High‐Performance Hydroxyapatite Scaffolds for Bone Tissue Engineering Applications

Abstract

Hydroxyapatite (HA) macrochanneled porous scaffolds were produced by polymer sponge templating method using a reactive submicrometer powder synthesized by hydroxide precipitation sol–gel route. The microstructure of the fine HA powder was carefully investigated and developed in order to optimize the mechanical properties and phase stability of sintered scaffold. The templating method ensured a highly interconnected macrochanneled porous structure with over 500 μm mean pore size and 90% porosity. The high reactivity of the powder led to an efficient sintering mechanism with a high and crack‐free linear shrinkage (19 ± 2%) and a significant BET specific surface area reduction (from 12 to 0.33 m2/g). The powder does not dissociate into secondary phases during sintering. Despite the extreme porosity, the scaffolds had high mechanical performance (compressive strength ∼0.51 MPa, Weibull modulus 4.15) compared with literature data and with scaffolds similarly prepared from high‐quality commercial HA powder.

Sintering of magnesium‐strontium doped hydroxyapatite nanocrystals: Towards the production of 3D biomimetic bone scaffolds

“…In fact, in hydroxyapatite substituted only with magnesium the crystallinity decreases, which is coherent with the distortion of the crystalline lattice as reported in literature (Gervaso et al, 2012;He et al, 2019;Iafisco et al, 2009;Moreira et al, 2016;Scalera et al, 2013;Scalera et al, 2017). It is worth noting that the crystallinity trend seems to follow the secondary phases percentage trend.…”

“…In order to obtain a highly porous scaffold, the sponge replica method was adopted according to our previous works (Gervaso, Scalera, Sanosh, et al, 2012;Scalera, Gervaso, Sanosh, Sannino, & Licciulli, 2013). In order to obtain a highly porous scaffold, the sponge replica method was adopted according to our previous works (Gervaso, Scalera, Sanosh, et al, 2012;Scalera, Gervaso, Sanosh, Sannino, & Licciulli, 2013).…”

“…The dried powders were calcined in air at 900 C for 120 min using an electrical furnace (CF_1600_12, SALENTEC S.r.l., Lecce, Italy), and employing a heating rate of 5 C/min. In order to obtain a highly porous scaffold, the sponge replica method was adopted according to our previous works (Gervaso, Scalera, Sanosh, et al, 2012;Scalera, Gervaso, Sanosh, Sannino, & Licciulli, 2013).…”

Ceramics and ceramic coatings in orthopaedics

“…Furthermore, there are constraints to the complexity and feature sizes that can be addressed with this process. Intricate 3-dimensional scaffolds, with sub-millimeter and hidden internal features are nearly impossible, although creative processing, machining, and bonding techniques have been employed to produce prototypes [633,634] . 18.…”

Biomaterials Obtained by Gelation

“…Sol-gel coating must be made from a sol. Sol-gel HA was, for instance, coated on titanium alloy implants and tested in vivo in rabbits, where they showed an improved osteointegration (Nguyen et al 2004), or onto natural sponge to produce strong porous scaffolds (Gervaso et al 2012). Other sol-gel HA coatings were made on porous BaTiO 3 scaffolds, a piezoelectric ceramic, so as to mimic the piezoelectric properties of collagen (Zarkoob et al 2012).…”