A biomimetic collagen–apatite scaffold with a multi-level lamellar structure for bone tissue engineering

Abstract

Collagen–apatite (Col–Ap) scaffolds have been widely employed for bone tissue engineering. We fabricated Col–Ap with a unique multi-level lamellar structure consisting of co-aligned micro- and macro-pores. The basic building blocks of this scaffold are bone-like mineralized collagen fibers developed via a biomimetic self-assembly process in a collagen-containing modified simulated body fluid (m-SBF). This biomimetic method preserves the structural integrity and great tensile strength of collagen by reinforcing the collagen hydrogel with apatite nano-particles. Unidirectional aligned macro-pores with a size of 63.8 to 344 μm are created by controlling the freezing rate and direction. The thickness of Col–Ap lamellae can be adjusted in the range 3.6 to 23 μm depending on the self-compression time. Furthermore, the multi-level lamellar structure has led to a twelve-fold increase in Young's modulus and a two-fold increase in the compression modulus along the aligned direction compared to a scaffold of the same composition with an isotropic equiaxed pore structure. Moreover, this novel lamellar scaffold supports the attachment and spreading of MC3T3-E1 osteoblasts. Therefore, owing to the biomimetic composition, tunable structure, improved mechanical strength and good biocompatibility of this novel scaffold, it has great potential to be used in bone tissue engineering applications.