Powder 3D Printing of Bone Scaffolds with Uniform and Gradient Pore Sizes Using Cuttlebone-Derived Calcium Phosphate and Glass-Ceramic

Francesca Cestari; Yuejiao Yang; Janka Wilbig; Jens Günster; Antonella Motta; Vincenzo M Sglavo

doi:10.3390/ma15155139

Powder 3D Printing of Bone Scaffolds with Uniform and Gradient Pore Sizes Using Cuttlebone-Derived Calcium Phosphate and Glass-Ceramic

Materials (Basel). 2022 Jul 24;15(15):5139. doi: 10.3390/ma15155139.

Authors

Francesca Cestari¹, Yuejiao Yang^{1

2}, Janka Wilbig³, Jens Günster³, Antonella Motta^{1

2}, Vincenzo M Sglavo¹

Affiliations

¹ Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy.
² BIOtech Research Center, University of Trento, Via delle Regole 101, 38123 Trento, Italy.
³ Division of Advanced Multi-Materials Processing, Bundesanstalt für Materialforschung und -Prüfung BAM, Unter den Eichen 44-46, 12203 Berlin, Germany.

Abstract

The pore geometry of bone scaffolds has a major impact on their cellular response; for this reason, 3D printing is an attractive technology for bone tissue engineering, as it allows for the full control and design of the porosity. Calcium phosphate materials synthesized from natural sources have recently attracted a certain interest because of their similarity to natural bone, and they were found to show better bioactivity than synthetic compounds. Nevertheless, these materials are very challenging to be processed by 3D printing due to technological issues related to their nanometric size. In this work, bone scaffolds with different pore geometries, with a uniform size or with a size gradient, were fabricated by binder jetting 3D printing using a biphasic calcium phosphate (BCP) nanopowder derived from cuttlebones. To do so, the nanopowder was mixed with a glass-ceramic powder with a larger particle size (45-100 µm) in 1:10 weight proportions. Pure AP40mod scaffolds were also printed. The sintered scaffolds were shown to be composed mainly by hydroxyapatite (HA) and wollastonite, with the amount of HA being larger when the nanopowder was added because BCP transforms into HA during sintering at 1150 °C. The addition of bio-derived powder increases the porosity from 60% to 70%, with this indicating that the nanoparticles slow down the glass-ceramic densification. Human mesenchymal stem cells were seeded on the scaffolds to test the bioactivity in vitro. The cells' number and metabolic activity were analyzed after 3, 5 and 10 days of culturing. The cellular behavior was found to be very similar for samples with different pore geometries and compositions. However, while the cell number was constantly increasing, the metabolic activity on the scaffolds with gradient pores and cuttlebone-derived powder decreased over time, which might be a sign of cell differentiation. Generally, all scaffolds promoted fast cell adhesion and proliferation, which were found to penetrate and colonize the 3D porous structure.

Keywords: Hausner ratio; binder jetting; bioactivity; biphasic calcium phosphate; cuttlefish; scaffold geometry.

Grants and funding

This research was funded within the program Departments of Excellence 2018–2022 (DII-UNITN) REGENERA and 3D PRINTING—Italian Ministry of University and Research (MIUR). This research has been funded by REMIX, funded by the European Union’s Horizon 2020 research and innovation programme under the Maria Sklodowska-Curie grant agreement n. 778078.