Novel synthesis method combining a foaming agent with freeze-drying to obtain hybrid highly macroporous bone scaffolds

Three-dimensional macroporous scaffolds are commonly used in bone tissue engineering applications since they provide sufficient space for cell migration and proliferation, facilitating bone ingrowth and implant vascularisation. The aim of this work was to combine two simple methods, freeze-drying and gas-foaming, in order to fabricate highly macroporous bone scaffolds made of chitosan/agarose matrix reinforced with nanohydroxyapatite. The secondary goal of this research was to comprehensively assess biomedical potential of developed biomaterials. In this work, it was demonstrated that simultaneous application of freeze-drying and gas-foaming technique allows to obtain hybrid (as proven by ATR-FTIR) macroporous bone scaffolds (pore diameter > 50¿µm) characterized by high open (70 %) and interconnected porosity. Novel scaffolds were non-toxic, favoured osteoblasts adhesion and growth and induced apatite formation on their surfaces, indicating their high bioactivity that is essential for good implant osseointegration. Biomaterials were also prone to enzymatic degradation, degradation in acidified microenvironment (e.g. osteoclast-mediated), and slow degradation under physiological pH of 7.4. Moreover, the scaffolds revealed microstructure (70 % open porosity, SSA approx. 30¿m2/g, high share of macropores with diameter in the range 100-410¿µm) and compressive strength (1–1.4¿MPa) comparable to cancellous bone, indicating that they are promising implants for cancellous bone regeneration.Peer ReviewedPostprint (author's final draft