Acrylic acid-grafted hydrophilic electrospun nanofibrous poly(L-lactic acid) Scaffold

ArticleinMacromolecular Research 14(5):552-558 · October 2006with12 Reads
DOI: 10.1007/BF03218723
Abstract
Biodegradable nanofibrous poly(L-lactic acid) (PLLA) scaffold was prepared by an electrospinning process for use in tissue regeneration. The nanofiber scaffold was treated with oxygen plasma and then simultaneously in situ grafted with hydrophilic acrylic acid (AA) to obtain PLLA-g-PAA. The fiber diameter, pore size, and porosity of the electrospun nanofibrous PLLA scaffold were estimated as 250∼750 nm, ∼30 µm, and 95%, respectively. The ultimate tensile strength was 1.7 MPa and the percent elongation at break was 120%. Although the physical and mechanical properties of the PLLA-g-PAA scaffold were comparable to those of the PLLA control, a significantly lower contact angle and significantly higher ratio of oxygen to carbon were notable on the PLLA-g-PAA surface. After the fibroblasts were cultured for up to 6 days, cell adhesion and proliferation were much improved on the nanofibrous PLLA-g-PAA scaffold than on either PLLA film or unmodified nanofibrous PLLA scaffold. The present work demonstrated that the applications of plasma treatment and hydrophilic AA grafting were effective to modify the surface of electrospun nanofibrous polymer scaffolds and that the altered surface characteristics significantly improved cell adhesion and proliferation. Keywordstissue engineering–PLLA scaffold–electrospun nanofiber–plasma treatment–acrylic acid grafting–fibroblast
    • "In all cases a positive influence was found on the scaffold's histological properties. Park et al. also obtained an increase in adhesion and proliferation after seeding NIH 3T3 fibroblasts onto PLLA nanotextile scaffolds that were grafted with an acrylic acid coating using a low pressure O 2 plasma [107]. He et al and Chan et al. performed a similar procedure compared to Feng et al. to immobilize collagen onto PLLA-PCL electrospun scaffolds [108, 109]. "
    [Show abstract] [Hide abstract] ABSTRACT: In the textile market industry, technical textiles are one of the fastest growing businesses. Part of that industry consists of textiles for medical and healthcare applications and are responsible for a continuous increase in its market potential [1]. Next to their need in hospital environ‐ ments, there is a growing demand in other sectors such as the food and hotel industry, due to stricter hygiene regulations. In most cases biomedical textile meets a well-defined set of requirements such as minimizing non-specific protein adsorption, drug delivery coatings or the presence of active functional coatings and most importantly excellent biocompatibility (blood-, tissue-or cyto-compatibility) [2]. In general there are very few materials meeting all these characteristics, while at the same time offering the needed structural and mechanical properties. Furthermore, depending on the application, the production process has to be cost- effective and approved by local legislation. In order to meet all these requirements, numerous modification techniques have been developed in the past [3-5]. Most of these techniques lead to the incorporation of extra/new functionalities and might lead to a change in surface free energy. For most biomedical applications, the preservation of material bulk properties such as elasticity, strength, ductility, structural integrity etc. is critical. For biomedical end-products, the use of solvents and chemicals based surface treatment techniques are reduced to a strict list approved by local legislation. Chemical-free techniques such as γ-radiation, UV treatments, corona discharges etc. have led to some excellent results in the field of tissue engineering [6,7]. One of those solvent-free techniques that have been around for over a century, has more recently found its way into the biomedical field: non-thermal plasma technology. Over time, it has extensively been proven that non-thermal plasma technology can profoundly change the surface properties of polymer films (PP, PET, PU, etc.) as well as material characteristics (adhesion, printability, dyeing etc.) of more complex substrates such as industrially produced textile [8-14]. Alongside the growing interest in tissue engineering and the booming of the electrospinning industry at the end of last century, non-thermal plasma technology found its way into the biomedical field. Today non-thermal plasma treatment can be consid‐ ered as a well-established technique for the surface treatment of (bio)materials. Before the start of the 21st century, the majority of contributions to scientific literature was focussing on oxygen plasma treatments at low pressures and the corresponding response on cell adhesion, growth and proliferation. Although today there is still a steady stream of publications on these low pressure oxygen plasmas, there is a growing interest in atmospheric pressure plasma treatments as they offer a number of practical advantages. In the next chapter part, a detailed overview will be given on plasma technology in general and the different treatments possible. After that, the chapter will continue on the use of plasma technology for (bio)medical textiles, according to the application. At the end there will be a critical conclusion and a look forward to the possible future of plasma technology for the biomedical textile industry.
    Full-text · Chapter · Jul 2015 · Biomaterials
    • "A recently published review [33] comparing different nanofiber/cell combinations found optimal pore diameter for nanofiber scaffolds ranging from 5 to 50 lm. With respect to PLLA nanofibers produced from DCM pore diameter of 30 lm were reported [34] while PLLA-collagen blend nanofiber scaffolds showed pore diameter below 2 lm [35] . Here the low pore diameter might be one reason for the lack of colonization. "
    [Show abstract] [Hide abstract] ABSTRACT: The reconstruction of large bone defects after injury or tumor resection often requires the use of bone substitution. Artificial scaffolds based on synthetic biomaterials can overcome disadvantages of autologous bone grafts, like limited availability and donor side morbidity. Among them, scaffolds based on nanofibers offer great advantages. They mimic the extracellular matrix, can be used as a carrier for growth factors and allow the differentiation of human mesenchymal stem cells. Differentiation is triggered by a series of signaling processes, including integrin and bone morphogenetic protein (BMP), which act in a cooperative manner. The aim of this study was to analyze whether these processes can be remodeled in artificial poly-(l)-lactide acid (PLLA) based nanofiber scaffolds in vivo. Electrospun matrices composed of PLLA-collagen type I or BMP-2 incorporated PLLA-collagen type I were implanted in calvarial critical size defects in rats. Cranial CT-scans were taken 4, 8 and 12 weeks after implantation. Specimens obtained after euthanasia were processed for histology and immunostainings on osteocalcin, BMP-2 and Smad5. After implantation the scaffolds were inhomogeneously colonized and cells were only present in wrinkle- or channel-like structures. Ossification was detected only in focal areas of the scaffold. This was independent of whether BMP-2 was incorporated in the scaffold. However, cells that migrated into the scaffold showed an increased ratio of osteocalcin and Smad5 positive cells compared to empty defects. Furthermore, in case of BMP-2 incorporated PLLA-collagen type I scaffolds, 4 weeks after implantation approximately 40 % of the cells stained positive for BMP-2 indicating an autocrine process of the ingrown cells. These findings indicate that a cooperative effect between BMP-2 and collagen type I can be transferred to PLLA nanofibers and furthermore, that this effect is active in vivo. However, this had no effect on bone formation. The reason for this seems to be an unbalanced colonization of the scaffolds with cells, due to insufficient pore size.
    Full-text · Article · Jun 2012
    • "Poly(Llactic acid) (PLLA) is a frequently used non-cytotoxic and biodegradable polymer in preparing electrospun fibers for drug delivery and tissue engineering applications [31e34]. However, the surface modification of PLLA fiber for bioconjugation poses a major chal- lenge [35] . Electrospun fiber mats prepared from other noncytotoxic polymers such as poly(vinyl alcohol), collagen [36], dextran [37], or hyaluronic acid [38] require additional treatment steps, such as heat curing or cross-linking to avoid the loss of fiber structure through gel formation on contact with aqueous media. "
    [Show abstract] [Hide abstract] ABSTRACT: With the emergence of "super bacteria" that are resistant to antibiotics, e.g., methicillin-resistant Staphylococcus aureus, novel antimicrobial therapies are needed to prevent associated hospitalizations and deaths. Bacteriophages and bacteria use cell lytic enzymes to kill host or competing bacteria, respectively, in natural environments. Taking inspiration from nature, we have employed a cell lytic enzyme, lysostaphin (Lst), with specific bactericidal activity against S. aureus, to generate anti-infective bandages. Lst was immobilized onto biocompatible fibers generated by electrospinning homogeneous solutions of cellulose, cellulose-chitosan, and cellulose-poly(methylmethacrylate) (PMMA) from 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), room temperature ionic liquid. Electron microscopic analysis shows that these fibers have submicron-scale diameter. The fibers were chemically treated to generate aldehyde groups for the covalent immobilization of Lst. The resulting Lst-functionalized cellulose fibers were processed to obtain bandage preparations that showed activity against S. aureus in an in vitro skin model with low toxicity toward keratinocytes, suggesting good biocompatibility for these materials as antimicrobial matrices in wound healing applications.
    Full-text · Article · Sep 2011
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