Mechanism of Reinforcements
Regarding the scaffold, it is generally agreed that a highly porous microstructure with interconnected pores and a large surface area is conducive to growth of tissues. In this way, a satisfactory scaffold should possess not only appropriate porosity but also ideal mechanical properties . The scaffold can only retain its shape and other related characteristics after a cell-seeding procedure and after following being embedded in the body. A number of solutions have been applied to reach this biomedical goal, while researchers found that the use of reinforced scaffolds, containing substrate materials as a basic platform and reinforcement materials, such as particles, fibers and nanotubes, can achieve the object referred above. Thus, in the composite material, the reinforcement part is essentially dedicated to increasing the mechanical properties of the entire material system. All of the different reinforcements in the composites have different properties and thus affect the properties of the composite in different ways.
The reinforced action requires that the generated structure should have a higher stiffness and strength than the matrix and be well bonded to the matrix polymer. As a consequence, the stress can be transferred from the “weak” matrix to the “strong” reinforcement structure, according to the “working principle” of all composites. The reinforcing phase in a composite can exist in a number of different forms. To date, several reinforcements, including particles, fibers and tubes, have been investigated and used for biocomposites. Particle-reinforced composites were once used as the cheapest and most widely used composite materials for industrial applications. However, in recent years, it has been seen that significant advances in the field of scaffold reinforcements for tissue repair strategies are the use of fiber/tube reinforcements in cell-seeded gel carrier systems [67, 68]. This section will provide a brief summary of the fiber-, tube- and self-reinforced biocomposite scaffolds.