Macromolecular Cross-linker Research Articles

A β-cyclodextrin-based supramolecular photonic crystal hydrogel biosensor with macroporous structures for naked-eye visual detection of cholesterol

Cholesterol (CHO) is an essential lipid in cell membranes and a precursor for vital living substances. Abnormal CHO levels can cause cardiovascular diseases. Therefore, simple and accurate monitoring of CHO levels is crucial for early diagnosis and effective management of cardiovascular diseases. Herein, we report a β-cyclodextrin-based supramolecular photonic crystal hydrogel (PCH) biosensor for naked-eye visual CHO detection. This sensor is composed of a poly(acrylamide-co-N-isopropylacrylamide-co-maleic anhydride-β-cyclodextrin) smart hydrogel with embedding Fe3O4 colloidal chains, which can translate CHO concentration signals into visually detectable color changes of the hydrogel. By carefully selecting a macromolecular crosslinker, a macroporous structure of the hydrogel was achieved, significantly enhancing CHO responsiveness. Molecular docking provides detailed information about the binding mode between MAH-β-CD and CHO. The cyclohexanol portion and alkyl chain of CHO molecule are inserted into MAH-β-CD cavity, driven primarily by hydrophobic interactions. Moreover, this sensor demonstrates excellent regenerability and could be facilely regenerated by washing using hot/cold water or acid solution. Furthermore, it is highly selective for CHO and is suitable for detecting actual human serums. Such a β-CD-based supramolecular PCH biosensor with visualization, excellent regenerability, and high sensitivity and selectivity toward CHO, provides a basis for clinical diagnosis of diseases relative to CHO abnormalities.

Poly(2-hydroxyethyl methacrylate-co-methacrylated hyaluronan-β-cyclodextrin) hydrogel: A potential contact lens material with high hydrophilicity, good mechanical properties and sustained drug delivery

A novel poly(2-hydroxyethyl methacrylate-co-methacrylated hyaluronan-β-cyclodextrin) [p(HEMA-co-mHA-β-CD)] hydrogel was developed as a potential contact lens for ophthalmic disease. The hydrogel was synthesized from the copolymerization of 2-hydroxyethyl methacrylate (HEMA) monomer and mHA-β-CD as a hydrophilic macromolecular crosslinker. By adjusting the methacrylate substitution degree in hyaluronan (20–29 %) and the mHA-β-CD content (5–11 %), transparent p(HEMA-co-mHA-β-CD) hydrogels were achieved. p(HEMA-co-m20HA-β-CD) hydrogels exhibited an enhanced tensile modulus (from 0.35 to 0.88 MPa) with a decreased elongation at break (from 255 % to 108 %), meanwhile they showed increased hydrophilicity with a decreased water contact angle (from 83.4° to 48.6°) and an increased equilibrium water content (from 38.2 % to 46.4 %). Increasing the mHA-β-CD content resulted in a higher encapsulation and cumulative release of hydrophilic levofloxacin hydrochloride or hydrophobic puerarin, due to the improved hydrophilicity and the formation of β-CD/drug inclusion complexes. Compared with pHEMA hydrogel, p(HEMA-co-m20HA-β-CD) hydrogels better inhibited the deposition of lysozyme and bovine serum albumin, and the bacterial adhesion against S. aureus and E. coli. The hydrogels were stable at physiological conditions and non-toxic to immortalized human keratinocytes. With good mechanical properties, tear protein deposition resistance, antibacterial activity, and sustained drug delivery capabilities, p(HEMA-co-m20HA-β-CD) hydrogels were identified as a promising contact lens material for eye diseases.

A dialdehyde pullulan cross-linking strategy for immobilizing protamine onto silk fiber surfaces to achieve durable antibacterial function

Covalent immobilization of antibacterial peptides (APs) onto silk protein-based materials has always been a challenge due to the lack of green and efficient macromolecular cross-linkers. Here, we proposed a dialdehyde polysaccharide cross-linker oxidized from pullulan for grafting a natural AP protamine (PM) onto silk fiber surface through a simple cold pad-batch process. The oxidized pullulan (OP) was linked to silk fiber surface through Schiff reaction and used for mediated cross-linking of PM also via Schiff base linkages. This modification introduced abundant PM guanidine groups on the fiber leading to much-desired antibacterial activity, and considerable improvement in the moisture transfer properties and shade depth. FTIR, XPS, SEM studies confirmed the presence of PM and the cross-linking structure between the polysaccharide and peptides on the fiber surfaces. The antibacterial activity imparted by this process was retained even after 20 washing and 50 rubbing cycles proving versatility and durability. Further, the process did not affect other critical silk properties such as appearance, tensile strength, biological safety, etc. Immobilization of PM onto silk fibers through this novel green polysaccharide cross-linker makes silk more appealing and usable and could also enlighten the attempts of cross-linking other protein materials.

Strategy in Synthesizing Longer-Chain Levan-Type Fructooligosaccharides by Selective Dextran Macromolecular Cross-Linked Bacillus lehensis G1 Endolevanase Aggregate Immobilization

The formation of cross-linked enzyme aggregates (CLEAs) using macromolecular cross-linkers improves substrate accessibility and enhances enzyme retention. However, there have been few studies exploring the use of macromolecular cross-linkers due to the challenges related to cross-linker screening. In compliance with our previous computational and experimental screening, dextran is the optimal macromolecular cross-linker to develop CLEAs of endolevanase from Bacillus lehensis G1 (rlevblg1-dex-CLEA) for levan-type-fructooligosaccharides (L-FOS) production. In this study, rlevblg1-dex-CLEAs was optimized, and the activity recovery continued to increase and reached 90.5%. Subsequently, the rlevblg1-dex-CLEAs were characterized and they displayed higher thermal stability after 1 h of incubation in comparison to the free enzyme. Moreover, the rlevblg1-dex-CLEAs were reusable for five cycles and exhibited greater storage stability over 180 days at 4 °C (60.9%) than that of free rlevblg1. In addition, the rlevblg1-dex-CLEAs demonstrated similar catalytic efficiency as the free enzyme and generated a substantial amount of L-FOS with a longer degree of polymerization, which is more beneficial for industrial use.

Tough and highly stretchable multifunctional ionogels based on phase-separated structure and nanocellulose macromolecular covalent cross-linker

Tough and highly stretchable multifunctional ionogels based on phase-separated structure and nanocellulose macromolecular covalent cross-linker

Mechanically Strong and Tough Organohydrogels for Wide Temperature Tolerant, Flexible Solid‐State Supercapacitors

AbstractHydrogel‐based flexible solid‐state supercapacitors (SSCs) hold great promise for wearable electronics, yet significant challenges persist in simultaneously achieving excellent mechanical properties, high ionic conductivity, outstanding electrochemical properties, and wide operating temperature ranges. Here, this study presents a straightforward method for synthesizing dual crosslinked polyvinyl alcohol‐polyimide (PVA‐PI) organohydrogels via a simple one‐pot synthesis followed by a freezing‐thawing process. The controlled dual crosslinked networks with significanonetly different crosslinking densities and robust intermolecular hydrogen bonding interactions facilitated by the macromolecular crosslinker of PI, endow the organohydrogels with both high mechanical properties and ionic conductivity. Furthermore, SSCs based on PVA‐PI organohydrogels are fabricated, which can exhibit outstanding electrochemical performance at temperatures ranging from −40 to 80 °C. Specifically, the energy density reaches 16.7 µWh cm−2 even at −40 °C under a power density of 410.0 µW cm−2. These SSCs also show excellent performance stability under various deformations, such as bending and compression, alongside exceptional long‐term cycling stability (over 10 000 cycles) with high capacitance retention from −40 to 50 °C. The synthesis strategy, along with a robust mechanism for enhancing mechanical properties of hydrogels, demonstrated in this study offers insights for the development of strong hydrogels/organohydrogels with broad temperature adaptability for soft electronic applications.

Strong and tough conductive hydrogels via an amphiphilic macromolecular crosslinker for flexible strain sensor

The strength and toughness of hydrogel are usually achieved through the synergy of chemical cross-linking and physical cross-linking from multi-component contributions. However, there are few reports on hydrogels that rely on a single component to obtain two cross-linked structures. Herein, we successfully synthesized an amphiphilic macromolecular crosslinker (polyoxyethylene 20 oleyl ether acrylate (O20AC)), and introduced it into a system composed of acrylamide (AAm), sodium chloride (NaCl) and water to prepare the P(AAm-O20AC)/NaCl hydrogel with high strength, outstanding toughness, and excellent good conductivity. Notably, the O20AC possess both crosslinker properties, which not only provide hydrogels with a stable chemical cross-linking network, but also its long hydrophobic chain act as physical crosslinking points to give the hydrogel a new pathway of energy dissipation.Depending on the O20AC crosslinker, the P(AAm-O20AC)/NaCl hydrogels exhibit good strength (tensile stress 714.46 kPa), toughness (elongation at break 3005 %), and fatigue resistance (overlap of hysteresis curves in repeated loading–unloading cycles). Besides, the existence of sodium ions and chloride ions also provides the hydrogel with highly sensitive deformation-dependent conductivity (GF is 5.8 in the 400 %-500 % strain range). Collectively, the strategy of preparing chemical and physical double-crosslinked hydrogels by amphiphilic O20AC will provide a bran-new insights for the development of hydrogel sensing materials.

Ultra-stretchable and highly tough ionogels with underwater repeatable adhesion and anti-swelling capacity for real-time motion detection, signal transmission and electrochemical monitoring platforms

Hydrophobic ionogels have received growing interest as a flexible underwater sensing material. However, it remains a significant challenge to improve the tensile properties, prolonged underwater repeatable adhesion, and multifunctionality of the hydrophobic ionogel due to the restricted selection of monomers and curing strategies. Herein, a hydrophobic multifunctional fluorine-rich ionogel with ultra-stretchability and superior long-term underwater repeatable adhesion is designed by virtue of the introduction of a rigid and flexible macromolecular cross-linker and a structure of rigid cationic imidazole-benzene rings in a hydrophobic ionic liquid monomer. The macromolecular cross-linker significantly improves the mechanical properties of the ionogel because of the reduction in stress concentration. And the structure of short imidazole-benzene rings with high rigidity exposes a larger amount of adhesion groups on the surface of the ionogels compared to the flexible groups, leading to enhanced long-term underwater repeatable adhesion performance of the ionogel. The ionogels are applied to real-time monitoring of exposure to water, underwater swimming motion monitoring, underwater Morse code transmission and electrochemical monitoring platforms. And this work is expected to provide ideas for the multifunctionalization of underwater sensing technology and the integration of functional units in underwater flexible electronic skin.

PROTEIN INTERACTION STUDIES OF CROSS-LINKED ENDOLEVANASE AGGREGATES FROM BACILLUS LEHENSIS G1

The efficiency of cross-linked enzyme aggregates (CLEAs) is mainly affected by the strength and binding site of the formed linkages between the enzyme and cross-linker. Therefore, this study investigated the impact of different macromolecular cross-linkers on various functional groups, their binding energy, and intermolecular interaction in generating CLEAs of endolevanase from Bacillus lehensis G1 (rlevblg1), through the combination of computational and experimental analysis. Due to the distanced bonding of dextran from the active site, rlevblg1 cross-linked with dextran (rlevblg1-dex-CLEAs) exhibited the highest binding affinity (− 7.1 kcal/mol) and activity recovery compared to six other cross-linkers. Thus, the role of computational cross-linker screening is confirmed as a crucial step to predict strong attachment and construct efficient CLEAs.

Improving the ohmic polarization of high-temperature proton exchange membrane fuel cells using crosslinked polybenzimidazole membranes containing acidophilic quaternary ammonium groups synthesized by one-step strategy

Ingenious crosslinked network structure in phosphoric-acid-doped polybenzimidazole membranes can mitigate the mutual restriction of proton conductivity and mechanical properties. However, the complicated synthesis of tailored macromolecular crosslinker and the time-consuming post-treatment hinder their practical application as high-temperature proton exchange membranes. Herein, crosslinked polybenzimidazole membranes are synthesized using small molecular crosslinkers containing acidophilic quaternary ammonium groups through a one-step crosslinking strategy. After doping with phosphoric acid, the quaternary ammonium-biphosphate ion-pair coordination and the crosslinked structure result in the improved anhydrous proton conductivity, oxidation stability, and mechanical strength of the formed membranes compared to the sample without the crosslinking structure. A membrane with the optimized degree of crosslinking exhibits an anhydrous conductivity of 72.27 mS/cm at 160 °C, with a tensile strength of 12.14 MPa. Benefiting from the crosslinked structure and high proton conductivity, the accordingly formed membrane electrode assembly possesses a high open-circuit voltage of 1.01 V and animproved ohmic polarization, delivering a peak power density of 0.66 W/cm2 using hydrogen as fuel and air as oxidant.

Macromolecule crosslinked composite PVA membranes for pervaporation desalination

Pervaporation (PV) has shown great potential in desalination. Polyvinyl alcohol (PVA) is a widely used material for PV membranes. In the present work, hydrophilic composite membranes for PV desalination were prepared by coating mix solutions of PVA and Poly(methyl vinyl ether-alt-maleic anhydride) (PMVE-MA) on porous polyvinylidene fluoride (PVDF) supports. PMVE-MA, which serves as a macromolecular crosslinker, is well-compatible with PVA. The methyl ether groups in PMVE-MA also endow the crosslinked membrane to maintain good hydrophilicity. To achieve better performance, influences of the PVA concentration, the mass ratio of PVA to PMVE-MA, the crosslinking temperature and time, and the PVDF support on the desalination performance of the composite PV membrane were studied. At optimal conditions, a PVA-(PMVE-MA)/PVDF membrane was prepared. The membrane had a water flux of up to 45 kg·m−2·h−1 for the feed of 3.5 wt% NaCl solution at 50 °C (92 kg·m−2·h−1 at 70 °C). The salt passage was at an extremely low level and the conductivity of the permeate was lower than 100 μs/cm. In addition, the membrane showed excellent antifouling performance. After 14 h desalination of a sodium alginate-containing feed, the flux can be fully recovered by flushing the membrane in situ. The PVA-(PMVE-MA)/PVDF composite membrane shows great potential in desalination applications.

Bottom-Up Extrusion-Based Biofabrication of the Osteoid Niche.

Bone regeneration remains a clinical challenge given the transplantation incidence rate and the associated economic burden. Bottom-up osteoid tissue engineering has the potential to offer an alternative approach to current clinical solutions that suffer from various drawbacks. In this paper, deposition-based bioprinting is exploited while the effect is explored of both the crosslinking mechanism (gelatin methacryloyl (GelMA) versus gelatin norbornene (DS 91) crosslinked with thiolated gelatin (GelNBSH)) and the degree of substitution (GelNBSH versus norbornene-norbornene-modified gelatin (DS 169) crosslinked with thiolated gelatin (GelNBNBSH)) on the presented biophysical cues as well as on the osteogenic differentiation. The incorporation of tris(2-carboxyethyl)phosphine (TCEP) to the step-growth inks allows the production of reproducible and biocompatible scaffolds based on thiol-ene chemistry. Dental pulp stem cell encapsulation in GelNBNBSH biofabricated constructs shows a favorable response due to the combination of its stress relaxation and substrate rigidity (bulk compressive modulus of 11-30kPa) as reflected by a sevenfold increase in calcium production compared to the tissue engineering standard GelMA. This work is the first to exploit a controlled biocompatible and cell-interactive thiolated macromolecular crosslinker (GelSH + TCEP) allowing the extrusion-based biofabrication of low concentration (5 w/v%) modified osteogenic gelatin-based inks (GelNBNBSH + TCEP).

Reprocessing and reconfigurable shape recovery of epoxy and Fe3O4 nanocomposites enabled by crosslinking with a polymeric hardener bearing disulfide bonds

In this contribution, we reported the preparation of the nanocomposites of epoxy with Fe3O4 with poly(α-lipoic acid) (PLA) as a polymeric crosslinker. It was found that the surface reaction between Fe3O4 nanoparticles and the macromolecular crosslinker significantly facilitated the fine dispersion of the inorganic nanoparticles. In the meantime, dynamic disulfide bonds were successfully introduced into the nanocomposites. Therefore, the nanocomposites displayed the excellent reprocessing (recycling) properties. In addition, the nanocomposites had the shape memory properties; the original shapes of the shape memory nanocomposites can be reprogrammed via the exchange of dynamic disulfide bonds. Owing to the incorporation of Fe3O4 nanoparticles, the nanocomposites possessed the excellent paramagnetic and photothermal properties. Furthermore, the photothermal properties can be utilized to trigger the shape recovery in a non-contact fashion.

Harnessing imidazole containing crosslinked AEM for HCl resurrection from industrial spent effluent by integrated diffusion dialysis and electrodialysis: Effect of small and macromolecular crosslinker

Herein, we report the preparation of crosslinked copolymer-based AEMs via a one-pot mechanism. AEMs were prepared by the nucleophilic substitution reaction of polyacrylonitrile-co-polyvinyl imidazole (PAN-co-PVI) copolymer (AN: VI = 63:37 mol/mol) with the small and macromolecular crosslinker. The AEM was then used for the separation and concentration of hydrochloric acid from its simulated waste mixture with ferrous chloride of the electroplating industry using diffusion dialysis (DD) followed by electrodialysis (ED). The separation has also been performed by the integrated approach of DD and ED processes. DD performance was carried out with three different crosslinked membranes namely M-PCMSt, M-XDC, and M-XDB synthesized using poly-chloromethyl styrene (PCMSt), xylene dichloride (XDC), and xylene dibromide (XDB) as crosslinker respectively. The DD performances were compared by measuring the diffusion coefficient and separation factor. M-PCMSt prepared using a macromolecular crosslinker (PCMSt) exhibited the highest crosslinking density and lowest extractable (%) in DMF due to strong network formation and lowest free volume. Due to its lowest water uptake and high mechanical strength in both water and acid swollen states, it was further used to concentrate the acid by ED and integrated the DD-ED process separately. A ∼2.49 and 1.575 times higher recovery was achieved by integrated process from DD and ED separately. Different parameters such as the effect of membrane-stack designing, current density, the effect of feed solution concentration, the effect of the volume ratio, flow rate of the circulating initial solution, and influence of gravity have been optimized. M-PCMSt shows the best separation behaviour with >92% recovered acid purity and ∼94.5 % acid recovery at 4 mAcm-2 current density which is better than polyethylene poly-(4-methyl styrene)-based interpolymer membrane.

3D bioprinted scaffolds based on functionalized gelatin for soft tissue engineering

3D bioprinting application in the medical field requires optimized and adapted bioinks/biomaterials, along with processing as scaffolds with morphology and structure that mimic human tissues. Various polymeric hydrogels have been tested in bioinks elaboration in order to support the cells biology. In this context, the paper presents the preparation of versatile bioadhesive hydrogels based on methacrylated gelatin, moderate crosslinked with poly (ethylene glycol) diacrylate, and 3D bioprinted as bioadhesive scaffolds for skin tissue engineering. Gelatin with various methacrylation degrees, confirmed by FTIR and H1NMR and analytical methods (TNBS, nynhydrin assay), mixed with poly (ethylene glycol) diacrylate and biocompatible photoinitiator led to stable gels, with rheological characteristics (yield stress and shear-thinning behavior) beneficial for bioprinting. Scaffolds with controllable shape and morphology have been obtained by bioprinting and polymers UV crosslinking. The 3D scaffolds absorb fluids and their biostability increases in presence of poly (ethylene glycol) diacrylate. Cell cultures of fibroblasts/ keratinocytes demonstrated the scaffolds cytocompatibility. The cells preserved the normal morphology, were adherent to substrate and formed uniform monolayers. The bioadhesion characteristics increased by adding poly (ethylene glycol) diacrylate as macromolecular crosslinker. The scaffolds absorb the blood plasma, promote the local accumulation of fibrinogen, and accelerate the adhesion of the blood components, with impact on angiogenesis, suitability characteristic for skin tissue engineering applications.

High strength polyurethane ionogel as a wearable strain sensor for human activity monitoring

Due to their superior elasticity and electroconductibility as soft wearable sensors, ionogels have received a lot of investigation. Electronic skin sensors based on traditional ionogel frequently have poor mechanical qualities, poor durability, and poor temperature resistance. Here, a new waterborne polyurethane based macromolecular cross-linker (MPU) is developed and used to create an ionogel containing 1-ethyl-3-methylimidazoliumdicyanamide (EMIM:DCA). Importantly, due of the internal hydrogen bonding, ionogels exhibit extraordinary mechanical properties with a strain value of 1.27 MPa, a deformation at breaking of 267%, and excellent puncture resistance. At normal temperature, EMIM:DCA gives the ionogels high electroconductibility. When combined as wireless strain sensors, the ionogel sensors exhibit exceptional sensing capabilities to track real-time mechanical conduction signals of human movement. It indicates that the ionogels as developed hold a lot of promise for wearable devices.

Crosslinked polybenzimidazole high temperature-proton exchange membranes with a polymers of intrinsic microporosity (PIM) macromolecular crosslinker

The macromolecular crosslinkers of bromomethylated polymer of intrinsic microporosity (PIM-BM) are successfully introduced into the poly(2,2’-(1,4-naphthalene)-5,5′-bibenzimidazole) (NPBI) to improve the phosphoric acid retention in high temperature proton exchange membrane fuel cell (HT-PEMFC). Thanks to the excellent miscibility between two polymers, the transparent and tough crosslinked membranes (NPBI/PIM-BM-x) have been obtained by the solution-casting. Compared with pristine NPBI membrane, the crosslinked membranes exhibit higher retention of phosphoric acid (PA) in various complicated temperature/humidity conditions due to the microporosity resulting from the micropore polymer of intrinsic microporosity (PIM) crosslinker. Specifically, the PA doped NPBI/PIM-BM-15 (NPBI/PIM-BM-15/PA) membrane shows 57.73% PA retention under 80 °C/40% relative humidity (RH), higher than PA doped NPBI (NPBI/PA) membrane (48.12%). Therefore, under accelerate stress test (AST) in fuel cells, the crosslinked NPBI/PIM-BM-15/PA membrane shows an excellent retention of peak power density, e.g. remaining 88.99% after 200 cycles of testing at 80 °C. This value is much better than pristine NPBI based fuel cell (only remaining 52.01% after 200 cycles under the same testing conditions). At a higher temperature of 160 °C without extra humidity, the fuel cells based on PA doped crosslinked membranes show comparable peak power density of 565–627.5 mW cm−2 to NPBI (632.5 mW cm−2) without an obvious sacrificing of initial fuel cell performance. Thus, the improved PA retention of the HT-PEM based on with PIMs crosslinker shows a great potential to broaden the operational temperature range and to be used for the next-generation HT-PEMs.

Collagen-based injectable and self-healing hydrogel with multifunction for regenerative repairment of infected wounds.

At present, the development trend of dressing materials is being multifunctional for convenient and long-term nursing care process of some complicated wounds. Here, basing on the theory of wound moist healing, an injectable and self-healing hydrogel comprising of collagen (COL), chitosan (CS) and oxidation modified Konjac glucomannan (OKGM), which acts as a macromolecular cross-linker to construct dynamic Schiff-base bonds was smartly designed. The strategy of introducing the silver nanoparticles (Ag NPs) into the COL-CS-OKGM hydrogel matrix achieved a markedly enhanced antibacterial activity derived from the synergistical effect between the Ag+ and the mild photothermal efficacy of Ag NPs, which also improved the local capillary blood circulation of the wound area to further facilitate wound healing process. The excellent syringeability and self-healing behaviors endowed the COL-CS-OKGM-Ag hydrogel with self-adapting ability for the wounds with irregular and large area needing frequent applying and changing without secondary injuries. In vitro and in vivo evaluations verified that so-designed COL-CS-OKGM-Ag hydrogel also with hemostatic performance is a promising multifunctional dressing for the treatments of infected wound with not only good biocompatibility and convenient use, but also with desired regenerative healing prognoses benefited from hydrogel moist environment and physiotherapy.

A Novel High Temperature Fuel Cell Proton Exchange Membrane with Nanoscale Phase Separation Structure Based on Crosslinked Polybenzimidazole with Poly(vinylbenzyl chloride)

A semi-aromatic polybenzimidazole (DPBI) is synthesized via polycondensation of decanedioic acid (DCDA) and 3,3-diaminobenzidine (DAB) in a mixed phosphorus pentoxide/methanesulfonic acid (PPMA) solvent. Ascribing to in-situ macromolecular crosslinker of ploly((vinylbenzyl chloride) (PVBC), a robust crosslinked DPBI membrane (DPBI-xPVBC, x refers to the weight percentage of PVBC in the membrane) can be obtained. Comprehensive properties of the DPBI and DPBI-xPVBC membranes are investigated, including chemical structure, antioxidant stability, mechanical strength, PA uptake and electrochemical performances. Compared with pristine DPBI membrane, the PA doped DPBI-xPVBC membranes exhibit excellent antioxidative stability, high proton conductivity and enhanced mechanical strength. The PA doped DPBI-10PVBC membrane shows a proton conductivity of 49 mS cm-1 at 160 °C without humidification. Particularly, it reveals an enhanced H2/O2 single cell performance with the maximum peak power density of 405 mW cm-2, which is 29% higher than that of pristine DPBI membrane (314 mW cm-2). In addition, the cell is very stable in 50 h, indicating the in-situ crosslinked DPBI with a macromolecular crosslinker of PVBC is an efficient way to improve the overall performance of HT-PEMs for high performance HT-PEMFCs.

Honokiol@PF127 crosslinked hyaluronate-based hydrogel for promoting wound healing by regulating macrophage polarization

Bacterial infection, oxidative stress and inflammation are the main obstacles in wound healing. Hydrogels with moist and inherent properties are beneficial to wound healing. Here, we fabricated a honokiol-laden micelle-crosslinked hyaluronate-based hydrogel by simply mixing honokiol-laden PF127-CHO micelles, 3,3′-dithiobis(propionohydrazide) grafted hyaluronic acid and silver ions. PF127 could not only effectively load hydrophobic small molecules but also be macromolecular crosslinker for preparing hydrogels. Hyaluronic acid plays an essential role in wound healing processes including regulating macrophage polarization towards M2 phenotype. The chemical dynamic acylhydrazone crosslinking and physical crosslinking among PF127-CHO micelles constructed hydrogel's networks, which endowed hydrogel with excellent self-healing properties. PF-HA-3 hydrogel also exhibited outstanding antioxidant and antibacterial capabilities. In a full-thickness skin defect model, this degradable and biocompatible hydrogel could promote wound healing by remodeling wound tissues, regulating M2 polarization and angiogenesis. In summary, this inherent multifunctional hydrogel will provide a promising strategy for designing bioactive compounds-based wound dressings.