Studies of electrospun regenerated SF/TSF nanofibers
Graphical abstract
Introduction
Recently, much attention has been paid to electrospinning, a very effective way to prepare nanofibers [1]. Electrospinning can be used to process many kinds of materials, like polymers, composite, ceramic materials, cellulose acetate [2], [3], and so on. Bombyx mori silk, Sussah silk, Samia cynthia, recombinant hybrid silk all have been electrospun to nanofibers which are probably used in biomaterials [4], [5], [6].
B. mori silk has been used for medical suture for a long time [7]. SF (silk fibroin) is a valuable candidate materials for biomedical applications for its distinctive biomedical properties including good biocompatibility, blood compatibility, good oxygen and water permeability, biodegradability, non-cytotoxicity and minimal inflammatory reaction [8]. Tussah silk is one of the wild silks, and its chemical structure, molecular conformation and physical properties have been extensively studied [9]. In contrast to domestic silk, its amino acid composition is characterized by more Ala, Asp and Arg contents and, less Gly. Moreover, it is well known that the presence of the Arg-Gly-Asp (RGD) tripeptide sequence may act as a biological recognition signal, promoting cell adhesion and, consequently, make this protein suitable for biomedical application [10].
The aim of this study was to prepare SF/TSF blend nanofibers by electrospinning of their solution and, to characterize the micro-structure properties of these nanofibers by SEM, FTIR, X-ray diffraction, and TG-DTG analyses. Furthermore, in order to evaluate the cytocompatibility and cell behavior on the SF/TSF nanofibers, MSCs, VECs, and NSCs were seeded onto the nanofibers.
Section snippets
Solution preparation
B. mori silk fibroin film and Tussah silk fibroin (TSF) film were made as per our previous report [11], [12]. The 10% concentration spinning solutions with the SF/TSF ratios of 0/100, 20/80, 40/60, 50/50, 60/40, 80/20, 100/0 were prepared by dissolving SF film and TSF film in HFIP, and oscillating in 25 °C water bath for one week.
Electrospinning and post-treatment
The electrospinning setup used in this study consisted of a syringe and needle (0.9 mm OD × 0.5 mm ID), a rectangular (20 × 10 cm) aluminum foil collecting plate, a high
Morphological characteristics
Fig. 1 shows SEM micrographs and diameters' distribution of SF/TSF nanofibers. The ribbon-like as-spun nanofibers had a smooth surface and round cross section. Due to the incomplete solvent evaporation and jet split, fibers' adhesion and bifurcation were observed.
As shown in Fig. 1, the diameters of SF/TSF blend nanofibers were between 300 and 3500 nm, the average diameters increased from 404 to 1977 nm with the increase of SF content in blend compositions, and the diameter of five groups with
Conclusions
In this study, the SF and TSF dissolved in HFIP were electrospun into nanofibers with the blend ratios of 100/0, 80/20, 60/40, 50/50, 40/60, 20/80, 0/100. A linear correlation was found between the average diameters and SF or TSF content. The estimated structure and physical properties of electrospun SF/TSF blend nanofibers suggest that the two fibrous proteins have low degree of compatibility after electrospinning. After 75% ethanol treatment, random coil, α-helix and β-sheet co-exist in the
Acknowledgement
The present work is supported financially by the Natural Science Foundation of Jiangsu (No. BK2007054) and Sponsored by National Base Research Program of China (973 program) (2005CB623906).
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