Hierarchical materials with interconnected pores from capillary suspensions for bone tissue engineering

TL;DR

This study introduces a novel, tunable method combining capillary suspensions and freeze casting to create hierarchically porous alumina and β-TCP scaffolds with controlled pore sizes for bone tissue engineering.

Contribution

It demonstrates a new manufacturing approach for hierarchical porous ceramics using capillary suspensions and freeze casting, with insights into rheological behavior and pore structure control.

Findings

Achieved alumina and β-TCP scaffolds with >60% porosity and controlled pore sizes.

Silica nano-suspensions create stronger networks in alumina, but not in β-TCP.

The method enables straightforward, tunable production of porous scaffolds for bone repair.

Abstract

The increasing demand for bone grafts due to the aging population has opened new opportunities for the manufacture of porous ceramics to assist in bone reconstruction. In our study, we investigate a new, promising method to manufacture hierarchically porous structures in a straightforward, and tuneable way. It consists of combining the novel technology of capillary suspensions, formed by mixing solid particles and two immiscible liquids, one less than 5 vol%, with freeze casting. We have successfully achieved alumina and $\beta$-TCP materials with both <2 $\mu$m and 20-50 $\mu$m as the smallest and largest pore size, respectively. The microstructure exhibits fully open pores and high levels of porosity (>60%). The capillary suspensions' rheological behaviour indicates that silica nano-suspensions as a secondary fluid creates a stronger internal particle network than sucrose for the alumina system. Conversely, the opposite was observed with the $\beta$-TCP system. These differences were attributed to the change in affinity between the secondary fluids and the solid loading. Our study, both systems has served to deepen the knowledge about the new area of capillary suspensions and proves their use in hierarchical porous scaffolds for bone tissue engineering.