Polyethylene Glycol Molecular Weight Research Articles

Factors Affecting the Partitioning of Peroxidase from Aqueous Two-Phase Extraction

Peroxidase is an enzyme that catalyzes the oxidation of various substances by utilizing hydrogen peroxide as an electron acceptor. It plays a significant role in multiple aspects, including laboratory analysis and immunoassays. Peroxidase is found abundantly in plant. Therefore, the purpose of this research is to study the factors affecting the partitioning of peroxidase using aqueous two-phase extraction (ATPE) consisting of polyethylene glycol (PEG) and inorganic salts. Cabbage was chosen as a source of peroxidase enzyme. The results showed that changes in the type of salt used to build the system (ammonium sulfate ((NH4)2SO4), sodium sulfate (Na2SO4), dipotassium hydrogen phosphate (K2HPO4) and disodium hydrogen phosphate (Na2HPO4), molecular weight of polyethylene glycol (PEG 1500 and 6000), polyethylene glycol concentration (19–31 %w/v), salt concentration (10–22 %w/v), system pH (4–8), and the effect of sodium chloride ( 0–5%w/v) affected the partition coefficient of the enzyme (KE), the partition coefficient of the protein (KP), volume fraction of phase (Vr), the percent yield (%Yield) and the purification factor (PF). The optimum condition for peroxidase extraction obtained in this study was using ammonium sulfate salt at a concentration of 16%w/v, polyethylene glycol molecular weight 1500 at a concentration of 25%w/v, the pH of the system was 6 and no sodium chloride was added. The partition coefficient of the enzyme was 15.75 ± 4.07, the percent yield was 97.06 ± 0.71, and the purification factor was 4.86 ± 0.70 times.

One Step In Situ Co-Crystallization of Dapsone and Polyethylene Glycols during Fluidized Bed Granulation.

Several studies have demonstrated the feasibility of in situ co-crystallization in different pharmaceutical processes such as spray drying, hot melt extrusion, and fluidized bed granulation (FBG) to produce co-crystal-in-excipient formulations. However, no previous studies have examined such a one step in situ co-crystallization process for co-crystal formulations where the coformer is a polymer. In the current study, we explored the use of FBG to produce co-crystal granules of dapsone (DAP) and different molecular weight polyethylene glycols (PEGs). Solvent evaporation (SE) was proven to generate DAP-PEGs co-crystals at a particular weight ratio of 55:45 w/w between DAP and PEG, which was subsequently used in FBG, using microcrystalline cellulose and hydroxypropyl methyl cellulose as filler excipient and binder, respectively. FBG could generate co-crystals with higher purity than SE. Granules containing DAP-PEG 400 co-crystal could be prepared without any additional binder. DAP-PEG co-crystal granules produced by FBG demonstrated superior pharmaceutical properties, including flow properties and tableting properties, compared to DAP and DAP-PEG co-crystals prepared by SE. Overall, in situ co-crystallization via FBG can effectively produce API-polymer co-crystals and enhance the pharmaceutical properties.

Spatial mapping and quantitative evaluation of protein corona on PEGylated mesoporous silica particles by super-resolution fluorescence microscopy

Nanoparticles (NPs) adsorb serum proteins when exposed to biological fluids, forming a dynamic protein corona that has a profound impact on their overall biological profile and fate. Polyethylene glycol (PEG) modification is the most widely used strategy to mitigate and inhibit protein corona formation. Nevertheless, the accurate mapping and quantification of PEG inhibition effects on protein corona formation have scarcely been reported. Herein, we demonstrate the direct observation and quantification of protein corona adsorbed onto PEGylated mesoporous silica particles by direct stochastic optical reconstruction microscopy (dSTORM). The variation tendency of protein penetration depth in terms of PEG molecular weights and incubated time is investigated for the first time. The maximum penetration depths present slight increase with the prolonged incubation time, while they tend to remarkably decrease with increased chain length of modified PEG. Moreover, the co-localization of preformed protein corona with lysosomes and the destination of adsorbed protein are demonstrated. Our method provides important technical characterization information and in-depth understanding of protein corona adsorbed onto PEGylated mesoporous silica particles. This shines new light on the behaviors of silica materials in cells and may promote their practical applications in biomedicine.

Chain entanglement-driven tough, fatigue-resistant PEG-based injectable hydrogel adhesive for joint skin wound healing

The development of effective wound dressings that can withstand the frequent movement and stretching of joint skin wounds remains a significant challenge. Traditional wound dressings are prone to damage or shedding, which increases the risk of bacterial infection and delays wound healing. To address this issue, a new type of injectable, stretchable, low hysteresis, and fatigue-resistant hydrogel (LZM/PEG) adhesive has been designed for wound healing in movable parts. The hydrogel is formed through the flexible chain entanglement of high molecular weight polyethylene glycol functionalized by Succinimide Carbonate (SC-PEG-SC) and Amidation crosslinking between LZM-NH2 and SC-PEG-SC. The long-chain of SC-PEG-SC enables the hydrogel to penetrate the surface of the target tissue, generating physical entanglements and covalent bonds with functional groups in the matrix, enabling close fitting of joint skin and wound healing without the need of secondary fixation. In a neck trauma model of full-thickness skin defect in vivo, the hydrogel dressing significantly promoted wound healing with milder inflammation, higher granulation tissue thickness and collagen disposition, demonstrating its potential for joint skin wound treatment in clinics. Overall, the LZM/PEG hydrogel is capable of adapting to the frequent movement of joint, promoting healing of joint skin wounds, which makes it a promising approach for joint skin wound treatment.

Preparation of polyethylene glycol/polyacrylamide interpenetrating network hydrogel for simultaneously enhancing the fire protection and aging resistance of fireproof glass

AbstractTo enhance the flame retardancy and aging resistance of grouting fireproof glass, different molecular weights of polyethylene glycol (PEG) were mixed with acrylamide (AM) to construct interpenetrating network hydrogels, then the obtained hydrogels were mixed with flame retardants to prepare a series of transparent flame‐retarded hydrogels applied in the fireproof glass. The effects of PAM/PEG hydrogel with varying PEG molecular weight on the optical transparency, heat insulation and aging resistance of fireproof glass were investigated. Optical transparency analysis shows that the light transmittance of grouting fireproof glass decreases with the increase of PEG molecular weight in the PAM/PEG interpenetrating network. Fire tests show that PAM/PEG hydrogel significantly enhances the heat insulation and aging resistance of the grouting fireproof glass compared to the single PAM network hydrogel. The flame‐retarded and anti‐aging effects of PAM/PEG hydrogel in the fireproof glass varies with the PEG molecular weight, and the order is PAM/PEG2000 > PAM/PEG1500 > PAM/PEG1000 > PAM/PEG800. Accelerated aging test shows that PAM/PEG interpenetrating network hydrogel is less affected by aging conditions and exerts durable heat insulation and transmittance. Especially, the backside temperature of 3600 s and transmittance of PAM/PEG2000 system after 264 h aging test only changed 38.3°C and 1.3%, respectively, compared to the unaged PAM/PEG2000 system.

Pegloticase co-administered with high MW polyethylene glycol effectively reduces PEG-immunogenicity and restores prolonged circulation in mouse

The interactions between polymers and the immune system remains poorly controlled. In some instances, the immune system can produce antibodies specific to polymer constituents. Indeed, roughly half of pegloticase patients without immunomodulation develop high titers of anti-PEG antibodies (APA) to the PEG polymers on pegloticase, which then quickly clear the drug from circulation and render the gout treatment ineffective. Here, using pegloticase as a model drug, we show that addition of high molecular weight (MW) free (unconjugated) PEG to pegloticase allows us to control the immunogenicity and mitigates APA induction in mice. Compared to pegloticase mixed with saline, mice repeatedly dosed with pegloticase containing different MW or amount of free PEG possessed 4- to 12- fold lower anti-PEG IgG, and 6- to 10- fold lower anti-PEG IgM, after 3 rounds of pegloticase dosed every 2 weeks. The markedly reduced APA levels, together with competitive inhibition by free PEG, restored the prolonged circulation of pegloticase to levels observed in APA-naïve animals. In contrast, mice with pegloticase-induced APA eliminated nearly all pegloticase from the circulation within just four hours post-injection. These results support the growing literature demonstrating free PEG may effectively suppress drug-induced APA, which in turn may offer sustained therapeutic benefits without requiring broad immunomodulation. We also showed free PEG effectively blocked the PEGylated protein from binding with cells expressing PEG-specific B cell receptors. It provides a template of how we may be able to tune the interactions and immunogenicity of other polymer-modified therapeutics. Statement of significanceA major challenge with engineering materials for drug delivery is their interactions with the immune system. For instance, our body can produce high levels of anti-PEG antibodies (APA). Unfortunately, the field currently lack tools to limit immunostimulation or overcome pre-existing anti-PEG antibodies, without using broad immunosuppression. Here, we showed that simply introducing free PEG into a clinical formulation of PEG-uricase can effectively limit induction of anti-PEG antibodies, and restore their prolonged circulation upon repeated dosing. Our work offers a readily translatable method to safely and effectively restore the use PEG-drugs in patients with PEG-immunity, and provides a template to use unconjugated polymers with low immunogenicity to regulate interactions with the immune system for other polymer-modified therapeutics.

Characterization of a chlorine resistant and hydrophilic TiO2/calcium alginate hydrogel filtration membrane used for protein purification maintaining protein structure

The development of membranes for protein purification has stringent requirement of disinfection resistance, low protein adsorption and anti-fouling, without changing protein structure. In this study, hydrophilic titanium dioxide (TiO2)/calcium alginate (TiO2/CaAlg) hydrogel membranes were prepared by a simple ionic cross-linking method. The effects of the porogenic agent polyethylene glycol (PEG) concentration, the molecular weight of PEG, and the concentration of TiO2 on the filtration properties were systematically investigated. The TiO2/CaAlg membrane exhibited excellent bovine serum albumin (BSA) rejection and anti-fouling properties. The mechanical properties and surface energy of the TiO2/CaAlg membrane were significantly improved. The chemical bonding mechanism of TiO2 and NaAlg was investigated by molecular dynamic simulation. The TiO2/CaAlg membrane had good chlorine resistance and could be disinfected or cleaned with sodium hypochlorite. The TiO2/CaAlg hydrogel membrane loaded with polyhydroxybutyrate (PHB) nanofibers maintained high flux (136.7 L/m2h) and high BSA rejection (98.0 %) at 0.1 MPa. The results of circular dichroism and synchronous fluorescence indicated that the secondary structure of BSA was maintained after membrane separation. This study provides one method for the preparation of green and environmentally friendly membrane for protein purification.

Improved bleached eucalyptus kraft pulp-based tissue papers incorporating wet-strength resins

Abstract Common tissue paper manufacturing trends aim at partial or total replacement of softwood pulp with hardwood pulp for its production, such as bleached eucalyptus kraft pulp (BEKP), in order to optimize the process and the final product properties such as softness. However, the use of a single type of hardwood fiber results in lower strengths of both wet and dry webs. To maintain necessary strength and desired properties, the incorporation of several additives is often required. In this context, low molecular weight polyethylene glycol (PEG) and different wet strength resins, such as polyamideamine-epichlorohydrin (PAE) and glyoxalated polyacrylamide (GPAM) resins, were combined to achieve an innovated product with improved properties. In particular, wet and dry tensile strength was significantly improved when combining PEG and wet strength resins, especially observed in tissue papers prepared with PAE resin, high-charge cationic agent and bulk applied aqueous PEG solution. Noteworthy that water absorption capacity and softness of tissue paper were not critically affected by PEG incorporation, regardless of application method used (in bulk or by spray).

Optical Polymorphism of Liquid-Crystalline Dispersions of DNA at High Concentrations of Crowding Polymer.

Optically active liquid-crystalline dispersions (LCD) of nucleic acids, obtained by polymer- and salt-induced (psi-) condensation, e.g., by mixing of aqueous saline solutions of low molecular weight DNA (≤106 Da) and polyethylene glycol (PEG), possess an outstanding circular dichroism (CD) signal (so-called psi-CD) and are of interest for sensor applications. Typically, such CD signals are observed in PEG content from ≈12.5% to ≈22%. However, in the literature, there are very conflicting data on the existence of psi-CD in DNA LCDs at a higher content of crowding polymer up to 30-40%. In the present work, we demonstrate that, in the range of PEG content in the system above ≈24%, optically polymorphic LCDs can be formed, characterized by both negative and positive psi-CD signals, as well as by ones rather slightly differing from the spectrum of isotropic DNA solution. Such a change in the CD signal is determined by the concentration of the stock solution of PEG used for the preparation of LCDs. We assume that various saturation of polymer chains with water molecules may affect the amount of active water, which in turn leads to a change in the hydration of DNA molecules and their transition from B-form to Z-form.

Continuous Monitoring of the Hydration Behavior of Hydrophilic Matrix Tablets Using Time-Domain NMR.

Time-domain NMR (TD-NMR) was used for continuous monitoring of the hydration behavior of hydrophilic matrix tablets. The model matrix tablets comprised high molecular weight polyethylene oxide (PEO), hydroxypropyl methylcellulose (HPMC), and polyethylene glycol (PEG). The model tablets were immersed in water. Their T2 relaxation curves were acquired by TD-NMR with solid-echo sequence. A curve-fitting analysis was conducted on the acquired T2 relaxation curves to identify the NMR signals corresponding to the nongelated core remaining in the samples. The amount of nongelated core was estimated from the NMR signal intensity. The estimated values were consistent with the experiment measurement values. Next, the model tablets immersed in water were monitored continuously using TD-NMR. The difference in hydration behaviors of the HPMC and PEO matrix tablets was then characterized fully. The nongelated core of the HPMC matrix tablets disappeared more slowly than that of the PEO matrix tablets. The behavior of HPMC was significantly affected by the PEG content in the tablets. It is suggested that the TD-NMR method has potential to be utilized to evaluate the gel layer properties, upon replacement of the immersion medium: purified (nondeuterated) water is replaced with heavy (deuterated) water. Finally, drug-containing matrix tablets were tested. Diltiazem hydrochloride (a highly water-soluble drug) was employed for this experiment. Reasonable in vitro drug dissolution profiles, which were in accordance with the results from TD-NMR experiments, were observed. We concluded that TD-NMR is a powerful tool to evaluate the hydration properties of hydrophilic matrix tablets.

Linear and multivalent PEGylation of the tobacco mosaic virus and the effects on its biological properties

Plant virus-based nanoparticles (VNPs) offer a bioinspired approach to the delivery of drugs and imaging agents. The chemical addressability, biocompatibility, and scalable manufacturability of VNPs make them a promising alternative to synthetic delivery platforms. However, VNPs, just like other proteinaceous or synthetic nanoparticles (NPs), are readily recognized and cleared by the immune system and mechanisms such as opsonization and phagocytosis. Shielding strategies, such as PEGylation, are commonly used to mitigate premature NP clearance. Here, we investigated polyethylene glycol (PEG) coatings on the tobacco mosaic virus (TMV), which was used as a model nanocarrier system. Specifically, we evaluated the effects of linear and multivalent PEG coatings at varying chain lengths on serum protein adsorption, antibody recognition, and macrophage uptake. Linear and multivalent PEGs of molecular weights 2,000 and 5,000 Da were successfully grafted onto the TMV at ≈ 20%–60% conjugation efficiencies, and the degree of cross-linking as a function of PEG valency and length was determined. PEGylation resulted in the modulation of TMV–macrophage interactions and reduced corona formation as well as antibody recognition. Linear and multivalent PEG 5,000 formulations (but not PEG 2,000 formulations) reduced α-TMV antibody recognition, whereas shorter, multivalent PEG coatings significantly reduced α-PEG recognition—this highlights an interesting interplay between the NP and the PEG itself in potential antigenicity and should be an important consideration in PEGylation strategies. This work provides insight into the PEGylation of VNPs, which may improve the possibility of their implementation in clinical applications.

Purification and concentration of infectious koi herpesvirus using steric exclusion chromatography.

Koi herpesvirus (KHV) is the causative agent of a koi herpesvirus disease (KHVD) inducing high mortality rates in common carp and koi (Cyprinus carpio). No widespread effective vaccination strategy has been implemented yet, which is partly due to side effects of the immunized fish. In this study, we present an evaluation of the purification of infectious KHV from host cell protein and DNA, using the steric exclusion chromatography. The method is related to conventional polyethylene glycol (PEG) precipitation implemented in a chromatographic set-up and has been applied for infectious virus particle purification with high recoveries and impurity removal. Here, we achieved a yield of up to 55% of infectious KHV by using 12% PEG (molecular weight of 6 kDa) at pH 7.0. The recoveries were higher when using chromatographic cellulose membranes with 3-5 μm pores in diameter instead of 1 μm. The losses were assumed to originate from dense KHV precipitates retained on the membranes. Additionally, the use of >0.6 M NaCl was shown to inactivate infectious KHV. In summary, we propose a first step towards a purification procedure for infectious KHV with a possible implementation in fish vaccine manufacturing.

Polyethylene glycol-modified mesoporous zerovalent iron nanoparticle as potential catalyst for improved reductive degradation of Congo red from wastewater

In this study, bare zero-valent iron nanoparticles (nZVI) have been modified using polyethylene glycol (PEG) of various molecular weight in a facile technique. The synthesized nZVI modified with PEG, M.W. of 600 and 6000 was denoted by nZVI-PEG600 and nZVI-PEG6000, respectively, and compared their catalytic activity towards the reductive degradation of Congo red (CR) using NaBH4.The existence of PEG layer surrounds the nZVI core was confirmed by several characterization tools, such as XRD, FTIR, FESEM and TEM. Herein, both nZVI-PEG600 and nZVI-PEG6000 exhibited remarkable removal efficiencies of 89.6% and 99.2% within 14 min of reaction time. The optimum reaction parameters were found to be as follows: 0.2 g L−1 catalyst dose and initial dye concentration of 2 × 10−5 molL−1 etc. Kinetic studies of dye degradation were investigated which follow pseudo-1st-order kinetics. The TOC analysis confirmed the complete mineralization of CR dye by nZVI-PEG6000 nanocatalyst. GCMS analysis of plausible degraded products was performed to elucidate a probable mechanistic pathway of CR degradation. Further, we have investigated the degradation of two anionic dyes mixture, i.e., CR and methyl orange (MO) using best catalyst, i.e., nZVI-PEG6000.

Effects of molecular weight of polyethylene glycol on the moisture-absorption capacity and morphology of the channeling structure in desiccant composite

Moisture removal inside the packaging of food and pharmaceutical products prevents their deterioration during storage. Therefore, the preparation of desiccants derived from moisture-absorbing materials is important. Herein, desiccant composites with channeling morphologies in the polypropylene (PP) matrix are prepared using polyethylene glycol (PEG) with different molecular weights (Mw) and molecular sieves (MS). The effects of the Mw on the formation, morphology, and stability of the channeling structure are investigated. All composites exhibit microphase separation morphology caused by the channeling structure. Accordingly, the PEG with an Mw of 8000 allows uniform microphase separation in the composite matrix owing to the higher chemical compatibility with MS in the formation of the channeling structure, thus inducing significant moisture absorption. Therefore, these composites can be used to introduce novel desiccant packaging in the food and pharmaceutical industries.

Discrete polyethylene glycol derivatives as a potent impetus for next-generation biomedicines

PEGylation, which covalently modifies small-molecule drugs, peptides and proteins with polyethylene glycol (PEG) to improve their pharmacokinetics and efficacy, has become one of the most widely used drug modification techniques. However, PEG and its derivatives have been verified to be immunogenic and antigenic, which directly lead to side effects such as accelerated blood clearance (ABC) phenomenon and allergic reactions to PEGylated drugs or PEG excipients. Recent development of single molecular weight discrete PEG synthesis methodology have led to continuous and extensive focus on the difference in biological activity between conventional polydisperse PEG and single molecular weight precise PEG. Discrete PEG has demonstrated obvious advantages in resisting protein adsorption, cell adhesion and enhancing drug efficacy. These preliminary results not only confirm the significant impact of PEG chain polydispersity on its biological effect, but also reveal the possibility and potential advantages of using discrete PEG to reduce the immunogenicity and antigenicity. Hopefully, single chemical structure and molecular weight ensure the batch repeatability of newly developed discrete PEG products, and facilitate the understanding of their physicochemical properties and biological effects that promoting the clinical conversion of precise PEG drugs.

Assembly and recognition mechanisms of glycosylated PEGylated polyallylamine phosphate nanoparticles: A fluorescence correlation spectroscopy and small angle X-ray scattering study

HypothesisModification of polyallylamine hydrochloride (PAH) with heterobifunctional low molecular weight polyethylene glycol (PEG) (600 and 1395 Da), and subsequent attachment of mannose, glucose, or lactose sugars to PEG, can lead to formation of polyamine phosphate nanoparticles (PANs) with lectin binding affinity and narrow size distribution. ExperimentsSize, polydispersity, and internal structure of glycosylated PEGylated PANs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). Fluorescence correlation spectroscopy (FCS) was used to study the association of labelled glycol-PEGylated PANs. The number of polymer chains forming the nanoparticles was determined from the changes in amplitude of the cross-correlation function of the polymers after formation of the nanoparticles. SAXS and fluorescence cross-correlation spectroscopy were used to investigate the interaction of PANs with lectins: concanavalin A with mannose modified PANs, and jacalin with lactose modified ones. FindingsGlyco-PEGylated PANs are highly monodispersed, with diameters of a few tens of nanometers and low charge, and a structure corresponding to spheres with Gaussian chains. FCS shows that the PANs are single chain nanoparticles or formed by two polymer chains. Concanavalin A and jacalin show specific interactions for the glyco-PEGylated PANs with higher affinity than bovine serum albumin.

Fluctuations of Dry and Total Mass of Cells Exposed to Different Molecular Weights of Polyethylene Glycol

Polyethylene glycol (PEG) is used in many applications, and in the clinical field, it is one of the main components of the latest Covid vaccines. Its wide use is justified by a relatively safe profile and few known side effects. However, little is known about the biophysical effects of PEG on cells such as, cell stiffness, dry mass, and total mass. Herein, exploiting a digital holographic microscope, an inertial picobalance, and a nanoindenter, these properties are characterized in rat embryonic fibroblast exposed to different molecular weights of PEG. Immediately after the first minutes of PEG exposure to the cells, a reduction in cell dry mass can be observed as well as a rapid fluctuation in total cell weight. Cell stiffness decreases significantly after 48 h, while no important morphological changes are observed. Here, it is revealed how dry mass and total mass are rapidly and finely regulated, highlighting how the maintenance of cell density is of primary importance in cellular activities.

Effect of Molecular Weight on the Dissolution Profiles of PEG Solid Dispersions Containing Ketoprofen

Solid dispersions are typically binary systems with a hydrophilic matrix polymer and a lipophilic active substance. During formulation, the drug undergoes a crystalline to amorphous phase transition, which leads to a supersaturated solution providing enhanced bioavailability. The interaction of the active substance and the polymer is unique and influences the level of supersaturation. We aimed to investigate the relationship between low molecular weight polyethylene glycol derivates PEG 1000, 1500, and 2000 and ketoprofen regarding the effect of molecular weight. The physicochemical properties of solid dispersions prepared with hot melt homogenization and their respective physical mixtures were investigated with Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy techniques. A phase solubility study was carried out in hydrochloric acid media which showed no difference between the three polymers, but the dissolution curves differed considerably. PEG 1000 had higher percentage of released drug than PEG 1500 and 2000, which had similar results. These results indicate that when multiple low molecular weight PEGs are suitable as matrix polymers of solid dispersions, the molecular weight has only limited impact on physicochemical characteristics and interactions and further investigation is needed to select the most applicable candidate.

Water-Soluble Polymer Polyethylene Glycol: Effect on the Bioluminescent Reaction of the Marine Coelenterate Obelia and Coelenteramide-Containing Fluorescent Protein.

The current paper considers the effects of a water-soluble polymer (polyethylene glycol (PEG)) on the bioluminescent reaction of the photoprotein obelin from the marine coelenterate Obelia longissima and the product of this bioluminescent reaction: a coelenteramide-containing fluorescent protein (CCFP). We varied PEG concentrations (0-1.44 mg/mL) and molecular weights (1000, 8000, and 35,000 a.u.). The presence of PEG significantly increased the bioluminescent intensity of obelin but decreased the photoluminescence intensity of CCFP; the effects did not depend on the PEG concentration or the molecular weight. The photoluminescence spectra of CCFP did not change, while the bioluminescence spectra changed in the course of the bioluminescent reaction. The changes can be explained by different rigidity of the media in the polymer solutions affecting the stability of the photoprotein complex and the efficiency of the proton transfer in the bioluminescent reaction. The results predict and explain the change in the luminescence intensity and color of the marine coelenterates in the presence of water-soluble polymers. The CCFP appeared to be a proper tool for the toxicity monitoring of water-soluble polymers (e.g., PEGs).

Low and High Molecular Weight Polyethylene Glycol as A Treating and Coupling Agent in High Density Polyethylene/Date Palm Tree Fiber Composites

nical properties and water absorption (WA) behavior of high density polyethylene/date palm tree fiber (HDPE/DPTF) composites were investigated. Two different parts of the date palm tree (mesh and leaflets) were used. The focus was on studding the combination effect of using both low and/or high molecular weight polyethylene glycol (PEG) as a treatment and coupling agent, respectively on shore D hardness, impact strength and water absorption behavior of the composites. Morphological properties of the prepared composites were also investigated. Results showed that treating the fibers with low molecular weight PEG had a significant effect, which resulted in composites with better shore D hardness and impact strength compared to pure HDPE and composites made with untreated fibers. Furthermore, the use of high molecular weight PEG as a coupling agent resulted in better impact strength and shore D hardness, indicating the presence of a strong interaction between the fibers and the HDPE matrix. Morphological observations of composites made with untreated fibers by scanning electron microscope (SEM) revealed the formation of some fiber aggregation, fiber debonding and fiber pullout in composites made with untreated fibers. Contrary, the composites made with PEG as a treatment and/or coupling agent showed no fiber aggregation or fiber debonding.