Osteogenesis capability of three-dimensionally printed poly(lactic acid)-halloysite nanotube scaffolds containing strontium ranelate

In this study, three-dimensional (3D) printing of 3D scaffolds containing halloysite nanotubes (HNTs) and strontium ranelate (SrR) as a carrier for the promotion of bone regeneration is investigated. SrR acts as an anabolic bone-forming and anti-catabolic agent, while HNTs act as a carrier of SrR. Poly(lactic acid) (PLA) is used as a biodegradable matrix and carrier for HNTs and SrR. The effects of the SrR addition on the morphological, biological, and in vitro release properties of the scaffolds are evaluated. The morphological results show a homogeneous structure with a proper pore size (approximately 400 μm) suitable for osteogenesis. The contact angle is decreased after the addition of SrR to the scaffold to 67.99°, suitable for cell attachment. X-ray diffraction shows that the SrR is homogenously and molecularly distributed in the PLA matrix and reduces the crystallinity in the prepared scaffolds. The in vitro release results demonstrate that the release profile of the SrR is stable, relatively linear, and continuous within 21 days (504 h). A cumulative release of SrR of approximately 49% is obtained after a controlled release for 504 h (21 days) and a low primary burst release (12%). Human adipose stem cells cultured on the 3D-printed scaffolds demonstrate that the SrR can efficiently promote biocompatibility, alkaline phosphatase activity, and alizarin red staining.