Composites of fatty acids and ceramic powders are versatile biomaterials for personalized implants and controlled release of pharmaceuticals

Treating mouse skull defects with 3D‐printed fatty acid and tricalcium phosphate implants

“…The nonsintered fatty acid/TCP material may be ideal for this purpose as we observed that the degradation rate could be tailored by changing the fatty acid tail length, the lauric acid‐based implants degraded within 24 h, whereas the stearic acid implants were undergoing slow resorption after 8 weeks. This confirms in vivo , our previous in vitro observations that fatty acid tail length correlates with degradation rate and drug release rate (Jensen et al, 2018). Scaffolds made from nanoparticles and microparticles of TCP could in principle trigger particle mediated inflammation, but the average particle size of >6 μm used here should be large enough to avoid this effect that is mainly a problem for particles smaller than 3 μm (Kusaka et al, 2014).…”

“…The nonsintered implants were well tolerated. This confirms the findings in our previous studies, where MSCs could grow directly on the implants and where a stearic acid/TCP material was implanted subcutaneously in mice in the form of a granulate, with the subsequent formation of cellular and vascularized bone‐free soft tissue in the granulate (Jensen et al, 2018). A similar tissue was seen to develop in the stearic acid/TCP implants in the present study.…”

“…Nonsintered fatty acid/TCP implants are highly hydrophobic, and this may be the reason. In a previous in vitro study (Jensen et al, 2018), we observed that MSCs took longer to attach, spread out, and achieve their fibroblastic shape on nonsintered stearic acid/TCP implants versus sintered TCP implants. It is well known that surface properties like nanotopography and hydrophilicity can modulate osteogenesis (Feller et al, 2015), and several studies have shown that hydrophilic metal implants promote faster bone formation than hydrophobic metal implants (Gittens et al, 2014).…”

“…The implants have been extensively characterized with SEM, Raman spectroscopy, mechanical testing, and in vitro cell culture previously (Jensen et al, 2018; Slots et al, 2017). But XRD had not been done to study the retention of the beta phase calcium phosphate during 3D printing and sintering nor had shrinkage during sintering been studied, and these analyses were therefore done (Figure 2a–d).…”

“…We recently discovered a new class of bioink that consists of solid particles, such as TCP powder, suspended in a solid fatty acid matrix (Jensen et al, 2018; Slots et al, 2017). When heated above the melting point of the fatty acid, the bioinks melt to become 3D printable by extrusion, even at very high solid loading (60% V/V ).…”