Meanwhile, an increase of sheath fluid rate could benefit an even better results, suggesting a clear process-property-performance relationship. The protocols reported here pave anew way for effective oral delivery of poorly water-soluble drug.The poor solubility of numerous drugs pose a long-existing challenge to the researchers in the fields of pharmaceutics, bioengineering and biotechnology. Many “top-down” and “bottom-up” nano fabrication methods have been exploited to provide solutions for this issue. In this study, a combination strategy of top-down process (electrospinning) and bottom-up (self-emulsifying) was demonstrated to be useful for enhancing the dissolution of a typical poorly water-soluble anticancer model drug . With polyvinylpyrrolidone (PVP K90) as the filament-forming matrix and drug carrier, polyoxyethylene castor oil (PCO) as emulsifier, and triglyceride (TG) as oil phase, Both a single-fluid blending process and a coaxial process were utilized to prepare medicated nanofibers. Scanning electron microscope and transmission electron microscope (TEM) results clearly demonstrated the morphology and inner structures of the nanofibers. The lipid nanoparticles of emulsions after self-emulsification were also assessed through TEM. The encapsulation efficiency (EE) and  Solubility of drug is one of the most important standpoints for developing drug delivery systems (DDSs) for oral administration, the most popular and convenient route for the patients . HoweverPaclitaxel (PTX) is one of the most representative anticancer drugs, and it is the most excellent natural anticancer drug . In 1963Self-emulsifying drug delivery system (SEDDS), as a kind of drug delivery system, has a history of more than 10 years . Self-emThe development of DDS also stimulates the development of raw material selection and the introduction of advanced techniques as pharmaceutical methods . ElectroHowever, there is very limited reports on the research to combine electrospinning with self-emulsifying methods to develop new types of drug delivery system. Thus, in the present study, both monolithic nanocomposites from the single-fluid blending process and core-sheath hybrids from the coaxial electrospinning were prepared and utilized as templates to manipulate the self-emulsifying processes. The encapsulation efficiency and drug release profiles were exploited to evaluate the self-assembled emulsions.Paclitaxel (PTX) was purchased from Shanghai Hao-Sheng Biotechnol. Co. Ltd. . Polyvinylpyrrolidone , polyoxyethylene castor oil , and triglyceride  were obtained from Shanghai Aladdin Biochemical Technology Co., Ltd. . Anhydrous ethanol was obtained from Sinopharm Chemical Reagent Co., Ltd. . Water was double-distilled just before usage.Four working fluids were prepared, which are included in The second sample was prepared using a coaxial electrospinning. A solution containing 3.22% (w/v) of drug and 8% (w/v) of PVP K90 was exploited as a core fluid. A solution containing 8% (w/v) of the emulsifier PCO, 5% (w/v) of the oil phase TG and 8% (w/v) of PVP K90 was exploited as a sheath fluid. The resultant core-shell nanofibers are denoted as S2, whose drug content is 10% (w/w). The third sample was similarly prepared using a coaxial electrospinning. A solution containing 5.56% (w/v) of drug and 8% (w/v) of PVP K90 was exploited as a core fluid. A solution containing 8% (w/v) of the emulsifier PCO, 5% (w/v) of the oil phase TG and 8% (w/v) of PVP K90 was exploited as a sheath fluid. The resultant core-shell nanofibers are denoted as S3, whose drug content is 10% (w/w).These arrangements are aimed to disclose the influences of two factors  on the self-emulsifying processes.The experimental apparatus was a homemade electrospinning system. A homemade concentric spinneret was exploited to conduct both the single-fluid electrospinning for preparing S1 and also the coaxial electrospinning for fabricating S2 and S3. To keep a continuous and stable working process, the applied voltage values during the fabrication was between 12 and 14 kV. The deposition distance was fixed at 15 cm. The environmental parameters included a room temperature of 25°C ± 2°C and a relatively humidity of 51% ± 6%. The collected fibrous films were placed in a dryer to a constant weight, and then were folded and sealed in a self-sealing bag for preservation.The fibrous films were cut into small patches, which were fixed on the double-sided conductive adhesive. After sprayed with Pt under a nitrogen atmosphere for 60 s, the samples were assessed using a scanning electron microscope . The nanofibers’ sizes were estimated on the SEM images through about 100 places using the ImageJ software .The inner structures of the prepared nanofibers S1, S2, and S3 were evaluated using a transmission electron microscope . The samples were collected by placing the copper grid-supported carbon films above the collectors for 2 min to collect some nanofibers.A weight of 100 mg fibrous samples was placed into 500 ml water to observe the self-emulsifying processes. The resultant liquids were semitransparent emulsions. The average hydrodynamic diameter and size distribution were assessed using BI-200SM static and dynamic light scattering instruments .Meanwhile, a millimeter of the self-assembled emulsion was diluted 10 times, and a drop of the diluted emulsion was dripped on the carbon films supported by 200 mesh copper grids. After naturally dried in the open air, the samples were assessed using the TEM as the above-mentioned manner.Ws, μg/ml) was measured using a UV-vis spectrophotometer  at 228 nm (the maximum absorption peak). A volume of 10 ml emulsion was mixed with 10 ml anhydrous ethanol for releasing all the loaded PTX through demulsification. The general PTX concentration  in the self-emulsified liquids could be determined.The supernatant of 10 ml self-assembled emulsion was separated from drug-loaded lipid particles by ultra-centrifugation. The free PTX concentration in the supernatant . An amount of 5.0 mg PTX raw powders were also investigated as a control. The dialysis sac was then dialyzed in 100 ml of phosphate buffer solution  at a constant temperature of 37°C and a stirring rate of 50 rpm. At predetermined times, the PBS was removed and replaced with the same volume of fresh PBS solution. The amount of drug released was determined by UV-vis spectrophotometer, as mentioned above. Released studies were conducted three times, and mean values were plotted against time.In general, SEDDS is an anhydrous pre-nanoemulsion dosage form, which mainly contain isotropic mixtures of oil, surfactant, co-surfactant, drug and polymer molecules traditionally . When inAlthough electrospinning is facile to implement, its process can be improved from several aspects such as the capability of creating complicated nanostructures, production on a large scale, creation of novel functional nanofibers and energy-saving . Shown iA digital picture about the homemade spinneret is given in The TEM images of the three kinds of nanofibers are included in The TEM observations about the nano emulsion particles assembled from the three sorts of nanofibers are included in Similarly, the particles self-assembled from the core-sheath nanofibers S2  and thosThe particle size and size distribution of self-emulsified particles were tested by the dynamic light scattering. The results are included in It can be seen from The small emulsion particles need to pass through the gastrointestinal mucosa for the final adsorption for oral administration. Thus, in general, the smaller the particle size is, the easier it is to be absorbed by the body; and the smaller the particle size, the more the number of particles can pass through, thereby the higher the content of the drug absorbed by the human body. One of the reasons is that when the diameter of the fiber is smaller, its specific surface area is larger, and it can disperse quickly and well when it contacts with water. Another reason is due to the physical and chemical properties of the components themselves, which have an effect on the diameter of the electrospun nanofibers. In this study, the aim is to disclose the influences of different kinds of electrospun inner structures  on the self-emulsifying. As for how to manipulate the diameters of nanofibers, and in turn the size of self-assembled particles, they will be investigated in another study, where modified coaxial and modified triaxial electrospinning with outer fluids of pure solvents will be exploited.2 = 0.99755), where A represents the absorbance of PTX at 228 nm and C represents the PTX concentration in the sample solutions (μg/ml). The measured contents from the self-emulsified emulsions for the nanofibers S1, S2, and S3 are 10.15 ± 0.27%, 9.76 ± 0.42%, and 9.81 ± 0.34%, respectively. These values are closely with the theoretical calculation data, i.e., 10% PTX in the solid nanofibers, suggesting that the electrospinning can completely encapsulate the PTX into the nanofibers, regardless of a single-fluid or a coaxial process. The reason is that the electrospinning is just a physical drying process, and the drying rate is extremely fast. Meanwhile, the drug PTX is stable without sublimation property. Thus, there is no any loss of PTX during the different electrospinning procedures.The standard curve of PTX for UV-vis spectroscopic measurements was A = 2.6801C-0.0137 , i.e. the ratio of drug encapsulated into the emulsion particles during self-emulsification, are 77.9%, 88.4% and 91.7% for S1, S2, and S3, respectively. The monolithic nanostructure of S1 released the most PTX to the environment. This is because of the homogeneous distribution of PTX all over the nanofibers S1, which means that there were many PTX molecules were distributed on the surface of S1. These molecules were easy to free into the environment during the formation of emulsion particles during the self-emulsification processes. In sharp contrary, the core-shell nanostructures S2 and S3 have no PTX on the surfaces. All the PTX molecules were located into the core section of nanofibers. Thus, during the self-emulsifying processes, the sheath components TG and PCO are easy to assemble around the PTX to form the emulsion particles. Meanwhile, the thicker the sheath section is, the better the encapsulation effect has. Thus, core-shell fibers S3 has a slightly higher value of 91.7 than S2 of 88.4%.in vitro dissolution tests are included in The results from the In order to reveal the drug release mechanism of PTX from the self-emulsified particles, Peppas Eq. Q is the accumulative drug release percentage when the time is t, k, and A are constant values, and the index n is an important parameter to indicate the drug release mechanism. When n < 0.45, it indicates that the drug is released through the typical Fickian mechanism; when n > 0.89, it indicates that the drug is released through the skeleton dissolution mechanism; when n is between them, it indicates that the drug is released through the mixed mechanism. It can be seen from n for nanofibers S1, S2 and S3 are 0.23, 0.27, and 0.32 respectively. All these values are smaller than the critical value of 0.45, indicating that the typical Fickian mechanism has played its role in manipulating the PTX molecules release from the self-emulsified particles in the emulsions.In the equation, A diagram showing the engineering mechanism on a molecular scale of the electrospun nanofibers-based SEDDS is proposed in When these nanofibers are placed into water, the soluble polymeric matrix will absorb water, swell, disentangle, and free into the bulk solution. During these processes, the anchored insoluble molecules such as PTX, PCO and TG will free from the polymeric restriction but within the confined region regulated by the nanofibers’ diameter. The hydrophobic interactions between themselves and from the surrounding water molecules will promote the self-aggregation to form the emulsion particles. These emulsion particles not only enhance the dissolution of PTX, but also benefit a useful trans-membrane for adsorption with smaller gastrointestinal irritation. The cytotoxicology tests and animal experiments of these nanofiber-based SEDDS will be further conducted in future.In this nano era, more and more “top-down” and “bottom-up” techniques are developed for bioengineering and biotechnology, accompanied with a series of novel functional materials such as hydrogels and new types of polymers  and evenin vitro dissolution tests suggested that the functional performances have an order of S1 ˂ S2 ˂ S3. A core-sheath structure is a better template for manipulating self-emulsifying than the monolithic nanofibers. Meanwhile, the thickness of the sheath section in the core-sheath structure can generate a positive influence on the self-emulsified emulsions, which can be facilely tailored by the sheath fluid flow rate during the preparation process. The protocols reported here pave a new way for effective oral delivery of poorly water-soluble drug.In this study, PVP K90 was used as a filament-forming matrix and meanwhile a carrier of oil phase, emulsifier and insoluble model drug for preparing SEDDS using both a single-fluid blending and two coaxial electrospinning processes. Electrospun monolithic nanofibers S1 and core-sheath nanofibers S2 and S3 were loaded with a fixed PTX content of 10%. These nanofibers are demonstrated to have the linear morphology and homogeneous or cores-sheath structures through the assessments of SEM and TEM. The TEM and SDLC experiments were conducted to characterize the self-emulsified emulsions. The particles’ sizes self-assembled from S1, S2, and S3 are 83.35 nm, 95.96 and 102.00 nm, respectively. The evaluation of EE and


They had similar inhibitory activities, with IC50 values of 29.6 ± 0.5, 33.4 ± 0.8, and 27.3 ± 0.4 μM, respectively. Their respective Ki values of 26.9, 46.8, and 44.5 μM—determined by enzyme kinetics—indicated that they inhibited the catalytic reaction by binding noncompetitively with sEH. The application of computational chemistry to the in vitro results revealed the site of the receptor to which the ligand would likely bind. Accordingly, three alkaloids were identified as having a suitable basic skeleton for lead compound development of sEH inhibitors.The quaternary isoquinoline alkaloids of palmatine ( Epoxyeicosatrienoic acids (EETs) produced by the epoxidation of olefinic bonds of arachidonic acid by the epoxygenase CYP enzymes exist in four regioisomeric forms, i.e., 5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET. They are endothelium-derived hyperpolarizing factors used to treat ischemic injury and have anti-inflammatory activity . sEH conPalmatine chloride (SMB00472) and berberine chloride (B3251) were purchased from Sigma–Aldrich . Jatrorrhizine chloride (6681-15-8) was purchased from Aba Chem Scene . sEH (10011669), AUDA (479413-70-2), and 3-phenyl-cyanomethyl ester-2-oxiraneacetic acid  were purchased from Cayman Chemical .The sEH assay was performed as described previously, with minor modifications . To deteΔC and ΔI are the difference of the solvent and compound intensities, respectively, after about one hour and0 is the minimum value along the y-axis, a is the difference between the maximum and minimum values, and b is the x value at 50 percent of the “a” value.sEH inhibition activity was calculated using2O and 4-cyano-N-[-2-phenylcyclopropyl]benzamide were then excluded from the A-chain. The A-chain was added to hydrogen using AutoDockTools ; the Gasteiger charge model was then applied. Flexible ligand docking was achieved using a torsion tree, with detection of the torsion root and rotatable bonds. The grid box was set to a size of 126 × 126 × 126 at 0.375 Å. Molecular docking was achieved via a Lamarckian genetic algorithm with the maximum number of evaluations. The resulting values were calculated and presented using AutoDockTools, Chimera 1.14 , and LIGPLOT  software.Molecular docking was performed as described previously, with some modifications . To dock–) anions. The energy minimization was stabilized to 10.0 kJ/mol using steepest descent minimization. The inhibitor–sEH complex was sequentially energy-minimized to constant temperature, constant volume (NVT) and constant temperature, and constant pressure (NPT) at 300 K using the particle mesh Ewald method with long-range electrostatics at 1 bar and MD simulation for 30 ns.Molecular dynamics (MD) was performed using the Gromacs 4.6.5 package . The 3D 1), berberine (2), and jatrorrhizine (3)  was used to evaluate inhibitory activities toward sEH of the quaternary isoquinoline alkaloids palmatine (zine (3) .50 value according to Equation (2) in Materials and Methods. The inhibitory activities of the three alkaloids (1–3) were thus calculated from their respective IC50 values of 29.6 ± 0.5, 33.4 ± 0.8, and 27.3 ± 0.4 μM in a dose-dependent manner. The positive control was AUDA  in Materials and Methods and the inhibition rate of the compound at concentrations of 6.2–100 μM was derived from the ICwas AUDA .v0) of inhibitor was determined as the rate of enzymatic conversion from substrate to product depending on the concentration of inhibitor at the start of the enzymatic reaction. The results were visualized using classic double-reciprocal Lineweaver–Burk plots. Km and four 1/Vmax values for the three inhibitors, which inhibited the catalytic reaction of sEH with PHOME in a noncompetitive manner. Furthermore, Dixon plots showed that alkaloids (1–3) had inhibition constant (ki) values of 26.9, 46.8, and 44.5 μM, respectively . The pdb files of sEH and the inhibitor were prepared and docking was simulated using the AutoDock ver. 4.2 package. The binding location between the three noncompetitively coupled inhibitors was identified via blind docking while setting the grid. 1–3) bound into the pocket surrounded by Pro379-Asn431, Glu494-Val500, and Cys522-Tr525 amino acids (left pocket) in sEH with similar AutoDock scores of −8.96, −9.14, and −8.82 kcal/mol, respectively . Inhibitor 3 formed hydrogen bonds with Lys495 and His524 amino acids at distances of 2.81 and 2.79 Å, respectively  pattern, while those interacting with compound 2 showed a slightly different RMSF pattern. In particular, compound 1 exerted an effect on amino acids in the 500th range, leading to a change in RMSF value of ~4.5 Å. In contrast, compound 2 did not have a significant effect  have sufficient activity against sEH. Enzyme kinetics and molecular simulations confirmed that these inhibitors bind to the small pocket on the left , rather than to the active site where substrates bind. However, synthetic inhibitors of the urea type were stably bound to the active site of sEH by computational chemistry [Alisma orientale also bound to sEH with a low energy value by CDOCKER [H-tomentosin, xanthalongin, and linoleic acid isolated from Inula helenium products can form a complex by bonding with Tyr343, ILe363, Tyr383, and His524 of the active sites [However, a similar study of alkaloid inhibitors from natural plants has not been reported until now; this research established that the three quaternary isoquinoline alkaloids  of the A ring. Molecular dynamic experiments confirmed that this difference may affect the mechanism of binding between the ligand and receptor. In particular, inhibitor 2—which was more rigid than compounds 1 and 3—showed a tendency to maintain binding in the vacant space of the active site rather than relying on a fluid enzyme loop. Accordingly, the RMSF value of compound 2 displayed a relatively small change in the RMSF value compared with compounds 1 and 3.The three compounds, which had similar inhibitory activity against the catalytic reaction with enzyme, differed only in the functional group , berberine (2), and jatrorrhizine (3)—which are found in a medicinal plants—displayed inhibitory activity toward sEH in vitro with IC50 values of 29.6 ± 0.5, 33.4 ± 0.8, and 27.3 ± 0.4 μM, respectively. Enzyme kinetics studies and molecular simulations established that they inhibited catalytic reaction by binding to the left pocket , of the active site of sEH as noncompetitive inhibitors. Isoquinoline quaternary alkaloids will play an important role in the development of new sEH inhibitors.Palmatine (


The paper describes the effect of the addition of alumina nanofibers on the mechanical properties of the epoxy resin. Alumina nanofibers functionalized with epoxypropyl functional groups are used in this work. The dependence of the mechanical characteristics on the amount of the additive, as well as the features of its distribution in the material, is investigated. In the work, nanocomposites were obtained, which are epoxy resin with aluminum oxide nanofibers. The mechanical properties of the samples were studied by bending tests and differential mechanical analysis (DMA). It has been shown that the addition of alumina nanofibers leads to an increase in ultimate flexural strength. The maximum of this increase is near the percolation threshold of alumina nanofibers in epoxy resin. With the addition of 0.2% alumina nanofibers, the ultimate flexural strength increases from 41 to 71 MPa. It is shown that after exceeding the percolation threshold of nanofibers, the ultimate strength decreases. In this case, the elastic modulus increases from 0.643 to 0.862 GPa. DMA is shown that the glass transition temperature decreases with increasing amount of the additive. This indicates a decrease in the molecular weight of the polymer. By implication, this suggests that the hardener connects the epoxypropyl functional groups on the nanofibers and the epoxy groups in the resin, and as a result of this process, the nanofibers become natural polymer chain length limiters. The data obtained from mechanical testing and differential mechanical analysis can be used to strengthen epoxy resins in polymer composite materials and molding compositions. Epoxy resins are an important basis for polymer composite materials . Modern In at least some notable examples, solutions of such highly anisometric particles are known to exhibit significant deviations from Raoult’s law, even going so far as to allow an anisotropic phase to separate from a solution in which the particles occupy no more than 1–2% of the volume of the suspension . This leAn important anisometric additive is alumina nanofibers , which iIn general, nanoalumina additives are a well-known strengthening additive. In ceramics, the additive cements and strengthens products . In metaIn most works, isometric compact additives of alumina nanoparticles are used. However, it is very interesting to study how fiber additives affect the properties of materials. It is clear that in addition to dispersion strengthening, the form of the additive will also provide some reinforcement of the material. The purpose of this work is to strengthen the epoxy resin with the addition of alumina nanofibers. For this, alumina nanofibers functionalized with epoxypropyl functional groups are used in this work. The mechanical properties of samples with different proportions of additives in the resin are studied. As well as the morphology of the distribution of nanofibers in the material.Alumina nanofibers were obtained from ENAW-1199 aluminum using the molten aluminum oxidation technology , similarAlumina nanofibers was coated with epoxypropyl functional groups for better affinity with the epoxy resin. For this, alumina nanofibers were treated in a solution of 3-glycidyloxypropyltrimethoxysilane  in toluene . For this silanization, 15 g of alumina nanofibers was taken and dried at a temperature of 140 °C in a ShS-40-02 SPU drying oven for about 8 h in order to remove all adsorbed water from the surface, and at the same time to preserve hydroxyl groups in the surface structure. Then, the nanofibers were dispersed in toluene using an overhead stirrer based on the SGR-1 YHCHEM reactor, with a stirring speed of 1000 rpm for 90 min. Next, the suspension was heated to 80 °C with stirring at 600 rpm for 40 min. The silane was added to the obtaining dispersion in the amount of 7 g. After stirring the mixture for an hour, it was cooled, rinsed with toluene, and decanted. Toluene residues were removed by drying at a temperature of 120–140 °C in a drying oven for 8 h.Alumina nanofibers were added to 180 g of epoxy resin in an amount of 0.12; 0.36; 0.9; 1.8; 3.6 and 7.2 g, then stirred with an OVS-S05 overhead stirrer  for 15 min at 300 rpm, then sonicated  for 5 min. Then the mixture was again alternately stirred mechanically and sonicated. In total, the mixture was treated alternately with a stirrer and ultrasound three times. The resulting suspensions were mixed with 90 g of a hardener, placed into a mold, and evacuated in a desiccator for a 24 h at a residual pressure of 1 mbar. Then the obtained samples were annealed in a ShS-40-02 SPU drying oven at a temperature of 180°C with a heating rate of 1 °C/min. As a result, six samples of nanocomposite material were obtained with a concentration of alumina nanofibers of 0.05; 0.2; 0.5; 1; 2; 4 wt.% and a reference sample without the addition of alumina nanofibers.The flexural strength was tested according to the method, ISO178:2010. The test bench used was an Instron 3369 testing machine . Maximum load 5 tons. The measurement accuracy was about 3%. Linear characteristics were measured using an fit digital caliper with measurement error 0.05%. Nanocomposite materials with different concentrations of alumina nanofibers in the resin were tested. From each nanocomposite material, a series of five plates with dimensions of 3 mm × 10 mm × 35 mm was cut out by circular saw with diamond blade and liquid cooling. Samples were cut out from those parts of the casting where there was no shrinkage gap. Each sample was tested on the test bench and the average value of all tests in each sample was taken as the nanocomposite material test result.A thermomechanical study of the viscoelastic properties of the samples was conducted using a dynamic mechanical analyzer Q800 . The studies were carried out according to ISO 6712:1996  and ISO 6721-11:2012 . Measurement of storage modulus (E’) of a sample was carried out using a 3-point bending clamp and a linear temperature scanning in the heating mode from 30 to 200 °C at a 5 °C/min rate. The frequency of dynamic loading of the sample was 1 Hz and the relative deformation was less than 0.1%. The samples were investigated in the form of plates with a size of 30 mm × 12.5 mm × 0.65 mm.The microstructure of the composite films’ cross-sections was studied using scanning electron microscopy  and transmission electron microscopy . For scanning electron microscopy (SEM), the pre-treated samples were coated with a thin conductive layer of platinum  using an EM ACE200 low vacuum coating system . For transmission electron microscopy (TEM), the samples were processed Leica EM UC7 ultramicrotome was used to obtain ultrathin sections.In this work, chip sections of epoxy resin with the addition of alumina nanofibers was studied. SEM shows the characteristic wrinkle texture , the lower, the greater the amount of additive in the polymer. A similar dependence is observed in the graphs for the peaks (Tmin dE/dT) of the storage module temperature derivative.Differential mechanical analysis allows a more fine-grained study of the substructure of nanofibers in a polymer and provides a rich set of data . The depThe main data from the graphs are summarized in It is clear that the drop in the storage modulus with the addition of alumina nanofibers compared to pure resin is associated with the dispersion of elastic stresses on the inhomogeneities of the nanocomposite material. Indeed, the addition of aluminum oxide nanofibers up to the percolation threshold (0.05%) has the largest loss tangent during the transition to the elastic state, since the scattered nanofibers introduce inhomogeneity into the material. That is, losses occur due to the inhomogeneity of the polymer material and the additive. Losses during the transition to the elastic state of nanocomposites are generally higher than those of pure resin.The decrease in the glass transition temperature, expressed as a decrease in the temperature of the peaks of the mechanical loss tangent and the derivative of the storage modulus, indicates that with an increase in the number of alumina nanofibers the molecular weight of the polymer, and, consequently, the chain length, decreases. This directly indicates that during the curing of the resin, the polymer chain is terminated due to the presence of nanofibers. By implication, this suggests that the hardener connects the epoxypropyl functional groups on the nanofibers and the epoxy groups in the resin, and as a result of this process, the nanofibers become natural polymer chain length limiters. Here, it should also be noted that the addition of alumina nanofibers does not significantly increase the number of epoxy groups in the resin, since the epoxypropyl groups on the surface of the nanofibers are about 12% , and theThe storage modulus above the transition temperature is higher than the viscosity state in a pure sample than with any addition of alumina nanofibers due to dissipative processes due to the inhomogeneity of the material. However, the storage modulus of the sample after the percolation threshold (0.5%) is maximum. This can be explained by the highest uniformity of the integral substructure of the nanofiber. The formation of an integral substructure of nanofibers also has a close value for the storage range for samples with readings of 0.5; 1 and 4% nanofibers. In these samples, the resistance is determined precisely by the substructure of the nanofiber. The reproducible deviation from this generality of samples with 2% additive in the resin is most likely due to the production of highly heterogeneous samples.The low temperature peaks in the storage modulus derivative plot are associated with residual low molecular weight components in the resin.The paper shows the dependence of the mechanical characteristics of epoxy resins on the amount of addition of alumina nanofibers. The maximum ultimate bending strength falls on the amount of additive close to the percolation threshold. The ultimate flexural strength increases from 41 MPa to 71 MPa with the addition of 0.2% alumina nanofibers. In this case, the elastic modulus increases from 0.643 to 0.862 GPa. It is the formation of an integral homogeneous substructure of nanofibers that leads to the maximum strengthening of the polymer. A further increase in the amount of the additive leads to the formation of nanofiber agglomerates and the appearance of inhomogeneities in the nanofiber substructure. The technique of introducing alumina nanofibers into epoxy resin makes it possible to uniformly distribute alumina nanofibers at low additive concentrations.Based on the presence of epoxypropyl functional groups on the surface of alumina nanofibers, there the hardener crosslinks them with the resin molecules are assumed. This is indirectly indicated by a decrease in the glass transition temperature of the nanocomposite with an increase in the amount of the additive. The morphology of the distribution of the additive and the interface between the nanofibers and the resin shows a high affinity between the polymer matrix and the epoxypropyl-coated alumina nanofibers.The data obtained can be used to strengthen epoxy resins in polymer composite materials and casting polymer compositions.Obtained nanocomposite samples with different concentrations of alumina nanofibersThe effectiveness of the use of alumina nanofibers with functionalized epoxypopyl groups has been shownTo strengthen the epoxy resin from 41 to 71 MPa in bending and from 0.643 to 0.862 GPa, 0.2 wt% of alumina nanofibers is sufficientThe dependence of the mechanical characteristics of the samples on the proportion of the additive was obtainedIt is shown that with an increase in the number of alumina nanofibers, the glass transition temperature decreasesAs a result, we can formulate the main highlights of the work:


The effect on the S−PANi distribution, surface morphology, thermal stability, gel content, and structural change after varying the PEG molecular weight of the polyurethane matrix was analyzed. Quasi-solid-state electrolytes were prepared by immersing the polyurethane matrix into a liquid electrolyte and the polymer matrix absorbency, conductivity, and ion diffusion were investigated. The formulated quasi-solid-state electrolytes were applied in dye-sensitized solar cells and their charge recombination, photovoltaic performance, and lifespan were measured. The quasi-solid-state electrolyte with a PEG molecular weight of 2000 gmol Dye-sensitized solar cells (DSSCs) are a promising renewable energy source due to their low manufacturing cost, ease of fabrication, and high efficiency . ConventThe use of polymer matrix-based quasi-solid-state electrolytes seems to have a great potential for solving the penetration and ion diffusion problems. This is because the liquid electrolyte (high ion diffusivity and penetrability) absorbed inside the polymer matrix penetrates the dye-sensitized semiconductor layer when squeezed during the DSSC assembly process. Numerous polymers have been studied as the polymer matrix for quasi-solid-state electrolytes in the DSSCs, such as polyacrylic acid ,13,14,15PAA is a superabsorbent. However, it is not a good absorbent when it is used as the liquid electrolyte of the DSSCs. This is because PAA consists of the −COOH group, whereas the common solvent for the liquid electrolyte  consists of the –C=O, C–O–C or –CN group. To improve the liquid electrolyte absorbency, PAA was grafted with polyethylene glycol ,10,11,12−4 to 10−3 Scm−1) [PVDF attracts attention due to its high dielectric constant, good electrochemical stability in the presence of titanium dioxide and platinum, good affinity towards the liquid electrolyte because of the electron-withdrawing fluorine atoms in the polymer backbone, and it is conductive at room temperature (103 Scm−1) ,19,32. H3 Scm−1) ,33. Ther3 Scm−1) ,35,36, a3 Scm−1) ,37. The 3 Scm−1)  and from3 Scm−1) . −/I3−) in the liquid electrolyte. It also has high segmental motion which facilitates the mobility of ions. The hard phase of the PU distributed or interconnected throughout the soft phase acts as a physical crosslinker and filler to the soft phase and contributes to the dimensional stability of the polymeric matrix [Polyurethane (PU) attracts attention due to its ability to absorb liquid electrolytes. PU has a unique structure due to its two-phase morphology, i.e., soft and hard segments. The main components in PU are polyol and isocyanate compounds. The soft segment is contributed by polyol, whereas the hard segment is from an isocyanate compound. In PU electrolytes, the soft phase acts as a polymeric solvent to solvate the redox couple  of PU on the performance of the formulated quasi-solid-state electrolyte  and the DSSC .There is no study reporting on the effect of the polyol molecular weight on the performance of the DSSCs. For the DSSCs based on the polymer matrix’s quasi-solid-state electrolyte, the absorbency of the polymer matrix towards the liquid electrolyte is a key factor that affects the DSSC performance. The polyol molecular weight of the PU matrix strongly affects the polymer matrix absorbency. Therefore, the novelty of this study is the investigation of the effect of the polyol (polyethylene glycol) molecular weight , sodium iodide (NaI), iodine (I2), propylene carbonate (PC), polyethylene glycol (PEG) with a molecular weight of 10,000, 8000, 6000, 4000, and 2000 gmol−1, 4,4′-diphenylmethane diisocyanate (MDI), 96% ethanol, and iso-propanol (IPA) were purchased from Merck. Titanium dioxide , 4-phenyl-polyethylene glycol (Triton X-100), Di-tetrabutylammonium cis-bis(isothiocyanato)bis ruthenium (II) (N719), chloroplatinic acid hexahydrate (H2PtCl6·6H2O), and a fluorine-doped tin oxide coated glass slide (FTO) were purchased from Sigma-Aldrich, Melbourne. Nitric acid, 69%  for 2 days. The label and formulation of the formulated polymer matrices are shown in To prepare the quasi-solid-state electrolyte, S−PANi was synthesized via the post-modification method . The pre2 paste was prepared by mixing 0.25 g of TiO2, 1.25 mL of HNO3 (0.1 M), 0.13 g of PEG 20,000, and 20 µL of Triton X for 15 min. After that, the TiO2 paste was coated onto the FTO glass and sintered at 450 °C for 60 min. Then, it was immersed in N719 solution (0.035 wt% of N719 in ethanol) for 24 h. To prepare the platinized counter electrode: 20 µL of H2PtCl6 (H2O)6 solution (0.5 wt% of H2PtCl6 (H2O)6 in IPA) was dropped onto the conductive side of the FTO glass and sintered at 450 °C for 45 min. To prepare the DSSCs: a slice of the formulated electrolyte (0.125 cm2) was sandwiched in between the prepared photoanode and the platinized counter electrode. A simulator was set up to measure the photovoltaic performance of the DSSCs. The simulator was equipped with a metal-halide lamp [−2. The solar irradiation was calibrated with a power meter . The photovoltaic performance of the DSSCs was measured from 0 V to 1 V at a scan rate of 10 mVs−1.The preparation of the DSSCs was divided into three parts, which included the photoanode, electrolyte, and counter electrode ,12,19,48ide lamp ,50,51,52−1 from 30 °C to 600 °C [b is the bulk resistance. The ion diffusion coefficient (Dff) measurement was performed by the cyclic voltammetry method using the GSTAT101 (Autolab) with a scan rate of 50 mV that ranged from of −0.8 V to 0.8 V [ff was calculated using the Randles–Sevcik equation as shown below:p is the maximum current; n is the number of electrons transferred in the redox event; v is the scan rate; A is the electrode area; and C is the concentration of the electroactive species. The gel content test was conducted to measure the crosslinking degree of the sample. The sample was prepared according to the ASTM D2765-95. This method is used with standard procedures by refluxing the samples in boiling xylene for 24 h. The sample was placed in 100 mesh cages, labeled, and weighed. After refluxing in xylene, the residual solvent was removed at a temperature of 140 °C and placed for 4 h in an oven. The cages were removed, allowed to cool, and reweighed. The gel content was calculated as:1 is the weight of the mesh cage, W2 is the weight of the mesh cage and sample, W3 is the weight of the stapled cage and sample, and W4 is the weight of the stapled cage and sample after extraction and drying. The dark current measurement was conducted to measure the charge recombination of the DSSC [−1. The data were collected by the Autolab PGSTAT101 with NOVA software used to measure and calculate various performance parameters.A microscope (Olympus BX60M) equipped with a camera (Paxcam) was used to investigate the surface morphology and porosity. The thermal property of the samples was studied by thermogravimetric analysis (PerkinElmer Pyris 6 TGA). The sample (5–10 mg) was heated under a nitrogen atmosphere condition at a heating rate of 10 °Cmino 600 °C ,54,55,56o 600 °C . The liqo 600 °C ,20,48:, N–H vibrations (3333 and 1539 cm−1), –CH2 vibration (2882 cm−1), C=O vibration (1702 cm−1), C=C vibrations , C–N vibration (1310 cm−1), C–H vibrations , C–O–C and Si–O–Si vibration (1100 cm−1), and C–C vibrations (956 and 843 cm−1). This was in agreement with the chemical structure of PU. The occurrence of the N–H group, C=O group, and C–O–C group as well as the disappearance of the N=C=O group (2267 cm−1) [67 cm−1)  of MDI pbration 12 cm−1, C67 cm−1) ,72,73,74A transmitted light microscope was used to investigate the distribution pattern of S−PANi in the PU matrix of different PEG molecular weights. The images obtained are shown in A reflected light microscope was used to investigate the surface morphology of the PU matrix . Pores o2/–NH groups of S−PANi and the –NCO groups of MDI [−1 to 10,000 gmol−1 is due to the S−PANi becoming the limiting factor. An insufficient amount of S−PANi is available for the crosslinking reaction with the –NCO group.As shown in s of MDI ,92,93,94The polymer matrix absorbency of the PU matrix with different PEG molecular weights was measured . The pol−1 to 8000 gmol−1 and then became constant. The conductivity trend was similar to that of the polymer matrix absorbency trend. The conductivity of the PU matrix decreased as the amount of the LE uptake by the PU matrix decreased [+, I− and I−3) and solvents were available to transfer the electron. This is also because S-PANi is more homogenously distributed as aforementioned, providing a more interconnected and continuous conductive path and leading to the increase in conductivity [The conductivity of the PU matrix of different PEG molecular weights was measured, as shown in ecreased . This isuctivity .−1 to 6000 gmol−1 and becomes constant as the PEG molecular weight increases from 6000 gmol−1 to 10,000 gmol−1. The ion diffusion coefficient correlated to the gel content, polymer matrix absorbency, and crystallinity level of the PU matrix. The trend of the ion diffusion coefficient is similar to that of the crosslinking level and polymer matrix absorbency trends. This is because ions are difficult to transfer through a highly crosslinked PU matrix [The ion diffusion coefficient of PU matrices with different PEG molecular weights is shown in U matrix ,100. As U matrix . The ion2. It was found that the trend of charge recombination is not in accordance to the trend suggested; this is because the charge recombination is also affected by the ion diffusion coefficient. The decrease in the ion diffusion coefficient as the PEG molecular weight increases suggests an increase in the charge recombination. A low ion diffusion coefficient indicates slow ion movement in the PU matrix, which increases the chance of triiodide ions to receive the electron at the interface of the electrolyte and TiO2 layer. These factors contributed to the insignificant changes in the charge recombination as the PEG molecular weight varied.Dark current analysis was conducted to investigate the charge recombination of the DSSCs . There ioc and Jsc were extracted from the IV curves, whereas the FF and the efficiency of the DSSCs were calculated and presented in oc of DSSCs did not have any significant changes as the PEG molecular weight varied, as it was affected by the charge recombination. A low degree of charge recombination results in a higher Voc and vice versa [sc decreases up to 8000 gmol−1 and then remains stable as the PEG molecular weight increases further. The decrease in the Jsc is attributed to the decrease in the conductivity as the PEG molecular weight increases.ce versa ,104. As sc decreases as the PEG molecular weight increases up to 8000 gmol−1 and then remains stable as the PEG molecular weight increases further. It was in good agreement with the conductivity trend as aforementioned. Higher conductivity indicates a faster electron movement, thereby meaning a higher regeneration rate of the oxidized dye [sc increased as the regeneration rate of the oxidized dye increased. The difference in the FF of all of the DSSCs was insignificant. The DSSC based on the PU−PEG 2000 showed the highest efficiency, followed by the DSSC based on the PU−PEG 4000, PU−PEG 6000, PU−PEG 8000, and lastly, the PU−PEG 10,000.The Jized dye . The Jscsc. Reducing the PEG molecular weight led to an increase in the polymer matrix absorbency and decrease in crystallinity, which contributed to the improvement in the conductivity and ion diffusion coefficient.Reducing the PEG molecular weight improved the efficiency of the DSSC. The effect of the PEG molecular weight on the lifespan and stability of the DSSC was insignificant. However, it was significantly improved as compared to the DSSC based on a liquid electrolyte. The improvement in the efficiency was mainly due to the improvement in the J


Yet, to further understand electrocatalytic MOF systems, one also needs to consider their capability to fine‐tune the immediate chemical environment of the active site, and thus affect its overall catalytic operation. Here, we show that electrostatic secondary‐sphere functionalities enable substantial improvement of CO2‐to‐CO conversion activity and selectivity. In situ Raman analysis reveal that immobilization of pendent positively‐charged groups adjacent to MOF‐residing Fe‐porphyrin catalysts, stabilize weakly‐bound CO intermediates, allowing their rapid release as catalytic products. Also, by varying the electrolyte's ionic strength, systematic regulation of electrostatic field magnitude was achieved, resulting in essentially 100 % CO selectivity. Thus, this concept provides a sensitive molecular‐handle that adjust heterogeneous electrocatalysis on demand.Metal–organic frameworks (MOFs) are promising platforms for heterogeneous tethering of molecular CO 2 reduction selectivity and activity in a Fe‐porphyrin based MOF. Specifically, we show that MOFs allow the incorporation of molecular catalysts and positively‐charged ligands one next to the other, in a manner which promotes catalysis by stabilization of reactive intermediates during electrochemical reaction conditions.Electrostatic secondary‐sphere interactions provide precise and systematic control over heterogeneous electrocatalytic CO In fact, judicious use of those properties can serve to systematically modulate the catalytically‐active site's immediate chemical environment. It is well‐known that enzymes which catalyze small molecule activation employ subtle secondary‐sphere interactions to increase catalytic performance.2 electroreduction are still rare.However, examples of incorporation of secondary‐sphere moieties in MOF‐based heterogeneous CO2 reduction rate and selectivity of an Fe‐porphyrin‐based MOF could be systematically tuned via a careful modulation of electrostatic interactions at close proximity to the catalytically active site. As a case study, we have chosen to explore a Fe‐porphyrin (Hemin)‐modified Zr6‐oxo based 2D‐MOF, Zr‐BTB (termed Zr‐BTB@Hemin), due to its chemical and structural robustness, and favorable mass‐transport properties. In order to modify the local environment surrounding the catalytic entity, we have post‐synthetically tethered a cationic functional group, (3‐carboxypropyl)trimethylammonium (TMA)2‐to‐CO conversion rate and selectivity. Moreover, through changing TMA's surface density and electrolyte's ionic strength, we were able to vary the extent of electrostatic interactions. By doing so, systematic tailoring of electrocatalytic selectivity was gained, reaching practically up to 100 % CO2 conversion to CO.In this work, we demonstrate that the electrochemical CO2 reduction, we have chosen to use a 2D‐MOF, Zr‐BTB  benzene).6‐oxo node (or 6 available carboxylate‐anchoring sites), thus allowing high surface loading of immobilized ligands , ii) It contains a 2D structure which exposes a large portion of solution‐accessible surface and permits better diffusion of reactants towards the catalytic sites.As a model platform for studying electrocatalytic CO4, 100 mg organic ligand 1,3,5‐Tris(4‐carboxyphenyl) benzene (H3BTB), 5 ml H2O and 6 g of benzoic acid, was put in an 120 °C kept oven for 48 hours. Thereafter, the resulting MOF was thoroughly washed in DMF and then in acetone. Then, the as‐formed Zr‐BTB was post‐synthetically modified with a Hemin CO2 reduction molecular catalyst via solvent‐assisted‐ligand‐incorporation (SALI)2O : propanol (v/v) with 70 μL of Nafion binder. An ink volume of 340 μL was then drop‐casted on the carbon cloth, to form a MOF surface loading of 5 mg cm−2. In turn, to engender electrostatic secondary‐sphere functionality to the MOF, an additional SALI was performed to tether the positively‐charged TMA ligand on the Zr6‐oxo node .[6‐oxo node for Zr‐BTB@Hemin and Zr‐BTB@Hemin‐TMA respectively. Using a combined 1H NMR and ICP‐OES analysis, the loading level of TMA ligand in the MOF was found to be 0.63 per Zr6‐oxo node . We note that similar TMA loading (0.66 per Zr6‐oxo node) was achieved when Zr‐BTB@Hemin powder was modified with TMA (compared to Zr‐BTB@Hemin electrode), as seen in Figure Scanning electron microscopy (SEM) images show that the as‐grown Zr‐BTB MOF exhibits a typical flower‐like 2D nanosheet morphology .31 Addit Figure Sc. We not2 reduction properties. Electrochemical analysis was carried out using a gas‐tight H‐cell three‐electrode setup, in CO2‐saturated MeCN electrolyte containing 0.1 M LiClO4 and 0.1 M trifluoroethanol (TFE) as proton source. Platinum foil, Ag wire, and MOF‐coated carbon cloth were used as counter, quasi‐reference, and working electrodes, respectively. The working and reference electrodes were separated from the counter electrode by an ion‐exchange membrane, Nafion 117 (see Supporting Information for details). Figure −1, under Ar (dashed curves) and CO2 (solid curves) environments. For both samples, in CO2 saturated solutions a clear catalytic CO2 reduction peak is observed at potentials corresponding to the Hemin's Fe0/+ redox couple, thus signaling their electrocatalytic activity.−2 compared to 1.8 mA cm−2), hence hinting that the electrocatalytic CO2 reduction is accelerated by the positively charged groups positioned adjacent to the molecular catalyst.We then set to investigate the effect of electrostatic secondary‐sphere interactions on the MOF's electrocatalytic CO2‐to‐CO selectivity was obtained for Zr‐BTB@Hemin‐TMA electrodes compared to Zr‐BTB@Hemin. Particularly, the highest CO production selectivity, 92 %, was achieved at the potential of −1.2 V vs. NHE, compared to 64 % CO obtained for Zr‐BTB@Hemin  was essentially 100 %, as seen in Figure S7). Furthermore, to understand the manner in which electrostatic secondary‐sphere functionality affects CO2 reduction kinetics, we have plotted the partial catalytic currents corresponding to CO (jCO) and H2 (jH2) generation .In order to further evaluate the electrocatalytic activity and selectivity of Zr‐BTB@Hemin and Zr‐BTB@Hemin‐TMA, bulk electrolysis experiments were conducted at an applied potential window of −1.1 V to −1.6 V vs. NHE . As can be seen in Figure 2‐to‐CO performance of Zr‐BTB@Hemin‐TMA compared to Zr‐BTB@Hemin. First, Raman spectroscopy characterization of Zr‐BTB@Hemin and Zr‐BTB@Hemin‐TMA provided an indication of possible electronic communication between MOF‐installed Hemin and TMA ligands. Specifically, upon TMA‐tethering a shift of ν2 and ν4 symmetric pyrrole stretching bands toward higher frequencies , indicating the conversion of low‐spin Fe3+‐Hemin into a high‐spin species .[Next, we were interested in gaining further insights on the mechanisms governing the improved electrocatalytic COgure S8).322 reduction properties. Generally, higher Raman shifts of CO stretching peaks is attributed to higher C−O bond order (and hence weaker Fe−C binding). As such, for both Zr‐BTB@Hemin‐TMA and Zr‐BTB@Hemin, in situ Raman measurements were performed at a set of applied potentials (−1.1 to −1.6 V vs. NHE) under CO2 reduction conditions . Indeed, for all applied potentials, the relative intensity of the 2060 cm−1 peak relates to the CO selectivity trends of Zr‐BTB@Hemin‐TMA and Zr‐BTB@Hemin  of Zr‐BTB@Hemin‐TMA with varying TMA/Zr6 concentration ratio . As shown in Figure 6 of 0.63). In other words, by increasing TMA surface loadings, the average Hemin‐to‐TMA distance is shortened, thus amplifying electrostatic secondary‐sphere interactions in our MOF system.At this point, we grasp that the installation of TMA ligand onto the MOF imposes a significant improvement in its electrochemical COκ−1:Secondly, it is well‐known that electrostatic potential in electrolytic solutions decay as a function of distance from a charged ion or surface, according to the electrolyte's Debye length, 0 the permittivity of the vacuum, I is the electrolyte ionic strength, and R, T and F are the gas constant, temperature, and Faraday's constant, respectively. Hence, we have reasoned that by varying the electrolyte's ionic strength, one would be able to modulate κ−1 and hence tune the extent of electrostatic interactions in the of Zr‐BTB@Hemin‐TMA system. To this end, we have compared the CO2‐to‐CO selectivity of BTB@Hemin‐TMA measured in different κ−1, ranging from 2.1 nm to 0.2 nm (LiClO4 concentrations in the electrolyte 0.01–1 M). Indeed, as shown in Figure 4) TMA's charge is effectively screened within a short distance of 0.2 nm, thus lowering the probability of reaching a neighboring Hemin active site, diminishing CO selectivity down to 78 %. On the contrary, at low ionic strength (0.01 M LiClO4) the influence of the electrostatic field is felt even 2.1 nm away from the cationic TMA ligand. In this case, TMA's secondary‐sphere interactions are not restricted solely to adjacent Hemins (mounted on the same Zr6‐oxo node), but also to Hemins anchored on the next‐residing Zr6‐oxo node, resulting in an impressive 100 % CO2 conversion to CO. In addition, we have performed a control experiment, examining the effect of electrolyte ionic strength on the catalytic selectivity of Zr‐BTB@Hemin. As can clearly be seen in Figure S10, in contrast to Zr‐BTB@Hemin‐TMA, for low ionic strength (Debye length >0.6 nm) the CO selectivity of Zr‐BTB@Hemin remains constant (67 %). In other words, in the absence of TMA, no clear effect is seen when the electrostatic potential is felt for longer distances. We note that for lower Debye lengths, the CO selectivity drops. In this case, the higher electrolyte concentration resulted in increased catalytic current densities, thus causing a more rapid CO2 depletion near the catalyst surface, which accelerated H2 evolution. Consequently, these results further confirm that the incorporated TMA ligands affect the MOF's electrocatalytic properties via an electrostatic mechanism.Where ϵ is the solvent's dielectric constant, ϵ6‐oxo node , thus explaining the slight drop in catalytic selectivity over time.Finally, the stability of the Zr‐BTB@Hemin‐TMA electrocatalytic system was evaluated by a bulk‐electrolysis analysis conducted at −1.3 V vs. NHE. As shown in Figure S11a–c, over the entire period of measurement, Zr‐BTB@Hemin‐TMA sustained over 85 % of its initial CO selectivity. Furthermore, PXRD analysis and SEM images of Zr‐BTB@Hemin‐TMA before and after bulk‐electrolysis show the preservation of MOF crystal structure and morphology during electrocatalytic operation . While no apparent decline in Hemin surface loading was detected, the density of MOF‐bound TMA decreased from 0.63 to 0.25 per Zr2 reduction performance of an Fe‐Porphyrin (Hemin)‐based MOF could be precisely tuned via electrostatic secondary‐sphere interactions. Specifically, we demonstrate that tethering of fixed cationic charge proximal to Zr‐BTB MOF‐installed Hemins, substantially enhance their electrochemical CO2‐to‐CO rate and selectivity. In situ Raman spectroscopy conducted under working electrochemical conditions, revealed that the improved electrocatalysis originated from electrostatic stabilization of a weakly‐bound CO intermediate, which accelerated its release as a catalytic product. Moreover, the degree of electrostatic field could be systematically manipulated by adjustment of either the density of charged ligands or electrolyte's ionic strength, resulting in practically 100 % CO2 conversion to CO. Notably, the presented concept provides a new perspective on MOFs capability of controlling the local chemical environment surrounding a catalytically active site. Hence, it should provide new means for molecular‐level modulation of heterogeneous electrocatalytic systems.In this work, we show that the electrocatalytic COAdditional experimental details, material characterizations, and electrochemical measurements are given via a link at the end of the document.The authors declare no conflict of interest.1As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re‐organized for online delivery, but are not copy‐edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors.Supporting InformationClick here for additional data file.


Zizyphus fruit species by improving the plant defense system’s potential to cope with the adverse effects of salinity. The supplemental application of melatonin has improved the generation of antioxidant assays and osmolytes involved in the scavenging of toxic ROS. The tolerance level of the germplasm is chiefly based on the activation of the defense system against the adverse effects of salinity. The current study explored the contribution of melatonin against salinity stress and provides information regarding which biochemical mechanism can be effective and utilized for the development of salt-tolerant germplasm in Zizyphus.Fruit orchards are frequently irrigated with brackish water. Irrigation with poor quality water is also a major cause of salt accumulation in soil. An excess of salts results in stunted growth, poor yield, inferior quality and low nutritional properties. Melatonin is a low molecular weight protein that shows multifunctional, regulatory and pleiotropic behavior in the plant kingdom. Recently, its discovery brought a great revolution in sustainable fruit production under salinity-induced environments. Melatonin contributed to enhanced tolerance in  Zizyphus is a rich source of ascorbic acid compared with other fruits. Therefore, it is famous as a poor man’s apple because of its higher nutrition, cheap prices and easy accessibility at markets. The population of the world is currently 7.7 billion, and this is expected to rapidly increase in the future to nearly 9.7 billion by 2050 [Zizyphus fruits provides healthy life due to their excellent nutritional properties; however, their cultivation is still poor because of poor agricultural lands [Minor fruit crops are a major source of minerals, vitamins, fiber, proteins, antioxidants and carbohydrates necessary for a healthy life. Among these,  by 2050 . It is nal lands . Climateal lands . Approxial lands . Zizyphus trees restricts quality fruit production because of the translocation of salts and toxic ions from the roots to other tree parts. Restriction in the uptake of water and mineral nutrients results in osmotic stress conditions [Zizyphus fruit crops [Zizyphus cultivars, i.e., Suffan, Mehmud Wali, Karela and Delhi White; these were recorded because they were growing under induced-salinity stress environments. Higher concentrations of salts within tree cells and compartments via the higher uptake, translocation and accumulation of ions may reach toxic levels. Induced-reduction behavior in CO2 diffusion, chlorophyll contents, carbohydrate buildup and photosystem II ultimately adversely affects the stomatal regulation. Photosynthetic pigments are also ruptured due to irregular conductance of the stomata because of higher NaCl concentrations [Zizyphus crop. The nutritional profiling of Zizyphus fruits is drastically damaged from excessive salt levels. Zizyphus plants face oxidative stress conditions due to the over-generation of ROS within plant cells, compartments and organelles. Optimum production of ROS is non-toxic and supportive in tree growth and developmental phases [Accumulation of salts in the root zone of nditions . Nutritiit crops . Fruit tit crops  assessedtrations . Accumull phases . Zizyphus crops. Fruit trees activate their defense system to scavenge these toxic ROS. However, ROS is an important stress indicator which determines the intensity of abiotic stresses [2O2, MDA and lipid peroxidation also indicate the stress intensities [Zizyphus trees growing under saline conditions, as reported by Li et al. [Zizyphus. Different factors such as mineral nutrients, molecular basis, proteomics, transcriptomics, metabolites and genomic variability can be utilized to cope with the adverse effects of salt stress in stresses . Moreoveensities . Activati et al.  and Backi et al. . Little Melatonin is a growth-promoter molecule with numerous diverse impacts in plants. It is effective for improving germination of seeds, root proliferation, flowering, fruit setting, fruit development, fruit ripening and shelf-life . MoreoveDifferent management practices, e.g., molecular breeding, seed priming, agronomic implications, grafting, rhizobacteria, bio-stimulants, and phytohormones, can be employed for the sustainable productivity of crops. Among these, phytohormones, e.g., melatonin, salicylic acid, branosteroids, polyamines, ascorbic acid, jasmonic acid, ethylene, and abscisic acid, are rapid stress-relieving bioactive molecules against stressful conditions. Among these phytohormones, melatonin is an emerging molecule against salinity for exogenous application on fruit crops .Zizyphus crops, even those growing in saline lands. Exogenous application of melatonin is a very promising approach to cope with saline conditions and enhance tolerance mechanisms in Zizyphus fruits. However, the application of melatonin is still unclear, and its effects on Zizyphus crop yield, quality and nutritional aspects in salinity-induced environments are poorly understood. The current study encourages and explores the significance of melatonin on the minor fruit crop Zizyphus species with regard to its yield, quality and shelf-life in salinity-induced conditions.Plant researchers are focusing on sustainable fruit production; therefore, appropriate management implications should be explored for enhanced productivity of + and Cl− taken up via roots from saline soil and brackish water. Halophytes are more tolerant compared with other plants due to their xerophytic properties. Zizyphus belongs to the Rahmnaceae family. Plants of this family mostly grow in arid and semi-arid regions. Therefore, an excess of Na+ and Cl− in the short term at the seedling stage, and long term in higher plants, is toxic by reducing seedling growth, yield and quality of Zizyphus fruits [Plants grown in salty zone naturally are halophytes. These plants survived well in 30–500 mM NaCl concentrations . Excelles fruits .+ and Cl− into vascular bundles of fruit trees. Na+ and Cl− were not accumulated at toxic levels in fruit tree leaves because of the salt-exclusion process [Zizyphus rotundifolia are capable toxic ion exclusion compared with other cultivated species. Wild species should be utilized in further breeding programs to develop salt-tolerant germplasm, focusing on fruit yield and quality to feed huge populations [Exclusion of salts is an important inhibitory mechanism to prevent entry of Na process . Generalulations . + and Cl− was found to be higher in tetraploid rootstocks than economic threshold levels compared with diploid rootstocks. However, uptake and accumulation of K+ was found to be lower in diploid than tetraploid rootstocks [Ploidy level is an essential genetic aspect of fruit trees helpful for plants’ survival against adverse climatic conditions. Ploidy in fruit species has greater involvement to cope with adverse effects of salinity and numerous other harsh environmental conditions . In someotstocks .+ and Cl− was found to be maximum in the root zone and then in leaves. The salinity-tolerance mechanism is chiefly based on the accumulation and translocation of Na+ and Cl− in different portions of the fruit trees [+ and Cl− in leaves of fruit crops. The increase in endogenous melatonin improved the plant defense system to uptake and translocate selective ions by excluding toxic compounds [Zizyphus against salinity is well described  is the cause of ROS production in all trees. ROS comprises different free radicals, e.g., hydroxyl radicals and anions of superoxide. On the other hand, non-radicals contain singlet oxygen and H2O2 . A drastroplasts . These sroplasts . Biotic roplasts .The toxic and beneficial level of ROS is mainly based on the type of species and its absorption rate. However, its optimum production is effective for the proper functioning of tree cells and organelles. Oxidative stress conditions occur because of over-generation of ROS. Higher concentrations of ROS are toxic for plant cells . ROS gen2O2 are well-known stress-indicating markers in plants for detecting the stress conditions of trees. Their production is drastically enhanced when trees are subjected to stressful conditions, e.g., salinity, drought, heavy metals, mineral malnutrition, temperate extremes and pathogen attacks [Lipid peroxidation, MDA content and H attacks . For the attacks .2O2 and lipid peroxidation under excessive saline conditions within the root zone of trees [Different major biomolecules, i.e., DNA, lipids and proteins, suffer production loss because of over production of ROS, MDA, Hof trees . The rupof trees .ROS generation is the first stress response when growing under saline conditions. Therefore, identification of salt-tolerant germplasm is more necessary for sustainable fruit production within the country. The development of tolerant germplasm is chiefly based on mitigation aspects of toxic ROS generation under salinity conditions . 2O2 and MDA, in fruit trees can be mitigated by exogenous application of melatonin [Zizyphus fruit tree tolerance can be enhanced by exogenous application of melatonin.Melatonin is an effective growth regulator involved in the mitigation of adverse effects of salinity in fruit trees for sustainable fruit production and superior quality with higher nutritional profiling . It is eelatonin . Hence, 2O2 and MDA activities. The production of enzymatic, non-enzymatic and different osmolytes is an effective strategy to cope with toxic ROS. These have excellent scavenging capability against toxic ROS by reducing membrane damage and protecting plants from oxidative stress injury. Adverse effects of salinity can include protein damage, cell membrane rupture, nucleotide disturbances, altered regulation of many enzymes and death of some cells, tissues and organs [Oxidative stress conditions occur due to over-generation of ROS. The level of ROS overproduction is indicated by oxidative stress markers such as Hd organs .2O2 and lipid peroxidation activities are reduced when there is balanced production of ROS because optimum production of ROS is effective for sustainable fruit production of horticultural crops, especially underutilized crops, as these are rich in essential nutrients and naturally hardy against harsh climatic conditions [The plant defense system, which involves enzymatic, non-enzymatic and osmolyte production, regulates the overproduction of toxic ROS. These activities are important to balance ROS generation and their scavenging activities depend on a good immune system of the plant body. MDA, Hnditions ,134.Some serious advancements are being used to improve oxidative stress resistance following the development of transgenic plants producing many antioxidants and osmolytes . An antiFertilization is effective for the control of adverse effects that occurs from salinity in fruit trees. The production of different bioactive compounds is important for fruit tree survival against different environmental stresses . SufficiZizyphus germplasm. The exposure of Zizyphus fruit trees to melatonin is very necessary because it is an underutilized fruit crop with excellent nutritional properties and hardy behavior against harsh climatic conditions. Therefore, supplemental application of melatonin can bring a greater revolution in yield and quality, not only in Zizyphus but also for numerous minor fruit crops. Melatonin increased the production of ROS scavengers by improving the plant defense system [Melatonin is one of the emerging phytohormones necessary for sustainable fruit production in harsh climatic conditions . Hence, e system . The tole system .Numerous environmental stresses disturb the photosynthetic mechanism of plants. An excess of salts results in an imbalance in the photosynthetic process and carbon-reducing paths, and disturbances in the electron transport chain . Chloropp-coumaric acid was also reduced following foliar application of melatonin on fruit plants growing under saline environments [Melatonin is found to be effective for fruit trees growing under saline conditions because of its higher antioxidant potential and stress-relieving property. Exogenous spray of melatonin revealed greater protection to fruit crops by restricting the damage that occurs in photosynthetic pigments , reducing oxidative stress conditions, activating the plant defense system and numerous other processes that occur within plant cells growing under saline conditions . The conronments . Thus, ironments ,148.Zizyphus fruits under salinity-induced conditions is still elusive and much effort is required for further exploration. Crosstalk of melatonin with numerous other phytohormones can regulate different abiotic stresses, especially salt stress, in fruit crops such as the Zizyphus species.Research on melatonin-mediated ripening of Zizyphus fruit crop.Alterations in the photo-pigment system and secondary metabolites as affected by exogenous melatonin levels against salt stress must be further explored. Accurate signaling, epigenetic paths and transcriptomic paths of melatonin still remain unknown and require more work on the Zizyphus fruit trees. This type of multifunctional phytohormone may possibly emerge as a sustainable alternative for regulating multiple stress responses in fruit trees.It will be more mechanistic to explore the regulatory contribution of melatonin to alleviating stress tolerance and delivering distinctive immunity in Zizyphus to plant breeders for enhancing tolerance mechanisms against an excess of salts. Zizyphus rotundifolia cv. Gola was found to be more tolerant to growing under saline conditions due to an excellent regulating potential for photosynthesis processes and activation of plant defense systems. Osmolytes and secondary metabolic activities are the major factors for alleviation of tolerance against an excess of salts present in the root zone. Exploring the biochemical mechanism of Zizyphus will provide more support for the development of resistant germplasm to attain higher quality produce growing under saline environments.The current study explored and provided detailed insights into the biochemical and physiological mechanism of


Rana chensinensis skin peptides (RCSPs) extracted from discarded Rana chensinensis skin; these two natural substances were successfully used to prepare composite nanofibers by coaxial electrospinning. The composite nanofibers are named SA@Ca2+/RCSPs nanofibers. SA@Ca2+/RCSPs nanofibers exhibited that the nanofibers contact with the liquid is unmelted, instead become gel, when compared to nanofibers of does not contain calcium ions, and the absorption rate reached 179.87%. SA@Ca2+/RCSPs nanofibers conform to the quasi-first-order dynamics model and the Ritger–Peppas release model. In vivo wound healing experiments showed that the wound-healing rate of SA@Ca2+/RCSPs nanofiber-treated wounds was 46.65% and 97.46% on days 5 and 15, respectively. In addition, SA@Ca2+/RCSPs nanofibers promoted collagen deposition and enhanced epidermal regeneration. The present study showed that composite nanofibers could quickly undergo hemostasis and effectively promote wound healing.Therapeutic drugs remain of great significance for the absorption of wound blood, the closure of wounds and rapid wound healing. Hence, we propose a novel composite nanofiber membrane with the above characteristics as a wound healing material. We utilize the reaction of calcium ion and alginate gel, sodium alginate (SA) and  Core–shell nanofiber membranes by coaxial electrospinning process that became gel after absorbing blood were used for wound repair. After the wound dressing is applied to the wound site, wound bleeding can rapidly be stopped, and the wound organization exhibits a certain prosthetic effect. Ideal wound dressings should maintain proper moisture,2,3 allow gas exchange, absorb excess exudates and maintain a damp environment. These conditions are beneficial for the generation of a hypoxic environment, promote capillary formation, enhance epithelial growth, avoid palingenetic epithelial tissue with dressing adhesion and reduce pain.4–8In daily life, skin trauma is unavoidable because of various causes. The wound healing process includes hemostasis, inflammation, cell proliferation and tissue reconstruction.9 and exhibits non-toxic,10 safe and mild gelation by the addition of divalent cations, such as Ca2+.11,12 Alginate can be used to deliver a variety of drugs.13,14 Alginate dressing has been used in post-operative wounds, ulcers, etc. and is conducive for wound healing, skin regeneration and reducing pain. Saarai et al.15 prepared gel by mixing alginate with gelatin, which exhibit high absorption for liquid. Alginate is widely used in biomedical applications.16,17 Alginate can optimize the performance of wound dressings, and thereby accelerate wound healing.Alginate is extracted from natural brown seaweed. Alginate has good biocompatibility,Rana chensinensis is a medicinal and edible amphibian economy animal, widely distributed in northern China. RCSPs are extracted from discarded Rana chensinensis skin, and the molecular weight of these compounds is 3.5 kDa. RCSPs mainly consists of peptides and proteins.18 Studies on RCSPs for the effect of proliferation of mouse fibroblasts have shown that these polypeptides have low toxicity towards normal cells.19 Additionally, RCSPs exhibit good biocompatibility20 and absorbability.21,22 A novel peptide from skin secretions of the odorous frog Odorrana margaretae can promote the formation of keratinocytes and human skin fibroblasts.23 Collagen peptide is widely used in wound healing, as this protein promotes wound healing and accelerates the healing speed.24,2526–29 Because the composite material maintains the advantages of the performance of each individual material and also the complementarity and correlation of the performances of the materials together, better overall performance can be achieved.30,31 For example, changing the performance of the original material,32,33 increased compatibility34 lipophilicity,35etc. Electrostatic spinning technology is particularly suitable for the preparation of biological materials,36–39 which can control drug release over time.40–44 The nanofibers prepared by electrospinning have several advantages, such as high porosity and large specific surface area.45 The technology is simple and low cost, with strong generality.46,47 Co-axial electrospinning can separate core solutions from shell solutions, avoiding contact between the two solutions until the last moment when they exit the nozzle.48Currently, nanocomposites are widely used.2+/RCSPs composite nanofibers by coaxial electrospinning using polyvinylpyrrolidone (PVP). PVP is a macromolecule compound widely used in the biological field. PVP has been used as a blood plasma substitute.49 PVP has been used as a rapidly dissolving matrix carrier in several drug delivery system formulations.50 The necessity of coaxial electrospinning was studied to analyze the fiber morphology and contact angle. The adsorption kinetics and drug release kinetics of SA@Ca2+/RCSPs composite nanofibers were studied by measuring their adsorption quantity and drug release properties, respectively. The full thickness excisional wound model was used to assess the wound healing efficiency of nanofibers with RCSPs in vivo. Compared with previous reported studies, we not only easily cross-linked nanofibers but also generated a moist environment and accelerated wound healing. The purpose of the present study was to develop dressings for wound hemostasis, the rapid release of drug and acceleration of wound healing.In the present study, we prepared SA@CaRana chensinensis skin peptides (RCSPs) were obtained from Fang Ping Technology Co., Ltd. . Sodium alginate (SA), calcium chloride and sodium chloride were purchased from Shanghai Chemical Reagent Purchasing Supply Station . Polyvinylpyrrolidone  were purchased from Ourchem Chemical and Technology Co., Ltd . Phosphate buffered saline (PBS) was purchased from Haibiao Chemical and Technology Co., Ltd . Deionized water is provided in our lab.PVP were dissolved in deionized water to prepare two concentrations of solutions; a and b solutions were 8% (w/v) and 11% (w/v), respectively. Calcium chloride was dissolved in deionized water to obtain 2% (w/v) calcium chloride solution. The appropriate amount of RCSPs dissolved in solution a. The solutions were stirred at room temperature for 2 hours, and then the appropriate amount of calcium chloride solution was added to the solutions, followed by stirring at room temperature for 2 h. The mixed solution was named A. Sodium alginate was dissolved in deionized water to obtain 2% (w/v) sodium alginate solution. Sodium alginate solution was mixed with solution b (2 : 8), and the mixed solution was named B, which was stirred at room temperature for 4 hours.51 Solution A was loaded in a 5 ml syringe connected to an internal, and solution B was loaded in 5 ml syringe connected to an external needle. The ratio of the flow rates of core and shell solutions was 1 : 3.43 The applied voltage was 20 kV, and the distance from the tip to the collector was 15 cm. According to the above steps, for the calcium chloride solution not added to solution A, the coaxial nanofibers were named SA@RCSPs nanofibers. All nanofiber mats were dried under vacuum at room temperature for 5 days.Coaxial electrospinning experiments were performed at room temperature. Solution A is the core solution and solution B is the shell solution.−1). The thermal properties of nanofibers and RCSPs were studied using thermogravimetric  and differential scanning calorimeter . The Fourier transform infrared spectrometer  was used to obtain the ATR-FTIR spectra of RCSPs, SA nanofibers, SA@RCSPs nanofibers and SA@Ca2+/RCSPs nanofibers in the region of 400–4000 cm−1. Liquid infiltration was measured for SA@Ca2+/RCSPs nanofibers and SA@RCSPs nanofibers using optical contact angle & interface tension meter .The morphologies of nanofibers were observed using scanning electron microscopy . The core–shell structure of the coaxial nanofibers was observed using transmission electron microscopy . The pore size of the nanofibers was measured using the membrane pore size analyzer  Co., Ltd). The crystalline nature of the nanofibers was analysed by X-ray photoelectron spectroscopy ; the NaCl–CaCl2 solution was named M. The ion content of the solution was equivalent to human serum albumin or wound exudate. Solution M was loaded into a syringe, then the appropriate amount was dripped onto the prepared SA@Ca2+/RCSPs nanofiber mats, and the results were observed.The coaxial nanofiber can be melted by water due to its strong hydrophilicity. To improve the stability and unchangeable chemical structure of the RCSPs in the nanofibers, we used an ion cross-linking reaction between sodium alginate and calcium ions, which leads to a gel structure. Using a syringe, calcium chloride solutions were dropped into a Petri dish containing a mixed solution of solution b with sodium alginate solution. NaCl–CaCl2+/RCSPs nanofibers was assessed by adsorption assay for solution M. At room temperature, SA@Ca2+/RCSPs fiber mats were cut into 5 × 5 cm2 then the mass of the fiber mats was accurately weighed. The fiber mats were immersed in solution M at 37 ± 1 °C for a different time until the fiber mats adsorption was saturated. After imbibition, surplus solution in the fiber mats were filtered. The liquid absorption rate was calculated using the following formula.M1 is the quality of the dry fiber mats and M2 is the quality of the fiber mats after imbibition.The ratio of the absorption liquid of SA@Ca2+/RCSPs nanofiber matrix was investigated in phosphate-buffered saline (PBS) at 37 ± 1 °C. Standards were prepared by dissolving known amount of RCSPs in solvent. Standard graphs were plotted using absorbance at 540 nm which is specific for peptide linkage. The SA@Ca2+/RCSPs fiber mats (5 mg) were cultured in 3 ml of PBS at 37 ± 1 °C for 10 min. At specific time intervals, 1 ml of solution was withdrawn from the release medium, and the same volume was replaced with fresh PBS. The relative concentration of the RCSPs was determined using an ultraviolet and visible spectrophotometer  at a wavelength of 540 nm by comparison with the standard plot.The release profile of RCSPs from SA@Ca−1). The dorsal surface of the black mice was shaved, then disinfected with 70% ethanol and a full thickness (diameter of 1 cm round) excision wound was created by excising the dorsal skin. Group 1 (control) animals were treated with normal saline, group 2 animals were treated with PVP nanofibers, group 3 animals were treated with SA@Ca2+ nanofibers and group 4 animals were treated with SA@Ca2+/RCSPs nanofibers. The wounds were wiped with normal saline before changing the dressing materials daily. The percentage of wound closure was calculated by the following formula.S0 is area of original wound and Sn is area of actual wound .Healthy male black mice (C57) weighing 17–20 g were used for wound healing experiments. All animal procedures were performed in accordance with the Guidelines for Care and Use of Laboratory Animals of Jilin Agricultural University and experiments were approved by the Animal Ethics Committee of Jilin Agricultural University. The mice were maintained on a normal diet and drinking water. Altogether, 24 black mice were divided into four groups. The black mice were anesthetized by an enterocoelia injection with 4% chloral hydrate  overnight and embedded in paraffin. The paraffin samples were cut into slices with a thickness of 5 μm using a Paraffin slicing machine (Leica RM2235) for staining with Hematoxylin–Eosin (H&E) and Masson's trichrome staining. Histological sections were observed using a Zeiss Axio Scope Microscope.p value < 0.05, **p value < 0.01, and ***p value < 0.001.All data were expressed as average ± standard deviations. Statistical differences were analyzed using one-way analysis of variance (ANOVA) with GraphPad Prism 6 software. For all tests, *48 As the shell solution has a large viscosity, the viscous stress of the inner solution was sufficient to overcome the internal tension between the two solutions, the shell has a sufficient surface tension to balance the electric field force under equilibrium forces, and the tip can form stable composite Taylor Cone.51 However, the larger viscosity of the shell solution can also guide the core solution to better form nanofibers. SEM images of SA@Ca2+/RCSPs nanofibers and SA@RCSPs nanofibers after vacuum drying are shown in 2+/RCSPs and SA@RCSPs nanofibers. The average pore size of SA@RCSPs nanofibers was 0.9087 μm and the average pore size of SA@Ca2+/RCSPs nanofibers was 0.5713 μm due to bending and swelling of the nanofibers after gelatinization, resulting in SA@Ca2+/RCSPs nanofibers with smaller pore sizes than SA@RCSPs nanofibers.Coaxial nanofibers were successfully prepared by coaxial electrospinning.2+ nanofibers, RCSPs, SA@RCSPs nanofibers and SA@Ca2+/RCSPs nanofibers is shown in 2+ nanofibers, SA@RCSPs nanofibers and SA@Ca2+/RCSPs nanofibers are basically the same. The weight loss in the first stage was 8.84%, 6.34%, 7.06% and 9.02% at 40 °C to 110 °C, respectively, due to residual moisture evaporated on the surface and inside of the nanofibers. For SA nanofibers and SA@Ca2+ nanofibers, the second stage was from 280 °C to 370 °C (7.71% and 13.61%). The alginic acid was split into intermediate products, and the adjacent hydroxyl groups were removed as water molecules. The third stage was from 370 °C to 460 °C, and the intermediate products are further decomposed and carbonized (62.47% and 51.92%). The fourth stage was from 460 °C to 560 °C, in which carbides of alginic acid were further oxidized and decomposed. For PCSPs, the first stage is from 60 °C to 190 °C, due to the evaporation of water in organics (4.82%). The second stage was from 190 °C to 480 °C because of the carbonization of the organic molecules (59.46%). The third stage was from 480 °C to 550 °C, in which carbides are further oxidate and decomposed (33.30%). For SA@RCSPs nanofibers and SA@Ca2+/RCSPs nanofibers, because of the existence of RCSPs, the second stage was from 110 °C to 460 °C (65.71% and 66.77%). The third stage was from 460 °C to 560 °C, in which carbides of RCSPs and alginic acid were further oxidized and decomposed. Obviously, the thermal performance of SA@RCSPs nanofibers and SA@Ca2+/RCSPs nanofibers are between SA nanofibers and RCSPs, indicating that the presence of SA increases the thermal stability of the composite nanofibers.TG analysis of SA nanofibers, SA@CaTg), due to residual moisture evaporated on the surface and inside of the nanofibers. The crystallization peak of SA nanofibers occurred at approximately 160 °C. Because the RCSPs composite with SA by coaxial electrospinning, the melting peak of SA@RCSPs nanofibers and SA@Ca2+/RCSPs nanofibers are between these molecules (approximately 195 °C), indicating their compatibility.The thermal performance of RCSPs and nanofibers was measured by DSC. 2+/RCSPs nanofibers, SA nanofibers and SA@Ca2+ nanofibers are shown in 2+ nanofibers show amorphous peaks appearing at approximately 20.4° and 19.7°, and there were weaker diffraction peaks at approximately 43.9°, 64.4° and 77.6°. Indicating that SA has weaker crystallinity and the main form was amorphous. RCSPs, SA@RCSPs nanofibers, SA@Ca2+/RCSPs nanofibers show amorphous peaks at approximately 22.7°, 22.4° and 23.6°. Due to the addition of RCSPs, the crystallization peaks of SA disappeared at 43.9°, 64.4° and 77.6°, indicating that the interaction between RCSPs and alginic acid reduces the crystallinity of the composite nanofibers.The X-ray diffraction patterns of RCSPs, SA@RCSPs nanofibers, SA@Ca2+ nanofibers were presented in −1 and 1676 cm−1, respectively. After the addition of calcium chloride, the SA nanofibers show O–H stretching vibration at 3409 cm−1 and COO– asymmetric stretching at 1619 cm−1 in 2+/RCSPs nanofibers are shown in −1, 1695 cm−1 and 1556 cm−1, which corresponds to the –NH stretching vibration, amide I and amide II. The RCSPs nanofibers contain sodium alginate, which causes the vibration frequency of amide I and amide II to shift to 1625 and 1470 cm−1, respectively. Primarily because of the electrostatic interaction between alginate and peptide molecules. The spectra of SA@RCSPs nanofibers and SA@Ca2+/RCSPs nanofibers showed that the peak of –NH stretching vibration broadened due to the formation of hydrogen bonds between alginate and RCSPs.The ATR-FTIR spectra of SA nanofibers and SA@Ca2+/RCSPs nanofibers are given in 2+/RCSPs nanofibers and then the solution was absorbed by the mats because the fiber mats, containing calcium ions, produce gelation reactions. The solution basically infiltrated into the fiber mats after 2 min. The results indicate that SA@Ca2+/RCSPs nanofibers were successfully gelled due to the ion exchange reaction of calcium ions with sodium alginate. Solution M was rapidly absorbed after contact with SA@Ca2+/RCSPs nanofibers, and the fiber mats were insoluble.SA@RCSPs nanofibers and SA@Ca52 The most common method of preparing hydrogels from aqueous alginate solutions was that the solutions combine the ionic cross-linking agents, such as divalent cations . The divalent cations may bind solely to the guluronate blocks of the alginate chains.53 Calcium ions are required in the human body, and these molecules are not toxic to the humans in a certain range, thus becoming the preferred material for alginate gel. 2+/RCSPs nanofibers adsorption solution M is shown in SA@CaThe linear form of the quasi-first order kinetic rate equations is as follows.where qe and qt represent the amount of adsorption (g g−1) at the adsorption equilibrium and time t respectively, and k1 and k2 are the adsorption rate constants.The linear form of the quasi-second order kinetic rate equations is as follows.R2 = 0.99505, and R2 = 0.28307. These results show that the adsorption process conforms to the quasi-first-order dynamics model. The quasi-first order kinetic rate equation was log(qe − qt) = −0.083491t + 0.34731. It is important that quickly enable hemostasis when healing skin wounds.The quasi-first and quasi-second order kinetic rate equations are shown in 2+/RCSPs nanofibers were completely released. To further understand the diffusion mechanism of RCSPs from the nanofibers, the Ritger–Peppas release model was used to analyze the experimental results by the following formula.54,55where Mt is the release amount of time t, M∞ is the amount of release at equilibrium, n is the diffusion index, k is the diffusion constant, and t is the release time.The release of RCSPs from the composite nanofibers is shown in n and k can be calculated to fit the curves, with ln(Mt/M∞) as ordinate and ln t as the abscissa curve. As shown in n and k were 0.6556 and 3.1982, respectively. According to the diffusion mechanism, for the thin film, n = 0.5 corresponding to the Fick release, and n = 1 corresponds to the case-II transport. When 0.5 < n < 1.0, the drug release mechanism was the non-Fick diffusion . Thus, the release of the thin film was the coupling results of two methods (drug diffusion and skeleton dissolution). Because the carrier degradation and dissolution accelerate the drug release rate, the value of n is higher than the Fick release.The kinetic parameters 2+/RCSPs through the proportion of the drugs diffusion and dissolution, respectively. We used amendment equations proposed by Peppas et al. based on the following formula.55W is the cumulative release of RCSPs from the nanofibers, m is the Fickian diffusion index, and k1 and k2 are the diffusion constants.To quantitatively explain the release of RCSPs from SA@CaThe diffusion of the amount of drug release accounting for the proportion of the total release was calculated by the following formula.The dissolution mechanism of the amount of drug release accounting for the proportion of the total release was calculated by the following formula.W = k1tm + k2tm2 used multiple regression and thus W = 28.90711t0.57625 + 0.24229t1.1525, R2 = 0.97724. Using the values of k1, k2, the plot for equations F = 1/(1 + k2tm/k1) and R = 1 − F to obtain curve of proportions of diffusion release and dissolution release in the amount of accumulated release RCSPs at some point, as shown in The equation 2+ nanofibers, SA@Ca2+/RCSPs nanofibers (the video2+/RCSPs nanofibers were wiped onto the wound of the black mouse). As shown in 2+/RCSPs nanofibers had the highest wound-healing rate. On the fifth day, the healing rate of SA@Ca2+/RCSPs nanofibers was approximately 46.65% whereas the wound healing rates of control, PVP nanofibers and SA@Ca2+ nanofibers exhibit healing rates of 21.63%, 27.62% and 35.03%, respectively. On day 15, a wound-healing rate of 97.46% was observed with SA@Ca2+/RCSPs nanofibers, whereas the rates 90.79%, 91.34% and 93.27% for control, PVP nanofibers and SA@Ca2+ nanofibers respectively. After 15 days, the wound-healing rates for these three groups reached more than 90%, but we do not know the internal wound situation, therefore we uses tissue biopsies to analyse the degree of wound healing of the four groups.For wound healing, the experiment was divided into four groups: control, PVP nanofibers, SA@Ca2+ nanofiber-treated wounds showed inflammatory cells, macrophages, neutrophils and fibroblasts. The fibroblasts of the upper layer were more intense. SA@Ca2+/RCSPs nanofiber-treated wounds showed small amounts of inflammatory cells, macrophages, neutrophils and fibroblasts, compared to the first three groups, and fibroblasts were not only dense but also uniform in distribution. On day 15, the control groups showed small amounts of inflammatory cells and increasing fibroblasts in the upper portion of the wound.The black mice from four groups were sacrificed on days 7 and 15 for tissue analysis. 2+/RCSPs nanofiber-treated group compared with the other two groups displayed an epidermal layer of thick, skin appendage regeneration and the surrounding tissue to combine well, thick wave-like collagenous fiber. These findings indicate that the wound of the SA@Ca2+/RCSPs nanofiber-treated group was completely healed.The other three groups showed epidermis and skin appendage regeneration, but the SA@Ca2+/RCSPs nanofiber-treated group, but not in the other three groups. On day 15, the SA@Ca2+/RCSPs nanofiber-treated group showed dense collagen deposition and thick wave-like collagenous fiber, compared to the other three groups. This observation was similar to the results of HE staining, indicating that the wound was completely healed.In parallel, 2+/RCSPs nanofiber-treated group had the best therapeutic effect. When the composite nanofibers contact the wet wound, these molecules quickly become gels, which can stop bleeding and close the wound, and the RCSPs are rapidly released into the wound site to speed up cell growth and promote cell proliferation. Thus, granulation tissue or epithelium can gradually grow, thereby accelerating the healing time of the wound. In general, the carrier degradation of the reported most composite materials was slow and incomplete, resulting in drug release slow and incomplete, which makes drug waste. While according to the drug release model, RCSPs from the composite nanofibers in this work released rapidly and completely. And the healing time is much shorter than that reported for most composite materials.The histological analysis showed that the SA@Ca2+/RCSPs nanofibers are prepared by coaxial electrospinning. Pore size analysis, gel test, contact angle test, TG-DTG, DSC, XRD and ATR-FTIR showed that solubility of the fiber mats was changed, producing a gelation reaction and good thermal properties. The liquid absorption of the composite nanofibers was consistent with the adsorption kinetics, and the release of RCSPs from the nanofibers was consistent with the release kinetics. In a short time, nanofiber mats can immediately stop bleeding and subsequently release drugs. In vitro wound healing studies showed that SA@Ca2+/RCSPs nanofibers increase wound healing rates and collagen deposition. The present study shows the feasibility of the gelation of SA@Ca2+/RCSPs composite nanofibers for wound healing. Moreover, according to the present work, we can further study the culture of skin fibroblasts in vitro and improve the functionalization of composite nanofibers, such as antibacterial activity, making the composite nanofibers more practical for the biomedical materials.In the present study, utilizing the gelation reaction of calcium ions with alginate, SA@CaThere are no conflicts to declare.RA-008-C8RA00784E-s001RA-008-C8RA00784E-s002