It has been unanimously recognized that enough mechanical properties lay the foundation of the successful implant surgery of tissue engineering scaffolds. Firstly, the scaffolds must provide sufficient mechanical strength and stiffness to allow surgical handling during implantation initially, and later being consistent with the host tissue. The implanted tissue engineering scaffolds must have sufficient mechanical integrity to function for the new tissues from the time of implantation to the completion of the remodeling process [28, 38]. Secondly, only if they possess proper mechanical properties, can the scaffolds keep their shape and characters after being embedded in the body. Thirdly, since the scaffolds, as artificial three-dimensional frames, must provide enough structural support for cellular adhesion, migration, proliferation, differentiation, and the desired tissue regeneration, they should possess and maintain satisfactory mechanical properties. Moreover, in most instances, mechanical properties of the tissue engineering scaffolds have been found to influence their other properties, such as biocompatibility, biodegradability, etc. It has been fully shown that lack of mechanical properties could restrict the use of tissue engineering scaffolds to great extent . On the other hand, as a dynamic and hierarchically organized composite, native ECM not only provides mechanical support for embedded cells but also provides mechanical stimulations to regulate various cellular behaviors and tissue regenerations. So, ideal scaffolds should possess adequate mechanical properties from both view of practical applications and biomimetic sense.
Therefore, at the time of scaffold material selection, it is essential to make sure that this material can contribute to the satisfactory mechanical properties of the whole scaffold by itself or the appropriate interactions with other components. Furthermore, all the materials in the scaffolds should coordinate appropriately to make sure that the mechanical properties of the scaffolds can match those of the growing tissues during the gradual biodegradation process. In this case, a further challenge is that the growing rate and mechanical properties of the new tissues vary with the age and sex of the patients. Since it has been highly recognized that the scaffolds, which are made of a single material, hardly meet all the requirements of tissue engineering according to the results of an enormous amount of research in this field during last several decades, more and more studies have been focused on the development of biocomposites as the tissue engineering scaffolds. Especially, in many cases some materials with high mechanical properties are used to reinforce matrix materials so that the mechanical properties of the biocomposites can meet the requirement of the tissue engineering scaffolds. Currently, more and more attention has been paid to the study of reinforcing materials. The traditional reinforcing materials include particles and fibers or tubes.