Green electrospun pantothenic acid/silk fibroin composite nanofibers: Fabrication, characterization and biological activity
Introduction
Silk fibroin (SF) from domestic silkworm (Bombyx mori) cocoons is a natural biological protein polymer. It has many established excellent properties: good biocompatibility and biodegradability, tunable mechanical properties, controllable biodegradable rate in vivo and easily processing properties in aqueous environment [1], [2], [3], [4], [5], [6]. Indeed, SF has received a great deal of attention from biomedical researchers since clinically used as surgical suture. It has been widely processed into particles, fibers, films, and gels for a variety of applications [2], [4], [7], [8], [9]. Recently, the research and application of SF nanofibers from electrospinning has become a hot topic in the biomedical field due to some unique properties of as-spun nanofibrous matrices. The specifically high surface-area-to-volume ratio and inherent porous structure of electrospun nanofibrous matrices closely mimics the natural extracellular matrix (ECM), making them very suitable for use as tissue regeneration and skin care matrices [2], [6], [10], [11], [12], [13], [14], [15], [16]. However, some performances of electrospun SF nanofibrous matrices (ESFNM) such as antibacterial activity, bone-induced ability and antioxidation capacity still need further enhancing for special benefits. A good strategy is to develop SF-based hybrid or composite nanofibrous matrices with improved function [2], [17], [18].
Pantothenic acid, usually termed as vitamin B5 (VB5), is an important component of coenzyme A. It plays a key role in numerous physiological responses and thus its deficiency often leads various diseases or disorders [19], [20], [21]. In particular, a wide range of studies have demonstrated the skin benefit of VB5. VB5 can assist mammalian cells to survive in oxidative stress by increasing the level of glutathione, as revealed by Wojtczak et al. [22]. Aprahamian et al. reported that VB5 supported fibroblast immigration and proliferation, and therefore promoted wound healing [23]. The clinical study from Leung et al. has also demonstrated that VB5 can reduce sebum secretion, cure acne vulgaris and make smooth skin [24]. Therefore, VB5 is a desired bioactive factor for personal skin care or tissue engineering products.
This work focuses on investigating the feasibility of fabricating VB5-reinforcing SF nanofibrous matrices via a green electrospinning process for biomedical applications (Scheme 1). The morphology of composite nanofibers was shown using SEM (scanning electron microscopy). The structure of nanofibrous matrices was analyzed by ATR-FTIR (attenuated total reflectance Fourier transform infrared spectroscopy). The loaded VB5 within SF nanofibers was investigated using XPS (X-ray photoelectron spectroscopy). The cytocompatibility of VB5/SF nanofibrous matrices was shown through in vitro MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) viability assay and microscopic imaging of cells cultured on the composite fibrous matrices. The skin benefit of nanofibrous matrices was demonstrated through the viability of L929 cells grown on nanofibers under oxidative stress induced by tert-butyl hydroperoxide (t-BHP) in vitro.
Section snippets
Materials
Cocoons from domestic silkworm (B. mori) were kindly provided by Jiaxing Silk Company (China). d-Pantothenic acid hemicalcium salt: C9H16NO5·1/2Ca (VB5-hs) (purity ≥ 95.0%, HPLC) was purchased from Sigma–Aldrich (China). Mouse fibroblast L929 cells (L929 cells) were from the Institute of Biochemistry and Cell Biology (Chinese Academy of Sciences, China). All other reagents in this work were of analysis grade or higher. Ultrapure water used throughout this study was produced with a purification
Morphology of VB5/SF nanofibers
The surface morphology of VB5-hs/SF nanofibers was revealed using SEM (Fig. 1). Clearly, the incorporation of VB5-hs did not significantly alter the ribbon-like and smooth morphology of SF nanofibers. The smaller width of composite nanofibers (625 ± 179 nm) than that of pure SF nanofibers (765 ± 256 nm) is probably due to the increased solution conductivity with VB5-hs species in the electrospinning solution [27]. Both pure and VB5-hs-loaded SF nanofibers became compact and cross-linked each other
Conclusion
In this work, we successfully fabricated pantothenic-acid-loaded silk fibroin composite nanofibrous matrices using a green electrospinning technique. As-spun composite nanofibrous matrices maintained a higher level of cell viability, especially in a long culture period and significantly assisted skin cells to survive under oxidative stress compared with pure silk fibroin nanofibrous matrices. The ongoing progress in our lab is to achieve pantothenic acid/silk fibroin composite nanofibers with
Acknowledgements
This research was supported by the Shanghai–Unilever Research and Development Fund (08520750100), the Natural Science Foundation of Shanghai (12ZR1400300), National Nature Science Foundation of China (31070871 and 31271028), Fundamental Research Funds for the Central Universities and Open Foundation of State Key Laboratory for Modification of Chemical Fibers and Polymer Materials (LK1111).
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