Polymeric nanofibers have been widely used as scaffolds for tissue engineering, drug delivery, and filtration applications, among many others. A high throughput melt coextrusion technique and post-processing functionalization chemistry was recently developed to fabricate functional fibers with nanoscale dimensions. This manuscript expands upon the development of nanofiber modification chemistry by functionalizing fiber mats using a surface-initiated photo-induced electron transfer reversible addition–fragmentation chain transfer (PET-RAFT) polymerization technique. PET-RAFT allows for the fabrication of chemically diverse nanofiber systems initiated with light, preventing the need for high temperature thermal initiators. This manuscript describes the scope of monomers polymerizable via this technique on the surface of poly ε-caprolactone (PCL) nanofibers. The PET-RAFT modification chemistry is used to introduce block copolymers, provide multiple modifications using an orthogonal RAFT-ATRP system, induce spatial photopatterning and to establish cell-adhesive capabilities. The development of surface-initiated PET-RAFT adds an additional tool to a growing strategy for nanofiber functionalization.
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Enhancement of the mechanical property of poly(ε-caprolactone) composites with surface-modified cellulose nanofibers fabricated via electrospinning
Abstract Poly(ε-caprolactone) (PCL) is one of the leading biocompatible and biodegradable polymers. However, the mechanical property of PCL is relatively poor as compared with that of polyolefins, which has limited the active applications of PCL as an industrial material. In this study, to enhance the mechanical property of PCL, cellulose nanofibers (C-NF) with high mechanical property, were employed as reinforcement materials for PCL. The C-NF were fabricated via the electrospinning of cellulose acetate (CA) followed by the subsequent saponification of the CA nanofibers. For the enhancement of the mechanical property of the PCL composite, the compatibility of C-NF and PCL was investigated: the surface modification of the C-NF was introduced by the ring-opening polymerization of the ε-caprolactone on the C-NF surface (C-NF-g-PCL). The polymerization was confirmed by the Fourier transform infrared (FTIR) spectroscopy. Tensile testing was performed to examine the mechanical properties of the C-NF/PCL and the C-NF-g-PCL/PCL. At the fiber concentration of 10 wt%, the Young’s modulus of PCL compounded with neat C-NF increased by 85% as compared with that of pure PCL, while, compounded with C-NF-g-PCL, the increase was 114%. The fracture surface of the composites was analyzed by scanning electron microscopy (SEM). From the SEM images, it was confirmed that the interfacial compatibility between PCL and C-NF was improved by the surface modification. The results demonstrated that the effective surface modification of C-NF contributed to the enhancement of the mechanical property of PCL.
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- Award ID(s):
- 1846628
- NSF-PAR ID:
- 10094659
- Date Published:
- Journal Name:
- MRS Advances
- Volume:
- 4
- Issue:
- 07
- ISSN:
- 2059-8521
- Page Range / eLocation ID:
- 385 to 391
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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In this work, we demonstrate the non‐synthetic surface modification of a co‐extruded multilayer poly(methyl methacrylate) (PMMA)/poly(ϵ‐caprolactone) (PCL) film with gas barrier properties through electrospinning of polystyrene (PS)/multi‐walled carbon nanotube (MWNT) nanofibers. As produced by forced assembly layer multiplying co‐extrusion, the heterogeneous nucleating crystallization of PCL was induced using the glassy confinement of the amorphous PMMA thus creating in‐plane lamellae crystallization, which is impermeable to most gas molecules. To complement these intrinsic gas barrier properties of the multilayer film, electrospun PS/MWNT nanofibers were deposited onto the surface of the PMMA/PCL film, which increased the surface roughness and resulted in superhydrophobic behavior (water contact angles>150°). Furthermore, the inclusion of the MWNT in the matrix caused an increasing antibacterial efficacy, which was determined to reach 97% inactivation against gram‐positive bacteria
Bacillus subtilis . The fiber mats were further characterized using scanning electron microscopy (SEM), Raman spectroscopy, and thermogravimetric analysis (TGA). -
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Abstract Nanofibers made by blending natural and synthetic biopolymers have shown promise for better mechanical stability, ECM morphology mimicry, and cellular interaction of such materials. With the evolution of production methods of nanofibers, alternating field electrospinning (a.k.a. alternating current (AC) electrospinning) demonstrates a strong potential for scalable and sustainable fabrication of nanofibrous materials. This study focuses on AC‐electrospinning of poorly miscible blends of gelatin from cold water fish skin (FGEL) and polycaprolactone (PCL) in a range of FGEL/PCL mass ratios from 0.9:0.1 to 0.4:0.6 in acetic acid single‐solvent system. The nanofiber productivity rates of 7.8–19.0 g/h were obtained using a single 25 mm diameter dish‐like spinneret, depending on the precursor composition. The resulting nanofibrous meshes had 94%–96% porosity and revealed the nanofibers with 200–750 nm diameters and smooth surface morphology. The results of FTIR, XRD, and water contact angle analyses have shown the effect of FGEL/PCL mass ratio on the changes in the material wettability, PCL crystallinity and orientation of PCL crystalline regions, and secondary structure of FGEL in as‐spun and thermally crosslinked materials. Preliminary in vitro tests with 3 T3 mouse fibroblasts confirmed favorable and tunable cell attachment, proliferation, and spreading on all tested FGEL/PCL nanofibrous meshes.
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ABSTRACT Three pseudorotaxanes (PpR) comprised of poly (ε‐caprolactone) (PCL) and α‐cyclodextrin (α‐CD) with varying stoichiometric ratios were synthesized and characterized. Wide‐angle X‐ray diffraction (WAXD) and thermogravimetric (TGA) analyses provided conclusive evidence for complexation between the guest PCL and host α‐CD. The as‐synthesized and characterized PpRs were used at 10 and 20% concentrations as nucleants to promote the bulk PCL crystallization in composite films. Both WAXD and TGA provided evidence for intact PpR structures in the composite films. Isothermal differential scanning calorimetric (I‐DSC) analyses, performed at various crystallization temperatures demonstrated significant differences in the crystallization patterns among the composite films. In addition, I‐DSC analyses showed higher Avrami constant values (n) in the PpR‐nucleated composite PCL films (n ~ 3), indicating 3‐dimensional crystal growth. In the case of neat PCL films, however, lower n values indicated crystal growth in 1‐dimensions or 2‐dimensions. Moreover, atomic force microscopic analyses showed large crests and pits in PpR‐nucleated PCL composites, with irregular morphologies leading to higher surface roughness. To the contrary, the crests and pits were much smaller in the neat PCL films, resulting in lower surface roughness values. Finally, mechanical testing revealed higher tensile strength for PpR‐nucleated PCL composites films, demonstrating larger load bearing capabilities. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.
2018 ,56 , 1529–1537 -
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Abstract PCL (poly‐caprolactone) nanofibers have good biocompatibility and high porosity, which are usually utilized for application in wound dressings. However, wound healing could be hindered by the overproduction of reactive oxygen species (ROS) and different factors. Pure nanofibers cannot satisfy these requirements of wound healing.
N ‐acetylcysteine (NAC), as an antioxidant, meets the requirements for wound healing by resisting the overproduction of ROS and by promoting angiogenesis and maturation of the epidermis. In this study, we prepared a sandwich structured PCL‐Col/NAC scaffold using the molding method, which consisted of PCL nanofibers at the core and NAC‐loaded collagen on both sides. The hydroscopicity and tensile modulus of PCL‐Col/NAC scaffolds showed best performance of these properties among groups. Meanwhile, the drug release profiles of PCL‐Col/NAC scaffolds were investigated using the HPLC method and the results suggested a sustained drug release of NAC for PCL‐Col/NAC scaffolds. In addition, PCL‐Col/NAC scaffolds presented better properties than the control groups in cell migration and proliferation. The in vivo wound healing therapy effect was studied using an oval (2 × 1 cm) full‐thickness skin defect wound model for SD rats. After 21 days, gross view and histological analysis showed a favorable beneficial therapeutic effect as well as better epidermal maturation compared with the control groups. CD31 immunohistology results revealed relatively more new vessels in the PCL‐Col/NAC group than the control groups. This study developed novel PCL‐Col/NAC scaffolds with an excellent hydroscopicity, tensile modulus and the ability to promote epidermal maturation and angiogenesis, demonstrating its promising potential in wound healing treatment. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1557/adv.2019.4
