High Degree Of Crosslinking Research Articles

Layer-by-layer aided β-cyclodextrin nanofilm for precise organic solvent nanofiltration

Synthetic interlayers with multiple functions and structural stability have a high potential to construct novel thin film composite (TFC) membranes with demanding permselective property for precise separations. Herein, a functional interlayer derived from the polyelectrolyte-based layer-by-layer (LBL) self-assembly is reported to prepare interlayer engineered organic solvent nanofiltration (OSN) membranes using β-cyclodextrin (β-CD) as a monomer via interfacial polymerization (IP) process. Compared to the interlayer-free OSN membrane, a smoother selective layer with higher crosslinking degree is obtained for our developed membranes, enabling an improved organic dye rejection (e.g., 91.9% for methyl orange and 98.8% for brilliant blue R). Importantly, the LBL-aided β-CD nanofilm exhibits competitive permeances towards both polar (e.g., methanol, 5.8 LMH/bar) and nonpolar solvents (e.g., hexane, 7.0 LMH/bar). These performances can be attributed to the multiple roles of LBL-based interlayer as preventing the intrusion of selective layer and creating dual linkages (i.e., amide and ester), along with tailoring the physicochemical properties of caped β-CD nanofilm. Besides, the newly developed OSN membrane can discriminate between dye molecules with similar molecular weights and same charge but different molecular configurations. Meanwhile, its good structural integrity and long-term stability are also demonstrated by the 7-day filtration test using tetracycline in methanol and β-carotene in hexane, respectively, as evidence of constant solute rejections (≥90%) during the entire filtration process. This work unravels the functions of LBL-based interlayer in enhancing the OSN performance, offering new insights into shaping the development of interlayer engineered OSN membranes for real-life applications.

Development of high-performance electrospun nanofiber based forward osmosis membrane by introducing graphene oxide‑calcium carbonate particle composite intermediate layer

Interlayer construction is considered as an attractive strategy for optimizing the performance of electrospun nanofiber (ENs) based forward osmosis (FO) membranes due to its outstanding effect on the regulation of surface roughness and pore size on substrates. Herein, calcium carbonate (CaCO3) particles were uniformly coated on the surface of graphene oxide (GO) interlayer and acted as sacrificial materials to induce the formation of high-performance polyamide (PA) active layer. The presence of CaCO3 particles was effective for promoting the formation of more polyamide and tuning the microstructure of PA active layer, attributing to the reaction between CaCO3 particles and H+ ions generated from the interfacial polymerization (IP) process in which numerous CO2 nanobubbles were simultaneously released on the reaction interface. The formed PA active layer on the optimized FO membrane had a highly loose and crater-like structure as well as the highest cross-linking degree, providing the membrane with superior performance on both water flux and specific salt flux compared to other previously reported FO membranes supported on nanofibrous substrates. This work offered a new technique route for the fabrication of high-performance ENs-based FO membranes through constructing a composite interlayer having the direct regulatory function on the microstructure of PA active layer.

Construction of Al-Mg-Zn Interatomic Potential and the Prediction of Favored Glass Formation Compositions and Associated Driving Forces.

An interatomic potential is constructed for the ternary Al-Mg-Zn system under a proposed modified tight-binding scheme, and it is verified to be realistic. Applying this ternary potential, atomistic simulations predict an intrinsic glass formation region in the composition triangle, within which the glassy alloys are more energetically favored in comparison with their solid solution counterparts. Kinetically, the amorphization driving force of each disordered state is derived to correlate the readiness of its glass-forming ability in practice; thus, an optimal stoichiometry region is pinpointed around Al35Mg35Zn30. Furthermore, by monitoring the structural evolution for various (Al50Mg50)1−xZnx (x = 30, 50, and 70 at.%) compositions, the optimized-glass-former Al35Mg35Zn30 is characterized by both the highest degree of icosahedral ordering and the highest phase stability among the investigated compositions. In addition, the icosahedral network in Al35Mg35Zn30 exhibits a much higher cross-linking degree than that in Al25Mg25Zn50. This suggests that there is a certain correlation between the icosahedral ordering and the larger glass-forming ability of Al35Mg35Zn30. Our results have significant implications in clarifying glass formation and hierarchical atomic structures, and in designing new ternary Al-Mg-Zn glassy alloys with high GFA.

Metal-organic framework enables ultraselective polyamide membrane for desalination and water reuse.

While reverse osmosis (RO) is the leading technology to address the global challenge of water scarcity through desalination and potable reuse of wastewater, current RO membranes fall short in rejecting certain harmful constituents from seawater (e.g., boron) and wastewater [e.g., N-nitrosodimethylamine (NDMA)]. In this study, we develop an ultraselective polyamide (PA) membrane by enhancing interfacial polymerization with amphiphilic metal-organic framework (MOF) nanoflakes. These MOF nanoflakes horizontally align at the water/hexane interface to accelerate the transport of diamine monomers across the interface and retain gas bubbles and heat of the reaction in the interfacial reaction zone. These mechanisms synergistically lead to the formation of a crumpled and ultrathin PA nanofilm with an intrinsic thickness of ~5 nm and a high cross-linking degree of ~98%. The resulting PA membrane delivers exceptional desalination performance that is beyond the existing upper bound of permselectivity and exhibited very high rejection (>90%) of boron and NDMA unmatched by state-of-the-art RO membranes.

Fabrication of high performance nanofiltration membrane by construction of Noria based nanoparticles interlayer

Improving the permeability and selectivity of the thin-film composite (TFC) nanofiltration membranes is the key to energy conservation and emission reduction in water treatment. Nowadays, the construction of interlayer is an effective approach to improve the performance of TFC nanofiltration membranes, and the construction of interlayer is a much more effective approach, which can directly form an interlayer in the interfacial polymerization (IP) process. However, there are few studies on the construction of nanoparticles based interlayer, due to the stability problem of nanomaterial dispersion system. Herein, Noria and 2, 2′-benzidinedisulfonic acid (BDSA) were used to prepare a novel kind of stable nanoparticles system, which can be formed as Noria-BDSA nanoparticles interlayer for follow-up IP process. The TFC membrane with Noria-BDSA nanoparticles interlayer had a thin and crumpled polyamide layer, which can reduce the hydraulic resistance and improve the effective area during the separation process. Hence, the permeability of this TFC membrane (24.01 L m-2h−1 bar−1) was about 3.5 times that of the conventional TFC membrane. Furthermore, the polyamide layer of this TFC membrane had a higher crosslinking degree, which made it have a higher rejection than conventional one.

Mechanical property and dielectric spectra analysis of solvent-free poly(ionic liquid)/poly(ethyl acrylate) double network elastomers under tensile deformation

Solvent-free double network elastomers have excellent mechanical properties and stability. However, there are few studies on ion transport in solvent-free double network elastomers. In this paper, we prepared a kind of poly(ionic liquid) (PIL)-based solvent-free elastomer with double network structure by using crosslinked poly[2-(methacryloyloxy)ethyl] trimethyl ammonium bis(trifluoromethanesulfonyl) imine (P[VBTMA][TFSI]) network as brittle network and crosslinked poly(ethyl acrylate) (PEA) as stretchable network. The mechanical properties and the ion transport of samples as a function of elongation strain were investigated by stress-strain curves and broadband dielectric spectroscopy, respectively. The results show the double network elastomer has medium elastic modulus of 0.4–0.9 MPa, high elongation strain of 1700–2300% and ionic conductivity of 1.04 × 10−7 S·m−1 at room temperature. When the sample does not yield, stretching almost does not affect the ion transport in the network. As the strain exceeds the yield point, the conductivity relaxation time of the samples with low crosslinking degree of PIL network increases little, while the conductivity relaxation time of the samples with high crosslinking degree increases significantly. This is because the former network breaks uniformly, while the latter appears phase separation when yielding. The result improves the understanding of ion transport in double network polyelectrolyte elastomers.

Selective recovery of lithium from spent coin cell cathode leachates using ion imprinted blended chitosan microfibers: Pilot scale studies provide insights on scalability

We report an approach on specific and scalable recovery of lithium ions from coin cells using functionalized chitosan microfibers. Low swelling ratios and high degree of crosslinking resulted from a dual combination of blended viscosities and crosslinking. Owing to their defined structure (pore diameter: 2.29±0.31 µm; fiber diameter: 176.5±3.44 µm; ion exchange capacity: 8.45 meq/g), imprinted microfibers exhibited high lithium uptake potential (100 mg/g), high distribution coefficient (6969.7 mL/g) and high separation factors (90) in a multi-metal system generated from leachates (co-ions: Co(II), Ag(I), Mn(II), Cu(II), Al(III), Ni(II), Na(I), K(I) and Ca(II)). The uptake phenomena followed a homogeneous monolayer adsorption mode and a spontaneous endothermic nature (ΔG:-20.3 KJ/mol). High values of relative lithium sorbed (RLS) (>20) and relative lithium released (RLR) (>9) in case of imprinted microfibers suggested high selectivity. Batch conditions showed a selective recovery of 45.7%/g/L of leachates (< 50 cathodes) at pH of 6.1. However, packed bed column studies showed that 14.3 g of biosorbent could recover up to 99.1% lithium (recovered lithium of up to 971.19 mg/L) over 9 cycles (250 cathodes; CoLi: 976.33 mg/L). The present study suggested blended and imprinted chitosan microfibers as a useful matrix towards scalable lithium recovery.

Study on preparing of diallyl maleate modified acrylic resin

PurposeThere are three double bonds in the chemical structure of diallyl maleate. The purpose of this study is that the acrylate is modified with diallyl maleic anhydride to make the propionate resin present a spatial network structure, thereby improving the performance of the acrylate resin.Design/methodology/approachMethyl methacrylate (MMA) and butyl acrylate(BA) were used as were used as main monomers. Diallyl maleate (DAM) was used as crosslinking monomer and dodecafluoroheptyl methacrylate (DFMA) was used as fluoromonomer. Potassium persulfate (KPS) was used as thermal decomposition initiator, sodium lauryl sulfate (AS) and sodium dodecyl sulfonate (SDS) were used as anionic emulsifiers, and EFS-470 (Alkyl alcohol polyether type nonionic emulsifier) was a non-ionic emulsifier.FindingsThrough optimizing the reaction conditions, the uniform and stable latex is obtained. The polymer of structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and contact angle (CA) were tested on latex films. The particle size and distribution range of emulsion were tested with nano particle size analyzer.Originality/valueThe experimental results showed that the thermal decomposition temperature of the acrylic coating film increased by 20.56°C after modification. In addition, the effect of cross-linking density on the water contact angle of the fluorocarbon groups in DFMA when they migrate to the surface of the latex film during drying has been explored. The experimental results show that a higher degree of cross-linking will hinder the migration of fluorocarbon groups to the surface of the resin film.

Mechanical properties of rubber vulcanizates containing Ethylene Propylene Diene Rubber waste at different types of vulcanization system

Ethylene Propylene Diene Rubber (EPDM) waste filled Natural Rubber (NR) that cured by using conventional vulcanization (CV), semi-efficient vulcanization (semi-EV) and efficient vulcanization (EV) system was successfully compounded by an internal mixer. The ratio of sulphur and accelerator is different for each vulcanization system, that finally affect the vulcanizate properties due to the different structural features of an accelerated sulphur vulcanizate of NR. 60 phr of pulverized EPDM waste was incorporated into 40 phr of NR in each vulcanization system. Studies about the usage of abundantly available EPDM waste as a potential filler is essential towards green environment and minimize landfill area in future. It is found that the cured rubber with CV system has the best properties due to high degree of crosslinking of polysulphidic crosslink. Tensile properties and abrasion resistance of the rubber compound indicated its mechanical properties were investigated. Density and hardness test were also done to study its physical properties. For tensile strength, CV system has 14% increment from EV system because of a stress-relieving mechanism that exhibited in this vulcanization system. As for tensile modulus, M500 for CV system shown 29% increment than EV system. As a result of the decreased chain flexibility caused by the increased crosslinking density in the CV system, the elongation at break of the vulcanizate is the lowest (174 mm) when compared to the EV system (336 mm). CV system shown highest Abrasion resistance index (ARI) i.e. 1820%. This indicate that very small amount of mass loss obtained for the CV cured rubber during the testing. CV system gives highest density and hardness values i.e. 1.0747 g/cm3 and 52.5 Shore A, respectively. Thus, the results indicated that NR containing EPDM waste cured by CV system is able to be utilized in the development of rubber compound with a compromise property.

Design of adjustable hypercrosslinked poly(ionic liquid)s for highly efficient oil-water separation

Considering the environmental problems caused by oily wastewater, how to realize oil-water separation has attracted extensive attention from researchers. Herein, a series of hypercrosslinked poly(ionic liquid)s (HCPILs) were fabricated by using dimethoxymethane as an external crosslinking agent combined with different auxiliary crosslinking agents to “weave” the ionic liquid of 1,3-dibenzylimidazolium chloride for oil-water separation. The hydrophilicity and hydrophobicity of HCPL can be adjusted by changing different auxiliary crosslinking agents. When using aniline as an auxiliary crosslinking agent, the resulting HCPIL-A2 with approximately 5500 L/m2·h of water flux exhibits super hydrophilicity-oleophobicity, its static water contact angle and underwater oil contact angle are close to 0° and 132°, respectively. When using benzyl alcohol instead of aniline, the obtained HCPIL-B2 exhibits good lipophilicity and hydrophobicity. Its static water contact angle and underwater oil contact angle are close to 126° and 0°, respectively. And its oil fluxes of chloroform and carbon tetrachloride are approximately 7645 and 7241 L/m2·h, respectively. However, when using toluene instead of aniline, the obtained HCPIL-C2 exhibits hydrophilicity-lipophilicity and can’t separate the oil-water mixtures. Moreover, HCPILs show permanent pore structure, good stability, and environmental friendliness due to their high degree of crosslinking are constructed. Their loose surface roughness can realize the separation of the oil-water mixture by gravity. Therefore, the designed new materials can selectively remove water or oil mixture. Efficient separation of crude oil and seawater mixture will provide new ideas for future environmental problems such as offshore oil spills.

Peptidomic analysis of digested products of surimi gels with different degrees of cross-linking: In vitro gastrointestinal digestion and absorption

To investigate the cross-linking degree on the in vitro gastrointestinal digestion and absorption properties of surimi gel, three types of surimi gels with low, moderate, and high cross-linking degrees were prepared, and then in vitro digestion models (static and dynamic) and a Caco-2 cell monolayer model combined with LC-MS/MS were used to do peptidomic analysis of digestive and absorbed juices. The results showed that an increase in cross-linking degree promoted the release of peptides after gastrointestinal digestion. These peptides originated from the myosin head and rod, the rod was the main digestion region. More potential bioactive peptides from intestinal digestive juice could be transported through the intestinal epithelium. Compared with static digestion, dynamic digestion digested surimi gels more thoroughly, especially during gastric digestion. This study provides a theoretical basis and guidance for the production of surimi products with higher nutritional value and the in vitro digestion methods of gelatinous foods.

Influence of crosslinking in phosphoric acid-doped poly(phenylene oxide) membranes on their proton exchange membrane properties

Phosphoric acid (PA)-doped membranes are promising electrolytes for high-temperature proton exchange membrane fuel cells (HT-PEMFCs). However, long-term durability issues have been an obstacle to their commercialization. Herein, we report a series of poly(phenylene oxide) (PPO)-based crosslinked membranes containing quaternary ammonium (QA) groups and exhibiting enhanced physicochemical stability and PA retention via ion-pair interactions between QA and PA. The degree of crosslinking in PPO by diamine crosslinker was controlled at 20, 30, and 40. The membranes were also crosslinked (degree = 20) using diamine crosslinkers with variable alkyl chain length (ethyl, butyl, and hexyl). All membranes exhibited sufficient thermal stability (5% weight loss temperatures (TD5%) = ∼230 °C) and oxidative stability (∼85% in the Fenton test). The PA uptake of the resulting membranes was controlled between 110 and 154% depending on their crosslinked structures. The membrane with the lowest degree of crosslinking (20) and shortest crosslinker exhibited the highest PA uptake and highest anhydrous proton conductivity (0.043 S/cm at 150 °C) in doped state. The proton conductivity was found to be significantly influenced by the PA uptake and crosslinked membrane structures. The highest PA retention of 89% was exhibited by the PA-doped membrane with the highest degree of crosslinking (40).

Effect of the Crosslinking Degree on Self-Healing Poly(1,2,3-Triazolium) Adhesive.

Dynamic covalent materials are a class of polymer that could be stress-relaxation, reprocessable, and self-healing due to dynamic crosslinks in network. Dynamic crosslinks play an important role in the typical characteristic of self-healing polymers. It is meaningful to understand the effect of crosslinking degree on the properties of poly(1,2,3-triazolium) (PTAM). In this article, the dynamic covalent network of PTAM adhesive has been used to study the effect of crosslinking degree. A series of PTAM adhesive with different crosslinking degrees have been obtained by changing the amount of crosslinker. Adhesion property can first rise then fall down with the increase of crosslinking degree and the best lap-shear strength is above 20MPa. Creep resistance and solvent resistance can be enhanced with the increase of crosslinking degree. Self-healing studies have shown that crosslinking degree can enhance the ability of self-healing, but too high crosslinking degree raises the temperature of self-healing and causes side reaction which reduces the self-healing efficiency. These results provide some insights for the influence of the crosslinking degree on the self-healing and the structural design of dynamic covalent materials.

Effect of Thermal Pretreatments on Phosphorylation of Corypha umbraculifera L. Stem Pith Starch: A Comparative Study Using Dry-Heat, Heat-Moisture and Autoclave Treatments.

Talipot starch, a non-conventional starch source with a high yield (76%) from the stem pith of talipot palm (Corypha umbraculifera L.) was subjected to three different thermal treatments (dry-heat, heat-moisture and autoclave treatments) prior to phosphorylation. Upon dual modification of starch with thermal treatments and phosphorylation, the phosphorous content and degree of crosslinking significantly increased (p ≤ 0.05) and was confirmed by the increased peak intensity of P=O and P–O–C stretching vibrations compared to phosphorylated talipot starch in the FT-IR spectrum. The highest degree of crosslinking (0.00418) was observed in the autoclave pretreated phosphorylated talipot starch sample. Thermal pretreatment remarkably changed the granule morphology by creating fissures and grooves. The amylose content and relative crystallinity of all phosphorylated talipot starches significantly decreased (p ≤ 0.05) due to crosslinking by the formation of phosphodiester bonds, reducing the swelling power of dual-modified starches. Among all modified starches, dry-heat pretreated phosphorylated starch gel showed an improved light transmittance value of 28.4%, indicating reduced retrogradation tendency. Pasting and rheological properties represented that the thermal pretreated phosphorylated starch formed stronger gels that improved thermal and shear resistance. Autoclave treatment before phosphorylation of talipot starch showed the highest resistant starch content of 48.08%.

Preparation of liquid crystal-based molecularly imprinted monolith and its molecular recognition thermodynamics

液晶分子印迹聚合物(MIPs)因刚性液晶单体的加入而在超低交联度水平下也能印迹和识别模板分子,有效解决了传统MIPs因高交联度造成的位点包埋、结合容量低、传质慢等问题。尽管液晶MIPs具有如此独特的优势,但却面临着由于交联度的大幅度降低而导致印迹效果下降的问题。为了研究液晶MIPs的结合特性,制备具有良好印迹效果的低交联液晶MIPs,该文通过二次接枝聚合,制备了一系列不同交联度的液晶分子印迹整体柱,用高效液相色谱法研究了聚合参数与印迹整体柱亲和性的关系。实验中选用三羟甲基丙烷三甲基丙烯酸酯(TRIM)为交联剂,以甲苯和十二醇为致孔剂合成整体柱骨架,并在此基础上以(S)-萘普生为模板,加入液晶单体4-氰基苯基单环己基乙烯(CPCE)进行二次聚合接枝。实验中系统考察了流动相中乙腈比例及缓冲液pH值对色谱保留的影响,结果发现液晶单体的加入使得MIPs对萘普生保留控制机制由原来的氢键作用变为了疏水作用;通过动态吸附实验得到的突破曲线经前沿分析及对吸附等温线Langmuir、Freundlich和Scatchard分析拟合,发现交联度为15%时液晶MIPs印迹因子最大(3.78)、非均一性最强,且特异性吸附量高于非特异性吸附量。液晶MIPs的计量置换模型(SDM-R)分析表明,液晶印迹整体柱对模板分子的总亲和力(ln A=0.645)明显高于其类似物;而从空间匹配程度看,与液晶印迹整体柱空间匹配程度最高的是酮洛芬而非模板分子,但液晶印迹整体柱对酮洛芬的总亲和力(ln A=0.242)不及模板分子的一半,表明在本低交联液晶印迹系统中,空间效应不是决定印迹系统识别能力的主要因素。进一步的分离热力学研究发现,低交联液晶印迹柱的|ΔΔH|<T|ΔΔS|,而交联度为70%的非液晶MIPs柱的|ΔΔH|>T|ΔΔS|,表明液晶MIPs的分离过程是一个熵控制过程,而常规无液晶MIPs的分离过程是一个焓控制过程。上述结果表明,液晶单体的加入改变了MIPs的识别机制,适当的低交联度可显著提高液晶MIPs的识别性能,因此液晶MIPs这些特质有望使其成为新一代的MIPs。

Additive manufacturing of high-performance vinyl ester resin via direct ink writing with UV-thermal dual curing

Vinyl ester (VE) resin is widely used as a thermosetting polymer for structural materials because of its high mechanical properties and excellent chemical resistance. Using additive manufacturing to produce high-performance VE structures with dimensional scalability and material efficiency has gained interest from both research and industry, however it is challenging due to the limitations of current techniques. In this work, a modified setup of direct ink writing (DIW) with ultraviolet (UV)-thermal dual curing is made compatible with commercially available VE resins thickened by 4 wt% fumed silica to fabricate three-dimensional structures with outstanding mechanical properties. The in-situ UV curing during DIW partially solidifies the resin to provide the structural shape, and subsequent thermal curing allows for a high degree of crosslinking. The printed and dual cured VE nanocomposites have a Young’s modulus of 3.7 GPa and a tensile strength of approximately 80 MPa, which outperforms conventionally molded neat VE cured with methyl ethyl ketone peroxide (MEKP) by about 10% and also indistinguishable from the tensile properties of molded VE nanocomposites with the same composition. The fracture toughness of the printed and dual cured VE nanocomposites is also 16% higher than the molded neat VE with MEKP curing due to the superior interfacial bonding between DIW infill paths and the additional 4 wt% fumed silica for toughening, and similar to the molded VE nanocomposites with the same composition. Along with the outstanding mechanical properties, the scalability and resolution of the DIW technique with dual curing is demonstrated by printing a 100 mm long wrench and a microscale lattice, thus showing the potential of this technique in additive manufacturing of high-performance VE structures.

Structuring emulsion gels with peanut protein isolate and fish oil and analyzing the mechanical and microstructural characteristics of surimi gel

Herein, peanut protein isolate (PPI) and fish oil (FO) emulsion gels are fabricated and added to surimi gel, and their effects on the mechanical and microstructural characteristics of surimi gel are investigated. Emulsion gels consisting of PPI, FO, and water were treated using microbial transglutaminase (MTGase) and termed PPI-based emulsion gels (PEG). Next, surimi gel samples were prepared with PEG contents ranging from 4 to 16 wt%. Texture profile and rheological analyses indicated that compared with the control group obtained by the direct addition of FO, surimi gels with 4–8 wt% PEG showed a significant improvement in hardness, adhesiveness, and chewiness, and had a higher degree of crosslinking. Nevertheless, the color attributes of the surimi gels containing PEG were evidently lower than those of the control group owing to the emulsification in the protein–oil–water system. Moreover, at a concentration of 4–8 wt%, PEG uniformly filled the void spaces of the protein matrix and formed a firmer network structure, as revealed using scanning electron microscopy and confocal laser scanning microscopy. This study provides new sustainable perspectives for the application of PEG fabricated from PPI and FO as a fat substitute in food products.

The Use of Copper Oxides as Cross-Linking Substances for Chloroprene Rubber and Study of the Vulcanizates Properties. Part I.

The purpose of this work was to verify the ability to cross-link the chloroprene rubber (CR) by using copper oxides: copper(I) oxide or copper(II) oxide. The use of copper oxides arises from the need to limit the application of ZnO as a cross-linking agent of CR. The obtained results indicate that CR compositions cross-linked with copper oxides are characterized by good mechanical properties and a high cross-linking degree. The results show that the type and the amount of copper oxides influence the cross-linking of the CR and the properties of the vulcanizates. For compositions containing copper(II) oxide, the properties are linearly dependent on the amount of CuO. Such a relationship is difficult to notice in the case of the use of copper(I) oxide—when analyzing individual parameters, the best results are obtained for different samples. Infrared spectroscopy (IR) studies confirmed the possibility of cross-linking of chloroprene rubber with copper oxides. This is evidenced by the characteristic changes in the intensity of the bands. Structural changes in the material during heating were determined by the thermal analysis—differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Regardless of the type and amount of copper oxide, all compositions exhibit similar characteristics, and there are no significant changes in the glass transition temperature of the material.

Therapeutic hydrogel sheets programmed with multistage drug delivery for effective treatment of corneal abrasion

Corneal abrasion (CA) is a leading cause of inflammation, scar formation, and even loss of vision in the eye if allowed to progress; however, current treatments remain constrained by complex and sequential conditions that impede access to most therapies for progressively abraded corneas. Herein, an advanced therapeutic hydrogel sheet (THS) constructed via electrostatic assembly of a functional hydrogel and a ternary drug-carrier system is reported. Specifically, the functional hydrogel comprises a poly(hydroxyethyl methacrylate), a positively charged chitosan, and zinc oxide nanoparticles. The ternary drug-carrier system is composed of dipalmitoylphosphatidylcholine liposome (DPPC) nanoparticles containing epigallocatechin gallate (EGCG) and hyaluronic acid nanoparticles with low and high crosslinking degrees, which separately carrying β-1,3-glucan and SB431542. Owing to the tailored degradability of the ternary system, the THS is able to provide multistage drug release, consequently allowing successive drug administration onto an ocular surface afflicted with CA for the suppression of inflammatory response in the early stage (by the fastest released EGCG) of corneal tissue repair, followed by promotion of wound healing in the middle stage (the moderately fast released β-1,3-glucan) and prevention of scar formation in the final stage (by the slowest released SB431542). In a rabbit model of CA, the THS has a significant treatment efficacy for repairing injured cornea tissues and demonstrates a percent recovery of greater than 90%, which represents a more than eight-fold improvement compared to conventional eye drops. The therapeutic hydrogel material demonstrated here can adapt to a variety of drug molecules, opening up a new avenue for the treatment of complex ocular diseases.

MicroRNA-activated hydrogel scaffold generated by 3D printing accelerates bone regeneration

Bone defects remain a major threat to human health and bone tissue regeneration has become a prominent clinical demand worldwide. The combination of microRNA (miRNA) therapy with 3D printed scaffolds has always posed a challenge. It can mimic physiological bone healing processes, in which a biodegradable scaffold is gradually replaced by neo-tissue, and the sustained release of miRNA plays a vital role in creating an optimal osteogenic microenvironment, thus achieving promising bone repair outcomes. However, the balance between two key factors - scaffold degradation behavior and miRNA release profile - on osteogenesis and bone formation is still poorly understood. Herein, we construct a series of miRNA-activated hydrogel scaffolds (MAHSs) generated by 3D printing with different crosslinking degree to screened the interplay between scaffold degradation and miRNA release in the osteoinduction activity both in vitro and in vivo. Although MAHSs with a lower crosslinking degree (MAHS-0 and MAHS-0.25) released a higher amount of miR-29b in a sustained release profile, they degraded too fast to provide prolonged support for cell and tissue ingrowth. On the contrary, although the slow degradation of MAHSs with a higher crosslinking degree (MAHS-1 and MAHS-2.5) led to insufficient release of miR-29b, their adaptable degradation rate endowed them with more efficient osteoinductive behavior over the long term. MAHS-1 gave the most well-matched degradation rate and miR-29b release characteristics and was identified as the preferred MAHSs for accelerated bone regeneration. This study suggests that the bio-adaptable balance between scaffold degradation behavior and bioactive factors release profile plays a critical role in bone regeneration. These findings will provide a valuable reference about designing miRNAs as well as other bioactive molecules activated scaffold for tissue regeneration.