Surface Modification and Characterisation of Silk Fibroin Fabric Produced by the Layer-by-Layer Self-Assembly of Multilayer Alginate/Regenerated Silk Fibroin.

Gaotian Shen,Xingyou Hu,Lu Wang,Guoping Guan,Michiya Matsusaki

doi:10.1371/journal.pone.0124811

Gaotian Shen, Xingyou Hu + Show 3 more

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https://doi.org/10.1371/journal.pone.0124811

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Abstract

Silk-based medical products have a long history of use as a material for surgical sutures because of their desirable mechanical properties. However, silk fibroin fabric has been reported to be haemolytic when in direct contact with blood. The layer-by-layer self-assembly technique provides a method for surface modification to improve the biocompatibility of silk fibroin fabrics. Regenerated silk fibroin and alginate, which have excellent biocompatibility and low immunogenicity, are outstanding candidates for polyelectrolyte deposition. In this study, silk fabric was degummed and positively charged to create a silk fibroin fabric that could undergo self-assembly. The multilayer self-assembly of the silk fibroin fabric was achieved by alternating the polyelectrolyte deposition of a negatively charged alginate solution (pH = 8) and a positively charged regenerated silk fibroin solution (pH = 2). Finally, the negatively charged regenerated silk fibroin solution (pH = 8) was used to assemble the outermost layer of the fabric so that the surface would be negatively charged. A stable structural transition was induced using 75% ethanol. The thickness and morphology were characterised using atomic force microscopy. The properties of the self-assembled silk fibroin fabric, such as the bursting strength, thermal stability and flushing stability, indicated that the fabric was stable. In addition, the cytocompatibility and haemocompatibility of the self-assembled silk fibroin fabrics were evaluated. The results indicated that the biocompatibility of the self-assembled multilayers was acceptable and that it improved markedly. In particular, after the self-assembly, the fabric was able to prevent platelet adhesion. Furthermore, other non-haemolytic biomaterials can be created through self-assembly of more than 1.5 bilayers, and we propose that self-assembled silk fibroin fabric may be an attractive candidate for anticoagulation applications and for promoting endothelial cell adhesion for vascular prostheses.

Highlights

With the increase in the number of cardiovascular patients, vascular prostheses have become more desirable in recent years [1]
The zeta potential measurements show that silk fibroin has an isoelectric point just between pH 4–5 and that silk fibroin is highly unstable at pH values from 3–7
Alginate and silk fibroin were assembled on Silk fibroin (SF) fabrics to create a biomaterial that could be used in a vascular graft

Summary

Introduction

With the increase in the number of cardiovascular patients, vascular prostheses have become more desirable in recent years [1]. There are no small-diameter vascular grafts that are approved for clinical use by the Food and Drug Administration (FDA). SF fibres are commonly available as sutures and have a long history of use due to their high strength and toughness [10,11,12,13]. These sutures are used in lips, eyes, and skin wounds [14]. Regenerated silk fibroin (RSF) has been shown to be a biocompatible material [16]. Endothelial cells rapidly became organised within the inner layer of the SF grafts [2, 18]

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