Novel sintering-free scaffolds obtained by additive manufacturing for concurrent bone regeneration and drug delivery: Proof of concept

Advances on the fabrication of sintering-free biphasic calcium phosphate (BCP)/natural polymer composite scaffolds using robocasting as additive manufacturing technique are presented in the present work. Inks with high amounts of BCP powders (45 vol%) containing different HA/β-TCP ratios, in presence of crosslinked polymer, were successfully fine-tuned for extrusion by robocasting. The non-existence of sintering step opened the possibility to obtain drug loaded scaffolds by adding levofloxacin to the extrudable inks. The drug presence induced slightly changes on the rheological behaviour of the inks, more emphasized for the BCP compositions with higher amounts of β-TCP, and consequently, on the microstructure and on the mechanical properties of the final scaffolds. The strong interaction of β-TCP with chitosan difficult the preparation of suitable rheological inks for printing. Drug delivery studies revealed a fast release of levofloxacin with a high burst of drug within the first 30 min. Levofloxacin loaded samples also presented bacteria growth inhibition ability, proving that antibiotic was not degraded during the fabrication process and its bactericidal efficacy was preserved. From the results obtained, the composite scaffolds containing higher amounts of HA (around 80% HA/20% β-TCP) constitute a promising bi-functional synthetic bone substitute for simultaneous local bone regeneration and infection treatments.