Effect of Pore Size on the Biodegradation Rate of Silk Fibroin Scaffolds

Zuwei Luo,Wei Tao,Meijing Shi,Qin Zhang,Yang Zhang,Mingzhong Li

doi:10.1155/2015/315397

Abstract

Controlling the degradation rate of silk fibroin-based biomaterial is an important capability for the fabrication of silk-based tissue engineering scaffolds. In this study, scaffolds with different pore sizes were prepared by controlling the freezing temperature and the silk fibroin concentration.In vitrodegradation results showed that the internal pore walls of the scaffolds with a larger pore size collapsed upon exposure to collagenase IA for times ranging from 6 to 12 days, and the silk scaffolds exhibited a faster rate of weight loss. The morphological and structural features of the silk scaffolds with a smaller pore size maintained structural integrity after incubation in the protease solution for 18 days, and the rate of weight loss was relatively slow. Scaffolds with a smaller pore size or a higher pore density degraded more slowly than scaffolds with a larger pore size or lower pore density. These results demonstrate that the pore size of silk biomaterials is crucial in controlling the degradation rate of tissue engineering scaffolds.

Highlights

Silk fibroin materials can support cell adhesion, growth, proliferation, and differentiation for a large variety of cell types [1, 2] and have aroused increasing interest in the field of biomedicine because of their excellent environmental stability, biocompatibility, morphologic flexibility, and mechanical properties [1, 3,4,5,6,7]
The degradation behavior of porous silk fibroin materials incubated in α-chymotrypsin, collagenase IA, and protease XIV solution demonstrated that 70% of the sample immersed in protease XIV solution was degraded within 15 days at 37∘C, but the weight loss of the samples
The concentrations of group C and group D silk fibroin solution were both 10.0 wt%; the average pore size of group C scaffolds frozen at −40∘C was remarkably larger than that of group D scaffolds frozen at −80∘C, while the pore density of group C scaffolds was smaller

Summary

Introduction

Silk fibroin materials can support cell adhesion, growth, proliferation, and differentiation for a large variety of cell types [1, 2] and have aroused increasing interest in the field of biomedicine because of their excellent environmental stability, biocompatibility, morphologic flexibility, and mechanical properties [1, 3,4,5,6,7]. Silk fibroin can be catalytically degraded by proteolytic enzymes. The rate and extent of degradation may be highly variable, depending on a collection of chemical, physical, and biological factors related to the molecularweight distribution [6, 16, 17] and secondary structure [9, 18,19,20] of the silk fibroin, processing methods [15, 21,22,23,24], and features of the enzymes [4,5,6, 12, 25]. Three-dimensional porous scaffolds prepared from regenerated silk fibroin using either an all-aqueous process or a process involving an organic solvent, hexafluoroisopropanol (HFIP), were implanted subcutaneously into rats. The degradation behavior of porous silk fibroin materials incubated in α-chymotrypsin, collagenase IA, and protease XIV solution demonstrated that 70% of the sample immersed in protease XIV solution was degraded within 15 days at 37∘C, but the weight loss of the samples

Methods

Results

Discussion

Conclusion