Development of composite scaffolds in the system of gelatin−calcium phosphate whiskers/fibrous spherulites for bone tissue engineering

Abstract Calcium phosphate whiskers have been suggested to be effective as the reinforcement in improving mechanical properties of composite biomaterials. Therefore, composite scaffolds of varying compositions were prepared by freeze drying of gelatin foams containing increasing amounts of calcium phosphate whiskers/fibrous spherulites, up to 50 wt%. The whiskers were attempted to synthesize in acidic solutions under thermal conditions using two different methods: aging of a highly crystalline beta-tricalcium phosphate powder in H 2 O 2 solution, and the precipitation−hydrolysis method using aqueous solutions of calcium and phosphate ions in HNO 3 solution and urea as an additive. The morphology and phase analysis of the whiskers were studied by scanning electron microscopy (SEM) and X-ray diffractometry (XRD), respectively. The results proved that the whiskers could not be obtained by first method at an appropriate period, but using the second method, a mixed plate-like and long whiskers, and fibrous spherulites could be formed. The XRD patterns revealed the biphasic mixture of octacalcium phosphate (OCP) and dicalcium phosphate anhydrate (DCPA). The composite scaffolds containing whiskers obtained by freeze drying were characterized by SEM, Fourier transform infrared spectroscopy and compressive mechanical test. Scaffolds with interconnective pores in a range of 150–350 μm and porosity of 65–74%, as well as homogenous dispersion of the whiskers could be produced which indicates their potential to use in bone tissue engineering applications. The prepared scaffolds showed the compressive yield strength of 4.3−6.2 MPa and Young modulus of 28−38 MPa. In the view of mechanical and microstructural features, the composite of 25 wt% calcium phosphate phase was introduced as the optimal composite for bone tissue engineering.