title: [Preparation of silk fibroin-chitosan scaffolds and their properties].
abstract: OBJECTIVE
  To prepare the silk fibroin (SF)-chitosan (CS) scaffolds by adjusting the mass ratio between CS and SF, and test and compare the properties of the scaffolds at different mass ratios.
  
  
  METHODS
  According to the mass ratios of 6:4 (group A), 6:8 (group B), and 6:16 (group C) between SF and CS, CS-SF scaffolds were prepared by freeze-drying method, respectively. The material properties, porosity, the dissolubility in hot water, the modulus elasticity, and the water absorption expansion rate were measured; the aperture size and shape of scaffolds were observed by scanning electron microscope (SEM). Density gradient centrifugation method was used to isolate the bone marrow mesenchymal stell cells (BMSCs) of 4-week-old male Sprague Dawley rats. The BMSCs at passage 3 were seeded onto 3 scaffolds respectively, and then the proliferation of cells on the scaffolds was detected by MTS method.
  
  
  RESULTS
  The results of fourier transform infrared spectroscopy proved that with the increased content of CS, the absorption peak of random coil/alpha helix structure (1 654 cm(-1) and 1540 cm(-1)) constantly decreased, but the absorption peak of corresponding to beta-fold structure (1628 cm(-1) and 1516 cm(-1)) increased. The porosity was 87.36% +/- 2.15% in group A, 77.82% +/- 1.37% in group B, and 72.22% +/- 1.37% in group C; the porosity of group A was significantly higher than that of groups B and C (P < 0.05), and the porosity of group B was significantly higher than that of group C (P < 0.05). The dissolubility in hot water was 0 in groups A and B, and was 3.12% +/- 1.26% in group C. The scaffolds had good viscoelasticity in 3 groups; the modulus elasticity of 3 groups were consistent with the range of normal articular cartilage (4-15 kPa); no significant difference was found among 3 groups (F=5.523, P=0.054). The water absorption expansion rate was 1 528.52% +/- 194.63% in group A, 1 078.22% +/- 100.52% in group B, and 1320.05% +/- 179.97% in group C; the rate of group A was significantly higher than that of group B (P=0.05), but there was no significant difference between groups A and C and between groups B and C (P > 0.05). SEM results showed the aperture size of group A was between 50-250 microm, with good connectivity of pores; however, groups B and C had structure disturbance, with non-uniform aperture size and poor connectivity of pores. The growth curve results showed the number of living cells of group A was significantly higher than that of groups B and C at 1, 3, 5, and 7 days (P < 0.05); and there were significant differences between groups B and C at 3, 5, and 7 days (P < 0.05).
  
  
  CONCLUSIONS
  The CS-SF scaffold at a mass ratio of 6:4 is applicable for cartilage tissue engineering.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.forename: Wenliang
authors.initials: W
authors.lastname: Wang
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001854:Bone Marrow Cells / Q000166:cytology; D049109:Cell Proliferation; D002478:Cells, Cultured; D048271:Chitosan / Q000737:chemistry*; D005349:Fibroins / Q000737:chemistry*; D008297:Male; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D016062:Porosity; D051381:Rats; D017207:Rats, Sprague-Dawley; D012996:Solutions; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D012996:Solutions; D005349:Fibroins; D048271:Chitosan