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The chain entanglement model: (a) Pure HA, stiff polymer chains, only form few flections, and polymer chains will slip away when elongated by electric field; (b) HA/PEO-100 blends. Flexible PEO-100 chains pass through HA and entangle with other PEO molecules, and stabilize electric spinning process; (c) HA/PEO-2 blends. PEO-2, much smaller molecules, reduce the electrostatic repulsive forces and hydrogen bonding interaction, to make HA chains more flexible and form efficient entanglements.
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Most of natural water-soluble polymers are difficult to electrospin due to their specific chain conformation in aqueous solution, which limits their applications. This study investigated the effects of polyethylene oxide (PEO) on the electrospinning of hyaluronic acid (HA) in HA/PEO aqueous solutions. The rheological properties of HA/PEO aqueous so...
Contexts in source publication
Context 1
... proposed chain conformation of HA involves an overlap between two stiff polymer chains. Figure 5a shows a schematic diagram of a stiff HA chain with only a few flections. Although the stiff polymer chains were elongated under an electric field, they slipped away rather than hooking on to each other. ...
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... demonstrates that the entanglements of the PEO-100 chains were sufficient for electrospinning. It can be proposed that the flexible chains of PEO can pass through HA and entangle with other PEO molecules, as shown in Figure 5b. Hence, the PEO chain entanglement was not disrupted under the electric field, and HA/PEO bicomponent fibers were obtained. ...
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... this study, the molecular chains of PEO-2 screened the electrostatic repulsive forces along the polymer backbones and weakened the hydrogen bonding interactions. These effects might have caused the HA molecular chains to become more flexible and form efficient entanglements, as shown in Figure 5c. Therefore, under an electric field, the HA chains hooked onto each other with PEO-2 coiled onto the HA. ...
Citations
... It is further confirmed by Fig. 5 that as the PEO ratio of PCL:PEO increases, the average fiber diameters decrease from 3.4 to 1.5 μm. This may be associated to PEO's high molecular weight, which results in increased viscosity and polymer chain entanglement [70,71]. Surface tension must be within an optimum range, otherwise beads will occur. ...
Combining a hydrophobic polymer such as polycaprolactone (PCL) with a hydrophilic polymer polyethylene oxide (PEO) in a binary polymer system can enable a range of novel applications in biomedical engineering by permitting exceptional therapeutic release, antimicrobial possibilities, and heterogeneous tissue engineering scaffolds. In this work, both PCL and PEO were dissolved in chloroform at 15 w/v % at six different ratios to prepare binary polymer solutions. The rheological properties of the singular and binary polymer solutions were measured, and fibers were spun using pressurized gyration. The fiber morphologies of the prepared materials were studied using scanning electron microscopy (SEM). By immersing samples in deionized water, binary polymeric fibers with varying swelling behaviors were developed and analyzed using optical microscopy. The results were used to identify an optimum PCL:PEO binary mixture in chloroform. Chemical compositions of singular/binary polymer composites loaded with ibuprofen (IBP) were characterized by Fourier-transform infrared spectroscopy (FTIR) and thermal analysis was examined using differential scanning calorimetry (DSC). In vitro studies on PEO–IBP exhibited an instant release rate of 90 % in 40 s, whereas PCL–IBP and PCL:PEO–IBP revealed a sustained release of 87–96 % in 72 h, respectively. The results were used to discuss the potential use of binary polymer systems in biomedical applications.
... 32,33 HA is often combined with other natural or synthetic polymers to both increase the spinnability of solution and obtain bioactive fibrous scaffolds. 34,35 On the contrary, the water stability of HA meshes can be increased by EDCmediated cross-linking, 36 by photo-cross-linking via backbone modification, 37,38 and with various synthetic and natural material blends. 39−42 For further bioactivation, RGD peptide was conjugated on fibrous HA scaffolds. ...
Fabricating a porous scaffold with high surface area has been a major strategy in the tissue engineering field. Among the many fabrication methods, electrospinning has become one of the cornerstone techniques due to its enabling the fabrication of highly porous fibrous scaffolds that are of natural or synthetic origin. Apart from the basic requirements of mechanical stability and biocompatibility, scaffolds are further expected to embody functional cues that drive cellular functions such as adhesion, spreading, proliferation, migration, and differentiation. There are abundant distinct approaches to introducing bioactive molecules to have a control over cellular functions. However, the lack of a thorough understanding of cell behavior with respect to the availability and spatial distribution of the bioactive molecules in 3D fibrous scaffolds is yet to be addressed. The rational selection of proper sets of characterization techniques would essentially impact the interpretation of the cell-scaffold interactions. In this timely Review, we summarize the most popular methods to introduce functional compounds to electrospun fibers. Thereafter, the strength and limitations of the conventional characterization methods are highlighted. Finally, the potential and applicability of emerging characterization techniques such as high-resolution/correlative microscopy approaches are further discussed.
Thin-film composite membranes are a leading technology for post-combustion carbon capture, and the key challenge is to fabricate defect-free selective nanofilms as thin as possible (100 nm or below) with superior CO2/N2 separation performance. Herein, we developed high-performance membranes based on an unusual choice of semi-crystalline blends of amorphous poly(ethylene oxide) (aPEO) and 18-crown-6 (C6) using two nanoengineering strategies. First, the crystallinity of the nanofilms decreases with decreasing thickness and completely disappears at 500 nm or below because of the thickness confinement. Second, polydimethylsiloxane is chosen as the gutter layer between the porous support and selective layer, and its surface is modified with bio-adhesive polydopamine (<10 nm) with an affinity toward aPEO, enabling the formation of the thin, defect-free, amorphous aPEO/C6 layer. For example, a 110 nm film containing 40 mass % C6 in aPEO exhibits CO2 permeability of 900 Barrer (much higher than a thick film with 420 Barrer), rendering a membrane with a CO2 permeance of 2200 GPU and CO2/N2 selectivity of 27 at 35 °C, surpassing Robeson's upper bound. This work shows that engineering at the nanoscale plays an important role in designing high-performance membranes for practical separations.
The manipulation of cell behaviors is essential to maintaining cell functions, which plays a critical role in repairing and regenerating damaged tissue. To this end, a rich variety of tissue-engineered scaffolds have been designed and fabricated to serve as matrix for supporting cell growth and functionalization. Among others, scaffolds made of electrospun fibers showed great potential in regulating cell behaviors, mainly owing to their capability of replicating the dimension, composition, and function of the natural extracellular matrix. In particular, electrospun fibers provided both topological cues and biofunctions simply by adjusting the electrospinning parameters and/or post-treatment. In this review, we summarized the most recent applications and advances in electrospun nanofibers for manipulating cell behaviors. First, the engineering of the secondary structures of individual fibers and the construction of two-dimensional nanofiber mats and nanofiber-based, three-dimensional scaffolds were introduced. Then, the functionalization strategies, such as endowing the fibers with bioactive, physical, and chemical cues, were explored. Finally, the typical applications of electrospun fibers in controlling cell behaviors (i.e., cell adhesion and proliferation, infiltration, migration, neurite outgrowth, stem cell differentiation, and cancer cell capture and killing) were demonstrated. Taken together, this review will provide valuable information to the specific design of nanofiber-based scaffolds and extend their use in controlling cell behaviors for the purpose of tissue repair and regeneration.Graphical abstract
With the degradation after aging and the destruction of high-intensity exercise, the frequency of tendon injury is also increasing, which will lead to serious pain and disability. Due to the structural specificity of the tendon tissue, the traditional treatment of tendon injury repair has certain limitations. Biodegradable polymer electrospinning technology with good biocompatibility and degradability can effectively repair tendons, and its mechanical properties can be achieved by adjusting the fiber diameter and fiber spacing. Here, this review first briefly introduces the structure and function of the tendon and the repair process after injury. Then, different kinds of biodegradable natural polymers for tendon repair are summarized. Then, the advantages and disadvantages of three-dimensional (3D) electrospun products in tendon repair and regeneration are summarized, as well as the optimization of electrospun fiber scaffolds with different bioactive materials and the latest application in tendon regeneration engineering. Bioactive molecules can optimize the structure of these products and improve their repair performance. Importantly, we discuss the application of the 3D electrospinning scaffold’s superior structure in different stages of tendon repair. Meanwhile, the combination of other advanced technologies has greater potential in tendon repair. Finally, the relevant patents of biodegradable electrospun scaffolds for repairing damaged tendons, as well as their clinical applications, problems in current development, and future directions are summarized. In general, the use of biodegradable electrospun fibers for tendon repair is a promising and exciting research field, but further research is needed to fully understand its potential and optimize its application in tissue engineering.
Blood vessels are fully lined on the heart and sternum. Massive bleeding following heart surgery significantly reduces the effectiveness of anti-adhesion materials, resulting in severe tissue adhesion. Adverse outcomes in the follow-up surgery can also be brought on by post-operative adhesion. In this study, a sandwich-like scaffold was developed. Hemostatic sponges made of sodium carboxymethyl cellulose make up the top and bottom layers. An anti-adhesion fibrous membrane with poly-lactic-co-glycolic acid and polyethylene glycol-polylactic acid block copolymer made up the intermediate layer. As a physical barrier, the intermediate layer preserved the morphological integrity for more than a week. Following hemostasis, the layers of the sponges and the blood clot may degrade quickly, reducing the inflammation and fibrin deposition around the wound. This sandwich-like scaffold potentially has hemostasis and anti-adhesion properties that lower the activation level of coagulation factors and lessen bleeding.
Diabetes mellitus is a chronic metabolic disease associated with long-term multisystem complications, among which are non-healing diabetic foot ulcers (DFUs). Electrospinning is a sophisticated technique for the preparation of polymeric nanofibers impregnated with drugs for wound healing, burns, and diabetic ulcers. This study describes the fabrication and characterization of a novel drug-eluting dressing made of core–shell structured hyaluronic acid (HA)–keratin (KR)-polyethylene oxide (PEO) and polycaprolactone (PCL) nanofibers to treat diabetic wounds. The core–shell nanofibers produced by the emulsion electrospinning technique provide loading of metformin hydrochloride (MH), HA, and KR in the core of nanofibers, which in return improves the sustained long term release of the drug and prolongs the bioactivity. Morphological and chemical properties of the fibers were examined by SEM, FTIR, and XRD studies. It was observed that the fibers which contain HA and KR showed thin fiber structure, greater swelling capacity, fast degradation and increased cumulative drug release amount than neat emulsion fibers due to the hydrophilic nature of HA and KR. MH showed a sustained release from all fiber samples over 20 days and followed the first-order and Higuchi model kinetics and Fickian diffusion mechanism according to kinetic analysis results. In vitro cell culture studies showed that the developed mats exhibited enhanced biocompatibility performance with HA and KR incorporation. The results show that HA and KR-based emulsion electrospun fiber mats are potentially useful new nanofiber-based biomaterials in their use as drug carriers to treat diabetic wounds.
Curcumin (Cur) is a natural polyphenol with multifaceted pharmacological functions, exploited extensively for biomedical applications. Traditionally curcumin is being used as an antimicrobial agent. However, to improvise the pharmacological properties, it is being modified synthetically. One of such modified Cur is 3, 4- difluorobenzylidene curcumin (CDF) which is aimed for enhancing the anti-cancer properties. Though there are reports on the studies of anti-cancer properties involving CDF, the anti-bacterial property is yet to be demonstrated. Accordingly, in our studies, we prepared bioinspired hyaluronic acid blends immobilized with CDF and fabricated non-woven nanofiber mats. These nanofiber mats were characterized and demonstrated in vitro cell culture studies, which involved cell viability, hemolysis, anti-bacterial and cell scratch assay to understand their efficacy in treating bacteria. The molecular docking studies of CDF and Cur were performed on the dihydrofolate reductase (DHFR) enzyme receptor, which is an essential protein of S.auerus (Staphylococcus aureus). The results of MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay, and hemolysis of the respective nanofiber mats with Cur and CDF showed non-toxicity and were compatible with blood cells. Further, the cell proliferation and adherence recorded >60% fibroblast cells for the nanofiber mats. The anti-bacterial property of Cur and CDF was similar. The in vitro release studies for the respective Cur and CDF loaded nanofiber mats recorded a release of 25 and 37%, respectively. From these studies, we concluded that the CDF sustained its anti-bacterial property in addition to the improved anti-cancer property; hence CDF being synergetic, it will have a better scope in cancer therapy.
The thermal degradation kinetics of high-performance polymer composite electrolyte membranes were investigated by thermal gravimetric analysis in this study. The novel porous polymer composite membranes were fabricated by crosslinking poly (ethylene-co-vinyl alcohol) (EVOH) with polybutylene terephthalate (PBT) nano fiber. The PBT nano-scale fiber non-woven cloth was first prepared by the electrospinning method to form a labyrinth-like structure, and the crosslinking was carried out by filtering it through a solution of EVOH and crosslinking agent triallylamine using the Porcelain Buchner funnel vacuum filtration method. The PBT–EVOH composite membranes with various crosslinking agent ratios and ethylene carbonate/dimethyl carbonate (EC/DMC) immersion times were investigated for their thermal stability and ionic conductivity. The results showed that the higher crosslinking agent content would lower the crystallinity and enhance thermal stability. The thermal degradation activation energy was dramatically increased from 125 kJ/mol to 340 kJ/mol for the 1.5% crosslinking agent content sample at 80% conversion. The triallylamine crosslinking agent was indeed effective in improving thermal degradation resistivity. The best ionic conductivity of the polymer composite membranes was exhibited at 5.04 × 10−3 S cm−1 using the optimal weight ratio of EVOH/PBT composite controlled at 1/2. On the other hand, the EC/DMC immersion time was more effective in controlling the Rb value, thus the ionic conductivity of the membranes. A higher immersion time, such as 48 h, not only gave higher conductivity data but also provided more stable results. The triallylamine crosslinking agent improved the membrane ionic conductivity by about 22%.
Membrane systems offer a broad range of applications in the field of tissue engineering [...]
