Polyamine-Polymeric Micelle Hybrid Hydrogel: Microscopic Properties of Crosslinkers Affecting Macroscopic Rheological Properties of Hydrogel

We have developed a hybrid hydrogel that is formed from a crosslinkable polymeric micelle and a polyamine. Under optimal conditions, the hydrogel rapidly formed in one second after a crosslinkable polymeric micelle solution was mixed with a polyamine solution. We could change the hydrogel’s gelation properties, such as the storage modulus and gelation time by tuning the molecular weights of block copolymers and by tuning the pH of the dissolving-solvent of the hydrogel’s constituent components. Furthermore, we have clarified here that the structural difference among the micelles acting as crosslinkers can affect the gelation properties of the hydrogel. According to our findings, the hydrogel that was formed from the polymeric micelles possessing a highly packed (i.e., well-entangled or crosslinked) inner core exhibited a higher storage modulus than the hydrogel that was formed from the polymeric micelles possessing a lowly packed structure. Our results demonstrate that a microscopic structural difference among crosslinkers can induce a macroscopic change in the properties of the resulting hydrogels. For medical applications, the hydrogel proposed in the present paper can encapsulate the hydrophobic compounds in crosslinkers (polymeric micelles) so that the hydrogel can be available as the biomaterial for their sustained release.

The flow behavior of droplet adsorption on a liquid-liquid interface accompanied by cross-linking reaction and phase separation in a microchannel

The adsorption process of droplets on the liquid-liquid interface and phase separation process can regulate the spatial distribution of the fluid system,which are crucial for chemical engineering.However,the cross-linking reaction,which is widely used in the field of polymers,can change the physical properties of the fluids and affect the flow behavior accordingly.A configuration of microchannels is designed to conveniently generate uniform droplets in one phase of the parallel flow.The flow behavior of the adsorption process of sodium alginate droplets on the liquid-liquid interface is investigated,and the subsequent process of phase separation is studied.In the process of droplet adsorption,the crosslinking reaction occurs synchronously,which makes the droplet viscosity and the elasticity modules of the droplet surface increase,thus affecting the dynamics of the adsorption process and the equilibrium shape of the droplet.The variation of the adsorption length with time is divided into three stages,which all conform to power law relationship.The exponents of the second and third stages deviate from the results of the Tanner's law.The flow pattern maps of droplet adsorption and phase separation are drawn,and the operating ranges of complete adsorption and complete separation are provided.This study provides a theoretical basis for further studying the flow behavior of droplets with cross-linking reaction in a microchannel.

B-COPNA resin formation from ethylene tar light fractions:Process development and mechanical exploration by molecular simulation

An efficient utilization strategy of ethylene tar(ET),the main by-product of the ethylene cracking unit,is urgently required to meet demands for modern petrochemical industry.On the other hand,condensed polynuclear aromatic resin of moderate condensation degree(B-COPNA)is a widely used carbon material due to its superb processability,the production of which is,however,seriously limited by the high cost of raw materials.Under such context,an interesting strategy was proposed in this study for producing B-COPNA resin using crosslinked light fractions of ethylene tar(ETLF,boiling point<260℃)facilitated by molecular simulation.1,4-Benzenedimethanol(PXG)was first selected as the crosslinking agent according to the findings of molecular simulation.The effects of operating conditions,including reactions temperature,crosslinking agent,and catalyst content on the softening point and yield of B-COPNA resin products were then investigated to optimize the process.The reaction mechanism of resin production was studied by analyzing the molecular structure and transition state of ETLF and crosslinking agents.It was shown that PXG exhibited a superior capacity of withdrawing electrons and a higher electrophilic reactivity than other crosslinking agents.In addition to the highest yield and greatest heat properties,PXG-prepared resin contained the most condensed aromatics.The corresponding optimized conditions of resin preparation were 180℃,1:1.9(PXG:ETLF),and 3%(mass)of catalyst content with a resin yield of 78.57%.It was the electrophilic substitution reaction that occurred between the ETLF and crosslinking agent molecules that were responsible for the resin formation,according to the experimental characterization and molecular simulation.Hence,it was confirmed that the proposed strategy and demonstrated process can achieve a clean and high value-added utilization of ETLF via B-COPNA resin preparation,bringing huge economic value to the current petrochemical industry.

Photoactivated growth factor release from bio-orthogonally crosslinkedhydrogels for the regeneration of corneal defects

In situ-forming hydrogels are an attractive option for corneal regeneration, and the delivery of growth factorsfrom such constructs have the potential to improve re-epithelialization and stromal remodeling. However,challenges persist in controlling the release of therapeutic molecules from hydrogels. Here, an in situ-forming bioorthogonallycrosslinked hydrogel containing growth factors tethered via photocleavable linkages (PC-HAColhydrogel) was developed to accelerate corneal regeneration. Epidermal growth factor (EGF) was conjugated tothe hydrogel backbone through photo-cleavable (PC) spacer arms and was released when exposed to mild intensityultraviolet (UV) light (2–5 mW/cm2, 365 nm). The PC-HACol hydrogel rapidly gelled within a few minuteswhen applied to corneal defects, with excellent transparency and biocompatibility. After subsequentexposure to UV irradiation, the hydrogel promoted the proliferation and migration of corneal epithelial cells invitro. The rate of re-epithelialization was positively correlated to the frequency of irradiation, verified through exvivo rabbit cornea organ culture studies. In an in vivo rat corneal wound healing study, the PC-HACol hydrogelexposed to UV light significantly promoted re-epithelialization, the remodeling of stromal layers, and exhibitedsignificant anti-scarring effects, with minimal α-SMA and robust ALDH3A1 expression. Normal differentiation ofthe regenerated epithelia after healing was evaluated by expression of the corneal epithelial biomarker, CK12.The remodeled cornea exhibited full recovery of corneal thickness and layer number without hyperplasia of theepithelium.

Detecting early changes in choroidal vascularity and thickness using optical coherence tomography in patients with corneal crosslinking for keratoconus

AIM:To investigate changes in choroidal thickness and vascularity in keratoconus patients treated with corneal crosslinking.METHODS:This study evaluated 28 eyes of 22 patients with keratoconus who underwent corneal crosslinking.The choroidal thicknesses were evaluated on enhanced depth imaging optical coherence tomography at the preoperative and postoperative 3d,1,and 3mo.Choroidal thickness in the four cardinal quadrants and the fovea were evaluated.The choroidal vascularity index was also calculated.RESULTS:There was no significant difference in central choroidal thickness between the preoperative and postoperative 3d,1mo(P>0.05).There was a significant increase in the 3mo(P=0.034)and a significant decrease in the horizontal choroidal vascularity index on the postoperative 3d(P=0.014),there was no statistically significant change in vertical axes and other visits in horizontal sections(P>0.05).CONCLUSION:This study sheds light on choroidal changes in postoperative corneal crosslinking for keratoconus.While it suggests the procedure’s relative safety for submacular choroid,more extensive research is necessary to confirm these findings and their clinical significance.

Stromal lenticule addition keratoplasty with corneal crosslinking for corneal ectasia secondary to FS-LASIK:a case series

●AIM:To explore the clinical efficacy and safety of stromal lenticule addition keratoplasty(SLAK)with corneal crosslinking(CXL)on patients with corneal ectasia secondary to femtosecond laser-assisted in situ keratomileusis(FS-LASIK).●METHODS:A series of 5 patients undertaking SLAK with CXL for the treatment of corneal ectasia secondary to FS-LASIK were followed for 4-9mo.The lenticules were collected from patients undertaking small incision lenticule extraction(SMILE)for the correction of myopia.Adding a stromal lenticule was aimed at improving the corneal thickness for the safe application of crosslinking and compensating for the thin cornea to improve its mechanical strength.●RESULTS:All surgeries were conducted successfully with no significant complications.Their best corrected visual acuity(BCVA)ranged from 0.05 to 0.8-2 before surgery.The pre-operational total corneal thickness ranged from 345-404μm and maximum keratometry(Kmax)ranged from 50.8 to 86.3.After the combination surgery,both the corneal keratometry(range 55.9 to 92.8)and total corneal thickness(range 413-482μm)significantly increased.Four out of 5 patients had improvement of corneal biomechanical parameters(reflected by stiffness parameter A1 in Corvis ST).However,3 patients showed decreased BCVA after surgery due to the development of irregular astigmatism and transient haze.Despite the onset of corneal edema right after SLAK,the corneal topography and thickness generally stabilized after 3mo.●CONCLUSION:SLAK with CXL is a potentially beneficial and safe therapy for advanced corneal ectasia.Future work needs to address the poor predictability of corneal refractometry and compare the outcomes of different surgical modes.

Biomimetic fibril-like injectable hydrogels for wound management

Soft tissue repair and regeneration present a significant clinical challenge.Soft hydrogels have emerged as a promising solution for promoting stem cell differentiation and facilitating soft tissue formation[1].Various materials,including synthetic polymers like polydimethyl siloxane and natural polymers like proteins,have been be used as hydrogel matrix for hydrogel preparation[2,3].However,the limited biodegradability,inhomogeneous network structure,and inadequate mechanical properties of these hydrogels hinder their long-term application in complex environments in vivo.Inspired by the nanostructure of collagen fibrils,Li et al.developed a strategy for creating injectable nanofibrillar hydrogels by combining self-assembly and chemical crosslinking of nanoparticles[4].Moreover,injectable hydrogels offer advantages as implantable materials,including better defect filling and reduced risk of infection compared to prefabricated hydrogels[5].

Crosslinking of viral nanoparticles with “clickable” fluorescent crosslinkers at the interface

Cu (I) catalyzed alkyne-azide cycloaddition (CuAAC) reaction,a typical "click" reaction,is one of the modular synthetic approaches which has been broadly used in various organic syntheses,medicinal chemistry,materials development and bioconjugation applications.We have for the first time synthesized two dialkyne derivatized fluorescent crosslinkers which could be applied to crosslink two biomolecules using CuAAC reaction.Turnip yellow mosaic virus,a plant virus with unique structural and chemical properties,was used as a prototypical scaffold to form a 2D single layer at the interface of two immiscible liquids and crosslinked with these two linkers by the CuAAC reaction.Upon crosslinking,the fluorescence of both linkers diminished,likely due to the distortion of the polymethylene backbone,which therefore could be used to indicate the completion of the reaction.

Synthesis and application of novel degradable crosslinkers

A novel divinyl ether was synthesized by a convenient method with high yield.Then the divinyl ether was combined with 2- hydroxyethyl methacrylate and acrylic acid,respectively,generating difunctional polymeric crosslinkers with（hemi）acetal structure that was labile in acid.The chemical structures of the divinyl ether and crosslinkers were confirmed by ~1H NMR and elemental analysis.The crosslinkers were employed in free-radical polymerization to prepare polymer gel and gel particles. Due to the（hemi）acetal structure in the crosslinking segment,the polymer gel and particles exhibited degradable ability in strong acid.

Carcinoma-associated fibroblast-derived lysyl oxidase-rich extracellular vesicles mediate collagen crosslinking and promote epithelial-mesenchymal transition via p-FAK/ p-paxillin/YAP signaling

Carcinoma-associated fibroblasts(CAFs)are the main cellular components of the tumor microenvironment and promote cancer progression by modifying the extracellular matrix(ECM).The tumor-associated ECM is characterized by collagen crosslinking catalyzed by lysyl oxidase(LOX).Small extracellular vesicles(sEVs)mediate cell-cell communication.However,the interactions between sEVs and the ECM remain unclear.Here,we demonstrated that sEVs released from oral squamous cell carcinoma(OSCC)-derived CAFs induce collagen crosslinking,thereby promoting epithelial-mesenchymal transition(EMT).CAF sEVs preferably bound to the ECM rather than being taken up by fibroblasts and induced collagen crosslinking,and a LOX inhibitor or blocking antibody suppressed this effect.Active LOX(αLOX),but not the LOX precursor,was enriched in CAF sEVs and interacted with periostin,fibronectin,and bone morphogenetic protein-1 on the surface of sEVs.CAF sEV-associated integrinα2β1 mediated the binding of CAF sEVs to collagen I,and blocking integrinα2β1 inhibited collagen crosslinking by interfering with CAF sEV binding to collagen I.CAF sEV-induced collagen crosslinking promoted the EMT of OSCC through FAK/paxillin/YAP pathway.Taken together,these findings reveal a novel role of CAF sEVs in tumor ECM remodeling,suggesting a critical mechanism for CAF-induced EMT of cancer cells.

Evaluation of different crosslinking methods in altering the properties of extrusion-printed chitosan-basedmulti-material hydrogel composites

Three-dimensional printing technologies exhibit tremendous potential in the advancing fields of tissue engineering and regenerative medicine due to the precise spatial control over depositing the biomaterial.Despite their widespread utilization and numerous advantages,the development of suitable novel biomaterials for extrusion-based 3D printing of scaffolds that support cell attachment,proliferation,and vascularization remains a challenge.Multi-material composite hydrogels present incredible potential in this field.Thus,in this work,a multi-material composite hydrogel with a promising formulation of chitosan/gelatin functionalized with egg white was developed,which provides good printability and shape fidelity.In addition,a series of comparative analyses of different crosslinking agents and processes based on tripolyphosphate(TPP),genipin(GP),and glutaraldehyde(GTA)were investigated and compared to select the ideal crosslinking strategy to enhance the physicochemical and biological properties of the fabricated scaffolds.All of the results indicate that the composite hydrogel and the resulting scaffolds utilizing TPP crosslinking have great potential in tissue engineering,especially for supporting neo-vessel growth into the scaffold and promoting angiogenesis within engineered tissues.

Plasma-activated hydrogel:fabrication,functionalization,and effective biological model

Hydrogels are biomaterials with 3D networks of hydrophilic polymers.The generation of hydrogels is turning to the development of hydrogels with the help of enabling technologies.Plasma can tailor the hydrogels’properties through simultaneous physical and chemical actions,resulting in an emerging technology of plasma-activated hydrogels(PAH).PAH can be divided into functional PAH and biological tissue model PAH.This review systematically introduces the plasma sources,plasma etching polymer surface,and plasma cross-linking involved in the fabrication of PAH.The‘diffusion-drift-reaction model’is used to study the microscopic physicochemical interaction between plasma and biological tissue PAH models.Finally,the main achievements of PAH,including wound treatment,sterilization,3D tumor model,etc,and their development trends are discussed.

Nano silica aerogel-induced formation of an organic/alloy biphasic interfacial layer enables construction of stable high-energy lithium metal batteries

Lithium metal batteries represent promising candidates for high-energy-density batteries, however, many challenges must still be overcome,e.g., interface instability and dendrite growth. In this work, nano silica aerogel was employed to generate a hybrid film with high lithium ion conductivity(0.6 mS cm^(-1)at room temperature) via an in situ crosslinking reaction. TOF-SIMS profile analysis has revealed conversion mechanism of hybrid film to Li–Si alloy/Li F biphasic interface layer, suggesting that the Li–Si alloy and Li F-rich interface layer promoted rapid Li+transport and shielded the Li anodes from corrosive reactions with electrolyte-derived products. When coupled with nickel-cobalt-manganese-based cathodes, the batteries achieve outstanding capacity retention over 1000 cycles at 1 C. Additionally the developed film coated on Li enabled high coulombic efficiency(99.5%) after long-term cycling when coupled with S cathodes. Overall, the results presented herein confirm an effective strategy for the development of high-energy batteries.

Tailoring the separation performance of a carbon nanotube-based mixed matrix membrane decorated with metal–organic framework

Synthesis of mixed matrix membranes(MMM)using carbon nanotubes(CNTs)has shown great prospects for achieving excellent selective separation because of its special structure.Nevertheless,the preparation of highly selective MMM faces challenges,which is attributed to the obstacles encountered by CNTs dispersion in polymer matrix and elimination of interface defects.A novel CNT-based composite decorated with metal–organic framework(MOF)was synthesized and applied to the preparation of MMM.MOF was post modified,and then carboxyl groups were inserted on the outer surface of CNTs.The synthetic MMM(Cu-MOF-en@MWCNT)not only has selective adsorption on dyes,but also has selective photodegradation on dyes.The method of using CNTs to wrap the outside of MOF has great potential in dye separation.The performance of MMM was further improved by decorating MOF on the filler to improve the selectivity to the designated dye.

Crosslinking Mechanism of Soy Protein-based Adhesives based on Glyoxal and a Compound of Protein Model

The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and 3,glyoxal reacted with asparagine in the form of major cyclic ether compounds.When pH=5,glyoxal reacted with asparagine in two structural forms of sodium glycollate and cyclic ether compounds.However,amidogens of asparagine were easy to develop protonation under acid conditions.Supplemented by the instability of cyclic ether compounds,the reaction activity and reaction degree between glyoxal and asparagine were relatively small.Under alkaline conditions,glyoxal mainly reacted with asparagine in the form of sodium glycollate.With the increase of pH,the polycondensation was more sufficient and the produced polycondensation products were more stable.The reaction mechanism between glyoxal and asparagine had strong correspondence to the practical performances of the adhesives.Glyoxal solution could develop crosslinking reactions with soy protein under both acid and alkaline conditions.Bonding strength and water resistance of the prepared soy protein-based adhesives were increased significantly.When pH>7,glyoxal had relatively high reaction activity and reaction intensity with soy protein,and the prepared adhesives had high crosslinking density and cohesion strength,showing relatively high bonding strength,water resistance and thermal stability.

Facile synthesis of chromium chloride/poly(methyl methacrylate) core/shell nanocapsules by inverse miniemulsion evaporation method and application as delayed crosslinker in secondary oil recovery

Cr(III)ehydrolyzed polyacrylamide(HPAM)gels have been extensively studied as a promising strategy controlling waste water production for mature oilfields.However,the gelation time of the current technologies is not long enough for in-depth placement.In this study,we report a novel synthesis method to obtain chromium chloride/poly(methyl methacrylate)(PMMA)nanocapsules which can significantly delay the gelation of HPAM through encapsulating the chromium chloride crosslinker.The chromium chloride-loaded nanocapsules(CreNC)are prepared via a facile inverse miniemulsion evaporation method during which the hydrophobic PMMA polymers,pre-dispersed in an organic solvent,were carefully controlled to precipitate onto stable aqueous miniemulsion droplets.The stable aqueous nanodroplets(W)containing Cr(III)are dispersed in a mixture of organic solvent(O1)with PMMA and nonsolvent medium(O2)to prepare an inverse miniemulsion.With the evaporation of the O1,PMMA forms CreNCs around the aqueous droplets.The CreNCs are readily transferred into water from the organic nonsolvent phase.The CreNCs exhibit the tunable size(358-983 nm),Cr loading(7.1%-19.1%),and Cr entrapment efficiency(11.7%-80.2%),with tunable zeta potentials in different PVA solutions.The CreNCs can delay release of Cr(III)and prolong the gelation time of HPAM up to 27 days.

Novel polyimide binder for achieving high-rate capability and long-term cycling stability of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode via constructing polar and micro-branched crosslinking network structure

LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)material,as the promising cathode candidate for next-generation highenergy lithium-ion batteries,has gained considerable attention for extremely high theoretical capacity and low cost.Nevertheless,the intrinsic drawbacks of NCM811 such as unstable structure and inevitable interface side reaction result in severe capacity decay and thermal runaway.Herein,a novel polyimide(denoted as PI-Om DT)constructed with the highly polar and micro-branched crosslinking network is reported as a binder material for NCM811 cathode.The micro-branched crosslinking network is achieved by using 1,3,5-Tris(4-aminophenoxy)benzene(TAPOB)as a crosslinker via condensation reaction,which endows excellent mechanical properties and large free volume.Meanwhile,the massive polar carboxyl(-COOH)groups provide strong adhesion sites to active NCM811 particles.These functions of PIOm DT binder collaboratively benefit to forming the mechanically robust and homogeneous coating layer with rapid Li+diffusion on the surface of NCM811,significantly stabilizing the cathode structure,suppressing the detrimental interface side reaction and guaranteeing the shorter ion-diffusion and electron-transfer paths,consequently enhancing electrochemical performance.As compared to the NCM811 with PVDF binder,the NCM811 using PI-Om DT binder delivers a superior high-rate capacity(121.07 vs.145.38 m Ah g^(-1))at 5 C rate and maintains a higher capacity retention(80.38%vs.91.6%)after100 cycles at 2.5–4.3 V.Particularly,at the high-voltage conditions up to 4.5 and 4.7 V,the NCM811 with PI-Om DT binder still maintains the remarkable capacity retention of 88.86%and 72.5%after 100 cycles,respectively,paving the way for addressing the high-voltage operating stability of the NCM811 cathode.Moreover,the full-charged NCM811 cathode with PI-Om DT binder exhibits a significantly enhanced thermal stability,improving the safety performance of batteries.This work opens a new avenue for developing high-energy NCM811 based lithium-ion batteries with long cycle-life and superior safety performance using a novel and effective binder.

Rational Design of Robust and Universal Aqueous Binders to Enable Highly Stable Cyclability of High-Capacity Conversion and Alloy-Type Anodes

The development of high-performance binders is a simple but effective approach to address the rapid capacity decay of high-capacity anodes caused by large volume change upon lithiation/delithiation.Herein,we demonstrate a unique organic/inorganic hybrid binder system that enables an efficient in situ crosslinking of aqueous binders(e.g.,sodium alginate(SA)and carboxymethyl cellulose(CMC))by reacting with an inorganic crosslinker(sodium metaborate hydrate(SMH))upon vacuum drying.The resultant 3D interconnected networks endow the binders with strong adhesion and outstanding self-healing capability,which effectively improve the electrode integrity by preventing fracturing and exfoliation during cycling and facilitate Li^(+)ion transfer.SiO anodes fabricated from the commercial microsized powders with the SA/0.2SMH binder maintain 1470 mAh g^(-1)of specific capacity at 100 mA g^(-1)after 200 cycles,which is 5 times higher than that fabricated with SA binder alone(293 mAh g^(-1)).Nearly,no capacity loss was observed over 500 cycles when limiting discharge capacity at 1500 mAh g^(-1).The new binders also dramatically improved the performance of Fe_(2)O_(3),Fe_(3)O_(4),NiO,and Si electrodes,indicating the excellent applicability.This finding represents a novel strategy in developing high-performance aqueous binders and improves the prospect of using high-capacity anode materials in Li-ion batteries.

Gelatin-based hydrogel functionalized with taurinemoieties for in vivo skin tissue regeneration

Functionalized hydrogels stimulate the migration and morphogenesis of endothelial cells(ECs)and are useful substrates for wound healing.The present study investigates the feasibility of covalent conjugation of taurine(Tau)on a gelatin-based hydrogel.This hydrogel is expected to maintain positive charged growth factors such as basic fibroblast growth factor(bFGF)and vascular endothelial growth factors(VEGFs)near ECs within the hydrogel microenvironment.The gelatin was conjugated with hydroxyl phenol(Ph)and Tau moieties,and in following that Ph residues were crosslinked through a horseradish peroxidase-catalyzed reaction.The migration characteristics of ECs were analyzed by scratch migration assay and microparticle-based cell migration assay.Cellular morphology and amounts of angiopoietin 1(Ang 1),bFGF,and VEGF proteins were evaluated for encapsulated cells.The potential of synthesized hydrogels in wound healing was assessed by the percentage of reduction from the original wound size and histopathological analyses of rat skin.The incorporated Tau molecules within the hydrogel remained stable through covalent bonds during incubation.During extended incubation,the gelatin-based hydrogel conjugated with Tau improved the migration distance and number of existing migrated ECs.Immobilized Tau within the gelatin-based hydrogel induced high motility of ECs,accompanied by robust cytoskeleton extension and a cell subpopulation that expressed CD44 and CD31 receptors as well as enhancement of Ang 1,bFGF,and VEGF.We found that injectable Gel-Ph-Tau effectively improves wound-healing parameters.

新型壳聚糖用于地下水中Pb^(2+)的吸附性能研究

利用聚乙二醇(PEG400)作为交联剂合成的壳聚糖材料,探讨Pb2+印迹量对吸附效果的影响,通过吸附动力学,吸附等温线等方面的研究,讨论其吸附的内在机理。研究表明印迹Pb2+质量占PEG-CTS质量4%的交联壳聚糖,去除率最高;吸附遵循准二级动力学模型,吸附速率为0.272 2 mg.g-1.h-1;在20℃,溶液pH为7的条件下,PEG-CTS对Pb2+的最大吸附容量为20.20 mg/g,平均吸附能量为13.12 kJ/mol;化学吸附为主。关键词:交联壳聚糖;聚乙二醇;地下水;Pb2+;