Cross-linked Poly Ethylene Glycol Research Articles

Heterometallic [2]Catenane-Crosslinked Supramolecular Networks with Improved Antibacterial Activity.

The construction of supramolecular networks with novel crosslinks is of great significance in expanding their chemical structures and exploring their advanced functions. Herein, we prepare a type of [2]catenane-cored supramolecular networks based on the crosslinking of polyethylene glycol (PEG) using a heterometallic [2]catenane unit. By adjusting the molecular weight of PEG, the solubility of the networks can be tuned and gels are formed using low molecular weight PEG. The introduction of heterometallic [2]catenane offers the networks good antibacterial properties owing to the synergistic antimicrobial activity of Pt(II) and Cu(I) ions in the [2]catenane. This study provides a simple and efficient strategy for constructing supramolecular networks with topological crosslinks as antibacterial materials, which will promote the structural design and biological applications of supramolecular networks.

Enlightenment the dynamic behavior of norbornene–modified ’click’ 4–arm polyethylene glycol hydrogel: Delving into framework properties and transport properties through molecular dynamics simulations

The thiol-norbornene cross-linked 4-arm Polyethylene Glycol (PEG) ’click’ hydrogel is a synthetic, sustainable, and bio-inspired polymer extensively used in biomedical applications. Experimental techniques are widely used to study this system, whereas all-atom molecular dynamics simulations, which offer insight into the dynamic behaviours of the system, are never used to study this system. Three models of thiol-norbornene cross-linked PEG ’click’ hydrogel and a base PEG hydrogel are crafted. It is immersed in water to study its structural and transport properties. Structural properties are analysed through root-mean-square deviation (RMSD), radial distribution function (RDF), hydrogen bonds (H-bond), and stress–strain behavior. The RMSD reveals that the norbornene component enhances hydrogel stability compared to the base model. The RDF illustrates interactions between oxygen in PEG chains and water. H-bond results underscore PEG’s strong H-bond acceptance. The norbornene-functionalized crosslinked PEG hydrogel displays maximum H-bonding. It demonstrates a superior swelling ratio attributed to freezing and non-freezing water effects, indicating high stability and potential suitability for applications. Mean square displacements (MSD) unveil the diffusion coefficients of the hydrogel. The base hydrogel model shows the diffusive behavior, and the diffusion coefficient is 1.97 × 10-10 m2/s. The base model has the highest MSD value compared to other systems. The thiol-norbornene crosslinked click hydrogel has the highest Young’s modulus, which signifies the stiffness of the material. Findings illuminate thiol-norbornene ’click’ PEG hydrogel behaviour, emphasising chemical cross-linking’s crucial role in advanced biomedical applications.

A bioinspired regenerative antimicrobial hydrogel coating for cardiovascular implantable electronic devices

Elderly patients predispose to cardiovascular implantable electronic devices (CIEDs) pocket infections due to multiple comorbidities. Treating infections with the antibiotics further carry higher risks for complications, and surgical intervention can be costly when device removal and reimplantation are required, both emphasizing the importance of novel preventive strategies to minimize the incidence of pocket infections. To meet the unique needs for elderly, we constructed an CIED surface modified hydrogel which crosslinked polyethylene glycol diacrylate (PEGDA) with hyaluronic acid-nitrobenzene (HN) to form the polymeric structures that mimic the natural environment for promoting “Pocket” surrounding tissue integration and healing. Importantly, we synthesized the new peptidomimetics FK-13 derived by shortening amino acid sequence of LL-37 which is the only human cathelicidin-derived antimicrobial peptide. By incorporating FK-13 with initial PN hydrogel via Schiff base formation, the created PN-FK hydrogel exhibited broad-spectrum antimicrobial activityagainst bacteria with excellent biocompatibility and mechanical properties in a long-term release manner. In an in vitro setting, PN-FK hydrogel demonstrated the regeneration capacity by expression of Hmox1, Col5 and Col6 associated genes in fibroblasts as well as expression of Gpx1, Cdc20 and MMP9 genes in stem cells to accelerate self-renewal, collagen secretion and reconstitution of matrix components. In the following in vivo model of subcutaneous implantation, CIED-shape titanium mesh with surface modification by PN-FK hydrogel efficiently subsided over-inflammation compared to bare titanium implant, and expedited collagen deposition and angiogenesis in peri-pocket tissues within 2 weeks. These findings underscore the potential of the PN-FK hydrogel as a transformative approach to CIED postoperative management, offering a dual-action solution that combines infection resistance with tissue regeneration capabilities.

Revolutionizing Knee Osteoarthritis Treatment: Innovative Self-Nano-Emulsifying Polyethylene Glycol Organogel of Curcumin for Effective Topical Delivery.

In the current study, self-nano-emulsifying (SNE) physically cross-linked polyethylene glycol (PEG) organogel (SNE-POG) as an innovative hybrid system was fabricated for topical delivery of water-insoluble and unstable bioactive compound curcumin (CUR). Response surface methodology (RSM) based on Optimal Design was utilized to evaluate the formulation factors. Solid fiber mechanism with homogenization was used to prepare formulations. Pharmaceutical evaluation including rheological and texture analysis, their mathematical correlations besides physical and chemical stability experiments, DSC study, in vitro release, skin permeation behavior, and clinical evaluation were carried out to characterize and optimize the SNE-OGs. PEG 4000 as the main organogelator, Poloxamer 188 (Plx188) and Ethyl Cellulose (EC) as co-gelator/nanoemulsifier agents, and PEG 400 and glycerin as solvent/co-emulsifier agents could generate SNE-POGs in PS range of 356 to 1410 nm that indicated organic base percentage and PEG 4000 were the most detrimental variables. The optimized OG maintained CUR stable in room and accelerated temperatures and could release CUR sustainably up to 72 h achieving high flux of CUR through guinea pig skin. A double-blind clinical trial confirmed that pain scores, stiffness, and difficulty with physical function were remarkably diminished at the end of 8 weeks compared to the placebo (71.68% vs. 7.03%, 62.40% vs. 21.44%, and 45.54% vs. 8.66%, respectively) indicating very high efficiency of system for treating knee osteoarthritis. SNE-POGs show great potential as a new topical drug delivery system for water-insoluble and unstable drugs like CUR that could offer a safe and effective alternative to conventional topical drug delivery system.

Hydrogels based on crosslinked polyethylene glycol diacrylate and fish skin gelatin

The aim of this work was to develop hydrogels based on poly(ethylene glycol diacrylate) (PEGDA) and fish gelatin for potential biomedical applications such as wound healing, drug delivery and biosensors. The hydrogels were prepared via in situ Michael addition of ammonia crosslinker to PEGDA in the presence of cold-water fish skin gelatin that was used as an additive. The fabrication conditions and properties of the hydrogels were examined using various amounts of fish gelatin to evaluate the influence of its concentration on gelation time, crosslinking density and swelling behavior of the hydrogels. FTIR spectra confirmed the formation of the crosslinked hydrogels and the degree of conversion (DC) of the double bonds for the hydrogels containing 5, 7.5 and 10 % w/v of gelatin was between 72 and 80 %. Fish skin gelatin had a strong effect on the dimentional stability and water absorbing properties of the hydrogels and the system containing 7.5 % w/v gelatin exhibited the longest swelling time of 18 h. The hydrophobicity of the hydrogels was achieved by covalent grafting of the residual double bonds with thiol-containing small hydrocarbon molecules using thiol-ene click chemistry reaction conditions, leading to the increase of the water contact angle from 0° to 60-73°.

Enhancing protein dynamics analysis with hydrophilic polyethylene glycol cross-linkers.

Cross-linkers play a critical role in capturing protein dynamics in chemical cross-linking mass spectrometry techniques. Various types of cross-linkers with different backbone features are widely used in the study of proteins. However, it is still not clear how the cross-linkers' backbone affect their own structure and their interactions with proteins. In this study, we systematically characterized and compared methylene backbone and polyethylene glycol (PEG) backbone cross-linkers in terms of capturing protein structure and dynamics. The results indicate the cross-linker with PEG backbone have a better ability to capture the inter-domain dynamics of calmodulin, adenylate kinase, maltodextrin binding protein and dual-specificity protein phosphatase. We further conducted quantum chemical calculations and all-atom molecular dynamics simulations to analyze thermodynamic and kinetic properties of PEG backbone and methylene backbone cross-linkers. Solution nuclear magnetic resonance was employed to validate the interaction interface between proteins and cross-linkers. Our findings suggest that the polarity distribution of PEG backbone enhances the accessibility of the cross-linker to the protein surface, facilitating the capture of sites located in dynamic regions. By comprehensively benchmarking with disuccinimidyl suberate (DSS)/bis-sulfosuccinimidyl-suberate(BS3), bis-succinimidyl-(PEG)2 revealed superior advantages in protein dynamic conformation analysis in vitro and in vivo, enabling the capture of a greater number of cross-linking sites and better modeling of protein dynamics. Furthermore, our study provides valuable guidance for the development and application of PEG backbone cross-linkers.

Poly(ethylene Glycol) Methyl Ether Methacrylate-Based Injectable Hydrogels: Swelling, Rheological, and In Vitro Biocompatibility Properties with ATDC5 Chondrogenic Lineage.

Here, we present the synthesis of a series of chemical homopolymeric and copolymeric injectable hydrogels based on polyethylene glycol methyl ether methacrylate (PEGMEM) alone or with 2-dimethylamino ethyl methacrylate (DMAEM). The objective of this study was to investigate how the modification of hydrogel components influences the swelling, rheological attributes, and in vitro biocompatibility of the hydrogels. The hydrogels' networks were formed via free radical polymerization, as assured by 1H nuclear magnetic resonance spectroscopy (1H NMR). The swelling of the hydrogels directly correlated with the monomer and the catalyst amounts, in addition to the molecular weight of the monomer. Rheological analysis revealed that most of the synthesized hydrogels had viscoelastic and shear-thinning properties. The storage modulus and the viscosity increased by increasing the monomer and the crosslinker fraction but decreased by increasing the catalyst. MTT analysis showed no potential toxicity of the homopolymeric hydrogels, whereas the copolymeric hydrogels were toxic only at high DMEAM concentrations. The crosslinker polyethylene glycol dimethacrylate (PEGDMA) induced inflammation in ATDC5 cells, as detected by the significant increase in nitric oxide synthase type II activity. The results suggest a range of highly tunable homopolymeric and copolymeric hydrogels as candidates for cartilage regeneration.

Surface Passivation Method for the Super-repellence of Aqueous Macromolecular Condensates.

Solutions of macromolecules can undergo liquid-liquid phase separation to form droplets with ultralow surface tension. Droplets with such low surface tension wet and spread over common surfaces such as test tubes and microscope slides, complicating in vitro experiments. The development of a universal super-repellent surface for macromolecular droplets has remained elusive because their ultralow surface tension requires low surface energies. Furthermore, the nonwetting of droplets containing proteins poses additional challenges because the surface must remain inert to a wide range of chemistries presented by the various amino acid side chains at the droplet surface. Here, we present a method to coat microscope slides with a thin transparent hydrogel that exhibits complete dewetting (contact angles θ ≈ 180°) and minimal pinning of phase-separated droplets in aqueous solution. The hydrogel is based on a swollen matrix of chemically cross-linked polyethylene glycol diacrylate of molecular weight 12 kDa (PEGDA), and can be prepared with basic chemistry laboratory equipment. The PEGDA hydrogel is a powerful tool for in vitro studies of weak interactions, dynamics, and the internal organization of phase-separated droplets in aqueous solutions.

Cytocompatibility Evaluation of PEG-Methylsulfone Hydrogels.

Methylsulfone derivatized poly(ethylene) glycol (PEG) macromers can be biofunctionalized with thiolated ligands and cross-linked with thiol-based cross-linkers to obtain bioactive PEG hydrogels for in situ cell encapsulation. Methylsulfonyl-thiol (MS-SH) reactions present several advantages for this purpose when compared to other thiol-based cross-linking systems. They proceed with adequate and tunable kinetics for encapsulation, they reach a high conversion degree with good selectivity, and they generate stable reaction products. Our previous work demonstrated the cytocompatibility of cross-linked PEG-MS/thiol hydrogels in contact with fibroblasts. However, the cytocompatibility of the in situ MS-SH cross-linking reaction itself, which generates methylsulfinic acid as byproduct at the cross-linked site, remains to be evaluated. These studies are necessary to evaluate the potential of these systems for in vivo applications. Here we perform an extensive cytocompatibility study of PEG hydrogels during in situ cross-linking by the methylsulfonyl-thiol reaction. We compare these results with maleimide-thiol cross-linked PEGs which are well established for cell culture and in vivo experiments and do not involve the release of a byproduct. We show that fibroblasts and endothelial cells remain viable after in situ polymerization of methylsulfonyl-thiol gels on the top of the cell layers. Cell viability seems better than after in situ cross-linking hydrogels with maleimide-thiol chemistry. The endothelial cell proinflammatory phenotype is low and similar to the one obtained by the maleimide-thiol reaction. Finally, no activation of monocytes is observed. All in all, these results demonstrate that the methylsulfonyl-thiol chemistry is cytocompatible and does not trigger high pro-inflammatory responses in endothelial cells and monocytes. These results make methylsulfonyl-thiol chemistries eligible for in vivo testing and eventually clinical application in the future.

The effect of three types of cross-linked hydrogels and volume fraction of polyacrylamide on the swelling and thermal behavior using molecular dynamics simulation

The technology of hydrogels is three-dimensional polymer networks with transverse connections that can adsorb water or biofluids. These compounds can adsorb water without dissolving. Natural hydrogels are considered due to their variety, abundance, cheapness, non-toxicity, and biocompatibility with synthetic hydrogels. In this research, the effect of three types of cross-linked hydrogels polyacrylamide (PAM), polyvinyl alcohol (PVA), and polyethylene glycol (PEG) hydrogels), and volume fraction (5–15%) of PAM on the swelling, and thermal behavior (TB) of simulated samples were studied using molecular dynamics (MD) simulations. The results show that among the simulated hydrogels, the structure of PAM had better atomic behavior and TB. PAM hydrogel had the highest swelling, heat flux (HF), and thermal conductivity (TC), with a numerical value of 342,722 Å3, 1583 W/m2, and 0.57 W/m.K after 10 ns. In the following, by increasing the volume fraction of PAM hydrogel from 5% to 15%, swelling increased to 377,986 Å3, and the TC with 10% of PAM increased from 0.53 (W/m.K) to 0.66 (W/m.K). Furthermore, HF of the sample with 15% of PAM was increased from 1423 (W/m2) to 1761 (W/m2) after 10 (ns). Consequently, by increasing the volume fraction of PAM hydrogel, TB of simulated structure was improved.

Development and In Vivo Assessment of an Injectable Cross-Linked Cartilage Acellular Matrix-PEG Hydrogel Scaffold Derived from Porcine Cartilage for Tissue Engineering.

The cartilage acellular matrix (CAM) derived from porcine cartilage, which does not induce significant inflammation and provides an environment conducive for cell growth and differentiation, is a promising biomaterial candidate for scaffold fabrication. However, the CAM has a short period in vivo, and the in vivo maintenance is not controlled. Therefore, this study is aimed at developing an injectable hydrogel scaffold using a CAM. The CAM is cross-linked with a biocompatible polyethylene glycol (PEG) cross-linker to replace typically used glutaraldehyde (GA) cross-linker. The cross-linking degree of cross-linked CAM by PEG cross-linker (Cx-CAM-PEG) according to the ratios of the CAM and PEG cross-linker is confirmed by contact angle and heat capacities measured by differential scanning calorimetry. The injectable Cx-CAM-PEG suspension exhibits controllable rheological properties and injectability. Additionally, injectable Cx-CAM-PEG suspensions with no free aldehyde group are formed in the in vivo hydrogel scaffold almost simultaneously with injection. In vivo maintenance of Cx-CAM-PEG is realized by the cross-linking ratio. The in vivo formed Cx-CAM-PEG hydrogel scaffold exhibits certain host-cell infiltration and negligible inflammation within and near the transplanted Cx-CAM-PEG hydrogel scaffold. These results suggest that injectable Cx-CAM-PEG suspensions, which are safe and biocompatible in vivo, represent potential candidates for (pre-)clinical scaffolds.

Single versus dual microgel species for forming guest-host microporous annealed particle PEG-MAL hydrogel.

Inter-particle secondary crosslinks allow microporous annealed particle (MAP) hydrogels to be formed. Methods to introduce secondary crosslinking networksin MAP hydrogels include particle jamming, annealing with covalent bonds, and reversible noncovalent interactions. Here, we investigate the effect of two different approaches to secondary crosslinking of polyethylene glycol (PEG) microgels via reversible guest-host interactions. We generated a dual-particle MAP-PEG hydrogel using two species of PEG microgels, one functionalized with the guest molecule, adamantane, and the other with the host molecule, β-cyclodextrin (Inter-MAP-PEG). In a different approach, a mono-particle MAP-PEG hydrogel was generated using one species of microgel functionalized with both guest and host molecules (Intra-MAP-PEG). The Intra-MAP-PEG formed a homogenous distribution due to the single type of microgels used. We then compared the mechanical properties of these two types of MAP-PEG hydrogels and found that Intra-MAP-PEG resulted in significantly softer gels with lower yield stress. We investigated the effect of intra-particle guest-host interactions through titrated weight percentage and the concentration of functional groups added to the hydrogel. We found that there was an ideal concentration of guest-host molecules that enables intra- and inter-particle guest-host interactions with sufficient covalent crosslinking. Based on these studies, Intra-MAP-PEG provides a homogeneous guest-host hydrogel that is shear-thinning with reversible secondary crosslinking.

In silico toxicity assessment and trace level quantification of two genotoxic impurities in silodosin using capillary gas chromatography

A capillary gas chromatographic method using flame ionization detection was developed and validated for the trace quantification of 2-bromoethanol (2-BE) and 2-bromoethylmethanesulfonate (2-BEM) in silodosin, used in the treatment of benign prostatic hyperplasia. Chromatographic separation was performed in spilt mode using nitrogen as carrier gas on a column containing crosslinked polyethylene glycol (30 m × 0.32 mm, 0.25 µm) stationary phase modified with nitroterephthalic acid. A simple matrix precipitation strategy was implemented to eliminate the sample overload and the matrix interference problems. The developed method was linear and accurate in the concentration range of 24–3000 ppm for 2-BE and 24–300 ppm for 2-BEM with r2 ˃ 0.999 and percent recoveries greater than 90% for both the analytes. The developed method was precise for both the analytes with RSD(%) of not more than 4.5%. In silico genotoxicity and carcinogenicity potential of 2-BEM were assessed using ICH M7 principles. The developed method can be applied in the quality control laboratories of pharmaceutical industries for trace level quantification of 2-BE and 2-BEM in silodosin.

Boosting the performances of lithium metal batteries through in-situ construction of dual-network self-healing gel polymer electrolytes

As an alternative to conventional liquid electrolytes, self-healing gel polymer electrolytes (SHGPEs) can effectively increase the safety performance and lifetime of lithium metal batteries (LMBs). However, the poor mechanical properties and unfavorable ionic conductivity limit its further use. Herein, based on a simple in situ polymerization strategy, a novel dual-network structure self-healing gel polymer electrolyte (DN-SHGPE) with mechanical strength and self-healing properties is designed and prepared. The brush copolymer PEG-UPy contains a large amount of dynamic urethane-pyrimidine (UPy) dimer, acting as the first network, which gives GPE great self-healing ability and increases the safety and cycle lifetime of lithium batteries. The second network is cross-linked polyethylene glycol diacrylate (PEGDA), which ensures the dimensional stability and mechanical qualities of GPE. In comparison to the unmodified polymer electrolyte PEG-UPy, DN-SHGPE exhibits better ionic conductivity, excellent mechanical property, and good thermal stability, as well as good interaction stability with Li metal anode. When assembled with LiFePO4 and lithium metal electrodes, the resultant cells show a high reversible specific capacity and good rate capability.

Efficiency Analysis of Fuel Cell Components with Ionic Poly-Arylether Composite Membrane.

We use polyethylene glycol as an additive to explore how the hydrogen bonding of this additive changes the properties of SA8 blended sulfonated polyetheretherketone (SPEEK) composite films. We mixed a 5%wt polyethylene glycol solution into a 12.5%wt SA8 solution, and then prepared a film with a total weight of 40 g at a ratio of 1:99. The SA8 (PEG) solution was prepared and then mixed with 5%wt SPEEK solution, and a film-forming solution with a total weight of 8g in different mixing ratios was created. Polyethylene glycol (PEG) was mixed into the sulfonated polyarylether polymer SA8 to form physical cross-linking. Therefore, the sulfonated polyether ether ketone SPEEK was mixed in, and it exhibited good thermal stability and dimensional stability. However, there was some decrease in proton conductivity as the proportion of SPEEK increased. Although SPEEK mixed with sulfonated polymer reduces the proton conductivity, the physical cross-linking of PEG can improve the proton conductivity of the composite membrane, and adding SPEEK can not only solve the problem of the high sulfonation film swelling phenomenon, it can also improve the dimensional stability of the film through the hydrogen bonding force of PEG and obtain a composite film with excellent properties.

Polyethylene glycol crosslinked decellularized single liver lobe scaffolds with vascular endothelial growth factor promotes angiogenesis in vivo

BackgroundImproving the mechanical properties and angiogenesis of acellular scaffolds before transplantation is an important challenge facing the development of acellular liver grafts. The present study aimed to evaluate the cytotoxicity and angiogenesis of polyethylene glycol (PEG) crosslinked decellularized single liver lobe scaffolds (DLSs), and establish its suitability as a graft for long-term liver tissue engineering. MethodsUsing mercaptoacrylate produced by the Michael addition reaction, DLSs were first modified using N-succinimidyl S-acetylthioacetate (SATA), followed by cross-linking with PEG as well as vascular endothelial growth factor (VEGF). The optimal concentration of agents and time of the individual steps were identified in this procedure through biomechanical testing and morphological analysis. Subsequently, human umbilical vein endothelial cells (HUVECs) were seeded on the PEG crosslinked scaffolds to detect the proliferation and viability of cells. The scaffolds were then transplanted into the subcutaneous tissue of Sprague-Dawley rats to evaluate angiogenesis. In addition, the average number of blood vessels was evaluated in the grafts with or without PEG at days 7, 14, and 21 after implantation. ResultsThe PEG crosslinked DLS maintained their three-dimensional structure and were more translucent after decellularization than native DLS, which presented a denser and more porous network structure. The results for Young's modulus proved that the mechanical properties of 0.5 PEG crosslinked DLS were the best and close to that of native livers. The PEG-VEGF-DLS could better promote cell proliferation and differentiation of HUVECs compared with the groups without PEG cross-linking. Importantly, the average density of blood vessels was higher in the PEG-VEGF-DLS than that in other groups at days 7, 14, and 21 after implantation in vivo. ConclusionsThe PEG crosslinked DLS with VEGF could improve the biomechanical properties of native DLS, and most importantly, their lack of cytotoxicity provides a new route to promote the proliferation of cells in vitro and angiogenesis in vivo in liver tissue engineering.

Enhanced pervaporation performance of PEG membranes with synergistic effect of cross-linked PEG and porous MOF-508a

MOF-508a with moderate 1D channels and large pore cavity size, was successfully synthesized and firstly incorporated into polyethylene glycol (PEG) to prepare mixed matrix membranes (MMMs) for desulfurization via pervaporation. Four kinds of cross-linkers were employed to cure PEG polymers, and PEG membrane cured with oxalic acid acquired much better comprehensive pervaporation performance. The uniformly dispersed MOF-508a in PEG matrix interrupted the crystalline region and decreased PEG crystallization degree. MOF-508a might act as facilitated transport carriers for thiophene molecules based on coordination interaction between Zn2+ and S, and large pore cavities provided multi-scale transport pathways for thiophene molecules. Besides, the strong interaction between MOF-508a and PEG enhanced the interfacial compatibility, which might provide more selective transport pathways for small molecules. Owing to the synergistic effect of cross-linked PEG and porous MOF-508a, the MOF-508a/PEG-5 MMMs exhibited outstanding enrichment factor of 30.4 with permeation flux of 0.485 kg/m2h, which were 98 % and 110 % higher than those of pristine PEG membrane. The enrichment factor of MOF-508a/PEG out-performed most the ever-reported membranes, which might provide some new insight in designing high-performance MMMs by rationally achieving synergy of porous fillers and polymer matrix.

Safety and efficacy of a new hydrogel based on hyaluronic acid as cosmeceutical for xerosis.

Hyaluronic acid (HA) is among the most effective and safe ingredients frequently used in cosmetics. However, a more economical and efficient formulation is still required. We sought to assess the safety and efficacy of a novel hydrogel manufactured only by irradiation containing cross-linked HA and polyethylene glycol polymers with addition of polysiloxane. The study included 30 people with normal skin and 30 patients with xerosis. In the normal skin group, to evaluate the safety, a patch test and a photopatch test were performed, and patients' discomfort was investigated. In those with xerosis, to assess the efficacy, a skin barrier function test was performed at baseline and at 2, 4, and 8 weeks after the application of the novel hydrogel. Additionally, the xerosis severity scale (XSS), patient satisfaction, Investigator's Global Assessment (IGA), and adverse responses were evaluated. In the safety study, there was no significant discomfort in the experimental group compared with the control group. In the efficacy study, at 2, 4, and 8 weeks after the application of the novel hydrogel, the mean value of skin hydration and sebum content increased and the mean value of XSS decreased with time in the experimental group, and a difference was observed when compared with the control group. IGA showed improvement in 97%, 77%, and 80% at each visit and the proportions of satisfied patients were 90%, 87%, and 90%, respectively. The novel HA-based hydrogel tested herein could be a safe and effective therapeutic remedy for xerosis.

In-situ formation of epoxy derived polyethylene glycol crosslinking network on polyamide nanofiltration membrane with enhanced antifouling performance

Nanofiltration (NF) membrane fouling is still an inevitable main challenge, which leads to the reduction of membrane performance. The large number of aliphatic chains in the poly (vinyl alcohol) (PVA) skeleton will reduce the increase in hydrophilicity. Therefore, the existing PVA grafting technology has certain limitations in the application of anti-fouling modification. A facile and effective strategy for enhancing membrane surface hydrophilicity and antifouling performance becomes very important. In this study, epoxy derived polyethylene glycol crosslinking network was in situ introduced on polyamide nanofiltration membrane through ring-opening reaction of poly(ethylene glycol) diglycidyl ether (PEGDGE) to enhance membrane hydrophilicity and antifouling performance. The large amount of ether units in PEGDGE endowed this crosslinked network with hydrophilicity and relative loose structure. Results of FTIR, XPS and WCA indicated that PEGDGE-polyether crosslinking network was successfully formed on the surface of the NF membrane. Water contact angle of the modified membrane was decreased to 23.7 ± 1.2° compared with pristine NF membrane (45.7 ± 2.1°). For the performance test, humic acid (HA) was used to evaluate the fouling resistance of membranes. FRR (Flux Recovery Ratio) value was as high as 91% (e.g., NF–10 S membrane) compared with the pristine membrane (71%). Meanwhile, NF–10 S membrane showed lower FDR (Flux Decline Ratio) (41%) than the pristine NF membrane (68%). Both the low FDR and high FRR of NF–10 S membranes indicated an excellent long-term anti-fouling property. The coating can provide a large number of ether bonds to improve hydrophilic properties, and the proposed strategy in the current study can offer a facile and effective method for membrane antifouling modifications.

Dynamic crosslinked poly(acrylic acid-co-acrylonitrile)/polyethylene glycol networks as reworkable adhesives

The classical covalent network structure is of significant importance to the durability and performance of thermosetting acrylic adhesives; however, its intrinsic unrecyclable property also brings heavy environmental burdens of end-of-life waste disposal. Herein, we demonstrate a robust strategy for developing recyclable and reworkable thermosetting acrylic adhesives. To realize this purpose, a rigid acrylic copolymer (PA2N) containing highly adhesive nitrile groups and curable acrylic acid groups was firstly synthesized from acrylic acid and acrylonitrile, and then directly crosslinked with flexible bis-epoxy capped polyethylene glycol (PEG) through exchangeable β-hydroxyl ester linkages. The obtained PA2N/PEG network exhibits a maximum lap-shear adhesion strength of 4.97 MPa on Al sheets, which is competitive with a series of state-of-art reworkable adhesives and typical commercially available adhesives. Upon heat stimulation, the network could “on-demand” decrosslink and rearrange through the transesterification reactions between PA2N backbone and PEG crosslinker, endowing the as-prepared thermosetting acrylic adhesive with extraordinary recycling and reworking ability, which presents an adhesion performance recovery ratio of ca. 91.8% after 15 min of heat treatment at 190 °C. Overall, this work provides a robust approach in developing reworkable and sustainable alternative to traditional acrylic thermosetting adhesives.