Functionalization of Calcium Phosphates with Ionic Dopants for Bone Tissue Engineering

There is an increasing scientific interest in the development of calcium phosphates (CaPs) functionalization to tailor its composition, structure, and performance, directing to bone tissue engineering requirements. CaPs are the chemical compounds of special interest due to their similarity with the inorganic part of calcified tissues of mammals. CaP materials are used in a variety of bone tissue engineering ranging from cements to implant coatings and, most commonly, bone void fillers. Essentially, CaPs act as scaffold in which they facilitate new bone creation through the migration and proliferation of bone forming cells.¹ In particular, CaPs are able to: (a) produce tunable drug release profiles, (b) be injectable using self-setting pastes, (c) deliver bioactive compounds, (d) accommodate an array of functional ions, and (e) be naturally antimicrobial. These biomaterials possess remarkable biocompatibility, osteoconductivity, and high mechanical strength. The functionalization of CaPs, with the partial substitution of Ca by different ions into the structure has shown significant osteogenic, angiogenic and neovascularization capability in the formation, growth, and repair of bone with faster patient healing times and high surgical success rates.² In addition, these ionic dopants can lend controlled degradation and increase the mechanical strength of the developed CaP biomaterials. This study targets to evaluate the functionalization of CaPs materials with the incorporation of different ionic dopants, namely zinc, strontium, and manganese, in order to improve its mechanical and biological performance for bone tissue repair and regeneration. The materials presented a suitable porosity, and adequate degradation behavior and mechanical strengths for bone tissue engineering. In vitro assays using human Adipose Stem Cells cultured on the materials showed that the presence of Zn led to improved proliferation, while the Sr- and Mn-incorporation presented higher osteogenic potential. The combination of Sr with Zn led to an average influence on cell proliferation and osteogenesis when compared with single ions.³

References

1. Pina S. et al., Advanced Materials, 27, 1143–1169, 2015.

2. Pina S. et al., European Cells & Materials 20, 162, 2010.

3. Pina S. et al., Cells Tissues Organs, 2017.