Effect of Sodium Carbonate Concentrations on the Formation and Mechanism of Regenerated Silk Fibroin Nanofibers by Electrospinning

Hao Dou,Baoqi Zuo

doi:10.1155/2014/646021

Abstract

Degumming is the first process for the preparation of all silk-based products. In this paper, effect of sodium carbonate concentrations for silk degumming on the formation of electrospun silk fibroin nanofibers was investigated and the reason for the silk electrospinning process was explained for the first time by differences from the microstructure of regenerated silk fibroin. With increasing the sodium carbonate concentration, microstructure both in the aqueous solutions and in the electrospinning solutions transformed from nanofibrils to nanoparticles, leading to obvious changes on rheological property; electrospinning solutions with nanofibrils behaved like the native silk dope and owned remarkably higher viscosity than the solutions with nanoparticles showing very low viscosity. More interestingly, nanofibrils favored the formation of silk nanofibers with ease, and even nanofibers could be electrospun at concentration 2%. However, nanoparticles were completely unable to generate nanofibers at high spinning concentration 8%. Importance of sodium carbonate concentrations is heavily emphasized for impacting the microstructure types and further influencing the electrospinning performance of regenerated silk. Hence, sodium carbonate concentrations provide a controllable choice for the preparation of silk-based electrospun biomaterials with desired properties.

Highlights

Silk is well known as a natural material which has been widely used in the traditional textile industry for its pearly luster and outstanding mechanical properties [1]
The trend became divided with the increase of shear rates
When Na2CO3 concentrations were 5% and 0.5%, the solutions behaved as a shear-independent Newtonian flow with relatively low viscosity (Figures 1(a) and 1(b)) while the viscosityshear-rate profiles from the Na2CO3 concentrations 0.05% and 0.005% indicated that shear thinning phenomenon continuously took place with increasing the shear rate similar to the behavior of the native silk dope [28, 29], showing obvious higher viscosities (Figures 1(c) and 1(d))

Summary

Introduction

Silk is well known as a natural material which has been widely used in the traditional textile industry for its pearly luster and outstanding mechanical properties [1]. Electrospinning has been extensively explored as a simple and versatile technique that can directly produce natural or synthetic polymer nanofibers for applications such as high performance filters, biomaterial scaffolds for cell growth, vascular grafts, wound dressings, and drug delivery systems [3,4,5,6]. As an ideal candidate of tissue scaffolds with several distinctive biological properties, nonwoven silk-based nanofibers prepared by electrospinning mimic the structure and biological function of native extracellular matrix (ECM) proteins, which provide mechanical support and regulate cell activities [7, 8]

Results

Discussion

Conclusion