3D printing of bioactive glass scaffolds with porosity gradient for bone tissue engineering

Reference Presenter Authors
02-028 Francesco Baino Baino, F.(Politecnico di Torino); Barberi, J.(Politecnico di Torino); Massera, J.(Tampere University of Technology); Verné, E.(Politecnico di Torino); In recent years, 3D printing of bioceramics has shown great promise in tissue engineering (TE) and regenerative medicine. One class of bioceramics that has drawn much are bioactive glasses (BGs). BGs not only promote the healing of hard tissues (e.g. bone) but are also promising for soft TE applications. The composition of BGs can be tailored to control their reaction rate or even to provide BGs with extra-functionalities such as antimicrobial or anti-oxidative properties. However, one drawback of such materials lies in their poor sintering ability. Indeed, sintering of BG particles post-printing often leads to partial to full crystallization. Crystallization can reduce, or even suppress, the glass bioactivity, depending on the crystal density, compositions and/or location. In this study, a silicate BG with enhanced hot forming domain was melted and crushed into powder smaller than 38 µm in size. The crystallization behavior of the glass powder was studied by hot-stage microscopy, differential thermal analysis and X-ray diffraction. 3D-printed scaffolds were produced and sintered at a temperature below any significant crystallization. Here, two set of scaffolds were produced, one set with monoporosity and another with graded porosity (i.e. the inner part of the scaffold has pores with smaller size than the outer part). The mechanical properties of the scaffolds as a function of porosity was assessed. The in vitro dissolution of both scaffold types was tested in the Kokubo’s simulated body fluid (SBF) for different time frames. The pH and the concentration of released ions were measured at each time point. The change in mechanical properties was assessed as a function of immersion time and related to the glass reactivity in SBF. The hydroxyapatite formation on the scaffold surface was confirmed by EDX/SEM. The processing of amorphous 3D-printed scaffolds with engineered porosity are of tremendous importance in bone TE.