Background:One of the new methods of scaffold fabrication is a nano-micro hybrid structure in which the properties of the scaffold are improved by introducing nanometer and micrometer structures. This method could be suitable for scaffold designing if some features improve.Materials and Methods:In this study, electrospun nanofibers of 9% weight solution of poly (3-hydroxybutyrate) (P3HB) and a 15% weight of chitosan by trifluoroacetic acid were coated on both the surface of a silk knitted substrate in the optimum condition to improve the mechanical properties of scaffolds for cartilage tissue engineering application. These hybrid nano-micro fibrous scaffolds were characterized by structural and mechanical evaluation methods.Results:Scanning electron microscopy values and porosity analysis showed that average diameter of nanofibers was 584.94 nm in electrospinning part and general porosity was more than 80%. Fourier transform infrared spectroscopy results indicated the presence of all elements without pollution. The tensile test also stated that by electrospinning, as well as adding chitosan, both maximum strength and maximum elongation increased to 187 N and 10 mm. It means that the microfibrous part of scaffold could affect mechanical properties of nano part of the hybrid scaffold, significantly.Conclusions:It could be concluded that P3HB-chitosan/silk hybrid scaffolds can be a good candidate for cartilage tissue engineering.

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Background:Poly (hydroxy butyrate) (PHB) is a biodegradable and biocompatible polymer with good mechanical properties. This polymer could be a promising material for scaffolds if some features improve.Materials and Methods:In the present work, new PHB/chitosan blend scaffolds were prepared as a three-dimensional substrate in cartilage tissue engineering. Chitosan in different weight percent was added to PHB and solved in trifluoroacetic acid. Statistical Taguchi method was employed in the design of experiments.Results:The Fourier-transform infrared spectroscopy test revealed that the crystallization of PHB in these blends is suppressed with increasing the amount of chitosan. Scanning electron microscopy images showed a thin and rough top layer with a nodular structure, supported with a porous sub-layer in the surface of the scaffolds. In vitro degradation rate of the scaffolds was higher than pure PHB scaffolds. Maximum degradation rate has been seen for the scaffold with 90% wt. NaCl and 40% wt. chitosan.Conclusions:The obtained results suggest that these newly developed PHB/chitosan blend scaffolds may serve as a three-dimensional substrate in cartilage tissue engineering.