize CNTs to a much larger extent than PEG 35000 stabilizes the large GO sheets.

Polyethylene-glycol-Stabilized Ag Nanoparticles for Surface-Enhanced Raman Scattering Spectroscopy: Ag Surface Accessibility Studied Using Metalation of Free-Base Porphyrins

Silver nanoparticles (Ag NPs) stabilized with a permeable layer of long-chain polyethylene glycol (PEG) represent a new generation of surface-enhanced Raman scattering (SERS) substrates for bioanalytical applications. This paper will shed light on their efficiency in the SERS detection of biomolecules. Two types of thiol-terminated PEG (average molecular weight 5000 g/mol) were used. Metalation of free-base porphyrins (10–9–10–6 M) of different size and charge was employed as the probe of accessibility of the Ag-PEG NP surface. The influence of NaCl (0.01 M) on the system was examined. The metalation was significantly decreased by the interaction of porphyrins with propionylamino groups of PEG1, while no interaction with the neutral chain of PEG2 was observed. Sterical hindrance of the porphyrin side groups seemed to cause a rather perpendicular porphyrin orientation on both types of Ag-PEG NP surfaces, inhibiting the metalation. Moreover, chloride anions influenced the structure of the polymer coating and improved the porphyrin accessibility on the Ag-PEG1 NPs. Finally, the studied Ag-PEG NPs remained isolated even after addition of porphyrins and chlorides, therefore being favorable for SERS applications inside the living cells.

Research Highlights

Research Highlights

Oligo- and polyethylene glycols in water-in-oil microemulsions. A SANS study

The influence of oligo- and polyethylene glycols (PEG) on ionic aerosol-OT water-in-oil (w/o) microemulsions has been investigated by small-angle neutron scattering (SANS). The scattering curves can be described with a model of polydisperse spheres, using an Ornstein–Zernicke structure factor, regardless of the PEG relative molecular mass. The results obtained at a constant temperature difference from the percolation point indicate that the droplet structure is maintained, the core radius is decreased and the polydispersity is increased with increasing PEG chain length. There is good evidence that long-chain PEGs induce aggregation of these droplets. The results support the model of polymer adsorption, which was deduced from the influence of PEGs on the percolation behaviour.

ChemInform Abstract: Properties of Solid Supports

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Synthesis and characterization of high-molecular mass polyethylene glycol-conjugated oligonucleotides.

The use of synthetic oligonucleotides as possible drugs for human therapy is usually hampered by their low in vivo stability and capacity to achieve high concentrations at their cellular targets. To overcome this, it has been suggested that they be modified chemically. Among the various options, conjugation with short- and long-chain polyethylene glycols (PEGs) has several advantages: PEG is nontoxic and very soluble, reduces immunogenic reactions, and increases the stability of the conjugated molecules. PEG is generally joined to oligonucleotides while bound to the insoluble solid-phase supports, after their synthesis, which does not allow for their being easy scaled up. The use of the liquid-phase approach as an alternative synthetic process, utilizing the PEG polymer both as a soluble, inert synthetic support and a stabilizing agent of the oligonucleotide, is proposed. A new protocol has been set up, characterized by a stable phosphate bond between the support and the oligonucleotide. This method has been tested on a 12mer previously investigated as an antisense agent against HIV. The PEG-conjugated 12mer was efficiently synthesized and purified. It was found that the high-molecular mass PEG chain results in enzymatic stability and does not interfere with the formation of the duplex with its nucleic acid target.

6] Properties of solid supports

Many supports including composite materials and functionalized surfaces are available for solid-phase synthesis. In the process of selecting the proper support it is important to consider the optimal performance during solid-phase synthesis. For most purposes the mechanically stable beaded gel resins are preferred. These resins are homogeneous, and the loading and physical and chemical properties can easily be varied. Optimal properties have been obtained by radical polymerization of end group acryloylated long-chain polyethylene glycols. However, polystyrene resins or amide bond free PEG-based resins may be more suited for general organic synthesis where reactivity of radicals, carbenes, carbanions, carbenium ions, or strong Lewis acids have to be considered. Loading of the resins can have a dramatic effect on the outcome of a synthesis and has to be considered separately for each synthesis. Synthesis of long peptides with 50-100 amino acids imposes completely different requirements on the performance, swelling, and loading than a large-scale synthesis of, for example, the pentapeptide enkephalin. Automated multiple synthesizers constructed for columns of beaded gel or composite supports are available from many suppliers. It is therefore expected that the optimization of support properties will continue in order to meet new synthetic challenges. In the synthesis for solid-phase screening of binding of biomolecules to ligands directly on the resin beads, it is an advantage if the resin is not permeable to the biomolecule so unbound molecules can easily be removed by washing. This is the case with polystyrene-based resins, but they do, however, often show nonspecific adhesion of proteins owing to the hydrophobic character of the polystyrene. Modification of the functional groups of polystyrene with polyethylene glycol as spacers for synthesis of the binding ligands can increase the available ligand concentration on the bead surface and eliminate most of the nonspecific adhesion. In contrast to binding studies, solid-phase assays of enzymes require beads that are permeable to the enzyme, as the progress of reaction can be followed and the product of reaction analyzed. The available amount on the surface of the polystyrene-based beads (approximately 0.3%) is not enough for product analysis. Therefore, in the case of enzyme assays, highly swelling permeable PEG-based gel resins or functionalized surfaces of a polar and porous matrix are preferred.